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LiPo sick ?


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During my flying session last Saturday I had completed a flight with my Sebart Angel and removed the battery pack for charging and just mentioned to a colleague that the battery was nice and warm, not overly so, just "warm".   He said his batteries never get that warm, but he also doesn't fly for very long either.

He said he would put the battery on his "Flightpower Balancer unit" to check the voltage and said it was low according to the lights on the unit.  I thought nothing of it and attached it to my Bantam BC 6 unit, when running through the start procedure,  the unit only recognised 5 of the 6 cells, now what ?  Despite turning the unit off and running through the programe again, it still did not recognise the fact the battery had 6 cells (battery is a Flightpower 3700 mah)

There is no "puffing" of the pack and no "magic smoke" from anything.  When connected to the Hacker ESC in the plane it gives the requisite beeps from the ESC and only gives 5 beeps and not the usual 6.

So my question is, what has happened and what can I do ? Can I just re-programme the BC 6 to charge 5 cells and fly it is a 3700 mah 5 cell pack or are there wires to be cut to ensure the battery charger does not try to charge a dud cell, or any other suggestions ?  I hope I haven't ruined a pack by letting it be attached to the "other unit" mentioned above.  It only has about 10 flights on it as that would have been a very expensive introduction to electric flight.

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You need to check the individual cells via the balance connector, you want to use a digital voltmeter (or multimeter) and you need to be careful not to short the battery out. Between each pair of pins you should read the voltage which should be above 3v, but 2.85v as a minimum. Also this will tell you if any of the cells have stopped working. If you have over discharged the cells then it might be possible to save the pack at a low charge rate, if one of the cells has stopped working then you could try sending it back to the supplier or manufacturer.

Cheers,

Tom

PS - if you find it has over discharged then you also need to find out what has caused this as well, check the ESC settings are correct

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Thanks for the reply Tom, I will check the pack.  However, I have a second pack (Thunder Power 3850 mah 6S) that was charged immediately after on the same charger i.e. the night before flying and this didn't show anything wrong with the cell count on the charger after a flight of roughly the same duration.

The problem in slow charging the pack will be getting the BC6 unit to accept the fact it is charging a 6 cell unit as the "R" setting (the number of cells the unit has detected) shows 5 and the "S" setting (the number of cells entered manually by me, shows 6). 

ESC settings are correct as have checked those with the Hacker Software and borne out y the fact the second battery is still OK.

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I think it has been mentioned here before that Flightpower may not merit their price or reputation - I wouldn't know.

I had the same issue with one of my Zippy 4S packs, my charger only recognised 3 cells, but I put it on slow balance charge anyway and checked it again after 15 mins and all 4 cells were showing fine 

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Hi Tom, sorry I didn't reply to your mail sooner, work got in the way of the hobby, as usual !!

The individual cell voltages are in the region of 3.9v, so all appears OK.  Will be flying again in the morning and will let you and Nick how it went on Sunday when we return to work.  Here in Dubai our weekend is Friday and Saturday, at the moment.  From 1st December we are only having the Friday off !!

We do finish early (15:30) on a Thursday and may keep a plane in the car during the cooler months and get a few flights in after work.

Heading home to South Africa on Dec 19 and will spend 2 weeks at home before heading back to Dubai. 

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Enjoyed the flying on Friday morning and had 3 very good flights with the Angel and 3 with my World Models Mustang. This apart from a few training flights with a couple of guys I am teaching at the moment.

The battery went well and had a 9 minute flight including taxiing and took out 2885 mah from each of the batteries (one is 3700 and the other 3850), so very happy and thanks for all of the advice.

As for the temperature at the moment, yep certainly cooler than a few months ago and "down" to about 17 in the morning and up to 30 at lunchtime.  The Dubai Rugby 7's have their new home about 5kms from our flying field and you may have seen some of it on Sky.  Don't know if they showed the surrounding area and the freakish weather on Saturday but we had a sandstorm, thunder and then rain !!  Luckily Friday was great and hardly a breeze blowing.  The temperatures do not seem to affect our planes in any way, thankfully, however, in summer I tend to try to keep the cockpit area covered between flights as we have no shade at the one flying field.  Our new filed has shade cloth and far more pleasant.  I do not fly the RCV 91 CD in the Mustang during summer as the engine gets quite warm anyway, but apart from that we fly all year round.  Just have shorter sessions early in the morning in summer as by about 09:00 it is far too hot and humid to stay outside.  Thanks once again for your help.

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