RC India

hi,
i have a 1300mah 2s 7.4v battery...
in battery one of my cell get discharge totally but i recover again..and it is show proper voltage...
but the problem is that battery one of cell which discharged, that cell get little  puffy.
so it this dangerous in using or it safe???

It's kind of unstable now. It can lead to further damage as well.
Lithium Polymer batteries (No matter which brand) are quite different than Lithium Ion batteries as once the voltage on any of it's cell goes below 3 volts than some chemical reaction takes place in it making that particular cell permanently unusable and unchargeable.

From safety point of view, recovering a cell is not advisable since that cell does become little unstable which is followed by puffing but people still do it from the economical point view ;D
Apart from that you are most likely not going to get the same kind of voltage levels, storage capacity from that cell again. You will notice a lot of voltage sag, that cell won't get fully charged and it will always be the first one to get discharged.

The key to recovery a cell is Time. The longer you leave the cell in 'less than 3 volts condition', the more it will get damaged.

I would prefer to be more cautious with this LiPo and keep it at a place which is not flammable.
Well, Just in case :)

A request to everyone
Guys please use LiPo Alarms and avoid getting into inconvenient situations.

Issued in Public Interest :rofl:

Well said...
Lipo's can be really dangerous if not used properly. I am myself still scared while using lipo's :giggle:. These batteries are very good if used cautiously and taken good care off and could prove dangerous if not paid attention...  :iagree: that using Low voltage alarm is a very good practice and an important step that should be followed.. Since, these are not very expensive so it is always better to use one instead of loosing a battery due to deep discharge.
BTW Nik, please be very careful next time while using and I strongly recommend you to buy a lipo voltage alarm... One of my friend lost his laptop, battery charger, battery everything just because of carelessness...

I'm attaching a few pics as to what happens when these lipo's misbehave ;D ;D These pics are of the lipo that burned due to overcharge costing my friend to loose his laptop.

Whoa!

What was he charging them with?
A regular (properly working) LiPo charger should not end up doing this.

 >:D >:D great pics na... :giggle: :giggle:
Well, he was using a Turnigy Accucel. I don't exactly know how it got burnt but yeah he told me he'd put his battery on charging and slept. That battery exploded, then started burning... When he smelled a peculiar smell of some chemical and saw battery burning then he woke up and checked that... :giggle: :giggle:

You have said "Laptop" and "Turnigy Accucel"

Was he using an Accucel to charge his Laptop Battery?

No no sir...
Actually, his laptop was kept near the charger. When the battery burnt then the body of laptop got heated I think and so something must have gone wrong inside.

Looks like Mystery to Me.... or some cooked up story  :giggle: ....... Accucel cannot end up like this.... Auto cut, beeper above all a micro processor is there..... even if people sleep after putting it to charge.

Maybe he used the laptop charger to power the Accucel???? as i said its mystery.....  8-)

NO blame to Lipo and charger.... i have full trust if things are used properly they work properly.  :bow:

Even I agree to that Sir... But, he was a newbie in those days and didn't knew how to charge and select charging voltage etc... He told me that he'd put it on fast charge. When I asked for current he said he kept the button pressed till max. ;D How could someone be so stupid, even charger showed some error too. Also, battery he was using was puffed. I even told him to be utmost careful with that battery... I too use a Turnigy Accucel. That works perfectly. I don't understand why people turn up doing things without properly reading the instructions and knowing the correct method and then loosing things...

Even I tried to understand whatever he said but wasn't able to conclude how all that happen. ;D ;D

Or another possibility could be that he must have the kept the laptop near the batteries while charging and became a victim. Since the battery was already puffed, it must have given up while charging at high current.

Also most laptop adapters output below 20v and 3-4-5amp, which near about matches with specs of Accucel
(11-17v upto 6amp,50watts), so cant they be compatible with chargers?

i have 2 lippo battery with the problem . in 2 c battery 1 cell is not charging. and in 3c also 1 cell is not charging. is that recoverable ?

i dispose my battery and trough out... bcz it was start puffing more ..
 my battery was 2s  ... one of cell was dead  the voltage of dead cell was below 2.4v.. in volt meter its show .22mv.
and battery get puffy.. i recovered that dead cell and voltage it  again came to 3.4v but still it puffy.
but as per senior suggestion .. i decided i don't want to use again ...  :) :)
and yeah it is very dangerous  . >:D >:D

and thank you for helping me  {:)} :)

So, now you need to invest for a new one. Be careful with it this time.

hahahah :) :) :)... yup now i have to buy new battery  for my quad...

So, which battery have you decided?

Same battery... Avonic 1300mah 2s 20c 7.4v

Why are you using a 2S 1300mAh... i mean why not go for higher rating....

I m already using 2s 3000mah...
And the reason is my quad motor capacity is only
Now this quad is working properly .. so nw  I planning to build bigger one ...
That time I vl go for some higer battery..

Ohk.. its fine. Whenever building a newer one do post about it....
 :hatsoff:

Yup sure...  :thumbsup: ;)