FYI........... Do So At Your Own Risk

[arrmadillo]

I had a 3s lipo that was run on nimh mode and went to lvc somewhere around 2.65 V per cell. Would not charge on lipo mode so put it in nimh mode. Once the cells got to 3.0 per cell, it would charge on lipo.

 

[Kla912000]

I had a 3s lipo that was run on nimh mode and went to lvc somewhere around 2.65 V per cell. Would not charge on lipo mode so put it in nimh mode. Once the cells got to 3.0 per cell, it would charge on lipo.

I just got done reviving my battery that I thought was dead, til I read your earlier posts. I used the NiMH mode til the voltage was high enough to charge and balance in Lipo mode. Worked perfectly.

 

[arrmadillo]

I just got done reviving my battery that I thought was dead, til I read your earlier posts. I used the NiMH mode til the voltage was high enough to charge and balance in Lipo mode. Worked perfectly.

Glad it worked for you, beats throwing a lipo away. Mine was puffed to hell. Let it sit for a day and all the puffing went away, so did the trick and still performs like before.

 

[Kla912000]

Glad it worked for you, beats throwing a lipo away. Mine was puffed to hell. Let it sit for a day and all the puffing went away, so did the trick and still performs like before.

Thanks for posting the info that you did. I thought my battery was toast. I mistakenly let the fans run to cool off motor and ESC after the rig hit LVC and the voltage went low enough that my charger wouldn't charge in lipo mode. Never thought of using NiMH mode til I read this thread. Battery balanced perfectly.

 

[jkflow]

Lots of different scenarios going below 3V impact your chance of recovery. Having a low load doesn't stress the battery as much compared to running it with a motor. Less heat is less stress, hence you see a lot of variability on success. Add the different lipo manufacturers to that mix.

 

[Greywolf74]

Lots of different scenarios going below 3V impact your chance of recovery. Having a low load doesn't stress the battery as much compared to running it with a motor. Less heat is less stress, hence you see a lot of variability on success. Add the different lipo manufacturers to that mix.

Success to me is a relative term also. Just because you can make something technically work again does not mean you repaired it. Without being able to see the IR of the cells you have no idea how badly or how mildly the cells were impacted. Its like having a heart attack and they shock you back to life and you go around telling your friends that the Doc fixed you up good as new. I mean I know you understand this but after experiencing a LiPo fire years ago on a 6S LiPo because of a cheap chinese charger that went bad. I get really worried when I see people talking about things like this or buying cheap junk chargers.

 

[Spoc85]

I have a 3S pack that has been in storage for a couple of weeks, but now it doesn't charge because 1 cell is now at 1.5V. The other two cells are OK

Is that single cell too low to try the NiMH trick? I am interested to try it if can save the pack, but I'll follow the AF experts if they think the pack is dead. I think it doesn't look good if the voltage of one cell is so far from the two other.

Thoughts?

Post a pic of the voltages.

 

[Greywolf74]

Post a pic of the voltages.

He already said what the cell voltages were. Not sure what good a pic is going to do?

 

[FlipSide]

He already said what the cell voltages were. Not sure what good a pic is going to do?

Yep!
2 cells at storage voltage, one at 1.56V.

 

[Ben&Sons]

Hi all, been reading this thread and although not identically related, thought I’d reach out with my issue.

my overlander 2s lipo, hard case has stopped balance charging. Its less than 6 months old Max. Have SkyRC t100 dule charger, same age. I’ve swooped charging ports and balance cables around so fully narrowed down to the battery. Charger states ‘balance cable not connected’ when set to charge.

question: assuming this is a loose balance cable connection within the battery, can these hard cases be opened up and can the connection be re-soldered?

or; can the battery be returned in this hobby?

 

[Kla912000]

Hi all, been reading this thread and although not identically related, thought I’d reach out with my issue.

my overlander 2s lipo, hard case has stopped balance charging. Its less than 6 months old Max. Have SkyRC t100 dule charger, same age. I’ve swooped charging ports and balance cables around so fully narrowed down to the battery. Charger states ‘balance cable not connected’ when set to charge.

question: assuming this is a loose balance cable connection within the battery, can these hard cases be opened up and can the connection be re-soldered?

or; can the battery be returned in this hobby?

I personally don't have enough experience in soldering to take apart a LiPo battery and repair it. Soldering battery connectors on is one thing but I wouldn't tear it apart and attempt a repair like that. If it was me, I would just pitch the bad battery and buy a new one. They aren't that expensive.

 

[jkflow]

Yes, you could carefully open the case. Make sure that you do not puncture the Lipo inside. You can throw the case away or re-tape with duct tape or similar. Frequent failure point is where the wires exit the hard case, that's why I dislike them a lot.
I'd check the outside connector for corrosion or similar, frequent offender.

You would have to check your manufacturer if they offer any returns or warranty, typically they do not or have it very limited.

https://www.arrmaforum.com/threads/lipos.23532/

 

[Ben&Sons]

Cheers Kla & JK...if I manage a repair I’ll take a pic and post what I did but no doubt I will pussy out and get a new one...!!

just sucks as it’s only had say 20 cycles

read a lot on hard V’s soft case and consensus was hard if your jumping/ bashing then soft if racing due to abuse levels. Do you guys have different opinions?

sorry....not trying to trash the original thread here!

 

[jkflow]

I bet, the opinion on this forum is that hardcase is not recommended at all, but don't want to speak for everyone.
In my opinion, hardcase is actually worse for bashing etc. very unforgiving and the wires get damaged at point of exit. I have 2 hardcase and swapped to all soft case ever since and never looked back. Add some duct tape on the outside to prevent scratching etc. but that's about it.
Stay with cheaper Lipos for bashing, check the Lipo thread.

 

[Kla912000]

Cheers Kla & JK...if I manage a repair I’ll take a pic and post what I did but no doubt I will pussy out and get a new one...!!

just sucks as it’s only had say 20 cycles

read a lot on hard V’s soft case and consensus was hard if your jumping/ bashing then soft if racing due to abuse levels. Do you guys have different opinions?

sorry....not trying to trash the original thread here!

Good luck. Hope it goes well.

 

[Spoc85]

Yep!
2 cells at storage voltage, one at 1.56V.

Let’s see it…….. not hard to post a pic.
Resistances too.

 

[Spoc85]

Cheers Kla & JK...if I manage a repair I’ll take a pic and post what I did but no doubt I will pussy out and get a new one...!!

just sucks as it’s only had say 20 cycles

read a lot on hard V’s soft case and consensus was hard if your jumping/ bashing then soft if racing due to abuse levels. Do you guys have different opinions?

sorry....not trying to trash the original thread here!

If I was racing other cars I would run a hard case battery………. There’s a high chance that the vehicles are going to collide into each other and if the stars align it’s possible to puncture a Lipo.

 

[Greywolf74]

Hi all, been reading this thread and although not identically related, thought I’d reach out with my issue.

my overlander 2s lipo, hard case has stopped balance charging. Its less than 6 months old Max. Have SkyRC t100 dule charger, same age. I’ve swooped charging ports and balance cables around so fully narrowed down to the battery. Charger states ‘balance cable not connected’ when set to charge.

question: assuming this is a loose balance cable connection within the battery, can these hard cases be opened up and can the connection be re-soldered?

or; can the battery be returned in this hobby?

You can but its not easy and i don't recommend it for anyone whos not well versed in LiPos, soldering, and has the correct tools to check IRs etc to determine if the repair is even worthwhile. The hard cases can be incredibly hard to remove though and typically the cells inside are glued or taped to the insides of the hardcase. First 2 or 3 times I tried to open a hard case I messed up the cells inside just trying to figure out how to remove the case without damaging the stuff inside.

I personally don't have enough experience in soldering to take apart a LiPo battery and repair it. Soldering battery connectors on is one thing but I wouldn't tear it apart and attempt a repair like that. If it was me, I would just pitch the bad battery and buy a new one. They aren't that expensive.

He makes a good point. Especially for 2S Lipos

 

[jkflow]

If you decide to pitch, discharge to 0V. Nothing else needs to be done if you do that.

 

[ARRMA King]

Didn’t bother reading all the wrong ways of risk on this but here’s the proper way of doing this:

1st if one cell is that low relative to others pack is now mismatched with a runt cell and you’ll always have long or out of balance charge times due to the incredible high IR of that cell. Reviving it is only a stop gap as this life cycle is now down hill.

2nd overcharging the other cells at the expense of an already bad cell, oh the irony!

Take a male Futaba plug or any pin that fits to the low cell ON the JST balance tap (find out with multimeter) and bring that low cell up on NiMH slowly and physically stay there to watch it cross 2.6-2.8v. Then you can switch it over to regular lipo mode to let it catch up with the other cells so to speak. No need to let things go that far on nickel mode, smh!

Bad practices like this is why lipos get a bad rap.