A couple basic questions about starting with lifepo4

[fxykty]

Originally Posted by John29

Thanks, if going for 400 Ah LPO am I better with 2x200 or 4x100? I assume same size at least is preferred ie. not 1x300 and 1x100. Space and weight are not an issue and cost appears very similar.

Individual cells are 3.2V nominal so you need four in series - aka 4S. That is the simplest layout, needing a single BMS, fuse (positive) and shunt (negative). If you have just 2S then you would have a 6V battery.

[Chotu]

Originally Posted by John29

Thanks, if going for 400 Ah LPO am I better with 2x200 or 4x100? I assume same size at least is preferred ie. not 1x300 and 1x100. Space and weight are not an issue and cost appears very similar.

It doesn’t really matter.

If you are doing 400AH, The only thing I would be concerned about is getting a single battery. Because if something went wrong with that single battery you would be out of power.

So at least 2x200 is appropriate.

That’s exactly what I did. 2x200.

If you want it even more redundancy you could break it down into 4x100

[CaptainRivet]

Originally Posted by John29

Thanks, if going for 400 Ah LPO am I better with 2x200 or 4x100? I assume same size at least is preferred ie. not 1x300 and 1x100. Space and weight are not an issue and cost appears very similar.

2x200AH is better, less can go wrong. And the less in parallel the better, you can eg use Jedi's reference diagram so you can monitor both with a smart shunt. With 4x100AH you need 4 shunts...expensive.

[fxykty]

Originally Posted by fxykty

Individual cells are 3.2V nominal so you need four in series - aka 4S. That is the simplest layout, needing a single BMS, fuse (positive) and shunt (negative). If you have just 2S then you would have a 6V battery.

My mistake, you are talking about paralleling 12V batteries. Definitely fewer larger batteries is better and likely cheaper, so go 2x200Ah. Much simpler and if using external BMS then only two required, if internal BMS then none. Put a battery monitor shunt downstream of where they are paralleled and the BM will show overall figures for both batteries.

[AKA-None]

Qq how are they with vibrations? Eg any concerns

I ask as I try to duplicate the boat and rv for electrical systems

[Chotu]

Originally Posted by AKA-None

Qq how are they with vibrations? Eg any concerns

I ask as I try to duplicate the boat and rv for electrical systems

The one thing I know about that is these were being used in RVs at the same time as boats from the start. So as long as you have been seeing them on this forum, people have been using them in RVs. They started with class A mostly because they were pretty pricey. But now everyone is using them.