A few days ago Larry Amato from Amato Consulting replied to our previous article that describes how to create 24 volts from two 12 volt automotive batteries. He continued our thought process by showing that you could take four automotive batteries and connect them in both series and parallel at the same time to achieve a 24 volt battery bank with double the capacity of a single 12 volt battery.
His application was for a solar installations where capacity is usually important, along with a typical requirement for 24 volts which is a common voltage on solar panel systems.
He describes how to do it using a matrix - I had to take a pencil to write it down to follow what he was saying. Then I had to think about it for a bit, so I figured some you might have had to think about it for a bit too...hence this article. I'll try to give some more detail to break it all down. Here is what he said:
My need was 24VDC power with 200 amp hours.
I purchased 4 each 12VDC AGM 110 amp hour batteries. Picture the 4 batteries in 2 rows (R) x 2 columns (C).
1) R1C1 positive is connected to R1C2 positive.
2) R2C1 negative is connected to R2C2 negative.
3) R1C1 negative is connected to R2C1 positive.
4) R1C2 negative is connected to R2C2 positive.
5) R1C1 positive and R2C1 negative provide 24VDC power with 220 amp hours.I take the R1C1 positive and R2C1 negative and run through a 24VDC Photovoltaic Charge/Controller which is connected Solar Panels with output to my various 24VDC devices including Programmable Controller, Instrumentation, and Spread Spectrum Radio.
Like I said, you need to draw it out. And for your benefit, I've done that (click to enlarge):
On the left is what Larry describes, and on the right is what I would have done. I've gotta say, Larry's way is WAY better. Less wires, less complex. So let's talk about it.
"My need was 24VDC power with 200 amp hours"
24 volts from 12 volt batteries: if you read our last article then you know that when you connect batteries in series, the voltages add together. So Larry took two of his batteries and connected the positive and the negatives together. Then he did it for the other pair. On the diagram, each pair is vertical - the negative of a top battery is connected to a positive of the battery directly below it. And so now there are two 24 volt battery banks, side by side.
On to the second criteria, 200 amp hours.
It's pretty tough to find an automotive battery that stores much more than 100 amp hours. In this case Larry found some 110 amp hour AGM batteries. But how do you get 200 amp hours? I describe this in detail in the last article, and if you've read it you know that if you connect batteries in parallel the amperages add together.
And so he added the amperages of the two battery banks together by connecting the positives on each bank and connecting the negatives on each bank. Presto, 100 amps plus 100 amps is 200 amps.
Lastly by taking a lead from the positive and a lead from the negative, he's got a 24 volt system, with the full capacity of 200 amp hours in reserve. On the image above you'll see what I call "our method". While it does the same thing, it's more complex, and after seeing how Larry does it, I'm converted. See if you can follow the differences - but really, they each do the same thing.
A few paragraphs ago I mentioned the AGM batteries that Larry purchased for his application. AGM battery - what is that?
What are Advanced Glass Mat Batteries?
AGM stands for Advanced Glass Mat, and is a type of deep cycle battery. Battery types is a whole other article that we need to write, but if you are reading this and you care to contribute, go ahead and leave a comment below. Hey, if you want to write a full blown article and give some good detail on what an Advanced Glass Mat battery is, go to our article submission page and do so - we come with benefits!
Related posts:
Hello,
My need is 12V DC power is to be converted into 220v AC.
i need to connect them to my wind tubine o/p 12v DC.
i have planned to purchase 4 batteries.
Please let me know
what kind of batteries i need to purchase?
how to connect them in series to get the 12v DC o/p ?
Regards
Raghu S P
Raghu,
You’ve asked a bunch of questions there – I’ll work up an article to try to answer them. But in short you’ll need:
1) An inverter to convert the 12V DC output of your turbine/battery system to 220V AC
2) Buy 12 Volt deep cycle batteries, try to find some with at least 100 Amp hour rating.
3) Connect the batteries in parallel, not series.
My questions for you are
1) Why 4 batteries?
2) What are you going to be powering? What is the load? For how long will you expect to run the devices without wind?
3) What are the specifications of your wind turbine? How many amps does it put out at a given wind speed?
4) Do you have the right electronics to charge your battery such as a blocking diode and charge controller?
Hope this helps,
Robin
i bought inverter that is 24vdc and i connected 2nos of 200ah batteries i connected the positive to negative and positive to negative to get 24vdc after that i connected the inverter positive cable to positive of battery A and the negative of the inverter negative cable to the negative of battery B hence it is still not working can you pls. help me thanks
pretendo ligar 3 baterias de 12v 17ha para scoter para motor 36vdc 19ha
I saw the article on connecting 4 12 110Ah batteries in series and parallel to achieve 24V at 200Ah. Will this work with 3 12V 75Ah SLA batteries to achieve 36V at 225Ah? If so what would the wiring look like?
Ed
No it won’t work. You would need 3 banks of 3 – 12 Volt batteries. Each bank of 3 batteries would be connected in parallel to make 36 volts. Each 36 volt bank would have 75 Ah capacity. You would then string the three banks together in series to make 225 Ah capacity.
In short you would need 9 batteries! But then 225 Ah @ 36 Volts is a bunch of power…
i was trying to find out how to charge 2 12 volt batteries in series with 1 12 volt battery charger
found your pages and this one helpfull
Many thanks for a clear, informative site suitable for novices like me!
I have an antique electric master/slave clock system that runs on a 24v battery happily for about 6 weeks, until the battery flattens, then it’s a recharge and half a day to reset them all!
If I wanted to add a trickle charger to Larry’s set-up, would I need a 12v or 24v one, and which terminals on which batteries should I connect to?
Many thanks in advance!
Ken, you would need a 24 volt charger for this, and the charger would be connected to the 24v positive and negative leads shown on the diagram (positive to positive, negative to negative).
But why add a trickle charger when you could add a transformer instead? Do you know how many amps the clock system draws? A small 120V AC to 24 V DC transformer available at an electronic supply store would do the trick. That way you get rid of the batteries altogether. You just need to make sure the output of the transformer meets the maximum number of amps drawn by the clock.
Check out this video on how to measure amperage from a small system.
I have three 12V12Ah batteries. I need 36V36Ah.Is the following thought correct ?
I connect all the plus together, then all the minus together. The result is: in parallel I would have 12V and 36Ah.
Then I connect from first battery plus to second battery minus and from the second plus to the third battery minus. This would be series and I achieve the 36V.
Thanks for your help Robin
George, it’s not going to work quite like that. I’ve written an article that hopefully explains the difference. Take a look at it here.
I want to run a low power 24volt lighting system and a low power 12 volt TV off two 12v 110a batteries.
Both batteries in series for the lights – fine.
But can I also put the batteries in parallel to run the tv? Parallelled so that they are used equally.
Trevor, you can’t put them in parallel as well. What you are trying to do is important though; load equalization when drawing 12 volts off the “low side” of a 24 volt cell. You either need to draw 24 volts and transform that down to 12 (your transformer needs to be rated for the current drawn by your TV), or else draw 12 volts from the low side and install a battery equalizer that shifts voltage between the two batteries to keep them on equal voltage.
Take a look at this article I’ve written on installing a battery equalizer.
Robin, I’m looking at a larger installation of battery back-up and considering using 40 x NiFe 1.2V battery array with each battery rated at 1220 Ah. This is for a large villa that is off the grid in Bali. We will have a 100Kva genset integrated in the system which should cover any power needs that arise, but I want to maximize on usage of the batteries to reduce gen-set time. How would you go about configuring the system for max amp hours? Would you series them up for 48volt system or do a series/parallel configuration and 24volt system? Any suggestions you have would be appreciated.
From what I understand, If you take 20 of your batteries say 5 rows of 5 labeled as R1-5(Rows) and C1-5 (Columns). Connect all of R1 negative terminals together. Then connect all R5 positive terminals together.Thus creating a paralleled type connection for combined amps. Then connect R1C1 positive terminal to R2C1 negative terminal and continue to do connect the batteries in this fashion for each column. This is an example of a series connection. Once you have set up the first “set” of batteries, create an identical connection with the other 20 batteries. Once you have two identical battery “cells” connect them in parallel to each other. Connect the positive of R1C5 from one “cell” to the positive terminal of R1C1 on the other “cell” that you made. Then connect the negative terminal from R5C5 from one “cell” to the negative terminal from R5C1 on the second “cell”. This should give you a combined total of 24v at 48,800 amps. I don’t know where to do from there or if this is even correct, so don’t do it until Robin looks my plan over. I did a drawing but can’t post it in the comment.
[...] like urself did not know series and parallel are possible at the same time with a relay or switch. Connecting Batteries in Series and Parallel at the Same Time | OverlandResource.com – An onlin… __________________ 2006 Honda TRX450ER -HMF slip on -HRC header -jetted -K&N air filter [...]
Sorry but couldn’t find where to post this question. If I connected a 24 volt wind generator to a 48 volt battery bank what would happen? Would I put in half the energy or would I destroy the Wind generator????
I have 4 12 volt batteries in serie to get 48 volt for one system. Can i connect the same 4 batteries in parralell to get 12 volt for a diffarant systym?
Yes.
I have 4 12 volt batteries to get 48 volt for a scooter.
Can i connect these 4 batteries in parrallel and series as in Larry’s example and then charge them with one 12 volt charger ?
HI
Thanks for the articles, they make for good geeky reading.
I have a question if anyone can help me.
I have a 12vDC starter motor that I want to put onto a gocart, I have several 7ah SLA 12v batteries, these are free for me so I will use them for now while I am learning, apparently this motor is rated at 19 amps, I think anyway, my question is If I setup my batteries 2 groups of 2 wired in series and parallel I will get 24volts at 14 ah, correct? so if I use your numbers ( 14ah * 90% = ?ah / 20 amps = ? hours * 60% = ?hours )
I think I got about 12 minutes run time with no load, Can you please advise if I have done this calculation correctly?
what would be the average power if i connect 50Ah and 180Ah battery in series to achieve 24 volts system?
Thanks a million for the article. You are a real life saver. I’ve been using a 24v input inverter with 2 12v batteries. I just got an additional 2 batteries and was finding it confusing to make the connection. Thanks to your article, I’ve finally succeeded. I now have 4 12v batteries connected in series and parallel to generate 24v. I’m truly grateful bro! Keep up the good work!
sir,may I know the minimum ampere-hour(of a 12volt battery) required to supply a inverter of 70watt output.
please answer me as earlier as possible
sir,may I know the minimum ampere-hour(of a 12volt battery) required to supply a inverter of 70watt output
please answer me as earlier as possible
hello, new to this so bear with me! for an EV kart i have the option of 24, 3V cells at 120Ah in series giving me 72V and 120Ah, costing and weighing a considerable amount more than if i had 24, 3V cells of 40Ah connected in packs of 8 in parallel and 3 packs of the parallel batteries connected in series to give me less cost and weight for the same 72V and 120Ah. does this sound feasable to do? are there any disadvantages to using series/parallel circuits with regard to charging or life? Any help would be much appreciated, thanks.
quiero hacer una pregunta no se si me pueden ayudar es la siguiente: para un auto a contol remoto que funcionan con tres baterias de 1.5v asiendo un total de 4.5v la incongnita es la siguiente una bateria de celular es de 3.7v la cual si la conecto a mi auto funciona pero q pasa si yo conect dos baterias de cel en paralelo a mi auto no se si daña algo de mi auto y si puedo conectar mas?gracias….
That doesn’t work for me. I have two 12v 3eh batteries for a large farm tractor. Can you tell me how to connect them?
Hi guys Patrick once again. Please is it possible to add 5 more batteries to my connection as detailed earlier? I’m hoping to make it 9 12v batteries in parallel and series to generate 24v for my inverter. Looking forward to your reply