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Hi

I am new to the forum but on solar for a while now.  My installation consists of the following:

1)  12 x 260W Enersol solar panels

2)  12 x 150Ah deep cycle lead acid batteries

3)  1 x Axpert  VP 5K-5000W invertor

I am trying to be off-the-grid but currently not enough storage capacity to take me through the night/cloudy conditions.

I hope to learn a lot from the forum.

Regards

Marthinus

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Thanks

I have tried something different with regards to connecting batteries in series and parallel.  I have paralleled 3 x 12V batteries = 450Ah

4 x 450Ah "batteries"" are then connected in series.

What will the problem with this configuration be compared to the conventional 4 x parallel trains?

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Well, let's think about what you've done.

Sometimes, I like to apply worst case scenario's to a situation and the effects seem clearer, than thinking about a slightly off impedance mis-match.

Lets call the worst case a) an open circuit cell & b) a short circuit cell

Situation 1: Lets name the dud as the middle cell in the 450Ah battery directly connected to the positive leg for the sake of visualizing where it is.

Situation 2 : Same battery but connected conventionally, in its own string.

Case a) Situation 1:  The 3 healthy downline strings will suck the current that is mean't for 3 batteries in parallel through the first two. So the first two will die first, when they are dead, all the batteries in the bank will suffer.

Case a) Situation 2: The affected string will not  current, and the three downline batteries will not get charged. Other two strings remain healthy.

Case b) Situation 1: the parallel batteries in the same 450 will be shorted out and not charged, and the the remaining 3 healthy strings will all be subject to full charging voltage and die from overcharging.

Case b) Situation 2: The parallel batteries will be largely unaffected, as will all the downline batteries in their string. The batteries in the faulty string will die from being subject to full charging voltage.

So to summarize: The method you have put forward is worse than the conventional method because it allows the damage cause from 1 string to spread to another string which otherwise would have survived. (Well at least have survived longer, as they would only have to endure deeper cycling, because have to carry more load). 

So I recommend you don't do this, it will work until stops working and then you may have spread the rot all over your bank.

Edited by phil.g00
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