More newbie questions ;-)

[Solarfun4jim]

Questions...
1/Looking at the above setup, any reason why i couldn't use thick copper plates to simultaneously make the 2P & Series connections?
2/Understanding that heat rises, if i insulate around each cell with kingspan 25mm, this provides rigidity within the confines of a casement, plus insulates in cold weather. If i connected a heat pad under a glass plate below the whole battery bank(for cold protection when needed) and connected a fan system for the air void above the terminals such that the thick copper connection plates would act as heat sinks and thus provide me the over temp heat dissapation when temp climbes above 10degC. Any downsides to insulation around the sides....bearing in mind i would generally only be discharging at 0.2C and never as much as 1C rates...so minimal heat generation??? I'm also assuming, that if any cell developed a 'heat spot', that the BMS would likely kick in to protect?
I'm looking to build a motorhome system, such that after 16 years of use, will still have a reasonable capacity to then reuse for my current grid tied home system, which at that point will no longer get feed in tariff monies...so long term dual purpose.
Any opinions on the thick copper connector plates or insulation proposals?

 

[jasonhc73]

The BMS can't see P connections, it only sees the P connection behind the S connection as one cell. A P connection is more storage, that equalizes it's voltage to it's P neighbor. Do you have a volt meter? Get two rechargeable batteries. Charge them fully, and use one for a while.

P cells equalize passively to each other just by connecting them to each other in P. The High V supplies the V to the Low V, just by being connected.


1.367 + 1.315 = 2.682 ÷ 2 = 1.341
Cells setup in parallel average each other out, and passivily balance each other instantly.

 

[Solarfun4jim]

@jasonhc73
Thanks Jason,
so for the sake of the cost of a second BMS, i would have better control/monitoring if i went 16S2P instead of 2P16S ???
Any problems with the BMS's reading each series string, when ultimately they are paralleled? Would both these series strings still self balance the way they are paralleled(assuming i keep all wire lengths the same etc?)

 

[Craig]

I'm not sure that is ultimately true because now you have twice as many cells to keep balanced. I don't think its a horrible option though and have considered it many times. The plus is you have less energy to move around for each BMS the minus more to go wrong.

 

[Solarfun4jim]

Thanks Craig, so do you think a 2P16S would still be better, but perhaps with a 6A active cell balancer in place with the BMS to aid balancing?

 

[Craig]

Yes and 6 amps would be plenty. Really probably overkill.

 

[jasonhc73]

My 16S balancer is only capable of 0.200 amps. Does "6 amps" really mean moving 6 amps between each cell?