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I have 4 Panasonic NCR18650B batteries and want to purchase a BMS to charge them in series. The following board looks promising, but I'm not sure if it's fully compatible with my batteries.

The main concern is that my batteries' chemical composition isn't specifically supported by the board I'm looking at. The board's product description says that it supports the LiCoO2, LiMn2O4, and Li(NiCoMn)O2 variants of lithium-ion batteries. However, my batteries are apparently of the LiNiCoAlO2 type (search for "panasonic ncr18650b" once on the page).

Will my batteries be charged without issue if I use this BMS? There doesn't seem to be much emphasis on my battery model's chemical composition, as even the product datasheet doesn't mention it. Furthermore, this is the only BMS product description that mentions specific variants of lithium-ion batteries, whereas almost every other description just says that lithium-ion batteries in general are supported. According to the second link, my batteries' lithium-ion variant is similar to Li(NiCoMn)O2, which is supported by the BMS.

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    \$\begingroup\$ The principal issue appears to be charge current; your variant should be charged at the 0.7C rate according to the link whereas the others can be charged at up to the C rate. The BMS very likely is designed to charge 18650 batteries at the C rate which is why the specific chemistries are listed. \$\endgroup\$ – Peter Smith Mar 18 at 16:10
  • \$\begingroup\$ Is there a safety risk to charging at a higher C-rate than what's recommended for the battery? \$\endgroup\$ – GreatHam Mar 18 at 21:24
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A primary consideration on cell ageing rate is rapid in time spent over Vmax duration time. The activity is accelerated by temperature rise. Therefore a better design incorporates thermal sensing for say a 10'C(est.) rise above ambient, along with recommended CC rate of 625mA or 0.5C with recommended CV level.

This unit is precise but a bit high above Panasonic spec where ideal to match spec. would be 4.20V +/-0.05V (est. typ. tolerance)

  • BMS SPec: Overcharge voltage: DC 4.25-4.35V ± 0.05V

The Panasonic specs are CC rate = C/2, 4.20V CV 4 hrs

  • C/2= 1625/3250 {from CC mA/capacity mAh}.

Batteries have memory effects from longer time constants you can see the effects of this during the CV decay curve. (See below) The slopes of V(t) for CC indicate the ESR*C=T1 effects and dV/dt=Ic/C and I(t) CV indicate the memory tandem capacitance which has a longer ESR2*C2 =T2 time constant.

enter image description here

The 3 specs for charging are; CC rate, CV max and CV current cutoff to get max capacity. Panasonic believes this is the best tradeoff for performance vs capacity. But the choice is yours on the effects to life charge cycles as going beyond these specs degrades life cycles.

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  • \$\begingroup\$ Thanks for the detailed answer. Is there a safety risk to overcharging in terms of voltage (for example, 4.3 V), or will it simply degrade the battery lifespan like you said? Also, is it dangerous to charge at a higher-than-advertised C-rate? \$\endgroup\$ – GreatHam Mar 18 at 21:23
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    \$\begingroup\$ The danger starts with undervoltage as Dendrites are formed. The upper range accelerates aging but if there are dendrites formed from under voltage, it could pose a risk at over current \$\endgroup\$ – Sunnyskyguy EE75 Mar 18 at 23:08

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