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HomeAircraftHelicopterMain Discussion › I Think I Damaged My New Lipo Battery
06-28-2014 04:50 PM  3 years agoPost 1
davehour

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Guayama, Puerto Rico 00785

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Hi all,

I would like your opinion on an incident I had with a new Lipo battery I was broken in on the bench using a bulb discharger I made. This discharger is made of six series-parallel connected 12V 50W bulbs. The discharger average discharge current for a 6S battery is 12A. The discharger has no over discharge protection.

While I was discharging the battery in one of the cycles, I went out of the shop and forgot about it. When I came back to the shop, I found all the bulbs of the discharger were off. From actual testing, I know that for all the discharger bulbs to be off, the voltage applied to the discharger must be 3V or less. This means each cells of the battery must had been at about 0.5V for some minutes.

Next, I disconnected the battery from the discharger, and checked the voltages of the cells. The voltages were at 1.6v and rising. The battery was warm and to my surprise, no puffing. I let the battery rest for a while and started charging it, and had no problem recovering to normal potentials, and charged normally. All the cells balance charge fine and the balance tracking during the charging process was good, as nothing had happened. I did a discharge capacity test with the discharger and the battery behaved normally.

I know the battery was affected as the absolute minimum voltage to avoid permanent damage to a Lipo cell is about 2V. This being the case, I would like to know guys, what do you think?

This battery was going to be used in a 12S configuration in a T-rex 700E Pro DFC with stock equipment.

Following are the battery specs:

Align HBP52004
Output: 22.2V 5200mAh 115Wh (6S1P)
Dimension: 138x61x42mm
Weight: 780g(Not including connectors)
Max Continuous Discharge: 60C (Using 10AWG wire, thermal resistance:200°C, max continuous current 140A)
Max Charge Rate: Supports 5C charging Normal Operating Temperature: Approx. 40-65°C (within 80% of rated discharge).
Max Temperature: 80°C.

I apologize for the long post but wanted to provide the most information possible for your analysis.

Thank you very much,

David

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06-28-2014 05:05 PM  3 years agoPost 2
Dr.Ben

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Richmond, VA, USA

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Dave,

Though not a good thing, packs do survive what you did. The thing you had going for you is that you did not run them that low and get them really hot, which would have puffed the hell out of them. Watch the IR's and charge carefully; it'll probably be ok.

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

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06-28-2014 05:28 PM  3 years agoPost 3
unclejane

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santa fe, NM, USA

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Agree that the batt is probably ok if it didn't get too hot and/or puff. I've done this accidentally on several occasions myself, though, and the batt did overheat and puff each time.

OTOH, I've had brand new batts with totally dead cells, the Thunderpower 2S fight packs I use for the flight systems on my helis were like this, that I've been able to put in service and still use (tho they need balance charging every time).

So I say fly the SOB if it charges and discharges ok....

LS

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06-28-2014 06:08 PM  3 years agoPost 4
Ace Dude

rrProfessor

USA

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Just as a FYI, there are some DIY discharger schematics available that use only a few simple parts including an auto relay and a Cellog to turn off the load when it hits the preset voltage the Cellog to prevent from over discharging a pack.

  

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06-28-2014 06:21 PM  3 years agoPost 5
nitro fun

rrApprentice

Oc ca

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By one of those cheap lipo alarm on ebay, the alarm connects to the balance lead, they go for for $4, you can set the alarm voltage, i got 5 of them for $10 on ebay, I use them for discharging because my orbit microlader chargers dont have a discharge setting for lipo voltage cut off..

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06-28-2014 07:23 PM  3 years agoPost 6
rcflyerheli

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Granbury, TX USA

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I forgot to unhook a 3s lipo off a a friend's flamewheel and ran it down to nothing. As soon as I found it, I put on my cell pro and charged it. Like you, no puffing, and it has been running fine since then.

I have it marked but all charge/discharge/IRs and cell balance is just like all the others I have. I think leaving them at the low voltage for a long period of time is what kills them, at least that is what it appears in my case.

Goblin 700, Trex 700DFC, Gaui X7, Logo 690SX, Logo 600SX; Trex 470 Trex 500
Amain Team Rep

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06-28-2014 08:02 PM  3 years agoPost 7
Ace Dude

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USA

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As soon as I found it, I put on my cell pro and charged it. Like you, no puffing, and it has been running fine since then.
The Revolectrix PowerLab chargers have a special recovery mode and when several conditions are met the charger will go into recovery mode and attempt to charge the pack at a very slow rate. It may take a while to complete the charge due to the low charge rate, but it's the best to way to try and recover the pack.

  

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06-28-2014 08:20 PM  3 years agoPost 8
InvertedDude

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USA

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Agree with gentlemen's comments
No puff.....full charge capacity.....voltage stable.....you are good to go.

Only one suggestion.....fly trex for 1 minute then recharge....then fly 2 minutes then recharge....fly 3 minutes then recharge....only to observe voltage discharge and stability. If it behaves normally, then your battery is acceptable.

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06-28-2014 08:26 PM  3 years agoPost 9
Jeff polisena

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westpalmbeachflorida usa

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I've had this happen, one time I was ok ,the second time battery was toast . Now I fly all my packs 2.5 min light load for a few cycles . Most flights are 5 min with my fly style and setups so 2.5 min is on the safe side .

I stole it ,flew it and gave it back ;)

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06-29-2014 03:10 AM  3 years agoPost 10
ICUR1-2

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Ottawa, Ontario

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you're breakin in Lipo's

thought 1 of their quallities was no memory

spending time, paying attention

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06-29-2014 09:09 AM  3 years agoPost 11
davehour

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Guayama, Puerto Rico 00785

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Hi guys,

Thanks so much for your advises and comments. I feel better knowing the pack might be good. I'll use it carefully and see how it does.

Forgot to mention the IR of the pack in question is the same as its companion, which is new too.

I'll keep you posted on what happens, and again, I appreciate your help.

David

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06-29-2014 09:25 AM  3 years agoPost 12
davehour

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Guayama, Puerto Rico 00785

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you're breakin in Lipo's
thought 1 of their quallities was no memory
Yes.

Lipo break in is recommended by manufacturers. It's a period where you charge the pack at 1C and discharge it conservatively (3C to 5C) in the first 5 cycles.

Lipo batteries, as many others, won't have their rated capacity after some use.

The packs may be broken in the model by flying them with care.

David

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06-29-2014 11:47 AM  3 years agoPost 13
Retired2011

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Lee's Summit, MO

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you're breakin in Lipo's
Yes, you should ALWAYS break in new new lipos.

I do it by flying them gently for the first few cycles.

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06-29-2014 01:36 PM  3 years agoPost 14
jason46

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MI

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Usually in situations like this capacity is reduced. I also don't understand the need to break in a lipo.

We made up some rules can we have your moneys now.

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06-29-2014 02:54 PM  3 years agoPost 15
ICUR1-2

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Ottawa, Ontario

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does it have something to do with the heat they build up when discharged.

spending time, paying attention

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06-29-2014 03:59 PM  3 years agoPost 16
Retired2011

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Lee's Summit, MO

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Here is an exerpt from a very informative site...

Brand new packs
New lipos ship in a "sleep" state. They have a chemical stabilizer in the cells that help them more easily handle shelf life, and are shipped at a storage voltage of approx 3.85V per cell. This stabilizer is lost when the packs are cycled, so it is important to let the packs remain asleep until they are needed.

Once a new pack is ready to be used, it needs to go through a "break in" process. Generally this means treating the new pack gingerly for the first few cycles, including charging it slowly (1C) and gently discharging it to 50% capacity for the first 5 flights. This does 2 things. First it makes sure the pack is in good condition and secondly it "loosens" up the pack for normal duty.

Note on break-in: I am seeing more and more forum posts about people trying to break in new packs on a charger. I recommend against this. Not only is it very time consuming but it is also wasteful. Instead charge a new pack at 1C and the go fly it. Take it easy and use the time to work on some basics like hovering in less comfortable orientations or slow, precise flying. Using a pack for break-in in this fashion gives you more flight time and gets you more useful cycles of the lipos. Just remember to take it easy.

https://sites.google.com/site/tjing...ipo-terminology

Recently I heard a podcast where David Gray of Progressive RC says you can even charge them at max levels when breaking in, just don't overdischarge.

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06-29-2014 04:13 PM  3 years agoPost 17
rexxigpilot

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Florida

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If the pack did not get hot, the Solid Electrolyte Interface (SEI) on the anode is likely still intact. The pack should be OK. If the low voltage condition lasted for a longer period of time it would have heated up and destroyed the SEI. The cell would then have puffed and been irreversibly damaged. Good thing you caught it in time.

The SEI is created during the forming process of a lithium cell. It acts like a buffer to prevent overreaction of the anodic materials, thus preventing thermal runaway. During forming of a lithium cell the voltage is slowly raised from 0 to the final full charge voltage to gradually build-up the SEI layer.

Break-in Period - a properly manufactured lithium polymer cell does not need any break-in. However, it is still a good idea to test any new battery by initially using it with short flight time (reduced capacity draw) and gentle flying (reduced power draw). This way if the new battery has any manufacturing defects or shipping/handling damage, it can be detected without putting your helicopter at risk.

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06-29-2014 04:39 PM  3 years agoPost 18
ICUR1-2

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Ottawa, Ontario

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Thanks for the info
helped me to figure out why it was I don't do a break in period maybe for a couple of reasons.
1 I don't fly hard 3d, just sport aerobatic stuff
2 I never charge above 3c = about a 15-20 min charge time since I take only 70% out of the battery and never fully charge to 4.2
I usually stop charging when the amps drop off on the charger to about 1 amp and let the external balancer do it's thing.

but definitely good info to know should I decide to do hard fast flying

My CC logs show my 450 pulling 8 amps mostly with 45 amps spikes now and then

spending time, paying attention

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06-30-2014 12:00 AM  3 years agoPost 19
jason46

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MI

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I have never seen mention of the chemical additive sleep state previously, alas it doesn't seem that long ago ballancing was thought to be a gimmick.

We made up some rules can we have your moneys now.

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06-30-2014 11:59 AM  3 years agoPost 20
davehour

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Guayama, Puerto Rico 00785

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Hi again guys,

Flew the pack yesterday, and it behaved exactly as its companion. The packs end voltages and temperatures were the same. Seems I'm good to go.

This incident has taught me a lot about Lipo's.

David

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