David LaFerney
10 mW
Since last fall I've been using a charger I built using a Drok boost voltage regulator ( https://www.amazon.com/DROK-Numeric...Adjustable/dp/B01GFVI6R6/ref=cm_cd_al_qh_dp_t ) to charge my home built 18650 battery packs for 2 bikes that my wife and I ride weekly - and no worries it has always worked great.
Until suddenly the charger started charging the 25.2 volt packs about 2 volts higher than the set point - about 4.43 volts per individual cell - which gave a noticeable performance boost, but of course is hard on the batteries and potentially dangerous.
So obviously I need to replace the charger or find and fix the problem. But I would also like to come up with some kind of over voltage safety cut off circuit to add some backup safety in case of future malfunctions. Hopefully, there is an off the shelf solution. Any ideas?
Also - what is a reliable charger for custom voltages like this?
Someone is probably going to ask about my BMS - I'm not using any. I have the packs internally separated into 6s4p modules with power and balance leads from each module - when charging I parallel everything and use a battery medic to parallel balance while charging and then use a wiring harness to connect the modules in series for use. So no balance on discharge - which isn't really an issue so far. And I use a fuse for overcurrent protection on the bikes.
Since everything starts out balanced to within 2-3 1/100s the battery medic keeps up pretty good during the main charge, and when the charging current starts coming down at the end of the process the BM has no problem correcting any remaining imbalance issues - so it all ends up perfectly balanced and fully charged. Until something broke that is.
Until suddenly the charger started charging the 25.2 volt packs about 2 volts higher than the set point - about 4.43 volts per individual cell - which gave a noticeable performance boost, but of course is hard on the batteries and potentially dangerous.
So obviously I need to replace the charger or find and fix the problem. But I would also like to come up with some kind of over voltage safety cut off circuit to add some backup safety in case of future malfunctions. Hopefully, there is an off the shelf solution. Any ideas?
Also - what is a reliable charger for custom voltages like this?
Someone is probably going to ask about my BMS - I'm not using any. I have the packs internally separated into 6s4p modules with power and balance leads from each module - when charging I parallel everything and use a battery medic to parallel balance while charging and then use a wiring harness to connect the modules in series for use. So no balance on discharge - which isn't really an issue so far. And I use a fuse for overcurrent protection on the bikes.
Since everything starts out balanced to within 2-3 1/100s the battery medic keeps up pretty good during the main charge, and when the charging current starts coming down at the end of the process the BM has no problem correcting any remaining imbalance issues - so it all ends up perfectly balanced and fully charged. Until something broke that is.