DIY 4S li ion charger Q.

alpg88 · Aug 3, 2018

i need a 4s li ion charger, i know there are few on sale, on many different sites, but i wanted to build one, i have this board

https://www.ebay.com/itm/191843557669?ViewItem=&item=191843557669

i have used them many times, as drivers, voltage regulators, and li ion chargers, but for 1S. from the description seller posted, i do not see why i can not use that for 4s, but i'm not 100% sure. anyone tried that board as a charger for more than 1 cell? or sees why it can not be used as such, i'd love to know. thanks.

id30209 · Aug 3, 2018

This is interesting! Although i'm a big noob in this field i'd like to try something similar.
Subscribed.

Gauss163 · Aug 3, 2018

Series charging of Li-ion requires a BMS in order to be safe. Among other things the BMS will monitor the voltage of each series string to ensure that it does not go overvoltage (and also may balance etc).

alpg88 · Aug 3, 2018

Gauss163 said:
Series charging of Li-ion requires a BMS in order to be safe. Among other things the BMS will monitor the voltage of each series string to ensure that it does not go overvoltage (and also may balance etc).

yes, however the device i need to build the charger for has pcb with balance function.

this one https://www.batteryspace.com/protec...-equilibrium-function-and-fuel-gauge-for.aspx

Gauss163 · Aug 3, 2018

alpg88 said:
yes, however the device i need to build the charger for has pcb with balance function.

If you already have a BMS then any CC/CV charger supporting 4S should work fine.

Note that some of those types of CC/CV modules don't terminate charging. Rather the simply turn on an LED at C/10 to signify the charge is done.

Also beware that those cheap CC/CV modules usually have exaggerated power limits. You'll be lucky to charge at 1A with that module without adding a heatsink.

alpg88 · Aug 3, 2018

i need less than 1A, as far as charge termination, good point i will check if it actually shuts off charging, or keeps charging, or drops current to almost 0, in any case the pcb has build in overcharge protection, so i think i should be ok. thanks Gauss163

this is the device,

Gauss163 · Aug 3, 2018

It shouldn't trip OVP = overvoltage protection, but it may end up essentially trickle charging at the termination voltage, which is not good for longevity if done for long periods. You could trip OVP if the buck module fails, since they commonly fail shorted, so pass through the full input voltage.

Those plywood flashlights are quite cool. Best of luck with your project.

DIY 4S li ion charger Q.

alpg88

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id30209

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Gauss163

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alpg88

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Gauss163

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alpg88

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Gauss163

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