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I have 5 12v 240ah AGM batteries. Which I need to wire in parallel question what size wire between batteries and what size fuse, question 2 what size wire from batteries to inverter. Inverter is a multi plus 2 12v 3000va 230v . The distance from the batteries to inverter is 2.5m
Hi,
I assume that you are aware tht high currents can be dangerous. So please make sure that you know what you are doing.
Coming to your question. Let's do some calculations. I will try to err on the safe side here.
An AGM battery at 0% chage has a voltage of ~10V, the inverter will pull no more than 3000w from the battery. At 10V this is then max. 300A. Hence your connection to the inverter has to be rated for at least that current (better more). The fuse you use has to handle that as well, a 350A fuse should be OK. For 2.5m and a maximal voltage drop of 0.3 at 300A you would need 90mm² cables.
The batteries are in parallel, so the current will be evenly split between them, therefore, the connections between the batteries will see no more than 60A and they are shorter so that you can use thinner cables than for the connection to the inverter.
How about charging? If the charging power is higher, your cables and fuse have to have a higher rating as well.
Have you ever thought about using 4 of the batteries in series? That would give you a 48V system and therfore 4 times lower currents, which would be way easier to handle. 90mm² is massive...
Hi @GGreen
For that model Multi Victron recommend 2x 50mm2 cables (that's 2x for both + and -) at < 5 metres. And a 400A fuse.
Depends how you wire them between the batteries what you do there, because some configurations (the easy ones) can still result in 80% of total current going through individual wires. Imbalance is your enemy with paralleled batts. http://www.smartgauge.co.uk/batt_con.html
