Just give any onboard charger a quick test to see whether/not to even use it.
Wait ’til it goes from red to green, then immediately pull the cell and measure the voltage. If it’s 4.20V or lower, great. Any higher, watch out, you probably don’t want to use it and overcharge your cells.
Getting most of the way there in case it’s running low, fine, but don’t let it sit ’til the indicator shows fully-charged.
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Eg, my Tacklife goes from red to green at 4.0V-4.1V or so, but keeps slow-charging. So if I pull the plug shortly after it shows green, that’s awesome, as it’ll extend cell life a lot by not stuffing it to the gills, but I won’t leave it overnight, as it might hit 4.25V or whatever (forgot how high it goes).