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Old Oct 18, 2014, 07:57 PM
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Joined Jan 2014
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Safe LiPo disposal of battery that was in a plane for three days

Hello,

One of my planes was stuck in a tree for three days. After I managed to get the plane back, the battery (a 3S, 1000 mAh LiPo) shows 0.1 V on one cell, and about 1.25 V each on the two other cells. There is no physical damage to the battery as far as I can tell.

How do I safely discharge and dispose of this?

I guess I could attach a resistor on the balance connector to slowly discharge the two cells that still have some voltage left. I'm not an expert at this, but a 100 Ω resistor would limit the current to 25 mA and the power dissipation to a few dozen milliwatts. Of course it will take a while.

Or is the resistance too high in this case to successfully drain the battery?

Any other suggestions?
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Old Oct 18, 2014, 08:17 PM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
21,010 Posts
Anything below 2.5V/cell is D E A D. 0% energy left.
If it were mine I'd just toss it. However, if you want to, you can put any resistor across the main power leads and leave it for a day.
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Old Oct 18, 2014, 08:48 PM
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Upper Hutt, New Zealand
Joined Apr 2006
2,246 Posts
Yeah, close enough to dead that, I'd just strip the leads and twist them together. Might get a few sparks, but it will have so little energy it won't even get warm. Then throw it in the trash.
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Old Oct 18, 2014, 08:50 PM
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Greenland, Qaasuitsup
Joined Apr 2013
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hey, why toss?? i had the same thing happen to mine. it flew into a tree 50 feet up and was fully charged at the moment. Lights were blinking all that day and all night, then 2 days later, i got city hall to get the plane for me from the tree.

battery was 0 volts total and was completely dead. I charged it up and it charged fine, still flying my airplane AND my heli. battery fits into either one. over 100 flights put through it since then..

battery is 2400 mah 3s 25C

here's the pic of internal resistance.


it's not exactly new anymore, but like i said, it survived complete "discharge of death" and many cycles down to LVC when i was learning to fly helis. This is where I use the pack and it still flies alright..

my cessna...


and the little guy on the left (450 CP heli)
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Old Oct 18, 2014, 08:57 PM
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Canton, Michigan USA
Joined Jul 2007
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The battery is useless now except for powering a lawn tool. If you had a ESR meter that load tests the pack and each cell you could measure the cell resistance. It is probably well over 50 milliohms. A new pack should be less than 5.


Just discharge and throw in the trash. I use an old style 1157 bulb (tail light) with leads soldered to it to fully discharge the pack. Of course, do so in safe environment like outside on concrete.
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Old Oct 18, 2014, 10:30 PM
Grumpy old git.. Who me?
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Aberdeen
Joined Mar 2006
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I once accidentally left a 3s 2200mAh battery connected in a model after flying and it was two or tree days before I discovered my mistake. The battery showed zero voltage.
I recovered it using the normal NiMh charge procedure. The battery recovered successfully, no puffing and all cells showed similar internal resistance to other identical batteries that had not been over-discharged. In flight it performs exactly like the other batteries.
Here's the cruncher.....The over-discharge incident was about two years ago and the battery continues to perform the same as the others, in fact I'm not even sure which battery was over discharge anymore as the mark i put on it wore off ages ago.

I've recovered two or three similar batteries over the years.

On the other hand I tried to recover a similarly over discharged battery and one cell puffed up and remained dead, so it doesnt work every time but based on my experience it's worth a go.
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Old Oct 18, 2014, 10:51 PM
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Canton, Michigan USA
Joined Jul 2007
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Quote:
Originally Posted by JetPlaneFlyer View Post
I once accidentally left a 3s 2200mAh battery connected in a model after flying and it was two or tree days before I discovered my mistake. The battery showed zero voltage.
I recovered it using the normal NiMh charge procedure. The battery recovered successfully, no puffing and all cells showed similar internal resistance to other identical batteries that had not been over-discharged. In flight it performs exactly like the other batteries.
Here's the cruncher.....The over-discharge incident was about two years ago and the battery continues to perform the same as the others, in fact I'm not even sure which battery was over discharge anymore as the mark i put on it wore off ages ago.

I've recovered two or three similar batteries over the years.

On the other hand I tried to recover a similarly over discharged battery and one cell puffed up and remained dead, so it doesnt work every time but based on my experience it's worth a go.

Measure the cell balance and cell resistance and come back and post the results. If what you say is true it is a first.
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Old Oct 19, 2014, 04:50 AM
Grumpy old git.. Who me?
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Aberdeen
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Quote:
Originally Posted by Prof100 View Post
Measure the cell balance and cell resistance and come back and post the results. If what you say is true it is a first.
I measured the cell resistance with my iCharger 3010b at the time. It was no different to any of the other identical (Gens Ace) batteries i have. I've flown the battery many times in the subsequent couple of years in high demand applications such as 3D models and in 450 size helis and performance is identical to all the rest of the batteries, in fact the model prop hanging in my sig could well be flying on that very battery. I'm afraid I cant re-test the i.r. now because (two years later) I cant tell which battery was over discharged, but all of them are still performing very well considering their age and cycles.

I've no reason to lie about this. I've recovered at least a couple of similar batteries with no apparent damage, but as i said in the last post I've also experienced at least one battery that wouldnt recover at all, so it's a lottery.
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Old Oct 19, 2014, 06:48 AM
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Kingston, Canada
Joined Jun 2004
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It's a lottery as Jetplane says. I bought 4 Rhino 5000ma 5 cell batts from HK a number of yrs ago and on one batt, one cell had 1.5 volts. I put it on the old FMA Balance Pro charger and plugged it into the computer to monitor it. It took 4 hrs to bring that one cell up to match the rest of them. I should have marked the batt to keep track of it but didn't. Now, all the batts run the same and I don't know which batt it was..
On the other side, I had a heli that went down in the bush and wasn't found for two weeks. I charged it up using the method mentioned above. It lasted about 6 months when it started to puff. Each time I charged it after that, it expanded a little more. After about 3 charges, I discharged it and dumped it.

Gord.
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Old Oct 19, 2014, 08:38 AM
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I would try to revive it. Then fully charge it and drive a nail through it. Enjoy the show x
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Old Oct 19, 2014, 08:53 AM
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Canton, Michigan USA
Joined Jul 2007
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Quote:
Originally Posted by JetPlaneFlyer View Post
I measured the cell resistance with my iCharger 3010b at the time. It was no different to any of the other identical (Gens Ace) batteries i have. I've flown the battery many times in the subsequent couple of years in high demand applications such as 3D models and in 450 size helis and performance is identical to all the rest of the batteries, in fact the model prop hanging in my sig could well be flying on that very battery. I'm afraid I cant re-test the i.r. now because (two years later) I cant tell which battery was over discharged, but all of them are still performing very well considering their age and cycles.

I've no reason to lie about this. I've recovered at least a couple of similar batteries with no apparent damage, but as i said in the last post I've also experienced at least one battery that wouldnt recover at all, so it's a lottery.

I know you have no reason to lie about this. I did not mean to impugn your character or motivation. Maybe it is a random act.


Bill

Quote:
Originally Posted by flypaper 2 View Post
It's a lottery as Jetplane says. I bought 4 Rhino 5000ma 5 cell batts from HK a number of yrs ago and on one batt, one cell had 1.5 volts. I put it on the old FMA Balance Pro charger and plugged it into the computer to monitor it. It took 4 hrs to bring that one cell up to match the rest of them. I should have marked the batt to keep track of it but didn't. Now, all the batts run the same and I don't know which batt it was..
On the other side, I had a heli that went down in the bush and wasn't found for two weeks. I charged it up using the method mentioned above. It lasted about 6 months when it started to puff. Each time I charged it after that, it expanded a little more. After about 3 charges, I discharged it and dumped it.

Gord.

Gord,
The second case is the norm for me.
Bill
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