1000 Watts Inverter

Hello I run both a 600 W 220 V AC out 24 V DC in and a 1500 W version the first is a pure sign wave unit the second a square wave type. The batteries are the major cost factor. I went for 24V DC to keep the current down to a manageable level. At 12V in it is just far too high. I was going to build my own but it would have cost twice as much to do so. Also it would have taken too long. I just had to run it all up in anger to day because of a power failure; some high voltage cable blew out. I also run this from a UPS so I don't get caught out. Soon I will up date to a solar system both for water and power. The grid is getting ever more dodgy.

Further info I use GLA Glass Lead Acid batteries. Deep discharge 100 Ah. and 70 Ah types. The reason not to mix Ah rated batteries is because this will discharge the lower rated battery and then not recharge the higher rated battery. Special chargers are required. These are totaly sealed units.

Please provide more information, specifically on what you intend to use it for (the load type will dictate what type you need and its complexity) and also your level of technical knowledge and experience (I am not going to provide circuits or links to websites to someone unless they are experienced enough to work with both the dangerous voltages and the hazardously high currents involved in a project of this type).

The best alternative is to buy one. Even the true-sine wave inverters are relatively inexpensive now.

any used UPS (uninterruptible power supply) of the right size has one of these built in.

You can get one of these for a lot less than designing one.

In essence, it is a mature and cheap technology.

Go to a scrap yard to get an old one

Why make (rhetorical question)? These sort of things are available off-the-shelf at caravan/trailer accessory outlets and at boat chandlers.

It is pointless designing your own, it will cost far more in both time and money than any finished product from a store, and you get a guarantee with the store bought version!!!

Just remember that they quickly empty a battery when in use.....so have a voltmeter included on the low voltage side to stop you over discharging the battery. If the battery is not a leisure (able to withstand deep discharge) battery or similar, do not let the voltage go below 12.6 volts on a nominal 13.2 volt (car battery for example). This does not give you much room to manouver, so buy a HUGE battery first (or 2!).

I use a 120 a/h battery for my caravan, but rarely use the inverter for that reason...it empties the battery so quickly......

Buy an inverter as SMALL as you need and get one that is efficient as possible!

a 12 volt battery may be discharged to 11.7 volts before sulfating begins.

Not true, please check on many web sites - only leisure batteries, designed to be deep discharged are LESS affected by discharges under 12.6 volts.....

Normal car batteries (the cheapest of all) ARE affected and lose a large part of their lifespan when discharged below 12.6 volts.

You are not to blame for your lack of knowledge, I am sure that large manufacturers of batteries let people believe just that, its money in their pocket!!

I would like to draw your attention to one of many references on the internet to this problem:- (please goto http://www.batteryuniversity.com/partone-13.htm to read this for yourself!)

" Always store lead-acid in a charged condition. Never allow the open cell voltage to drop much below 2.10V. Apply a topping charge every six months or when recommended. "

2.10 volts per cell = 12.6 volts on a 6 cell 12 volt car battery.....!

In practise, this is very difficult to maintain and each time the battery goes below 12.6 volts, sulphation starts. One of the relatively cheap electronic devices, commonly called a Battery activator, will help in reducing the effects of sulphation.

The point of this is, its a fact, if you want the maximum life out of your battery, you MUST keep it between 12.6 and fully charged....if you are not bothered by a shorter life, then do what you want!!

Andy, thank you for your reply to my small comment as it is clear you can read the work of others. Lead acid batteries have been on this planet for more than 100 years now and will likely be here for many many more years. As and engineer would you bet your life on the things you have read or would you test all information? Each time I put to sea I trust 30 year old batteries to save my life in the event of a storm. The point here is that my batteries are now 30 years old and the question is; how have they lasted so long? Could it be battery care and maintenance or just luck? Their are 3 different types of battery's and 3 different makes on my boat. The youngest battery is 15 years of age.

Here my young friend is my point: the research of others is not the absolute. The finest mother of invention is your own research and testing. In that, proving or dis-proving the research of others to and absolute end. IE it looks good on paper but does it work and is it right or final. Do not be influenced by marketing, that is for the consumer.

The question is about 1000 watt inverter by a "Guest". This person is likely not and engineer and will find a way to build his inverter by trail and era. I can respect his desire. That is a mind at work and not stalled by so called facts, set by the marketing people. Conduct your own test and report your findings as a useful tool. TY

Hi 5Star,

nice to hear from you. I am not young though, my next birthday in October will be my 61st.....just young at heart!!

Your batteries are thanking you in many ways, firstly you would appear to have bought quality (Deep discharge or leisure or car?) products, secondly it would appear that they are carfully maintained - not either over or under charged (or charged too quickly!), which is a major factor and lastly, it would appear that you top them up BEFORE the plates are exposed to air!!

So many people basically ignore their batteries and are surprised when they fail....!

When I tell people how old my caravan battery is (6 years) and that it has NEVER been topped up even, they do not really believe me!!! It is charged for over 99% of the year!!! Or better said, attached to the charger!!

Andy, I have no doubt you find this link interesting for your battery life and perhaps you will discover something new for your battery.

www.zimmermanmarine.com/tech/

I found some more references that you should read, although referring to Sealed Lead Acid, the differences to normal Lead Acid are minimal and chemically the two are the same, just the SLA can recombine the gases produced by over or too fast charging.

Please visit " http://dataweek.co.za/news.aspx?pklNewsId=24069&pklIssueId=621 " for the full documentation:-

An approximate charge-level indication can be obtained by measuring the open cell voltage while in storage. A voltage of 2,11 V, if measured at room temperature, reveals that the cell has a charge of 50% and higher. If the voltage is at or above this threshold, the battery is in good condition and only needs a full charge cycle prior to use. If the voltage drops below 2,10 V, several discharge/charge cycles may be required to bring the battery to full performance. When measuring the terminal voltages, the storage temperature should be observed. A cool battery raises the voltage slightly and a warm one lowers it.

Some buyers who inspect the battery during quality control reject SLA batteries arriving from vendors with less than 2,10 V per cell. Low voltage suggests that the battery may have a soft short, a defect that cannot be corrected with cycling. Although cycling may increase the capacity of these batteries, the extra cycles compromise the service life of the battery. Furthermore, the time and equipment required to make the battery fully functional adds to operational costs.

Andy, thank´s for the good information, which leads me to somoe questions:

1.- What is your opinion about using a deep cycle battery, like the ones used in UPS, for automotive application?

2.- Is it true that using high voltage pulses in a battery, desulfatation occurs in an old battery?

3.- Can you recommend a good process for rejuveneting old car bateries and ups batteries?

Thanks, Eduardo

http://www.dallas.net/~jvpoll/Battery/aaDesulfatorSurvey.html

Incobar asked:-

Andy, thank´s for the good information, which leads me to somoe questions:

1.- What is your opinion about using a deep cycle battery, like the ones used in UPS, for automotive application?

I read recently an article about this and the recomendation was to increase the AH of the deep cycle battery by at least 10% over that for the car, which may mean it will not physically fit in the place for a battery on the car. The reason being that Deep cycle batteries have thick plates which slightly reduces the amount of current the battery can supply at stating (cranking) the motor. This might be a problem if you get a very cold winter. The DC (Deepy Cycle) battery will probably last 10 years or more, will you keep your car so long?

2.- Is it true that using high voltage pulses in a battery, desulfatation occurs in an old battery?

Yes, but you need to know exactly how to do it, units to buy are relatively cheap, but might cause interference on your car radio or car electronics. Therefore may I suggest that the unit only be set up to run when the engine is not running with a simple relay circuit.

3.- Can you recommend a good process for rejuvenating old car batteries and ups batteries?

There are some chemical rejuvenators around on the internet, but I have never actually used one, but if the battery is going to be thrown away anyway, you might try one first and let us know the results.

The best thing to do is not to let them get bad in the first place, which is why I built my own charger for caravanning usage, particularly for DC batteries and I will be going to produce it sometime in the near future and sell it. My test battery is nearly 6 years old and has never needed distilled water and is charging (at least connected to the charger!) for over 99% of the year....it should achieve at least a 10 year life I feel......call me in 4 years!

I hope that I have answered your questions, but if not, please be so kind as to request more infos.

Why build one ???

first of all, as a UPS engineer, I can tell you for certain that UPS' do not use deep cycle batteries like those used in your car, truck or marine vehicles. UPS' use a more flat discharge rate battery because they do not need the 'Cold Cranking Amps' that is needed in mobile equipment with that use the battery to starter the vehicle (the cold cranking amps is the deep cycle part since the battery take more of a deep jolt at vehicle start-up than after the engine is running). UPS' do not have this need, so their batteries have no deep charge/discharge characteristic. in fact if you used a UPS battery to try to start your car (same Amp-hours as your car battery) it would probably explode because it is not designed for this type of use.

anyway, back to the inverter. 12V dc is too low to get an efficient 220V ac output; plus the battery, depending on the amps being pulled by the load, will be drawn down below the inverter's operating voltage far too quickly to be useful....unless you are thinking of putting many 12V batteries in parallel or using a 12V dc power supply which can be tricky depending on what safety feedback circuits you install (dc & ac overcurrent, dc & ac overvoltage, etc) which should be considered reguardless.

most UPS' use multiple batteries strung together in series, then this dc voltage is chopped up via SCRs and Diodes (smaller ups' can use mosfets and diodes), then filtered smooth with dc capacitors. I don't really have a schematic of such a low voltage UPS, but this should give you some idea.

V

What a wonderful signature line. Love it!

I must correct you, sorry, cars generally DO NOT use Deep Cycle (or leisure) batteries as they are generally 60-100% more expensive for similar characteristics and size.

They have more difficulty in producing the cranking amps (I do not know about exploding, but they may warm up a bit!) because the plates are thicker and more stable than a normal cheap car battery's plates.

They handle deep discharge far better than a car battery and would normally be used in boats, caravans, UPS modules etc....

Car batteries are cheap, give higher discharge rates, have thinner plates which sulphate quicker and can distort when over cranking and therefore have shorter lives......

All a bit simply put, but correct.

Andy,

You are correct about the differences in plate thickness.

However, I don't know what the industry is like in Europe, but the web links you are referring to and the comments about car batteries not being deep cycle, just are not correct here in the USA. I don't know how much you have actually worked with various batteries, but we all must be very careful believing what we read on the internet. Not all technical articles are precise, some are written by the salesmen that do not know the real technical truth, they just want to sell their product.

So, beware of bad technical data, always double and triple and quadruple check it with other completely different technical sources before going forward with applications. especially with batteries and other chemical and high voltage applications.

I hope this does not give ill will. I just do not want people to get hurt because of mis-information.

In europe car batteries are not thick plated leisure batteries that can stand being severely discharged, they are thin plated for maximum cranking amps and they do not like deep discharge.

Some documents refer to these as deep cycle (the thin plated car batts) some refer to the thick plated batts as deep cycle......I can find US documentation that does both.....very confusing.

I am sure that I could find european docs that mix them up too.....

I should have been more accurate with my own documents, sorry.

There are 3 types of Electrical Engineers, The ones who have blown something up and the ones who will blow something up, and the ones that will blow themselves up....

Even better!

You can find information and circuit diagram from ELEkTOR magazine site www.elektor.com

Hello,

FYI, from this website http://www.roadtripamerica.com/dashboarding/Power-Inverters.htm has great information about inverter for everday use.

Cheer,

Congratulations to all...you have posted very good information on this topic...I see some of you guys are involved in the ups business, so I would like to ask if anyone can help on getting information to service Prestige and Ferrups equipment, from Eaton-Powerware, thank´s to all...Edi

Edi,

Here is another website 12DC to 220AC inverter, I think is affordable. http://www.topsalesdepot.com/poinwichfure.html

Have fun,

Perstige is kind of considered 'disposable' UPS in my line of work and I may have worked on a Ferrups a long time ago, but don't recall having drawings for it.

What do you need to know? what problems are you having with these units??

V

On the Prestige unit, 3kva,one fan was damaged, the coil got shorted, causing some diodes overheat and damaged too, I cannot distiguish the part numbers to replace them.

On the ferrups unit, 10kva, after 10-15 minutes working normally, an alarm is activated, and the battery charger is off, the charger can be be activated but few seconds it turns off again. I am using new batteries, 132 vdc is the voltage of the bank.

Thank,s Edi

Thank you all for some great input. allow my to clearify what I define as the difference between "deep cycle" and what has been refered to in this forum as "deep discharge". again this is my interpretation of the lingo....

Deep cycle means (I learned this from C&D battery school) that a battery can take a somewhat deep draw from the load (such as an engine starter) for a short time and then the battery will recover to the 12.5 to 13.5V level without any problems (ie. their output curve dips really low and then pops back up almost parabolically over seconds in time ).

The UPS battery and what are called "Multi-Purpose" Batteries, on the other hand have a deep discharge in that they can be discharged to a very low Vdc (and stay low and stable until it goes to zero or until the UPS trips to Bypass or OFF) and still be recharged by the UPS' rectifer or other stable chargers with minimal damage to the over-all life of the battery. This is true for UPS batteries as long as they are not kept in the discharged state for any long period of time (more that a couple of days) plus, as with any Lead Acid battery (anywhere possible), you should always store the battery with a rectifier/charger connected to it, feeding it 'float voltage' , which is usually 2.25Vdc per cell or 13.5Vdc for a "12V" battery (minimum ripple of course).

I hope this helps anyone I may have confused.....

P.S. A rectifier is the same as a charger except a rectifier is usually inside a UPS, and a charger is usually stand alone and may be variable voltage DC.

P.P.S. Also, it is ill advised, all though (as we have read in this forum) not unheard of, to string different batteries together in the same series circuit. I was taught that this would supposedly shorten the batteries' life...

I am interested in the batteries the guy who is using those 15 to 30 year old batteries on his boat....are they wet cell batteries (the kind you have to fill with water once in a while)? what exactly are they-model, Ah, Volts?? I am really curious.

V

THANK YOU "V" ! You have stated the truth about a lead acid battery! However and my mistake, I thought it was common knowledge.

I confess I was rather enjoying the debate/exchange of information and somehow I doubt it ends here? Without question their are many different views. I wonder what the next simple and hot topic will be that will gets my reading attention?

http://www.instructables.com/id/250-to-5000-watts-PWM-DCAC-220V-Power-Inverter/