BATTERY PROBLEMS

[MARK???]

I moved the watt meter to where I could see it whilst riding & even though the battery reads as 41.2V fully charged it draws down power really quickly so within minutes the watt meter is reading 35V or less. Then after giving the battery a rest the power reading goes back up to just under the original fully charged reading. Is this normal ??? I don't know ! So since I thought something was wrong I decided to open up the battery pack again to see what was wrong. Well I don't know there's anything wrong but something was right. The battery was still balanced so what does all this mean ???. The BMS seems to be working so why does the battery cut out under load & drain its power so quickly. The in line fuse has a number 5 on it so does that mean 5A & that makes no sense to me. Shouldn't it be the same as the battery rating of 12A if the battery is 12A ???. Hope you can help MARK???.

 

[dnmun]

the 5A fuse is on the charging circuit.

can you measure the cell voltages under load?

can you charge it up fully, measure the cell voltages when it gets up to fully balanced and then put it on a dummy load using electric toasters and electric heaters without fans that can be used on the DC current and then watch the cell voltages as the battery discharges and see if you can find the cell that goes down to the LVC first and cuts off the BMS.

 

[MARK???]

I'm having problems with the recharging again. I balance out the cells then put it on to recharge but had the same problem of the fist cell in the pack going to a higher charge than the rest before the charger light went to green. So I went back to the IMAX B6Ac charger to increase the Voltage in the lower charged cells. What does this mean, the screen goes from LiPo 1.8A 3.7V to the checking battery screen then to another screen saying Li1S then an Amp reading that had started at 1.8 A but I can now see it reducing over time, now that the voltage has reached 4.20V. Am I supposed to wait till the Amps fall to 0 ???. Can someone please tell me what's happening. HELP!!! MARK???.

 

[MARK???]

Well after 5 Hours+ stuffing around, recharging & re-balancing the battery. The problem has gotten worse. Its like there's a hole in a bucket that drains out faster than it can be filled but if you stop the hole it will fill up again. MARK???.

 

[dogman dan]

Yes, good description of what it's like when you have one or more dead cells in a pack. They charge too fast, then won't hold the charge. Under load, sag like crazy.

There is a method for measuring each cells internal resistance, You tube has many tutorial videos on how to do it. You'll find all the cells have high resistance, and perhaps one really sucks.

 

[dnmun]

I'm having problems with the recharging again. I balance out the cells then put it on to recharge but had the same problem of the fist cell in the pack going to a higher charge than the rest before the charger light went to green. So I went back to the IMAX B6Ac charger to increase the Voltage in the lower charged cells. What does this mean, the screen goes from LiPo 1.8A 3.7V to the checking battery screen then to another screen saying Li1S then an Amp reading that had started at 1.8 A but I can now see it reducing over time, now that the voltage has reached 4.20V. Am I supposed to wait till the Amps fall to 0 ???. Can someone please tell me what's happening. HELP!!! MARK???.

i did already explain what happened. it is hard to follow what you say. actual voltage measurements are what is needed to examine your pack from a distance.

if you can measure the cell voltages and have a watt meter then you can find the bad cell just like i walked you through before by discharging the battery through a dummy load.

like i said, the cell that has the highest internal resistance is the one that will show the biggest voltage drop when discharging. it will have the least capacity also so when discharging through the watt meter you can see how much capacity it has when that cell reaches the LVC and turns off the BMS. if you replace the worst cell then you can see how much capacity you still have in the remaining cells. it may be enuff for you to get some use from the pack.