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defective charger ?

sundown57

Well-known member
#1
ok in the last few months I have gone through 5 new lipo batteries . 4 were 850 MAH Tattu 3s and 1 2200Mah zippy 3 s. Being a newbie I kinda blamed it on my self . maybe ran it too low. didn't store it right, whatever. But now I've noticed a pattern. it seems on everyone it's always the center cell that fails. so my question now is could I have a faulty charger? I have 2 chargers, one is an Imax B3 the other is an Imax B6. but I'm sure I have put all 5 batteries on both chargers. so if one was defective could it damage the battery?
 

ElectriSean

Eternal Student
Mentor
#2
Check the voltage of fully charged packs from both chargers with an independent meter. If they aren't very closely balanced at full charge, your charger is having problems. Having the center cell fail first is common as it is exposed to much less air and heats up more, especially if you are drawing too much current or discharging it too far.
 

The Hangar

Well-known member
#3
I use the venom pro duo, and it shows me the voltage of the individual cells. Do your chargers show this? As far as running the batteries go, try to not run the voltage of each cell under 3.8 volts. That way your battery should last longer and plus, you wont have any dead stick landings, which are always a pain.
 

sundown57

Well-known member
#4
Check the voltage of fully charged packs from both chargers with an independent meter. If they aren't very closely balanced at full charge, your charger is having problems. Having the center cell fail first is common as it is exposed to much less air and heats up more, especially if you are drawing too much current or discharging it too far.
I have checked them. 4.20, 3.80, 4.20. I also have the beeper that you put on the plane when flying and it shows the same. but i have it set to beep at 3.4. however, it has never gone off, mainly because I haven't learned to fly that long yet
 

sundown57

Well-known member
#5
I use the venom pro duo, and it shows me the voltage of the individual cells. Do your chargers show this? As far as running the batteries go, try to not run the voltage of each cell under 3.8 volts. That way your battery should last longer and plus, you wont have any dead stick landings, which are always a pain.
yes. the B6 shows each cell
 

ElectriSean

Eternal Student
Mentor
#6
I have checked them. 4.20, 3.80, 4.20. I also have the beeper that you put on the plane when flying and it shows the same. but i have it set to beep at 3.4. however, it has never gone off, mainly because I haven't learned to fly that long yet
If all your meters agree, I doubt the charger is at fault.
 

ElectriSean

Eternal Student
Mentor
#8
they do agree. and I believe it is accurate. my concern is that it was the charger that caused all the batteries to go bad in the first place.
The charger doesn't charge each cell individually, it charges all 3 in their series configuration, meaning they all get the same amount of current. Balancing is done by discharging the higher cells through the balance leads, so it can't really overcharge just one cell unless it's measurements are all out of whack. Because your meters agree, I don't think that's the case. Overheating causes the internal resistance of a cell to increase, making it take longer to charge, or be unable to charge at all past a certain point in really bad cases. Because the middle cell sees more heat and dissipates less, it usually fails first. Keep them cool. Hot cars are the worst, I've had brand new packs puff like mad after 4-5 hours.
 

sundown57

Well-known member
#9
I just bought the 2200 . I've only used it like 4 times. Never left it in a car or anything like that. But yeah this is getting expensive not knowing what I'm doing wrong.
 

ElectriSean

Eternal Student
Mentor
#10
I just bought the 2200 . I've only used it like 4 times. Never left it in a car or anything like that. But yeah this is getting expensive not knowing what I'm doing wrong.
Are you balance charging? Some chargers have a straight charge option that should be avoided, make sure you're using the balance charge mode.
 

Wildthing

Well-known member
#12
Set your battery alarm to 3.8V or even 3.9V , 3.4 is way to low.
Are the batteries warm or hot after a flight? Are the puffy at all?
Do you let your batteries rest after each flight? I like to let mine sit for 15 minutes minimum.
How many amps is your charger set at for charging?
 

FDS

Well-known member
#13
The individual cell voltages should be within 0.1v of each other. The 4.2, 3.8, 4.2 pack is out of balance enough that I would try and rebalance it and it would be getting watched every flight.
Somewhere you have a problem with your battery management, either you are over loading the cells or the charger is not doing it’s job, you shouldn’t get them out if balance like that. I have some packs that are several years old and still balance to +/-0.1v
Do your ESC’s have battery protection? Many fixed wing ESC’s cut the throttle or blip if the voltage drops even momentarily to 3.5v. This has saved my small packs a few times where it was cold and my timer showed I had some gas left but the battery capacity had dropped with the temp.
 

sundown57

Well-known member
#14
Set your battery alarm to 3.8V or even 3.9V , 3.4 is way to low.
Are the batteries warm or hot after a flight? Are the puffy at all?
Do you let your batteries rest after each flight? I like to let mine sit for 15 minutes minimum.
How many amps is your charger set at for charging?
i have never felt them warm and they are not puffy, As for letting them rest Yeah because usually, I crashed so it rests for a few days till i build another one. as for charging. I charge the 850 at.8 and the 2200 at 2.2. I will change the beeper to 3.9. thanks
 

sundown57

Well-known member
#15
The individual cell voltages should be within 0.1v of each other. The 4.2, 3.8, 4.2 pack is out of balance enough that I would try and rebalance it and it would be getting watched every flight.
Somewhere you have a problem with your battery management, either you are over loading the cells or the charger is not doing it’s job, you shouldn’t get them out if balance like that. I have some packs that are several years old and still balance to +/-0.1v
Do your ESC’s have battery protection? Many fixed wing ESC’s cut the throttle or blip if the voltage drops even momentarily to 3.5v. This has saved my small packs a few times where it was cold and my timer showed I had some gas left but the battery capacity had dropped with the temp.
Umm. I have no clue. the Esc is a (4X 30A Speed Controller ESC Simonk Firmware) i bought off ebay, here is the link https://www.ebay.com/itm/4X-30A-Spe...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

I really do suspect the charger. I bought it from banggood as a genuine Imax but then when i get it I found out is a cheap knock off.
 

basslord1124

Well-known member
#16
I'd monitor the cells during a charge rather than wait til the end to check. I would say your charger should let you be able to do that. I'm wondering if you might just have to run a few charge and/or discharge/storage cycles (without running them in your planes) to get them to balance better. Switch to your other charger and see how it does there. Do you have anything other than 3 cells...like a 2 cell or 4 cell? That would be a good way to check too.
 

sundown57

Well-known member
#17
I'd monitor the cells during a charge rather than wait til the end to check. I would say your charger should let you be able to do that. I'm wondering if you might just have to run a few charge and/or discharge/storage cycles (without running them in your planes) to get them to balance better. Switch to your other charger and see how it does there. Do you have anything other than 3 cells...like a 2 cell or 4 cell? That would be a good way to check too.
I can try that, right now all i have is the 2200 with the bad cell and 1 brand new 850 that came in the mail today that im afraid to charge. I will put the 2200 back on the charger and set it to discharge and watch the cells . maybe it will come back. Like i say is only like 3 weeks old.
 
#19
I have checked them. 4.20, 3.80, 4.20. I also have the beeper that you put on the plane when flying and it shows the same. but i have it set to beep at 3.4. however, it has never gone off, mainly because I haven't learned to fly that long yet
From my experience it seems that you are not actually balance charging. You need to selected "BALANCE " mode on charger NOT "CHARGE", you should never see it that far out of balance (4.20, 3.80, 4.20).