Lipo problems

[AlbaRC]

Ok, so I'm running a Kraton 6s EXB and it's developed a weird problem. Lipos keep "losing" cells.

The electronics are a Hobbywing max8 ESC and Corally Kuron 825 2050kv motor. Lipos that have lost cells are 2x Zeee 3s 60c 6000mah and 1x gens-ace-r-spam bashing 3s 50c? 5500mah.

The first battery I noticed this on was a Zeee, it was when I went to charge it and the charger only recognised it as 2s, tried different chargers and battery checkers and they all showed the same. I put this down to bad luck and discarded the lipo. Took the rig out that day with the gens-ace-r-spam and after about 30 seconds it to failed in the same way, I put this down to coincidence and bad luck. Now here is the weird part, had the rig out yesterday and the run times were significantly shorter. Checked the lipos after the run and one cell in another Zeee was down to 2.1v and by the time I got home the cell was gone, charger not picking it up.

3 lipos failing the same way can't be coincidence so I'm suspecting a fault with the max8.

Another thing that might be connected to this. The original Hobbywing 2200kv motor failed a couple of months ago (magnet shattered), replaced that with a racestar 1700kv motor that was lying around, that failed too a month later (overheated, windings burnt). The Kuron motor is brand new and is performing well. Does this sound like all roads point to the ESC?

Does anybody have any insight or similar experiences?

 

[Xjeepguy]

Ok, so I'm running a Kraton 6s EXB and it's developed a weird problem. Lipos keep "losing" cells.

The electronics are a Hobbywing max8 ESC and Corally Kuron 825 2050kv motor. Lipos that have lost cells are 2x Zeee 3s 60c 6000mah and 1x gens-ace-r-spam bashing 3s 50c? 5500mah.

The first battery I noticed this on was a Zeee, it was when I went to charge it and the charger only recognised it as 2s, tried different chargers and battery checkers and they all showed the same. I put this down to bad luck and discarded the lipo. Took the rig out that day with the gens-ace-r-spam and after about 30 seconds it to failed in the same way, I put this down to coincidence and bad luck. Now here is the weird part, had the rig out yesterday and the run times were significantly shorter. Checked the lipos after the run and one cell in another Zeee was down to 2.1v and by the time I got home the cell was gone, charger not picking it up.

3 lipos failing the same way can't be coincidence so I'm suspecting a fault with the max8.

Does anybody have any insight or similar experiences?

Check the wiring to the balance plug on your charger. Maybe it’s not picking up the cell because it doesn’t know it’s there.

 

[AlbaRC]

Check the wiring to the balance plug on your charger. Maybe it’s not picking up the cell because it doesn’t know it’s there.

Checked the lipos on 3 different chargers and a battery meter/checker. All showing same result

 

[Xjeepguy]

Checked the lipos on 3 different chargers and a battery meter/checker. All showing same result

That’s really weird. I guess your ESC is the only other related component that could be causing the issue. But it is strange that it’s only affecting one cell.

 

[morrjr71]

If your cells are down to 2.1, then the LVC isn't working properly; it isn't enabled at all; or you have it set too low. There's no way a cell should get that low unless one of the three things above are occurring. Did you notice LVC kicking in before you checked the voltage?

 

[AIan]

Or did it get really slow but you kept running till it stops kind?
I usually top around 3.1-3.2 volts per cell

 

[AlbaRC]

If your cells are down to 2.1, then the LVC isn't working properly; it isn't enabled at all; or you have it set too low. There's no way a cell should get that low unless one of the three things above are occurring. Did you notice LVC kicking in before you checked the voltage?

Yeah, lvc kicked in. The other 2 cells were at 3.8v and the other lipo was showing all 3 at 3.8v so I'm assuming the bad cell brought the average down to lvc.

 

[AIan]

huh weird
Sry I don’t know en about lipo’s to be of more help

 

[AlbaRC]

Or did it get really slow but you kept running till it stops kind?

Lvc seems to be operating properly, I had a pair of Abisma 3s 7100mah packs through the rig just before the Zeee packs and it cut off perfectly (although the run time was way shorter than usual)

 

[AIan]

Did you mix batteries? Like 2different 3s brands to run 6s?

 

[AlbaRC]

Did you mix batteries? Like 2different 3s brands to run 6s?

No, my lipos are always run in the same pairings from new

 

[AIan]

I’ll post if I find something or think of something else

 

[Sandracer_NL]

About a month ago I thought two almost new lipo's (2 or 3 runs) were dead, since they both lost 1 cell; charger was sounding alarm it could not start charging. As already mentioned by @Xjeepguy the balance plug in my charger was not fully plugged. After plugging it correct everything was OK.

I had one (oldest) lipo die on me about a half year ago. After gearing up way too much and putting much bigger and heavier tires on my car it just stopped after about a minute or so. Three cells were 4.1v and one cell was 2. something volts. Did try to revive the lipo (storage charge - real slow charge), but didn't help. Thanked the lipo for services performed the last two years and bought new ones.

If you bought the two Zee's together and have about the same runtime with it I could understand they going bad at about the same time. But a third AND a different brand the next day as well...

When you say your charger does not pick up one cell I'm thinking the charger is not properly balance charging the cells. If you lipo is already under the LVC threshold at the start, LVC does no longer work. Balance charge a lipo and check with a lipo checker (battery meter) the results of the individual cells between the readings of the charger and liopo checker.
If you can rule all that out I'd say it's the esc (LVC no longer working?)

 

[AlbaRC]

About a month ago I thought two almost new lipo's (2 or 3 runs) were dead, since they both lost 1 cell; charger was sounding alarm it could not start charging. As already mentioned by @Xjeepguy the balance plug in my charger was not fully plugged. After plugging it correct everything was OK.

I had one (oldest) lipo die on me about a half year ago. After gearing up way too much and putting much bigger and heavier tires on my car it just stopped after about a minute or so. Three cells were 4.1v and one cell was 2. something volts. Did try to revive the lipo (storage charge - real slow charge), but didn't help. Thanked the lipo for services performed the last two years and bought new ones.

If you bought the two Zee's together and have about the same runtime with it I could understand they going bad at about the same time. But a third AND a different brand the next day as well...

When you say your charger does not pick up one cell I'm thinking the charger is not properly balance charging the cells. If you lipo is already under the LVC threshold at the start, LVC does no longer work. Balance charge a lipo and check with a lipo checker (battery meter) the results of the individual cells between the readings of the charger and liopo checker.
If you can rule all that out I'd say it's the esc (LVC no longer working?)

Thanks for the reply. I've definitely ruled out the charger as it works fine with my other lipos. Separate battery checker too. My instinct is telling me the ESC is drawing to much current somehow, although I would have thought a max8 would have some kind of failsafe against this? It's got me puzzled for sure.

 

[Sandracer_NL]

Thanks for the reply. I've definitely ruled out the charger as it works fine with my other lipos. Separate battery checker too. My instinct is telling me the ESC is drawing to much current somehow, although I would have thought a max8 would have some kind of failsafe against this? It's got me puzzled for sure.

The Max8 should be able to handle that Kuron 2050kv motor.
I see you added you burnt up two motors prior to the Kuron motor. It looks like you (the motor) are pulling too much amps. Over you (way) overgeared, run bigger/heavier tires compared to stock, have binding in your drivetrain (gear mesh, diffs), have bad bearings?

 

[Velodromed]

Make sure one of the small balance wires isn’t broken. I’ve had that happen a couple times.

 

[AlbaRC]

The Max8 should be able to handle that Kuron 2050kv motor.
I see you added you burnt up two motors prior to the Kuron motor. It looks like you (the motor) are pulling too much amps. Over you (way) overgeared, run bigger/heavier tires compared to stock, have binding in your drivetrain (gear mesh, diffs), have bad bearings?

It's running 16t pinion with stock spur, backflip lp's and the drive train is running free. I've actually got a V5 Kraton that's M2C beefcaked running stock firma electronics and a 17t pinion that runs sweet so I presume the lighter EXB is easier on the electronics and lipos. I'm usually good at fault finding too, this one has me completely stumped.

Make sure one of the small balance wires isn’t broken. I’ve had that happen a couple times.

Yeah, I've checked over all the wiring, looks ok.

 

[RCbuzz]

Sounds like some bad battery luck!

 

[AlbaRC]

Sounds like some bad battery luck!

Yeah, sure is. Guess I'm just trying to find if there's a cause before getting new ones.

 

[Camaroboy383]

I find it quite odd that only one cell per pack has dumped off.. The esc doesn't differentiate cells.. as far as the esc knows, it's one cell.. it just counts off cells based on total voltages...

A lvc that doesn't work isn't going to pick on one individual cell of the pack, it will drain them all.. so, something isn't adding up here.. what were the other cell voltages?