Draw from varied points in battery bank

Chris11

I'm relatively new to solar but slowly I'm getting there.

Recently I read some guy saying he wasn't able to draw all the power he needed for his 4000 amp inverter from his 8 battery bank he had so he drew some power from different points in his bank. Sorry if this isn't clear.....I assumed he meant he couldn't just use the "final" positive and negative leads producing 24 volts, so tapped into different batteries in the bank.

Is this a normal way of doing it to higher capacity inverters?

Thanks, Chris

vtmaps

Re: Draw from varied points in battery bank

Chris11 wrote: »

Sorry if this isn't clear.....

It's not clear at all. He has a 24 volt system with 8 batteries. If he has 6 volt batteries, he has two strings in parallel, each string being 4 batteries in series. If he has 12 volt batteries, he has 4 strings in parallel, each string being 2 batteries in series.

Either way, I don't understand what you're trying to describe.

--vtMaps

Mountain Don

Re: Draw from varied points in battery bank

Details needed.... as vtmaps stated. Also what is the voltage input on the inverter being used? 12? 24? ???

Chris11

Re: Draw from varied points in battery bank

I spent an hour trying to find where I'd read about that....no go.

The gist of it was that he said he couldn't use all available amps from the battery bank via the normal single positive and single negative leads so he tapped into other spots in the bank, then fed all the wires to the inverter.

Thanks anyway.

Chris

inetdog

Re: Draw from varied points in battery bank

Chris11 wrote: »

I spent an hour trying to find where I'd read about that....no go.

The gist of it was that he said he couldn't use all available amps from the battery bank via the normal single positive and single negative leads so he tapped into other spots in the bank, then fed all the wires to the inverter.

Thanks anyway.

Chris

Electricity does not work that way. Connecting two points in a battery bank that are at different voltages to the same inverter terminal will make a short circuit.

Now if he has, for example, four strings of two 6V batteries each, making a 12 volt system (not a good idea in the first place, but let's suppose), then he can either connect all four + terminals together and all four - terminals together and then try to run one large or four smaller sets of wires to the inverter.
Or he could avoid having all of the amperage going through one connection point by running separate smaller wires from each strings plus and minus terminals to the inverter.
Either way the four strings are in parallel, all that is changing is how the connections to the individual batteries are made and whether they are paralleled at the battery bank, at the inverter, or at both.

Cariboocoot

Re: Draw from varied points in battery bank

I don't think we should speculate on this as the original premise is not at all clear. Guessing at what is meant will only confuse things further.

bill von novak

Re: Draw from varied points in battery bank

Chris11 wrote: »

Recently I read some guy saying he wasn't able to draw all the power he needed for his 4000 amp inverter from his 8 battery bank he had so he drew some power from different points in his bank. Sorry if this isn't clear.....I assumed he meant he couldn't just use the "final" positive and negative leads producing 24 volts, so tapped into different batteries in the bank. Is this a normal way of doing it to higher capacity inverters?

He may be describing just "doubling up" on cables i.e. he connected an additional cable from the "other" negative battery terminal to the inverter ground (similar for the + side.) If he is using a 4s2p battery then it's roughly the same as using a single thicker cable. Only thing I can think of that makes sense.

waynefromnscanada

Re: Draw from varied points in battery bank

Sounds like something may be very wrong with the way the battery bank is wired together. Without a diagram of the wiring and additional information, we can only guess, and like Cariboocoot says, guessing only confuses things.

vtmaps

Re: Draw from varied points in battery bank

bill von novak wrote: »

He may be describing just "doubling up" on cables ...<snip>... Only thing I can think of that makes sense.

That does make sense.... although sometimes to troubleshoot someone's (poorly designed or mis-wired) system it helps to think of things that don't make sense.

waynefromnscanada wrote: »

like Cariboocoot says, guessing only confuses things.

I think that Bill von Novak's guess made things a little clearer... assuming that there is any sense to be made of the situation.

--vtMaps