one big battery or two small.?

[rob1234]

hi i am thinking of going to lithium ,,is it better to get one larger, say 300ah--400ah or two 100--200 ah thanks

 

[Lenny HB]

I fitted 2 x230, with a 4 way switch so i can select off/batt 1/ batt 2/ or Both, so in the worst case and one failed I can still have power.

 

[Lofty1]

Just a thought, if one large battery is faulty you are stuck , but with two you can disconnect the bad one and still continue using the good one.

 

[Kannon Fodda]

Assuming you have the physical space one battery is simpler to wire and most modern ones will support higher currents for large inverters.

Some will say two batteries in case one fails (unlikely) so you still have something. Used to be the case with older BMS that two gave you better current. Of course two may be better if you have awkward space to fit into.

 

[rob1234]

Assuming you have the physical space one battery is simpler to wire and most modern ones will support higher currents for large inverters.

Some will say two batteries in case one fails (unlikely) so you still have something. Used to be the case with older BMS that two gave you better current. Of course two may be better if you have awkward space to fit into.

thanks ,,there is plenty space in the locker

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[rob1234]

I fitted 2 x230, with a 4 way switch so i can select off/batt 1/ batt 2/ or Both, so in the worst case and one failed I can still have power.

hi do you have a link to the four way switch you used please ?

 

[Lenny HB]

hi do you have a link to the four way switch you used please ?

I got it from 12v planet about 30 quid but if doing it again I would use a Blue Sea one 12v planet sell them, they are lot dearer.

The ones I used I found the nuts on the studs your cable terminal rests on need to be at the right tension or the switch didn't make contact. OK once I got it sorted.

Don't use the cheap ones on ebay & amazon they get very hot under high loads.

 

[AdrianChen]

Looked at possibly changing my setup recently (to make better access to the black tank valve) I have a couple of 216AH batts with 200amp output each, and could go to a bigger 560ah single battery with 250amp output. 250amps is just enough for us I think, 400 is very comfortable - better for the battery?

The most likely failure that would disable one of my existing batteries is if the BMS itself were to fail (a single cylindrical cell would not have much impact). OK the likelihood of that is low, but the impact? Well the 200amp output would make little difference to our use of the van, just have to charge up more frequently.

With the single 560AH a BMS failure would be a blackout, even if a single cell went. The 250amp output would be enough though.

So for a robust system I prefer the option for two, because although the likelihood is low, it will pick its moment of most inconvenience!

 

[AdrianChen]

I got it from 12v planet about 30 quid but if doing it again I would use a Blue Sea one 12v planet sell them, they are lot dearer.

The ones I used I found the nuts on the studs your cable terminal rests on need to be at the right tension or the switch didn't make contact. OK once I got it sorted.

Don't use the cheap ones on ebay & amazon they get very hot under high loads.

Never heard of a problem with Blue Sea stuff that I can recall, that will have been hundreds installed (not by me, or....), and reading the various forums.

I have seen cheap copies though, and almost identical to look at - not sure how good they are! So I would source from a reputable seller like 12v Planet/Offgrid etc.