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15s vs 16s

Stewfish

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Oct 20, 2020
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I know that the nominal voltage 48v is not necessarily 48 volts, but rather like 51 or 52 volts, I can't remember. However I'm wondering why not do 15s versus 16s with my lichen 3.2 volt 280ah lifepo4 cells. If I do 15s then I will be saving about $400 on my two BMSs.
 
how does 15s save you $400 on BMS?

what 48v inverter and charge controler do you plan to use? What is the acceptable voltage range for those items?
 
A batrium wm5 is $660 and only does 15s but says its for 48v systems then add on a Multimon for another 15s at 190 then its 190 for every 15s if I ever want to expand down the road. Otherwise to get 32s it's $1260 for the wm4 and 32 blockmons that individually monitor each cell. I haven't seen a BMS that can manage 32s and Batrium can. I need to do 32s with the wm4 or 15s2p with the WM5+MM8

Wm5 -
  • 10 to 15 cells in series (suitable to typical 48v lithium battery)
Chargery was 800+ with the DCCs and 130+ was for shipping. Plus no way to communicate between the 2p of 16s2p.

Daly also cannot communicate between the two strings.


MPP LV6548 high and low cutoffs are 44v to 66v.
So 44v ÷ 15 = 2.9v max discharge at 15s possible
66v ÷ 15 = 4.4 max charge possible


Lifepo4 cells
  • Minimum discharge voltage = 2.5 V[27]
  • Working voltage = 3.0 ~ 3.2 V
  • Maximum charge voltage = 3.65 V[28]
 
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15s is fine, going back a decade that was standard for 48V.
 
"15s" seems to be shorthand for 15 series cells, and "16s" 16 series cells.
Correct. I swear there was a nice write up in the Resources section on this but I can't find it at the moment.

16S2P would be 16 series paralleled with another set of 16.
 
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