Reconditioning a dead lipo

[Frank v B]

CAUTION:  DO NOT USE THIS METHOD.  I am deferring to the TEMAC braintrust that this is not a safe method.

A quote from Davidk's post further down "I would have tried setting the charger to NiCd, the amps to .1 and trickle charge until you reach a point where the charger will recognize the battery as LiPo.  The balance lead is not connected during this process".  This method is supported by Gil and Ben and that is all the proof I need.

Frank



An experiment.

This battery was found inside the UMX A-10 Warthog that had crashed a while ago.  The battery was still connected to the radio.  It was deader than a doornail (deadest?).

Photo 49- the battery tested dead on the battery tester.  It was a 2S,  860 mah.
Photo 50- took a 2S, 1200 mah battery and connected it to the dead battery- positive to positive, negative to negative so voltage could be transferred.  Wanted enough voltage in the battery so the charger would take hold. (15 minutes old and new battery linked +to+, -to-)
Photo 52- the dead battery now registers 7.37 volts (11%), enough for the charger to take hold.
Photo 53- used a conservative 500 mah (.6 C) charge rate and it is charging the battery.


I have no idea whether the voltage will hold once charged.
Note: I am sitting right by the charger and battery just in case something..........

Report - after 23 minutes the battery is now at 7.78 volts and 199mah has gone into the battery (23% charged).
           - after 68 minutes the charger is at 8.19 volts and has put in 585 mah (68% charged)

Frank

[Gil.E]

Hi Frank,
Just a quick comment on behalf of the local Fire station, regarding the "Photo 50" step in your recovery attempt.

Normally to bring a dead cell (i.e. 0V or below 3V/Cell for a typical Lipo) you need to "trickle" charge it, with the trickle current being below or at 10% of the regular full charge current. Typically you would do this by connecting the dead cell or battery to a constant current source, or a current limited supply, and typically inject not more than a hundred mA until the dead cell floats above 3.3V/Cell , which would make the battery more palatable to your Lipo charger. 

Bringing the voltage up as you did, by directly connecting a fully charged Lipo to a fully dead Lipo, was not a pleasant or healthy experience to either Lipo involved in this mating experience to say the least.

Luckily, it worked smokelessly for you this time, but in general you should try to use one of the following on future trickle charge experiments  (based on availability):

(a) a benchtop power supply that has current limiting/control.
(b) A power resistor in series between the two batteries to reduce/control the initial inrush trickle charge current
(c) A small wall-adapter power supply that has inherent power/current limiting


 

[Frank v B]

Gil,

You are the voice of reason.

Luckily the 7.4 volt battery I attached it to was at storage voltage and nowhere near full.

I have turned everything off as a result of your post and will leave the battery overnight in a Lipo bag and test it again tomorrow.

I will report the voltage tomorrow evening and will do any further charging at 10%C  (80 mah).

Thanks for the advice.

Frank

[davidk]

I would have tried setting the charger to NiCd, the amps to .1 and trickle charge until you reach a point where the charger will recognize the battery as LiPo.  The balance lead is not connected during this process.

This has worked for me in the past and is very safe.

This was "field knowledge" passed along to me by several at the field.

[Andy Hoffer]

I have used @davidk 's method successfully on several occasions.

I only wish I could get @frank to experiment so boldly with his camera!! 

Andy

[Frank v B]

David,Andy,

re: "This has worked for me in the past and is very safe."
re: "I have used Davidk 's method successfully on several occasions."

....not until Gil says it's OK.

Frank

[Gil.E]

I would have tried setting the charger to NiCd, the amps to .1 and trickle charge until you reach a point where the charger will recognize the battery as LiPo.  The balance lead is not connected during this process.

This has worked for me in the past and is very safe.

You are right David, since almost all  Lipo smart chargers support other chemistries with lower voltage/current profiles  this is probably the best way to go about. Brilliant. I have been spoiled by having access to bench top power supplies.

Frank,
By now your battery is above the voltage threshold level for Lipo charging. Have fun at full 1C charging and good luck with the A-10 restoration (your first EDF if no one comes forward to claim it?)

[Frank v B]

The 24 hour report.

The battery read 8.216 volts or 90%.

It was never fully charged because I disconnected it and stored it in a lipo bag immediately upon reading Gil's note. 
The charge held.  My house is still in one piece.  Nothing is charred!

Back to repairing the UMX A-10 Warthog, the dust blower (small leaf blower).


Frank

[bfeist]

I'm with Gil. Connecting positive to positive like that gives an unrestricted amount of current. No way to tell at what rate you charged the battery at.

The same concern exists with these parallel charging setups. The rule of thumb with them is if each of the batteries you are going to parallel charge are within 1/100 V of each other, it's safe to connect the balance connectors to the parallel charging board. Of course these are all positive to positive and negative to negative.

[sihinch]

Seriously? 1/100th of a volt? Wow!  That's scary - I use these all the time. 

[bfeist]

According to joshua bardwell

[pmackenzie]

You don't have to be that close. Not even sure most of us can even measure voltage to that sort of precision!

0.1 volts per cell is a common suggestion, but some have measured the actual current flow with larger mismatch, and it is not that high.

https://www.google.ca/search?sxsrf=ALeKk03ubvyWOk9JhxYwGfTI6qf8XGDaTg%3A1606801441205&source=hp&ei=IdjFX83wB8OvggeC4rXoCA&q=parallel+charging+lipo+voltage+difference&oq=parallel+charging+lipo+&gs_lcp=CgZwc3ktYWIQARgDMgUIABDJAzICCAAyBggAEBYQHjIGCAAQFhAeMgYIABAWEB4yBggAEBYQHjIGCAAQFhAeMgYIABAWEB46BAgjECc6CwguELEDEMcBEKMCOg4ILhCxAxCDARDHARCjAjoFCAAQsQM6CAgAELEDEIMBOgIILjoICC4QxwEQowI6CAguELEDEIMBOgUIABCSAzoFCC4QsQM6CAgAELEDEMkDOggILhDHARCvAVCmA1i7LWCxT2gAcAB4AYABhxKIAd5RkgEMMi4xMi4xLjgtMi4ymAEAoAEBqgEHZ3dzLXdpeg&sclient=psy-ab

Pat MacKenzie

[bfeist]

I bet it's my memory that's off by an order of magnitude. Apologies.