Espritmodel.com Telemetry Radio
Reply
Thread Tools
Old Jun 29, 2009, 07:59 PM
WARNING: May contain spam
Xpress..'s Avatar
Joined Oct 2007
20,933 Posts
Mini-HowTo
(HOW TO) Recovering over discharged lipos

Since I noticed a lot of posts lately on how to recover an over discharged lipo, I thought I would post the method for recovering them.

It's pretty easily actually. All you need to do is get a NiMH charger, and set it to the approximate voltage to your lipo pack. (I.E. 7.2v for a 7.4v pack, or 12v for an 11.1v pack) Now, plug in your lipo, and set the charge current for ~1/3-1/2C charge rate (1/3c for a 1000 mah pack is .33 amps, 1/2C for a 1000 mah pack is 0.5 amps) and start the charge.

You only need to charge the lipo for a couple minutes to bring it back to the proper voltage for your lipo charger to recognise it, and charge it again. It is important that you keep a constant watch on the lipo while charging it with an NiMH charger!

If your lipo is still not recognised by your charger, then charge it a bit more on the NiMH charger.

Note: Some lipos may last for numerous more cycles, whereas others might only last a couple more cycles before they die completely. Your results may vary

Battery experts: Do feel free to chime in and correct any information on here that may be wrong.
Xpress.. is offline Find More Posts by Xpress..
Last edited by Xpress..; Jun 29, 2009 at 08:20 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Jun 30, 2009, 07:14 AM
Registered User
Arendal Norway
Joined May 2008
87 Posts
It might be worth it to mention that there *is* a reason why a Li-Po charger refuses to charge an overdischarged batterypack: They can become unstable by overdischarge.
torqueflite is offline Find More Posts by torqueflite
Reply With Quote
Old Jun 30, 2009, 04:01 PM
Registered User
E-Challenged's Avatar
United States, CA, Garden Grove
Joined Oct 2000
11,825 Posts
i've rescued three packs by charging to 3+ volts per cell in Nimh charge mode, then continuing with the normal lipo charge mode. I suppose that a lot depends on how old and how deeply discharged the pack was and how long it was in that condition. Normally happens when you forget to disconnect and remove a pack from the plane at the field and discover the mistake the next day or so. Watch for swelling etc. of the pack while charging. It should take the normal number of milliamps to fully charge. Good idea to check the balance of the pack after charging.
E-Challenged is offline Find More Posts by E-Challenged
Reply With Quote
Old Jun 30, 2009, 06:32 PM
Registered User
flydiver's Avatar
United States, WA, Seattle
Joined Jan 2007
5,203 Posts
Quote:
Originally Posted by torqueflite
They can become unstable by overdischarge.
Where do you get that? They become relatively more inert and harmless with over discharge. Completely discharged they are just a bag of inert chemicals.

The over discharge can lead to compromises in the chemistry that may make them less stable when charged. This would be more of a problem if a balance charger is not used.

Long lasting damage seems to be all over the map from informal reading in the groups, anything from it seems fine to it's shot. I think this is related to a host of factors: age and condition of the lipo, rapidity and degree of discharge, time spent at discharge, brand of lipo, etc. Willingness (and ability) to deal with this issue are similarly widespread.

I certainly see where Xpress is going with this. The forum gets a half dozen of exactly this kind of question a week. Lots of people have absolutely no idea what they are dealing with.
flydiver is offline Find More Posts by flydiver
Last edited by flydiver; Jun 30, 2009 at 06:50 PM.
Reply With Quote
Old Jun 30, 2009, 11:24 PM
Registered User
Challenger 413's Avatar
Dickinson, Tx.
Joined Sep 2004
5,345 Posts
Quote:
Originally Posted by flydiver
I certainly see where Xpress is going with this. The forum gets a half dozen of exactly this kind of question a week. Lots of people have absolutely no idea what they are dealing with.
This has been covered so many times for the last 4 years, people don't read instructions on the LVC, on the care of Lipos, etc., etc., Should we also ask for this to be a stickie? Really, trying to charge up a lipo with a Nimh/Nicad charger has been covered...We should make a stickie on how to avoid this,,, oh wait, there is one

Also, there should be warnings added, about the pack being compromised..

Challenger413
Challenger 413 is offline Find More Posts by Challenger 413
Reply With Quote
Old Jul 01, 2009, 03:11 AM
Registered User
Arendal Norway
Joined May 2008
87 Posts
Quote:
Originally Posted by flydiver
Where do you get that? They become relatively more inert and harmless with over discharge. Completely discharged they are just a bag of inert chemicals.

The over discharge can lead to compromises in the chemistry that may make them less stable when charged. This would be more of a problem if a balance charger is not used.
The thread is about *charging* overdischarged batteries. It is then self explanatory that we are not discussing inertness of depleted cells. especially when I mention that there is a reason why Li-Po chargers refuse to charge cells under a set voltage.
torqueflite is offline Find More Posts by torqueflite
Reply With Quote
Old Feb 14, 2011, 11:05 AM
Registered User
Canada, BC, Salmon Arm
Joined Feb 2011
1 Posts
I recently over discharged a newer Lipo 2800 Mah, it barely indicated any voltage and my balanced charger would not initiate a charge.

Whith the dead Lipo connected to the charger, I took a second fully charged Lipo and briefly connected the negative and positive leads together, I mean very briefly.

The voltage bump passes through both batteries and switches the balanced charger into charge mode.

The battery took a full charge and is stable.

While this method worked for me, I did use safety glasses and a fire resistant charge bag. There is always some form of risk when working with a discharged Lipo so use caution.
sundeer is offline Find More Posts by sundeer
Reply With Quote
Old Feb 14, 2011, 11:08 AM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
20,802 Posts
hmmmmm, there is a sticky on this subject.
http://www.rcgroups.com/forums/showthread.php?t=1074181
hoppy is offline Find More Posts by hoppy
Reply With Quote
Old Feb 14, 2011, 11:36 AM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,629 Posts
Indeed there is and has been long enough for regulars atleast to have noticed it.

Sticky: "My battery is dead - HELP" info. ( 1 2 3) - 591 days old
hoppy



But then this is not a new Thread either

Jun 29, 2009, 08:59 PM 594 days old
Charles
everydayflyer is offline Find More Posts by everydayflyer
Last edited by everydayflyer; Feb 14, 2011 at 11:41 AM.
Reply With Quote
Old Feb 14, 2011, 12:44 PM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
20,802 Posts
Might have been the impetus for writing a sticky.
hoppy is offline Find More Posts by hoppy
Reply With Quote
Old Feb 14, 2011, 02:01 PM
Registered User
Vancouver, BC
Joined Jan 2011
189 Posts
Maybe this could turn into a HOW TO for bringing (or not to bring) a dead thread back to life instead?
zapadoo is offline Find More Posts by zapadoo
Reply With Quote
Old Feb 14, 2011, 07:49 PM
characters welcome!
Mark Wood's Avatar
United States, CA, Bear Valley Springs
Joined Feb 2000
26,261 Posts
Thread necromancers...

mw
Mark Wood is offline Find More Posts by Mark Wood
Reply With Quote
Old Apr 25, 2011, 08:06 AM
Registered User
ferdous7466's Avatar
Joined Mar 2010
447 Posts
Quote:
Originally Posted by sundeer View Post
I recently over discharged a newer Lipo 2800 Mah, it barely indicated any voltage and my balanced charger would not initiate a charge.

Whith the dead Lipo connected to the charger, I took a second fully charged Lipo and briefly connected the negative and positive leads together, I mean very briefly.

The voltage bump passes through both batteries and switches the balanced charger into charge mode.

The battery took a full charge and is stable.

While this method worked for me, I did use safety glasses and a fire resistant charge bag. There is always some form of risk when working with a discharged Lipo so use caution.
YOu are a crazy genious...hooooh!
ferdous7466 is offline Find More Posts by ferdous7466
Reply With Quote
Old Apr 25, 2011, 07:08 PM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
20,802 Posts
Or maybe, how to kill 2 batteries at the same time.
hoppy is offline Find More Posts by hoppy
Reply With Quote
Old May 05, 2011, 07:36 AM
Registered User
Joined May 2011
16 Posts
how long does a recoverd 3s lipo batery take to charge completely
uday is offline Find More Posts by uday
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Kokam over-discharged ? OAK Batteries and Chargers 10 Aug 22, 2010 12:40 PM
Discussion TP610C - With Over Discharged LiPos bradg2 Batteries and Chargers 5 Jun 25, 2008 09:50 AM
Over discharged Lipos? Charger Batteries and Chargers 9 Dec 03, 2004 01:36 PM
Over-discharged LiPoly Help Radioguy Batteries and Chargers 11 Jul 11, 2004 09:08 PM
Over discharged lipoly cells? Pierre Audette Batteries and Chargers 4 Sep 18, 2003 08:05 AM