Overheating Lipo on charging

[David Pearce 4]

I have a Nano-Tech 1500mah 3S battery which has only been used 6 times although it's two years old. Like others of this type I own it's already a little puffy. It's not be damaged or misused in any way.

Yesterday I used it and it was at 37% capacity after the flight. On charging, at 1C, it became hot so I stopped the charge. Cell capacity is now 3.997, 4.041, 4.188 or 77%, 82%, 98%.

Obviously this battery is faulty and won't be used again. But my question is this; could this fault be due to the charger or is overheating on charging a typical sympton of a faulty battery? My charger charged two other batteries successfully after this one.

Obviously I will monitor all charging very closely in case there is a charger fault but I'd appreciate any input..

Edited By David Pearce 4 on 27/05/2016 10:06:27

[The Wright Stuff]

Interesting. I will be curious to know the answer too. The one question that immediately springs to mind is whether there was significant imbalance between the cells before the charge.

Can you tell us which charger, too?

It will be great to have a good technical discussion on LiPo health issues!

[Engine Doctor]

As The Wright Stuff says, the problem may be due to the un-ballanced cells. Try charging one cell at a time via the balance lead. You will need a servo p[lug with the signal pin removed . Staring at the black lead on the balance plug The black will be the Neg to Cell 1 and the next wire will be Pos . Fit your servo plug into this and set your charger to One cell and the same capacity as the pack and charge . Repeat for cell 2 using the second wire asthe Neg and the third wire as the Pos continue until all cells are charged .This may restore some balance . If cells are too damaged then bin it.

[iqon]

Just out of curiosity, was you balance charging

[The Wright Stuff]

My take on it is that the charger is unlikely to have caused the battery failure. The Nano-Techs have fairly mixed reviews (never used them myself) and we should expect batteries to die from time to time. Failing at a couple of years old (depending upon how they've been stored) isn't ideal, but probably not unheard of either.

The far bigger issue, in my mind, is why the charger didn't detect the problem and stop the charge.

[gangster]

It could have been a result of serious out of balance. Looking at those figures you could be a lot bettet balanced than you started. Personally my next step would be a couple of more cycled on balanced charge. May be at 0.5c of you are worried

[David Pearce 4]

Thanks for your replies. In answer to your questions:

The charger is a Tamco 50W TAB6s.

Yes I was balance charging, I always do.

I'm in the habit of checking each cell when I finish charging so it is unlikely that they were seriously out of balance when used. But not impossible, I'm not quite perfect . . .

I agree Nano-techs aren't perfect. I'm gradually replacing all mine with Zippys which have a strong following in our club. I also like Dynamics. So I'm happy to bin this battery, my only concern is whether I need to replace the charger.

Thanks again.

[MattyB]

Short answer - yes you can keep using the charger, but keep a close eye on it until you are certain it is performing well over a series of charges of other batteries. You could also try putting that pack onto a "balance only" cycle if your charger can do that, then charge it at 0.5-1C after that completes and see if ti comes back into balance.

If that doesn't work simply discharge it to 0V (or near) over a load like a 12V lamp, cut the connector off, twist the ends together then take to battery recycling centre. Do not stab the pack or place in a salt water bath; those methods are now discredited, polluting and risky from a safety perspective.

[The Wright Stuff]

I'm currently wondering whether a simple LCD thermometer, with an audible alarm (if it exceeds a set point) would be a good idea, with the sensor placed on the charging batteries. The sort you can buy in aquarium shops!

For example.

Apologies if this has already been thought of / discussed!

Edited By The Wright Stuff on 27/05/2016 15:25:44

[MattyB]

A lot of the mid-high end chargers come with a temperature probe you stick in the liposack/ammo box with your batteries; both my iChargers have this. If there's an issue they are supposed to stop the charge automatically; thankfully I have never had to test this functionality!

Edited By MattyB on 27/05/2016 15:46:53

[David Pearce 4]

Thanks again for all your responses.

I agree with your suggestions and have fully discharged the faulty battery and will put in my local battery bank. I'm going to continue using the charger but keep a very close eye on it. My newer 4S batteries really need an 80w charger so maybe it's time to upgrade.

Cheers

[Eagle 899]

Keep an eye on the BMFA ads....I bought an iCharger 306B for £70 last year; excellent charger with temp sensor.

[David Pearce 4]

Posted by Eagle 899 on 27/05/2016 16:47:43:

Keep an eye on the BMFA ads....I bought an iCharger 306B for £70 last year; excellent charger with temp sensor.

Thanks, I will.

[MattyB]

Posted by David Pearce 4 on 27/05/2016 16:23:48:

Thanks again for all your responses.

I agree with your suggestions and have fully discharged the faulty battery and will put in my local battery bank. I'm going to continue using the charger but keep a very close eye on it. My newer 4S batteries really need an 80w charger so maybe it's time to upgrade.

IMO opinion there is really no point in going from 50-80W - kit yourself out with a 250-300W setup at minimum and a meaty server power supply to go with it and you are pretty future proofed. Remember with a setuyp like this you can parallel charge all your packs of the same cell count together at 2C and be ready to fly in half an hour. Job done!

Charger recommendation - Junsi iChargers or the Turnigy Reaktor clones from HK.

Power supply - Coolice Server PSUs or convert your own bought on ebay.

Edited By MattyB on 27/05/2016 17:53:44

[David Pearce 4]

Thanks Matty

Food for thought. Although I don't think I'll go bigger than 4S going future proof does make sense.

Cheers

Edited By David Pearce 4 on 27/05/2016 19:58:48

[MattyB]

Posted by David Pearce 4 on 27/05/2016 19:53:37:

Thanks Matty

Food for thought. Although I don't think I'll go bigger than 4S going future proof does make sense.

Cheers

Cell counts are not the important bit, it's watts and amps that are key. Even if you only fly 3S machines with a high wattage charger and PSU you can parallel charge all your batteries simultaneously to cut overall charge times. The big additional advantage is you can do this without stressing yor packs with the high C charging - 5 packs charged in parallel at 1C takes the same time as 5 charged individually at 5C, but is much better for your batteries.

[David Pearce 4]

Thanks again Matty

I was already looking for a dual 80w charger but as a typical flying session is 4 or more flights it would make sense to follow your advice. Time to shop . . .

Cheers

[MattyB]

I have just bought an iCharger 406 Duo, but i am not a huge fan of dual output chargers generally - in most situations they offer no real advantage over a good parallel charging setup. I bought mine because (for the wattage and features it offers) it is relatively cheap compared to the competition, and my 106b is still going strong after 4 years of use. This will be great for the 6S 4500 packs I have bought for my new Miss Wind, but in general I think you are better with two cheaper lower wattage chargers that can use one meaty server power supply.