Cell discharged to 0v

[currentFlo]

Hi everybody,
I left my battery pack stored for several months with no checking.
I recently measured the cell balancing and found that a string of 4 paralelled Turnigy 5s 20c had one cell at 0v !!
So I have 4 Turnigy packs with 1 out of 5 cells at 0v, I also noticed one of the packs is puffed.

What should I do with the puffed and not puffed packs, should I tryb recharging the 0v not puffed cells ?

Thanks for the advice.

Flo

 

[wesnewell]

You could strip the bad cells out and use what good cells you have left to make as many good packs as you can.

 

[izeman]

yes dispose the 0V cell and the puffed one, buy a new pack and take it's cells to replace the broken ones.
or buy a new 5s pack, and save the good cells of the old pack as spares. it's up to you

 

[currentFlo]

ok thanks very much for the advice so you confirm there is absolutely no way to use the not puffed 0v cell anymore ?

This make me think, these turnigy have very random quality... I may switch to 18650 for next projects

 

[izeman]

ok thanks very much for the advice so you confirm there is absolutely no way to use the not puffed 0v cell anymore ?

This make me think, these turnigy have very random quality... I may switch to 18650 for next projects

absolutely NO (safe) way. you could try charging that with 1/10c or 1/20c so 500mA for a 5000maH pack and watch it very closely. it may be possible to revive it, but it could just explode as well if something unexpected happens. it's just not worth the risk.
i tried charging 18650 cells (li-ion) which are safe more or less, but even those did not hold their charge.

 

[currentFlo]

ok I'll try to revive it in the garden, just for fun

 

[izeman]

ok I'll try to revive it in the garden, just for fun

bonne chance!

 

[dnmun]

if you were bulk charging with the this dead cell then you may have overvolted the other cells in the pack so the risk is in the other cells, not the dead one. you did not list the other cell voltages though so there must be a reason.

 

[currentFlo]

if you were bulk charging with the this dead cell then you may have overvolted the other cells in the pack so the risk is in the other cells, not the dead one. you did not list the other cell voltages though so there must be a reason.

Hi dnmun,
I always charge with hyperion 1420 with individual cell monitoring, so no bulk charging, other cells are around 3.9v so no problem with other cells I think...

Is it difficult to replace the 0v pouch in a 5s turnigy pack ?

 

[izeman]

easy? hard? depends on your knowledge. are you used to solder? do you have the right tools? then it's EASY.
if you've never used a soldering iron before: HARD.
but in case #1 is correct, this is the way i do it:

.) discharge as much as possible. the less energy there is in the cells the better! don't do this with fully charged cells!
.) remove the heat shrink, or hard case - whatever it's packed in. take GREAT care not to perforate the cells!! use care!
.) now remove the insulation (there is some damping foam lying on the solder pads)
.) you strictly want to avoid shorting the cells. so use some tape to cover the soldering pads you are not trying to open.
.) use a high power soldering iron (80w) to heat one pad, use a pump to remove the solder
.) take a small screwdriver to pry away the soldering tabs of the cell from the pads.
.) to be super safe once done, use some tape to isolate the tabs.
.) the individual cells are glued together. you have to pry them apart. but you don't want to use too much force. i use a little injection filled with glue solvent (eg paint thinner). let some drops go in between the cells, then use an old credit card to push in between. easy.
.) remove the broken cell
.) replace it with a new one.
.) solder the tabs, don't forget the balance wire
.) put some insulation on it and some heat shrink
.) DONE

i hope this did help. if you search this forum afair there somewhere is a video as well.

 

[neptronix]

A cell discharged to 0v is dead and dangerous if you charge it. This is how extreme lipo fires start. Take it out, never charge it again, and dispose of it properly.

Any other cell that is puffed is damaged and may be a danger in the future as well. Especially if it has been below 3v for a long period of time.

 

[currentFlo]

easy? hard? depends on your knowledge. are you used to solder? do you have the right tools? then it's EASY.
if you've never used a soldering iron before: HARD.
but in case #1 is correct, this is the way i do it:

.) discharge as much as possible. the less energy there is in the cells the better! don't do this with fully charged cells!
.) remove the heat shrink, or hard case - whatever it's packed in. take GREAT care not to perforate the cells!! use care!
.) now remove the insulation (there is some damping foam lying on the solder pads)
.) you strictly want to avoid shorting the cells. so use some tape to cover the soldering pads you are not trying to open.
.) use a high power soldering iron (80w) to heat one pad, use a pump to remove the solder
.) take a small screwdriver to pry away the soldering tabs of the cell from the pads.
.) to be super safe once done, use some tape to isolate the tabs.
.) the individual cells are glued together. you have to pry them apart. but you don't want to use too much force. i use a little injection filled with glue solvent (eg paint thinner). let some drops go in between the cells, then use an old credit card to push in between. easy.
.) remove the broken cell
.) replace it with a new one.
.) solder the tabs, don't forget the balance wire
.) put some insulation on it and some heat shrink
.) DONE

i hope this did help. if you search this forum afair there somewhere is a video as well.

thanks for the detailed explanation ! yes I have some experience with soldering

 

[Ykick]

RC Lipoly cells never seem to revive from below 2V in my experience.

Brick surgery is an excellent skill to learn and perfect. Sooner or later a cell goes belly-up but the rest of the brick is still quite useable. I'm beyond 3 years on a several bricks that have been extended by replacing a cell or two. 60W iron and Hammer Head tip is the best IMO.

 

[wineboyrider]

I have 300 watt wood burner that works great for getting the initial glob of solder off.....

 

[Ykick]

I have 300 watt wood burner that works great for getting the initial glob of solder off.....

Good question - high watts or large mass? I'll take large mass when given the choice. 300W is great for burning wood and with some skill can work for flowing tabs but it's much too hot IMO.

60W is not so hot but when delivered with enough mass/size it's plenty for the job of flowing solder on cell tabs.

Neither choice is bunk and many folks here do this work with high wattage pencil/chisel tips but if you can find a $6 Hammer Head tip and $15 60W iron you won't regret it for brick surgery.

 

[dnmun]

it takes a lotta heat since they use the no lead solder. once you get the solder liquid then the trick is to make the tab stand up by hooking underneath it with one of the soldering irons, i use two, and when the tab is standing up then you can cut the little pcb that the tab sticks through the slot. cut the edge in line with the slot so that the pcb comes apart where that ta is and you can heat some more to remove the tab from the pcb.

you do not have to replace the cell since you are using a balancing charger. but the connections will now be offset since that cell is missing so you have to use a jumper across that connection by soldering a wire in place of the missing cell and then you have to move the sense wires in the plug down by one to fill the gap.

 

[wineboyrider]

I have 300 watt wood burner that works great for getting the initial glob of solder off.....

Good question - high watts or large mass? I'll take large mass when given the choice. 300W is great for burning wood and with some skill can work for flowing tabs but it's much too hot IMO.

60W is not so hot but when delivered with enough mass/size it's plenty for the job of flowing solder on cell tabs.

Neither choice is bunk and many folks here do this work with high wattage pencil/chisel tips but if you can find a $6 Hammer Head tip and $15 60W iron you won't regret it for brick surgery.

Both LOL It takes a lot of heat IMHO too get it to melt and then after that I use the regular soldering iron and the wood burning kit has all kinds of tips

 

[silviasol]

I had many 18650 lithium cells I had, most less then 1v some 0v. I revived over 75% of them by paralleling one good cell with the low or 0v cell. I have not done this with lipo! But 75% of the 18650 revived themselves and held a solid charge. This is what they call sleeping lithium cells. Maybe put the 0v cell in a metal bucket just in case when you do it. It should take only minutes to get a charge if it will wake up.

 

[izeman]

i never managed to revive one of the broken 18650 cells from the makita packs i had. maybe because those cells were BROKEN, and not just emty. this of course is a big difference as well. if a cell just discharges by itself over time, or if it was heavily used and now doesn't take a charge are two totally different things.
that's why is still prefer NIMH over li-ion technology in my battery powered tools. safe, cheap technology.

 

[currentFlo]

I had many 18650 lithium cells I had, most less then 1v some 0v. I revived over 75% of them by paralleling one good cell with the low or 0v cell. I have not done this with lipo! But 75% of the 18650 revived themselves and held a solid charge. This is what they call sleeping lithium cells. Maybe put the 0v cell in a metal bucket just in case when you do it. It should take only minutes to get a charge if it will wake up.

Hi silviasol,
in your case maybe it was the protection circuit of the cell masking the actual remaining voltage ?
Did your cells had protection circuits built-in ?

Flo

 

[silviasol]

They are standard sized 18650, I think the models with the protection circuit are about a 1/4 inch longer? They came from laptop batteries which have circuit boards. I bought hundreds of these batteries from a school, some dead some working. They probably sat for a long time, there was date marks on them from 2006, probably when they stored them, and it was 2009 when I got them. Plus the extra few years the dead batteries sat until I recently pulled them apart. So that would be 6 years of sitting after the laptop battery was depleted(all good cells at a low 3v or so).

My thoughts on your battery is the puffed one is dead and dangerous to mess with. The 0v one had interested me because of what I saw with mine and how you said it sat for awhile. I wish I knew exactly how long I would have needed to leave them in parallel before it reactivates, I just let 5 charged batteries then 5 dead batteries sit in a custom holder I made for an hour. What I do know is when it reactivated not much charge was pulled from the other battery so the ions must have been dormant/inactive then jumped back to life. So I would say leaving yours in parallel with another cell for maybe 5 minutes then check the voltage may be a safe bet, then if there is a voltage and the battery is not extremely hot or anything leave it sit under watchful eye for an hour or so. I did see some cells I had make the spring in the cell holder glow red hot so there can be danger.

 

[Ykick]

By all means, give it a try in a safe spot but out of the dozens of RC Lipoly pouch cells I've tried to revive from 0V I've yet to have one come back around. However, 1.5-2V it works majority of the time, in my experience.