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Expanding Battery Bank - Charging Limitation?

Paratus

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Joined
Sep 8, 2020
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When I picked up my solar panels, bought used for this beginner stage, the guy made an interesting comment. I am planning a 24v (4x6v) system, 4x240w panels. He made a comment that I could only add two more 6 volt batteries due to the charging of the solar panels. He said if I added any more batteries, they would start to discharge.

So I had to really think about this and it brought up the concept of adding batteries. Can you have too many batteries to a solar system, if charging time is not of extreme importance?

Second question: If my limit is actually 6 230ah 6v batteries, how the heck would I create a 24v system?

Thanks and appreciate any feedback!!
 
4 x 240W = 1kW
6 x 230Ah x 6V = 9 kWh

Are these flooded lead acid, "wet cell" or FLA? I understand they like 0.2C charge rate to stir electrolyte, so 1800W of PV might be more ideal.

If AGM or gel-cell, then close to 0.1C is about ideal.
 
When I picked up my solar panels, bought used for this beginner stage, the guy made an interesting comment. I am planning a 24v (4x6v) system, 4x240w panels. He made a comment that I could only add two more 6 volt batteries due to the charging of the solar panels. He said if I added any more batteries, they would start to discharge.

So I had to really think about this and it brought up the concept of adding batteries. Can you have too many batteries to a solar system, if charging time is not of extreme importance?

Second question: If my limit is actually 6 230ah 6v batteries, how the heck would I create a 24v system?

Thanks and appreciate any feedback!!
sounds like you have some kind of lead acid; I think what the guy means is you need to keep lead acid "topped up."
It is not good for that battery chemistry to remain at a 70% charge state or something like this. @Hedges is probably asking you about your battery chemistry because if you have Lithium batteries, the opposite is true.
Also if you have Lithium you can keep adding additional batteries in parallel to increase your AH.
 
The vendor guy may also have thought you shouldn't have too many strings of batteries in parallel, and didn't know what voltage you planned to operate.
4x 6V battery in series gives you 24V, and 8 batteries as two strings of 4 is fine too. The two strings can be connected in parallel with same gauge of wire, or that could be done with wires as little as half the ampacity (but still fat enough for whatever fuse you use) because it only carries half the current.
With two strings, connect inverter with negative cable to negative side of one string, positive cable to positive side of other string of batteries. That balances current draw evenly, because all paths have exactly same IR drop.
There are ways to exactly balance wire length with more than two strings of batteries. I've seen how that's done with 4, not sure about 3.

Of course number of "batteries" doesn't matter much, since batteries are just groups of cells and are available 2V, 6V, 8V, 12V ...
 
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