Battery Charging in Parallel

same time

If they are connected in parallel, then it's equivalent to being one larger battery with plates 4x the size.

First good answer reading down from the top.......and you are right of course!!! Batteries are individuals and need individual handling, it would be even better at the cell level, but probably impossible to arrange with modern LA Batteries.....

GA.

There are further reasons for individual charging, but you have mentioned enough already.

The OP should have bought a single battery, at least twice as large as one of the actual ones......paralleling needs too much knowledge and extra work....to do properly!

Batteries connected in parallel, have problem when one of the battery shorts inside in some way. Normally battery which has worn off gets disconnected or as good as not being there. If you monitor discharge path then such battery can'y deliver any current.

If you are not charging battery then you are either losing power or have excess current to functional batteries. Watch out?

You are correct about the cells possibly shorting out but this is comparatively rare versus cells going bad in ways that increase the internal resistance of each cell.

There are too many UPS to count that charge their batteries in parallel or series/parallel. They do not have problems that can prevented with a little preventative maintenance. Several examples are 1) for over 20 years I have had two 12 volt batteries in parallel for my work bench for 12v repairs with never any problems (these batteries are ones that I no longer have confidence in for use in my cars or boats (deep cycle for boats). When a battery fails it has always been due to a bad cell with high internal resistance. They are charged either with a 750ma battery monitor or a 7amp charger depending on the current needs. 2) There is a well known communications company site about 1-1/2 miles from me which I have toured several times as a first responder. As standby they have over 2 megawatts-hours of UPS batteries for standby and their engineering staff told me several years ago that they have never had a problem such as you have described. Their main problem is due to cell resistance getting higher. When this happens they take the battery out of service and replace the cell. The company has over 100 years of experience so they must have some knowledge with lead-acid batteries.

As a note they now have 10 megawatts of diesel-generator standby and are currently doubling it. They are tripling the the lead-acid UPS capabilities. As with most facilities of this type they will not answer all questions or are very evasive.

Good Luck, Old Salt

In one mishap battery terminal melted due to poor connection caused by copper acid reaction. As contact resistance increases, contact heats up and passes heat to the cell dielectric as well and cell fluid evaporates rapidly in the first cell of the battery causing the entire battery to become bad.

I think for larger power backup systems, temperature monitoring of each cell in the batteries is very good thing and if cell fluid level is also monitored then this can make sure that all is well with the backup system for a better protection system.

Performance check like charging current and delivery current also to be used for finding the battery condition along with other data then it can make a complete automatic battery monitoring design.

In one mishap battery terminal melted due to poor connection caused by copper acid reaction. As contact resistance increases, contact heats up and passes heat to the cell dielectric as well and cell fluid evaporates rapidly in the first cell of the battery causing the entire battery to become bad.

The heat generated is also dependent upon the current being discharged or charged thru the cell and the ability of the battery case and other components to absorb and radiate this heat. Also as the area of the poor contact increases the resistance of the terminal connection reduces thereby reducing the the current flow through the connection. An example of this is the loss of contact area between an automobile battery and the clamp of the wire failing due to the accumulation of "corrosion", or scum as it is sometimes called. As the corrosion increases the capability to conduct reduces to the point that sufficient current is not available to operate the starter of the car. This is usually indicated by the lights and radio working (low current use therefore the resistance has little effect) but the starter not working since it uses in excess of 100 amps to operated. It is also sometimes indicated by the starter solenoid "clicking" since it can only get enough current when the starter is not attempting to operate.

I do understand your thinking on this problem but its risk is extremely small as compared to the benefits of charging batteries in parallel.

I think for larger power backup systems, temperature monitoring of each cell in the batteries is very good thing and if cell fluid level is also monitored then this can make sure that all is well with the backup system for a better protection system.

Commercial installations of UPS batteries usually utilize "truck" size batteries in parallel or series/parallel. Larger sites use batteries that are have clear bottoms, sides and tops so that the internals can be easily seen. They are placed on numerous shelves and all are connected to a battery monitor. Each cell is not monitored for temperature or internal resistance. If temp. is monitored it is done with a probe on the outside of the clear case for each battery or statistically chosen sample batteries.

For very large installations there are hundreds if not thousands of lead/acid batteries utilized. The monitoring you are recommending would not be cost effective when the risk vs. benefits are investigated. The most effective way to increase the effectiveness of an installation and reduce problems is a very small quantity of the correct preventative maintenance for the system and its uniqueness.

Good Luck, Old Salt

I use Exide INVA

http://www.exideindustrialbatteries.com/pdf/inva_queen500+.pdf

What Lyn said...

Normally it's fine...but use a regular maintenance period to keep an eye out.

You can use a cheap battery minder program to monitor current/voltage for each individual cell, or simply rely on a switchable meter. Temperature for each battery can also be a good indicator of health.

Flir is a good method to do a quick check.

Oh! Bing! Gravity...that's going old school. GA.

Do Batteries connected in Parallel need to be disconnected from each other while being charged? No, charging in parallel is the preferred, and easier method for charging. They will all charge to the same level (if all the cells are good).

When charging the batteries, should the batteries be charged individually or simultaneously as a bank of batteries connected in parallel? Simultaneously will allow all batteries to charge fully if in parallel and a bad cell in one will not hinder the charging of others (such as charging in series will).

With the proper cheap equipment (a voltage meter and some pins to pierce the insulation on the conductors between adjacent cells) it is possible to read the voltage of individual cells which the batteries are being charged. This is in relationship to the voltage of other cells since they have a higher voltage while under charge than they do at no load conditions. This would indicate the potential for a cell to be going bad or is bad already.

Good Luck, Old Salt

Dug, As you've probably found out, the answer to your question is yes.

You mention the age of the batteries as 1.5 years old. In a vehicle, you can get a pretty good idea of the lifespan of the battery at 3-4 years. In your situation, the lifespan will have a few determinants.

1. Lead acid batteries have a set number or charge/discharge cycles. The heavier the lead plates, the more cycles.

2. If a lead acid battery is left discharged for a period of time, the plates become sulfated, which shortens the life of the battery (unless you remove the coating with electrical pulse charging).

3. If you expose the plates to air for too long a time, they will become sulfated.

4. Excess heat damages a battery. Look for bulging cases.

5. People think that cold weather kills a battery. This is not true - heat is the killer.

I hope this helps.

In summary,

Since I am using batteries in parallel to increase the total capacity, then I will charge the batteries in parallel as it is convenient (I don't need to disconnect the set up) and it will allow me to charge the batteries at the same time to the same level of charge using a single charger.

However, as part of a preventative maintenance program (say, once a month) I should disconnect the batteries, clean the battery terminals, check/top up liquid level and charge the batteries individually. This will allow me to monitor the charge and temperature of each battery and perhaps notice when a battery is beginning to fail.

Thanks for all the comments, it was quite a flurry of discussion.

use the hydrometer once a month too.....its the best way

some of these batteries come with float in each cell but they only let you know only the depleted water/acid level and not the density of the water/acid. Fully encapsulated batteries don't let water escape. These do allow water to escape so they require distrilled water filling regularly up to the marked level. See the picture

They will ONLY require regular refilling of water IF regularly charging to 100% capacity or even overcharging...

Those cheap unregulated chargers probably damage more batteries than anything else.......certainly a $10 charger on a $100 battery is not a good idea.....

LA Batteries kept at a max of around 70% of charge (as I do, but the battery is selected to be 30% higher capacity or more larger than generally accepted size for the job), will probably need refilling less than once a year.

In my experience, only gassing loses water. Maybe in Africa the temperatures might accelerate water loss, but not here in Europe where I live, at least not so you would notice....

My caravan battery has been topped up maybe three times in over 10 years if I remember correctly, maybe even only twice.....certainly not more than three times....in spite of summers spent in warmer climates and some hot summers here in Germany.....but it is never allowed direct sunlight and although I have not actually checked the temperature where it is stored. In winter it sits on my special charger cycling between 50 and 70% of capacity, this keeps it fit and prevents freezing.

What would I do if it was too hot anyway, air condition it? No way!! So the temperature is almost immaterial to my mind....In a perfect world I would cool it down, but experience shows no need here....

That is what I have found out about water loss in LA Batteries....its simply up to the user....

By the way, fully sealed LA Batteries have a vent, if due to overcharging or failures in a cell(s) the gas pressure gets too high, they vent off the excess pressure, water and some acid.....otherwise they might explode. They are called "Sealed LA Batteries", but they are not truly "Sealed"!

They cost more but are simply not worth the extra, they must still be in a properly vented area to be safe, the same as other LA batteries.....I never waste money on them.

I have integrated charger within the Inverter Module supplied by Indian company Microtech. It has fast charging and slow charging methods with current control and over charge sensing. Most of these Inverters use over charge sensing mechanism. They also sense load driving capacity of the battery and trip on over load and low battery capacity to retain safe amount of charge for their decision making. These are very effective high quality machine but they come for just $150-$200 range. I use two numbers 4kW capacity 12V 150A batteries that come for about $500. My Inverter has 1.5kW power delivery capacity which can operate 50 CFL lamps, 6 sealing fans, 40cm Sony TV, and 2 computers, 2 Laptops, wireless phone lines, wireless home and car safety alarms. I have a small home with built up area of 3000 sq. ft. Just one Inverter runs for nearly 4-5 years without changing batteries. Two 12V batteries are in series to form 24V input to the Inverter. Batteries are still going strong and I am yet to see any fault. Perhaps some cells may become weak over time and load driving capacity may drop and then Batteries to be changed irrespective of their left over capacity. This is normal practice for me.

Simple charging devices sure not good. Cheap device is not a criteria but functional capability sure is.

Over use or under use of Batteries sure not good.

Not charging Batteries regularly will kill them.

Health of the Batteries to be monitored and sustained by proper regular service.

There are maintenance free Batteries for computer UPS in all computers we use

I have over current trip installed for most of the power lines and there are about 24 such protection device that trip on over current in any instrument to save Inverter and Batteries. Inverter itself has an Over current trip mechanisms. I do not want my house on fire so there are multiple safety trip mechanisms at least double safety level.

How do you know if the batteries are fully charged? Or how do you know if the batteries are only 70% charged?

It would seem that I am inadvertently not fully charging (my bank of 4 of 8D size lead acid batteries connected in parallel that are used to supply 12 VDC power) because I have never need to add water in 1.5 years. Also, I have only rarely got bubbling and a hydrometer reading seems to always show needs charging or fair charge level. The batteries are outdoors (so venting is outdoors), off the ground on a wooden pallet next to the wall of the house but shaded by a rain/snow shelter. The inverter sounds an alarm when the voltage drops below 11 VDC and automatically shuts off if the voltage drops below 10.5 VDC. I then charge at a 50 Amp setting until the voltage is 14 VDC ( I get a high voltage alarm if the voltage goes to 15 VDC). I picked 14 VDC because the solar panel has a controller that shuts off solar charging if the voltage is over 14 VDC so I assumed that must mean 14 VDC is fully charged. I recall reading somewhere that a full charge was 13.2 VDC. The problem here is that if I stop charging a 13.2 VDC then when I shut off the charger the voltage drops 1 VDC to 12.2 VDC so now I am wondering what is the charge of the batteries? As it will depend on whether the charger is on or off when I look at the voltage display.

I drain on the batteries is about 1000 watts with occasional motor start up peak loads of 2500 watts. Even so the batteries only last about 2 or 3 hours to drop voltage from 14 with charger on to 11 VDC alarm with charger off. In the winter, -10 deg C, the batteries only last 1/2 hour although a 50 watt heater put under the batteries raised the battery temperature liquid from 1 deg C to 8 deg C and I then got about 1 hour of battery time in the winter.

I unplug the 120 VAC charger but leave the charger clamps connected to the terminals of the battery so also wonder if there is a phantom discharge through the charger transformer?

The battery charger is a Motormaster Professional Engine Starter Battery Charger with 2 Amp, 30 Amp, 50 Amp and 225 Amp engine start settings. It also has 6 VDC settings that I don't use.

It would seem that the battery bank is only storing 1000 watts x 2 hours = 1000 watts/12 VDC x 2 hours = 167 Amp-Hours

So, am I fully charging the batteries?

Fully charged batteries will show full charge voltage across terminals. 12V Battery can be fully charged when voltage developed is 13.5V and this voltage figure is given by the manufacturer. 24V battery this figure may be 27V. I strictly advice that you refer to the Battery manufacturer's datasheet for this.

If you find that voltage is going very high above 13.5V while charging current is applied then that meant that some cell has become open and can not be charged at all.

Fully charged does not meant that it has same charge as it had when you have purchased it as new one. Fully charged meant that whatever charge battery can be charged, has been charged.

How much charge battery has can be estimated by the momentarily charging estimate process.

The approximate charge level can be easily read with a voltmeter, reading the unloaded voltage across the terminals.

Usually the manufacturer will have graphs of capacity against voltage for his products, or you can look here:-

http://www.scubaengineer.com/documents/lead_acid_battery_charging_graphs.pdf

Here it is called the SOC or State Of Charge.

14 volts is quite reasonable and will give you around 80-85% capacity, not overly stressing the battery or gassing it. Well done.

It is also just before the steep slope of inefficiency......

The accuracy of your voltmeter is paramount, some cheap ones can be well off and mislead you....

Andy Germany:
This parameter fully charged voltage initially to be taken at 13.5V for new batteries else they may get over charged and may also explode in some cases if excess heat is generated under fast charging schemes.

Once batteries are used up for about 2 years, you may go up to 14V charging level easily as by that time batteries develop greater internal resistance and their charge storage and charge delivery fall to about 80% level.

Over 4-5 years only greater thickness of Lead in Battery and Generally Tubular type do survive but have nearly 50% of their charge storage capacity and thin Lead sheet type may become functionally useless. I have seen some Batteries becoming dead in about 2 years on an average life time and these are generally used in UPS. It all depends on how these Batteries are internally designed and how much material is used in them. Batteries used in communication towers are generally of longer life. I do not know their actual usable life but they may run above 6 years I suppose.

It is nice that you have added this reference for charging graph. Also notice that Temperature also plays a role. One of our Battery exploded once and perhaps due to heat and trapped gases. As now I use these Batteries with some opening to let pressure remain at atmospheric pressure level, they are not developing pressure to explode.

You have a plus point here.

I liked your post.

I have never had a battery explode myself (probably more by luck than judgement I have to admit many years ago!), but I have seen photos of the damage that:-

a) the explosion itself can cause to Battery cabinets

b) what the acid did to surrounding electronic equipment in a US Radio Station.

Many thousands of $$$$ of damage for what was a relatively cheap battery, maybe too cheap.

Renault bought cheap Turkish batteries for many of its cars some years ago (6 or 7 if I remember correctly), they leaked acid when charging from the alternator while driving, probably due to overfilling, but I never saw an official reason given.

That is nothing to what the acid did to some models due to the fact that the battery box had been placed right over important parts of the chassis members, the cars had to be junked, some less than 2 years old...

Where proper acid resistant paint and an overflow tube, costing maybe a Dollar in production, would have spared them millions of $$$$$$s.

I looked around on the web and was unable to find more details or a web link for that problem, though what I did find convinced me (- further, I hate French cars!) that Renault will never ever be one of my cars again after seeing their problems, any of them!!

Andy Germany:
Yes, this was a unique event when Battery Exploded and spilled Acid all over and there were fumes as Acid reacted with whatever came in contact. Battery supplier was handling the Battery was actually taking back for replacement and then one of the two Batteries exploded.

I now make sure that Batteries are kept in ventilated area where fumes can't enter the enclosed area and can be cleaned easily. Event did not repeat so far but it has helped in keeping the Acid fumes out from our lungs.

Battery explosion is not anything new now Even Laptop Batteries can explode right on your Lap. Once you see such explosion then such experience is worth remembering for life.

I am more keen in water based batteries. I think it will be great if we discuss all that somewhere on CR4. I have one such Battery used in RadioSonde for weather data transmission - Balloon Experiments. Picture Reference http://www.dwd.de/bvbw/appmanager/bvbw/dwdwwwDesktop?_nfpb=true&_pageLabel=_dwdwww_spezielle_nutzer_internationaleprojekte_gruan&T166401147011228224855496gsbDocumentPath=Navigation%252FProjekte%252FGruan%252FConception%252FCampaigns%252Fcampaign__luami__node.html__nnn%253Dtrue&switchLang=en

Make sure that all batteries are equally functional and all terminals are cleaned and tightly connected with no heat developing on terminal connection. Maintain acid level in all cells and do not spill it out. Don't fill dirty water from tap having minerals. Density floats are to be watched out for acid level and its density regularly. I am using tubular lead acid type having float in each cell. They have already run 4.5 years now and still working.

There are PM items to be performed cell by cell.

If they are OK, you can charge prallel.

Until the next PM.

Charging in parallel CAN work, we all know that.

But few here appear to understand the possible pitfalls fully.

It is simply not a good idea.

A battery with the same capacity as the two paralleled together is the best in most situations.

Only if you are just "using up" a pair of older batteries AND you accept and fully understand the possible problems, then its OK, otherwise not.

Though as even older batteries with all cells still working, can deliver a good amount of energy, I still wonder why anyone needs to run/charge them in parallel with the possible problems aused.....?

I personally would have one battery on a (quality) charger and use the other and swap them over when needed!!! Never a need to use in parallel......and always a full one available.

Just because UPS companies, who often show a complete lack of understanding of ANY Battery type, except that liability is not theirs once the guarantee is gone, do this...It cannot be taken as a recommendation.

With all due respect to you and all other contributors: Parallel combining batteries is not perfect but it sure is better than trying to use them in series!

In series, if a cell goes bad it shuts down the whole battery string. In parallel, unless it is a complete short across one cell it will "keep on running". Even then the lower voltage of that battery will be mostly be compensated by the other batteries until the bad battery/cell is repaired/replaced. In order to do this repair, unless the system is at its capacity current wise, it is simply a task of disconnecting the battery from the parallel bank of batteries. With a series arrangement the whole string must be disconnected therefore shutting down that whole bank of batteries with the subsequent temporary loss of that bank of batteries, usually not a good thing.

Batteries of different age and capacity are used daily on many installations. Large UPS installations replace battery/cells on a daily basis therefore having many cells/batteries of different ages.

As for Just because UPS companies, who often show a complete lack of understanding of ANY Battery type, except that liability is not theirs once the guarantee is gone, do this...It cannot be taken as a recommendation. There are many reputable and honest UPS manufacturers, sellers and service organizations around that this is seldom a problem. They are honest because to conduct business in a dishonest manner means that they will be out of business very quickly. The telecommunications company I previously cited has been using UPS systems for longer than I have been alive and I'm now retired. They are probably the largest telephone service corp in the world. Personally I trust there knowledge on the subject a lot more than I trust mine and many other people!

Just a short list of items that use parallel batteries includes: olmost all diesel trucks and tractors (Kenworth, Freightliner, Peterbuilt, Mercedes, Ford, GMC, Western, almost all diesel powered fire trucks, etc.) UPS systems, portable and stationary generators, portable and stationary standby pumps, large portable welders, solar powered signs and battery storage solar energy systems to name a few of many more. They can't all be wrong!

Has anyone consulted with the battery manufacturers before they contributed to this forum? What do they say?

Based on industries many years of experience I would take a parallel battery system over a series system if the output voltage and current capacity both meet the usage. I have experienced the pitfalls of both systems and know what I would want- parallel!

Good Luck, Old Salt

On the very right track!

Shyam-

THANK YOU!

Good Luck, Old Salt

Comparing batteries (not cells I believe you meant) in parallel and series is like comparing chalk and cheese.....it demonstrates a deep misunderstanding of the possible problems.

Either you need 12 volts or 24 or 36.......but comparing 12 volts with say 24 volts (parallel against series ) is simply laughable.....what you need for a voltage is what you must make available.

By the way, I never mentioned series connection, I compared parallel connected batteries with non parallel.... please look back at my post and read MUCH more carefully.....

Sometimes cells go open circuit on LA Batteries, sometimes they go short circuit.....I hope that you are not around if one of your parallel batteries gets an internal short !!

It can get quite interesting as one battery starts discharging through the other.....It can get quite hot depending upon charge level and charge differences......at least the series connected ones (a normal battery is series connected internally by the way!) only lose a few volts per bad cell when a short occurs!!

Loss of a cell open circuit makes its effects easily apparent - no or low volts.

It usually happens to older batteries....like the ones you apparently use...

Quoting from Wikipedia:-

One of the problems with the plates is that the plates increase in size as the active material absorbs sulfate from the acid during discharge, and decrease as they give up the sulfate during charging. This causes the plates to gradually shed the paste. It is important that there is room underneath the plates to catch this shed material. If it reaches the plates, the cell short-circuits.

So you are still at the mercy of an open circuit cell even when two batteries are in parallel, but you would probably not notice till the both batteries are "empty ", usually far quicker than normal......so no real plus points....

You end up with one battery to junk and the other empty and needing a full charge.....where is the plus you appear to find?

Keeping them separate allows you to always have one fully charged ready for use, and it does not matter too much if the one in use gets a short or an open, you just replace it....

Please be so kind as to explain to us all the "real" plus points of parallel lead acid batteries, I cannot see any REAL pluses! Just a few imagined ones!!

If what you are looking for is my withdrawal from this forum based solely on you opinion, you have it! I don't have the time to argue the few, seldom and rare instances where a series set of batteries are better than parallel. No, I don't have a deep misunderstanding of the problems, what I do have is the knowledge of what works and is accepted world wide. Also, Wikipedia is not the ultimate authority for things such as this, it is only the opinion of one or more persons.

What I do have though are a few scars on my arm where a person was trying to work on a series set-up of batteries while in use because the power was needed. After the whole set-up exploded spraying acid all over the place he needed instant aid (he got it into his eyes and about 50% of his body). Although another guy and I were only passing by we donned rubber gloves and aprons and pulled the guy out and to a safety shower/eye wash. Unfortunately I was more concerned with his life than my own injuries so I got some burns. Shame on me for damning series batteries setups. Never had the same problem with parallel setups. I'll take 12 volts over 6 + 6 volts!

As to laughable, what about 6 volt batteries in series and these sets in parallel to provide 12 volts. This arrangement is a popular set-up for diesel trucks, but minor compared to the parallel 12 volt set-up. I guess those trucks are laughable!

Correct you did not mention parallel, but I did in my explanation. Does that wipe out the validity of my whole posting?

Yes, things can get quite hot if the seldom internal short does occur but that's why almost all parallel set-ups use a fuse or circuit breaker (just as series set-ups should) when this could occur and cause secondary problems.

No I don't apparently use old batteries, I use what I have available. Right now I am using a 3 year old deep cycle 12 volt salvaged from a boat that was destroyed in hurricane Sandy (a house was blown over the boat while it was on a trailer) and a 2 year old 12 volt battery from my lawn tractor. If they still work I still keep on using them! Just like me they still have a few good volts left in them, why send them out to the grave yard?

Don't have the time, nor the inclination to waste my time with: Please be so kind as to explain to us all the "real" plus points of parallel lead acid batteries, I cannot see any REAL pluses! Just a few imagined ones!! Please refer to my previous posting for a list of the plus points. Unless you think that almost the whole world is wrong and you are right. Me, I just try to enjoy life to its fullest and if I think I am right and the rest of the world is wrong I don't try to make them believe me.

Oh, by the way, that telecommunications giant I mentioned previously, they probably handled that last text message or picture you sent on your phone. They and their parallel UPS system handles approx. 90% of them world wide.

Good Luck, Old Salt

You are still laughable when you write:-

As to laughable, what about 6 volt batteries in series and these sets in parallel to provide 12 volts. This arrangement is a popular set-up for diesel trucks, but minor compared to the parallel 12 volt set-up. I guess those trucks are laughable!

That you obviously do not understand why is a further problem.....

What is needed for a truck for a few years of service is one thing, but what is good for many years is something else......that you don't properly understand, but you base your whole understanding on is error...

Car(truck) batteries do not last as long as they should, is 100% due to the way car batteries are used/charged. Nothing more. Nothing less.

Many do not understand that.....you are obviously one and the same.

I can help you to achieve a) Battery long life and b) not to damage any battery. But do you want to learn something new, no!!

You remain with your old wrong assumptions.....that is your problem.....not mine.

The only thing laughable is your deviation from the original post and your totally senseless insinuation about someone else's intelligence or knowledge of a subject as diverse as the whole spectrum relevant to lead acid batteries! Your insistence on bringing up tangential replies to the original subject or postings from people who are trying to impart their knowledge for the originator's use is deplorable, sickening and a total waste of time for the others involved (sometimes called "looking for pepper on a gnat's as_!)

The original post was:

Do Batteries connected in Parallel need to be disconnected from each other while being charged?

I have 4 of 8D size lead acid batteries connected in parallel that are used to supply 12 VDC power to a 3000 watt inverter to supply off the grid 120 VAC household power. The batteries are about 1.5 years old.

The batteries are charged by solar panels or by a small gas powered generator.

When charging the batteries, should the batteries be charged individually or simultaneously as a bank of batteries connected in parallel?

I see no relevance between your most recent posting, or most of them for that matter, and the original question. As for your replies to my postings the are the laughable submissions you have tried to take one minuscule things about them and tried to expand them to where you infer that only you and your gibberish could ever be correct! Apparently you have a lot to learn about the application and communication of scientific and engineering research, development and application. NO I make no assumption, as you do, to be the ultimate authority on all things. Many readers of your comments in the past have been given that impression!

As I stated in my last posting concerning the age of the batteries that I use for my work bench: If they still work I still keep on using them! Just like me they still have a few good volts left in them, why send them out to the grave yard? I make no claim as be the world's smartest in everything as you infer to be. What I do claim to be is someone who is smart enough and knows enough about some things to know that there are a lot of things that I want to learn and there are many things that I do not know. The "do not knows" for me are the majority and I readily admit it!

As I previously stated: If what you are looking for is my withdrawal from this forum based solely on you opinion, you have it! I have no desire to joust with you and your tangential irrelevance concerning minuscule properties using what you conceive to be major factors. I say, as do others, off the soap box and back to reality.

Oh, by the way, I am a volunteer fireman and just got back from a fire where I was driving/operating an engine which has batteries that are over 12 years old. The tender has batteries that are 8 years old. Why so long? Because I give them some TLC and do about 5 minutes of PM on a monthly basis with the right tools and materials! My knowledge about Lead-acid batteries also helps but I am not the world's authority on them. I am at least smart enough to keep things going good. With about 5-10 minutes I or many others can train even you what needs to be done and how to do it.

Next time you are looking for pepper on a gnat's as_ please skip over my postings. I don't have the time or inclination to waste on your jousting with windmills.

Old Salt

Nothing that you have or can post will change my opinion on the subject. Please try basing your arguments on facts that you can support with say Weblinks or similar, that way your comments will have far more value. You will find many talking about paralleling batteries, most of them with no warnings or safety reminders at all....

Also, several web pages support the comments that I have made fully, I quoted one source, you appear to either have not read the quote or not wanted to understand it. Only you know which....

I have posted more today to try and educate you further.

Here is a video, probably from the Motor/Truck world, where paralleling is sometimes done, as we both agree on. Listen to the final comment from the two Gentlemen, it should make alarm bells ring with in your head with your own system as you have portrayed it on this blog!!! Exactly as I have been trying to get across to you....

http://www.youtube.com/watch?v=bfvLcTxgvzo

One can do many things that are intrinsically dangerous and/or wrong, and get away with it for many years. That does not mean it is safe to do.....

Even driving on the LH side of the road in the USA will not automatically cause an accident, though if a vehicle coming towards you arrives at high speed on that side, there could be a problem!

Many people do as such every day of the year, they take risks either though a love of danger, or through ignorance......

You can charge and use batteries in parallel and be lucky....for years and years possibly, but if they are not identical in every way such as age, type, manufacturer and even charge state, you could still cause an accident......and even if they are identical, one could develope a serious problem and the accident happens anyway...

Many forget that in a battery, every cell is an individual. Every cell really needs a different charge rate and time. Some are "full" early, some are "full" much later, some are weaker and some are stronger.

What I do with the LA Battery chargers I build is to never ever discharge the battery completely, as always, at least one cell (the weakest) will be reverse biased. This makes it even weaker, till that cell is so damaged, the battery is then useless, even though all the other cells are still good!!!

I also never fully charge any LA battery (usually only to about 13.0 to 13.2 volts which equates to around 70% of capacity. This is the "sweet spot" for efficiency as well by the way), as some will be full early and will gas if charging to 100%, losing water and changing the strength of the acid in that cell till its topped up again. That cell will be one of the candidates for the weakest cell shortly and start to degrade fast....

By fast, I mean instead of achieving 10 years or more of useful life, probably 2 years or less.

Have you ever seen or heard of what can happen to a (any) gassing battery? Say one with a shorted cell being fed from a good one?

Here is a picture of one taken from a Wiki article:-

The power of the explosion has not only wrecked that casing, but may have cause injury to anyone nearby. Acid spraying into eyes can cause a complete loss of sight....It happens every year at a battery near you (and me!)

Car battery life is shortened due to both its construction and the way it gets used.....everyone is aware of that problem I believe...they often fail at 2 years in some makes of car, but live for 5 years in some others. Due to charging to slightly different levels and battery quality of course.

Here is an "instructable" about parallel charging/usage that is sadly very badly written from someone who knows enough to be dangerous, basically he says what you say, with no qualification of how it needs to be done, and no warnings of any dangers, he does not even state the chemistry being used I believe:-

http://www.instructables.com/id/How-to-Wire-Batteries-in-Series-or-in-Parallel/

Read the replies that have been sent to him, the writers knew exactly what was wrong.....but has he changed his article to reflect those warnings? Of course not. He is stuck on being right!!!

There are many people on the web who do not understand the inherent dangers and pitfalls. They does not make them correct in any way.

I particularly liked the first reply to the following web link on parallel charging, he was dead right. Some others are good too. See them here:-

http://www.beesource.com/forums/showthread.php?267885-charging-12V-batteries-in-parallel

and here for some humorous videos that will make you laugh (but little to do with batteries!):-

http://www.allboating.com/

Don't get yourself into a tizzy...

You have to understand how Andy works. First off, assume that everything he says is right (like he does). Then, accept it as gospel (because he likes to preach). Finally, do what is right (which may very well be his stance, as well).

Nothin' but love!

P.S. If anyone wants to see a real cool series/parallel lead-acid battery arrangement for one of my 500KVA UPS's, come on over.

You're only jealous!!!

You know it!

1,. The argument is moot, until the basics are examined.

2,. In a long string an open can ruin your day, a short not so much.

3,. In a parallel array, a short can do a bad display, while an open is no big deal.

4,. I do strongly doubt, that any of you have the equipment, nor the mental setup for a scheduled PM.

That is my long sum on the debate.

If you have 24-V Inverter and 12-V batteries then only choice is to use them in series. If your batteries have 150A current and your Inverter needs 300A to run then you need to use the batteries in parallel.

You also use series and parallel both combinations in single system if you need both larger voltage and larger current.

All this talk makes little sense as this is a practical sense and all people just do that irrespective of the pit falls.

You are so right with your comment of:-

All this talk makes little sense as this is a practical sense and all people just do that irrespective of the pit falls.

Its like one of my favorite sayings:-

"You can lead a horse to water, but you can't make it drink"

"You can lead a horse to water, but you can't make it drink"

Horse may drink or may not drink but that dirty water may sure affect you if you drink it is what often house conveys to us but we often forcefully want horse to somehow drink it. If you drink along with horse then also horse may not drink it. Horse may use its senses after all they are here for millions of years. Technology is so young that human being are utter confused about it. Even those we call engineers keep debating right and wrong and are yet undecided and finally follow some simple rules called common sense.

you guys definitely beat that one to death

AT LAST!!!

LOL!!!

Wait! What about series parallel? Or Parallel series? And what if the ambient outside temperature reaches over 105 farenheit?

Hmmm???

Do you have a choice?

You can increase voltage using two in series which is easily feasible or boost voltage using DC-DC converter which is not feasible. Perhaps you can change your DC to AC converter / Inverter to meet the battery voltage rating.

If you need more current then what your battery can give, you need to put them in parallel. Question is, will they work? Yes, they do work as long as they have same voltage and all fully charged and they don't start wasting each other's current.

You can then use in series and then in parallel.

Note: This posting is not addressed to any single individual! It is an expression of what many participants consider to be good manners and effective communications.

Yes! You are very correct in that! Originally this type of forum was intended to have a person post a question (whether they knew the answer or not) asking for help from the other members of the group. It was intended that there would be no references to the intelligence of anyone because that doesn't help resolve the question, only agitate people and waste many other's time. Give a short, concise and easily understood answer, simply that and no more than that. This is a guideline that all of the members should follow.

One short fall about this and many other forums is that as the person with the question you can not easily determine which answer is the correct one or most applicable one. Also you don't know the contributors background or relative knowledge of the subject unless you as the questioner already knows the answer. Answer the originator's question and only supply supplemental information if absolutely necessary. Many of us make our answers confusing by deviating from the original question and cloud the answer with what we think the questioner should know about other things that usually only the answerer thinks are important.

Albert Einstein knew that he didn't know everything about everything. We should follow his example. Stick to the things that you know about and let others more knowledgeable handle the other subjects.

Do not ever attack the intelligence of another person. This is a subject that you really don't know about and only lowers the respect for you. This is an item that I need to work on with my replies when someone, who know nothing about me, has blatantly questioned my intelligence and insulted the time that I have spent learning about a subject. I do admire contributors who give intelligent and clear answers. Unless I can do this with any potential reply from me I don't reply.

I spent a lot of time and effort to become intelligent on the subjects I am proficient in just as many of us have. If you want a verbal joust with me please try elsewhere. If you are persistent you may become sorry that you started it, just as many other will do to you. Verbal jousting is often an indication that you have the knowledge but don't know how to effectively communicate it. What good is science and engineering if we can't communicate it to others? There are other provisions within this forum to send a private message to another individual, if you are so pis_ed off at someone that you feel it necessary to contact that individual do it via the private message system.

Don't depend upon the spell checker of the forum. It isn't the best. Try to watch the grammar and composition which for some of us, myself leading the pack, wasn't our forte in school.

Please no attacks about this message. If you agree and like it let me know. If you don't like it, don't let me know and simply use your "delete" key to express your opinion.

Thank you all for the time you spent reading this!

Good Luck, Old Salt

Considering that you have about a 15% GA rating, I would say that a lot of the stuff that your fingers spell out is usually intelligent and likely correct.

Thank you! It's nice to get an Ata-boy once in a while. As with probably you also, it takes a lot of time and hard work to get to know any subject good let alone be a master at it.

Good Luck, Old Salt

<...The batteries are charged by solar panels...>

That process is probably continuous, meaning that parallel charging is already within the observational domain.

What does the installer's Operation and Maintenance Manual say?

If they were <...disconnected from each other while being charged...>, then they wouldn't be <...connected in Parallel...>.