Multiple Chargers for Batteries

You need a diode capable of carrying the 20A (plus surge) in series with the output of each source to prevent the higher-voltage source from feeding backwards into the lower-voltage source (and damaging one or both). They will seldom be exactly the same voltage. You will lose a fraction of a volt (the exact amount depends on the diodes used) from each source.

Since the two 20A sources only total 40A, you are well within the limits of the charge controller.

Good post.

If possible, he should check carefully to see if such blocking diodes are already part of each unit or not, (to my mind they should be part of any properly designed solar/water generator system), but only a proper examination will tell for certain.

Even if only one unit has it already, he only needs to add a diode (correctly orientated of course) to the other (unfitted) particular unit.

Not having "double" diodes will slightly improve battery charging from that unit.

If he cannot be 101% certain that they are already fitted, then he should fit them anyway, exactly as you yourself said.....no chances to be taken....safety first.

Thank you for your help , next week when i am back in my finca i will check about the diodes.

I have an almost identical system as yours and it has an IOTA charger connected at all times. The OutBack MX60 charge controller takes care of the solar panels at night time so you dont have to worry about any power draining backwards from your batteries. You didn't mention how you power your charger. I will assume it runs from an AC source such as a generator or grid. You didn´t mention how your water power charges the batteries so I will assume its a DC turbine and is connected directly to the battery bank. This means you have 3 power sources, solar, water, and grid or generator. Is this correct? The turbine power probably has a controller so reverse drain is probably no problem. If you supply more information the answers will be better.

In my case I get power from the solar array via the OutBack MX60 controller or the grid via the IOTA charger and both are always connected to the battery bank.

My system operates at 12volts instead of 48volts which you have. I set up the OutBack charge controller to a voltage slightly higher than the IOTA charger so that during sunny periods the panels are doing the charging and the IOTA charger is "sleeping". If it is cloudy or its at night time and the battery voltage begins to decline then the IOTA charger takes over to keep the batteries full.

I also have, as an option, a relay which is controlled by the AUX output from the OutBack charge controller and this relay will connect or disconnect grid power to the IOTA charger depending on the voltage of the battery bank. We use this if we are away from the house for long periods. It will lower the power consumed by the IOTA charger being plugged in all the time.

So, in resume, I would say yes you can leave the charger and solar system via the OutBack controller connected all the time or use a relay as mentioned above.

The waterpower is a ac generator i build the whole system little by little myself. The ac power 110 v goes into a charger that produces 48 v and 20 amps. I will check about setting the outback charger a little higher than the 110 v charger. Thank you very much for the help. Sometimes it can be difficult doing everything yourself without beeing an electrician, thank you

OK, I now understand what kind of power you are producing with the water turbine. Since you are not paying for grid power this setting is not important however I would try to have both the charger voltage and the OutBack voltage as close to each other as possible so during a sunny day when you also have water power both will be contributing equal amounts. You can program the OutBack quite easily however there are different voltages in the OutBack charging system. There is an Absorption Voltage, an Equalize Voltage and a Float Voltage so it gets a bit more complicated to make these settings. You must also know the type of battery you are using and the average temperature if you want to do a precision set up.

What kind of batteries are you using? What is the temperature (average) and what type of charger are you using on the water turbine circuit? If it is a comercial charger then leaving it connected all the time might be OK but if its a home made one then the diodes suggested earlier might be important.

Good luck.

John

Hi john I am using wet batteries. The average temperature is about 22 defrees centigrade all year round. Yes i do have a comercial charger. Both chargers are in the same room as the batteries. I have seen the adjustments on my outback equalize float and absorption voltage but if never touched it. Before i had a 12 volt system then i changed to 48 volt. The outback did change almost evrything by itself. Thanks a lot again

I loved the misspelling "22 defrees", almost "defrost" which 22°C is, but which 22°F isn't! You don't mention where you live either.....

You neglected to mention which "degree" you meant and there is a world of difference!!!

By the way, do you have "positive" air renewal (assuming your "wet" batteries are freely venting in your battery room? You didn't say....) as Browns Gas has killed more than a few over the years since the invention of LA Batteries and blinded a lot more!!!

Even today there are regular accidents caused by a cigarette or simple static spark......see Wiki for full details and some worrying pictures....

Not to mention the damage caused to the surroundings of explosion and sprayed sulphuric acid!!!

Such a battery room must be forced "purged" before using unsealed (gas tight) light switches or other electrical equipment due to the dangers of the gas that can collect......especially when exceeding around 70% charge capacity of any single battery, though this point does also depend on charge rate as well......

A good method is to have all switches "outside" the room where the batteries are stored, where no gas can get to them.....

See here for a Potted history of Browns Gas (also called HHO or Oxyhydrogen):-

Browns_gas

Also here for general information on such batteries:-

Lead_acid_battery

Pictures to ponder - OW!! :-

Hi andy , I meant 22 C . I do not care much about spelling . I live in cost rica. My battery room is totally open lots of air circulating, no ceiling , the roof is about 6 m high and air circulating underneath. After reading your comments i got nervous since all the equipment ,fuses, transformers ,...., is directly on a wall above the batteries. Batteries are 50 cm above ground, equipment about 1m above them but as i said very open. Thank you for your help.

Juergen-

The conditions of the battery environment you have are very good. The air circulating is the most important component of the safety factor. The Hydrogen given off by the batteries is not an instantaneous rush of high concentration vapors but a slow dissipation which readily mixes with air and then separates itself from the air due to its much lighter molecular weight, Remember the Hindenburg?

A very good comparison of your situation and the real world is to compare it to some automobiles, at least some in the USA. When a batter4y charger is used without the engine running and the hood closed the hydrogen must go down before it can go up. No problem there. Even more dramatic is the cars that have their batteries in the trunk, covered over with the floor panel alongside the spare tire "donut". A good example is a 2002 Lincoln LS. The trunk lid is closed at all times while driving or parked with no air circulation at all. Compare that with what you have.

For example, I have two size 27 deep cycle batteries under my workbench for working with 12v and 24v things. I have tested them for Hydrogen discharge while charging with a LEL Meter and it hardly makes the digits change. Other than within a couple of inches the concentration is slight and well below the LEL Further away (6" or more) there is no reading.

The whole thing is relative. Relative to what? If you hold a match to a battery cap in a slowly ventilated area there will seldom be any problems. Hold it within the cell of the battery and you probably will get a puff of flame. It certainly isn't like the old diesel/electric submarines with their huge battery banks of batteries.

Good Luck, Old Salt

OK. The 22°C is not too bad. Most battery manufacturers like to keep thier batteries at around 25°C and the recommended voltages are for 25°C. When you have large differences in temperature the voltage settings must be adjusted. Here, where I live, its around 29 to 34°C so I lower the voltage (.003 Volts Per Cell, for each degree above 25°C, for my Liberty Batteries).

With your comercial charger and the OutBack MX60 I´m pretty sure you can leave everything connected all the time. Try adjusting the Float Voltage of the OutBack so it is the same as your charger since that is where the system will spend most of its time. The OutBack probably has the Float set for around 54.4Vdc if you haven´t touched it so leave it there unless it gets really cold.

Yes, Andy is correct. Be very careful regarding accumulated explosive gases and sparks. Keep your battery room well ventilated. In my opinion the battery room should only have batteries (if Wet Type are used) and your other equipment should be in another room. In my case I use sealed batteries so they are in the same room as my equipment.

Good luck

John

Thank you john It never gets cold so i think i leave the float. I only just finished the installation. It would be easier to move the battery bank but even if i moved them to the next room it would be the same open air ventilation. I put them in a barn, everything is wide open . My only concern is, as you can see in the note i wrote earlier is the close distance, about 1 m above the batteries. Once i get back i will try to send a foto, once i find out how to do that.

It is thought that about 12,000 accidents happen per year in the USA for example with LA Batteries. (Search with Google.....)

It is unlikely that your well ventilated area will cause problems, but do not forget the gas problem, it is still there. Only reduced.....no lights, cigarettes, naked flames etc etc..

Furthermore many accidents simply involve contact with the acid, not exploding gas necessarily.... Acid in the eye, with no fresh water to hand, you may lose your sight. Look how easy this accident happened for example:-

Accident with Battery Acid

Be careful and live safe. Have all the necessary safety equipment to hand AND USE THEM!!

DO NOT LET ANYONE KID YOU THAT ITS NOT A PROBLEM!!

Make it unlikely with good safety procedures....

Andy Germany-

Please provide citations of your source of the 12,000 accidents happening per year. The only Google link mentioning 12,000 is

http://www.eri-safety.com/Documents/8917lg.pdf

And those are total accidents, not accidents from this type of equipment set ups. Of the 12,000 annually, other sites state that many of the accidents occurring yearly are from untrained personnel jump-starting cars/trucks. Also lumped in there are such things as people dropping batteries on their feet and other irrelevant situations. Also a web site for a producer of safety based training materials

http://www.eri-safety.com

might tend to exaggerate about difficult to substantiate statistics. If posting statistics on a subject it would be appropriate to provide citations of the source, just as I have. This would be in line with one of your most frequently demanded items from other contributors.

It would also be appropriate to use relevant statistics and not grouped statistics. Would it be fair to list the annual sinking's of ships based on the accident rate for all floating objects? These would include recreational boats from row boats and canoes up to commercial ships in excess of 1,000ft? The definition of a boat is a vessel that can be carried by another vessel. A ship is the vessel that is capable of carrying the boat.

Good Luck, Old Salt

Andy Germany-

My original posting to you was not a personal attack on you, such as your reply is on me. I simply requested citations of the data that you had posted because the 12,000 accidents you mentioned was all accidents and not just accidents relevant to this type of utilization and use. Also the figure was given by a reasonably biased source that had a profit interest in giving unsubstantiated high figures. No personal attack, just a request for the site/link.

As for your picture of the deceased battery, please provide further documented information on this unit. Pictures many say a thousand words but please provide some additional applicable information concerning the failure of the battery pictured. There are many other scenarios that could have caused its failure. One prominent cause could have been the overcharging of it causing the shell to expand and deform non-explosively. Remember Andy, just asking for more information including citations/links as you frequently request/demand.

As for the projection of imminent doom because of the closeness of the OP's batteries to other apparatus, I still state that the set-up is good. He stated: I live in cost rica. My battery room is totally open lots of air circulating, no ceiling, the roof is about 6 m high and air circulating underneath. After reading your comments i got nervous since all the equipment ,fuses, transformers is directly on a wall above the batteries. Batteries are 50 cm above ground, equipment about 1m above them but as i said very open. "Totally open lots of air circulating, no ceiling, the roof is 6m high and air circulating underneath, ……batteries 50cm above ground, equipment about 1m above them and ……very open" are extremely good for a gas that has a LEL of 4.0%, much higher than many other flammable gasses that are not treated with the same cautions. The conditions the OP is describing are much better than the most common use of KA batteries, in vehicles. It is also exceeding better than a vehicle battery located in the trunk. What about a truck with a 300amp alternator charging batteries in an almost completely sealed battery box?

The middle of your posting is complete gibberish making completely untrue statements about someone else who you do not know the slightest about and only want to project him as a "thoughtless, even stupid" technical idiot just as you do for most other members of CR4. Andy, that's your style not mine. If you want to contribute, do it in a realistic technical manner, not by attacking others if they don't agree with you 110%. Instead of elevating oneself, it tends to show a lack of technical interest and substituting personal attacks for realistic technical replies.

As for your citation of the Dept. Of Energy publication, it appears to be irrelevant to the situation listed by the OP except for: "Precautions must be routinely practiced to prevent explosions from ignition of the flammable gas mixture of hydrogen and oxygen formed during overcharge of lead-acid cells…….With good air circulation around a battery, hydrogen accumulation is normally not a problem. However, if relatively large batteries are confined in small rooms, exhaust fans should be installed to vent the room constantly or to be turned on automatically when hydrogen accumulation exceeds 20% of the LEL." You stated "Do concentrate on the chapter "Precautions"; it follows exactly my personal take on the subject of LA Batteries, as well as being US Government approved". Perhaps a rereading is appropriate since the only applicable section to the OP is what is listed above.

One last comment- One of the largest wireless communications corporations uses a variety of electric energy sources to assure no loss of power. One site in particular has the capability of bringing in excess of 20MegaWatts of power from the public utility. It also has in excess of 12 MW of in-house diesel/generator capabilities. Finish it off with in-excess of 3 MW of LA battery based UPS. Why don't they treat it with the doom and gloom that is being projected? They use ventilated rooms to store all those batteries in and that's a lot of batteries!

Andy- keep the personal attack crap to yourself! Most others don't care to see it, read it, think about it or be associated with it. Please do not bother with any more of it directed to me or any others. Come up with some technical information to contribute, not a demonstration of failure to be able to communicate with others in a reasonable manner.

Also the expression is "If the shoe fits, wear it"

As stated above, cut out the crap!

Good Luck, Old Salt

Andy Germany-

Thank you for all the complements. It is amazing how an engineer versed in all aspects of each discipline of the profession could also be so well informed in the field of forensic psychotherapy! Simply amazing!

On the same track as always demanding citations and sites, Google this one: NARCISSISTIC. No, it doesn't apply to me. You have found so many things wrong with me I couldn't be narcissistic. Perhaps it is in that "hat that fits you and you wear"

Again, thank you so much for abandoning me. I'm so happy now I might soil my pants!

Good Luck, Old Salt