I should've read this forum before I bought my battery from sun-

[elmobob]

ok took it out for 3 mile ride, no problems, battery meter stayed full got back and voltage was still at 40.

My previous bike kit was a bionx 350watt I got around 2008, this generic 500w motor kit has a bit less low end torque but much better high end and top speed, I hit 23mph with very light pedaling on a flat. Taking it to work tomorrow 13 miles for an extended test.

 

[dnmun]

keep charging. it takes time for it to get balanced. that is when you can get the maximum range.

 

[dogman dan]

Badass Dnmun! I noticed a bad looking solder at that point immediately, but I'm too ignorant to know what is going on there.

Equally badass elmobob, to be able to pinpoint the area with the problem, and see the solder bridge. You are on your way now, just keep it on the charger all night for a week or so, or till you confirm that you are getting a full and balanced charge. All cells to at least 3.5v-3.65v.

A thread like this is what makes this forum great. The reality is, we have to fix this stuff ourselves and the forum helps it happen. You do have to filter out a few helpful comments that don't lead towards a fix though.

Still totally sucks that this battery passed inspection!!!! But also worth noting that sunthing is sending another bms. At least he sends you a part that could help, much like ping would.

 

[dnmun]

what happened here is that the big wire that was soldered to the surface of the pcb was ground and when it was soldered part of it was hanging over the trace which carries the gate voltage signal for the charge mosfet. so it would charge, maybe, initially and then after vibration or maybe just time sitting there squeezed inside the shrink wrap the big wire finally wore through the plastic film on top of the gate trace.

then when he wiggled it while pulling on the sense wire plug, the gate was 'unshorted' so the mosfet would turn on and then the charger would charge. so it helped that he did that while he was charging the battery.

that's why i thought it would help if he moved the power lead.

 

[StudEbiker]

Great work dnmun! 8)

 

[dnmun]

not me that did it. this guy did it himself and had to overcome alotta obstacles on the way.

i know how they work so it is easy to diagnose but when they are a black box it is difficult to manage how to approach it as a problem that has to be fixed.

which is what you need to be self reliant so you don't get stranded by electrical problems.

 

[dogman dan]

Still, your staying with the guy led him through to solving it himself. I guessed right too, that it must be a bms issue, but that was pure guess.

But we rely on you to look at one and say this is where to look. Your patience with him helped as well. I share your frustration with some of these guys.

 

[elmobob]

Did 17 miles on the bike today with little pedaling and still had charger left. 8)

Yea, to be honest I was scared to open up the battery, I imagined it being sensitive and overly complex with too many wires that I wouldn't be able to put it back properly, turned out not at all. I had a bad experience once taking an Iphone apart trying to replace the LCD glass and it proved to be beyond my patience. Anyways, dnmun he kept insisting and he was replying quick to the posts so I felt comfortable. Thanks

 

[bachmaninoff]

That's awesome that you were able to fix this!

I also have 25ah battery (but 48V) that has stopped charging yesterday (looks like the same BMS). Tried two different chargers, lights up red and green on both. Voltage on battery reads 47V with a multimeter (has been 57V fresh off the charger up until yesterday). Plugging it into the bike nothing turns on (CA, lights - so I'll have to test that with a different battery to ensure those things didn't fry). Most of the voltages off the BMS are around 3.5, but there's one pair where I can't get a solid reading on it, so possible bad cell there. A couple of times I thought it went from 6~ish V then went down quickly. Worked great up until yesterday, putting 1200+ miles on my KMX. The plan tonight is to do a detailed walk-through of troubleshooting efforts with pics.

 

[dnmun]

you should start your own thread and we need to know who made the battery and pictures of the battery and BMS to show you where to measure.

 

[bachmaninoff]

Indeed I shall thanks:

http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=64888