Spektrum Battery Cell 1 Stuck @ 3.95 Vdc

[FriedOne]

Hi Guys,
I already posted a thread about my new Spektrum battery not charging all 4 cells to 4.20 Vdc. I have already reached out to my retailer who asked me to contact Horizon. Who knows how long this process is going to take with Covid and all. I was wondering if anybody experienced an issue like this. Is there a way to get the cell to bounce back. Charger's charging current stays as low as 0.4 amps when set to charge @ 5.0 Amps on port 1.
Any ideas ?

 

[SrC]

Perhaps a cell that is no good. R U using both smart battery and smart charger??? Balancing takes awhile at the tale end of the charge cycle. and usually drops down the charge rate to accommodate balancing all the cells. Balancing can take much time if one cell is not as good as the rest. Use a volt meter to test the volts of each cell. Or use a Lipo testor to do the same. Compare it to what the charger states for resting volts. That's a start. When speaking to HH on the phone, having those numbers helps your position and shows you are educated enough to understand that there is an issue. Just some food for thought.

 

[FriedOne]

Perhaps a cell that is no good. R U using both smart battery and smart charger??? Balancing takes awhile at the tale end of the charge cycle. and usually drops down the charge rate to accommodate balancing all the cells. Balancing can take much time if one cell is not as good as the rest. Use a volt meter to test the volts of each cell. Or use a Lipo testor to do the same. Compare it to what the charger states for resting volts. That's a start. When speaking to HH on the phone, having those numbers helps your position and shows you are educated enough to understand that there is an issue. Just some food for thought.

Hi SrC,
Thanks for your response. Yes I'm using both , smart charger Spektrum S2100 and Spektrum 4S 5000 mAh 100C batts. I always plug in the balancing leads as well. I know the charging current drops down to the end of the cycle. I knew something was not right when the charge rate did not increase to the set rate of 5 amps.
I have a feeling the cell could have gone bad as it does the same thing on the second port. I don't think I could measure each cell with a volt meter but all cells as one. I don't have a lipo tester. I just plugged this battery into my charger. Wanted to see if anything has changed. Only difference is that it went a bit higher up to 2 amps then dropped down to 0.4 amps. I have this battery set to auto discharge to 3.8 v
When plugging it in it was showing cell 1 @ 3.93 and the remainder of the cells @ 4.19v. Battery last charged on Sunday and did not use it.. I would have expected it to all be at 3.80 volts at the set storage voltage.

 

[SrC]

You will get a parasitic loss with cells as they get old. And in general lipos resting voltage will drop over a lengthy time. But should not be as much as you state for the short duration that you are talking. Inquire with HH about a Replacement battery. One cell should not fall off that much. Can your charger check the Internal resistance of your cells for comparison.

 

[jkflow]

Can you take a picture of your balance plug with wires?
Only other idea, besides a bad cell, is a bad wire/pin on the balance plug.

Just curious, why are you not letting the charger balance the pack or does it refuse to do anything?
No, that will never happen at 5A but that is normal. It should balance within 30-45min. Use the balance mode.

You can do this in standard charging mode and just let it go at it, maximum of ~ 1h I'd say and it should be very close.
If not, than you truly have an issue. Don't charge this one unattended and preferably in a fire safe environment.

 

[SrC]

These smart lipos do a self discharge to 3.8v per cell after a preset length of time of being fully charged if I am correct. Those parameters can be adjusted. You probably know this already. They do discharge very slowly perhaps not all at the same rate? Try balancing them again manually.

 

[matty]

I believe that with the S2100 you can set the time period before auto discharge begins to as high as 240 hrs, with the default at 48 hrs - and the discharge rate will likely be fairly slow (though I can't easily find an exact number online). If the battery started to self-discharge after 48 hours, then that wouldn't have been until Tuesday. I believe that the unwanted charge needs to be converted to heat by the self-discharge circuitry, and we're talking decreasing 0.4V per cell, or 1.6V for a 4S battery. That conversion would need to happen slowly so as to not generate enough heat to damage the battery, and "slowly" may actually mean that it takes several days to go from 4.2V per cell to 3.8V per cell. If that is indeed the case, your batteries may take as long as a week to self-discharge to the storage level.

Not sure about the balance issue. Leave it in balance mode on the charger for a bit? If you're still having issues, I believe that Spektrum warrantees their batteries for a year.

 

[FriedOne]

Thanks Guys for all your responses. I got a response from Horizon. I was told that the battery is fine. Because three cells were at 4.2v and 1 @ 3.95v the charger will not charge at 1C which I had mine set to. He said that it will automatically revert to a trickle charge 0.4 amps in my case.The charger is not needed to charge at the 1C rate of 5 Amps. He said to just leave it on the charger and it will eventually balance charge up to 4.2 Vdc. I followed his advise and it did come back up to voltage.

 

[SrC]

The word "trickle" charge is not a good analogy or term if HH told you that. Trickling only occurs with other types of non Lithium batteries/cells. 1C charge rate is the industry standard for charging any lipo. 0.4 amps is a fraction of 1C. 0.4 may/should occur during Balancing at the tail end of the charge cycle. 0.4 is not a trickle rate per se. If I am wrong hopefully someone wil correct me. If your Smart setup is charging/discharging/balancing and doing what its supposed to, then all is good. No user intervention should be needed. I agree. There is not much to read into this being a Smart lipo/Smart charger. Good luck.

 

[jkflow]

Correct, a trickle charge for a Lipo (going by definition) would be fatal for a Lipo.
A trickle charge was originally meant for Lead acid batteries to maintain their level while not in use (winter storage etc).

Don't ever buy a trickle charger for Lipo's.

 

[SrC]

Even trickling LA batteries is frowned upon for extended periods, these days. Maintainers are now used for long term and short term charges. Nims and Nicads were supposedly trickled for RC use back in the day. But it was frowned upon because you were dealing with memory issues with Nickel based cells. Charge slow and your discharge will be slow. Charger fast and dump fast. Trickle charging saturates LA cells too much without any cutoff.
Lipo+ trickling =a bad day. I can picture a newcomer to RC making that mistake. Thinking he can use his 12v car's charger.....
don't be that person.

 

[FriedOne]

Finally got this issue resolved. I had new battery that turned out to be bad. The difficult thing in troubleshooting my issue was that my smart charger
did not pick up on the bad cell. It would charge the battery and give me the blue screen to show that charging is complete. It would also show me a voltage that the cells were all within spec but in truth it was not. I picked up a cell checker and this showed a very big discrepancy in the voltages.
One cell was only reading 2.51Vdc. Returned it to my retailer and they checked it out and replaced the battery. Went out twice now without any issues. My charger has been working pretty good with the new battery. Both batteries charging as it should and so far all voltages are spot on.