lifepo4 charger failures... possible cause?

[kokopelli314]

Ok, like so many others I have been plagued with lifepo4 charger failures, related to overheating at the output stages (60v and 48v). Ping has been very good about this and even gave me a replacement. My temporary solution was to use a lower amperage charger and monitor the heat. Last month, I decided to replace the Signalab BMS on my 48/20 pack as it was also running hot. Suddenly everything is cool as a cucumber. Hmmm....
Could faulty BMS's be leading to premature charger failures? Seems to be a lot of them. Going to check the BMS FETs

 

[dogman dan]

That sounds plausible to me. Wasting heat into the bms is making the charger run harder.

But, it's got a pot inside that limits the amps. Tweaking that back down to where your charger is putting out 350w max for the 48v 5 amp version should be within the spec that the charger can run at for years.

Since my chargers have been so reliable for so long, I'm inclined to just suspect the real problem is the same old one. One batch of chargers gets parts that are good, another batch gets crap counterfeit ones. China. Even with the bms acting up, I think your chargers should have still been able to put out spec wattage indefinitely. But don't, with just one bogus part inside.

 

[kokopelli314]

.... it's got a pot inside that limits the amps. Tweaking that back down to where your charger is putting out 350w max for the 48v 5 amp version should be within the spec that the charger can run at for years.

Thanks Dogman. I'll try this.

 

[dnmun]

can you post up a picture of the charger so we know what you are talking about? did you measure the charging current and voltage? does it not charge the battery now and which mosfet was getting hot?