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Electric Tug Battery Life

Be kind to our tug pilots, we cant do without them.
Chris Hurst
Posts: 10
Joined: 12 Apr 2015, 17:10

Re: Electric Tug Battery Life

Postby Chris Hurst » 18 Apr 2016, 10:54


I wonder if the batteries were 'run in' at all, as I understand that higher power LiPo batteries need a few initial gentle charge/discharge cycles before they learn what their real capacity is. Maybe, a failure to do this can shorten their effective life.
Thanks Peter

No, sadly they weren't. I was not aware of that issue at the time but will certainly do so with any new batteries.

GordonT
Posts: 49
Joined: 18 Mar 2015, 11:10

Re: Electric Tug Battery Life

Postby GordonT » 20 Apr 2016, 11:30

Chris - for 25 to 35C, read 12.5 to 17,5C, which is probably much closer to the truth for those batteries. As John said, better batteries required. :D
It's OK to leave Lipos fully charged for a day or two, but every day more than that will shorten their life. Discharge to 3.8V per cell for storage. I keep all my batteries in a beer fridge at a constant 5C, winter and summer. In a steel cabinet in a garage, the temperature is going to vary quite a bit. The cooler the better really, but you don't want to freeze them.

Gordon

Chris Strong
Posts: 67
Joined: 18 Mar 2015, 12:06

Re: Electric Tug Battery Life

Postby Chris Strong » 20 Apr 2016, 14:43

Yes, battery life. I have always kept my batteries fully charged and in the garage with no apparent problems? I've just charged some 6,500ma batteries which were last fully charged in October last year and none of them took more than 300ma with the lowest showing 97% and the highest 100%% - am I just lucky? Concerned of Andover!

GordonT
Posts: 49
Joined: 18 Mar 2015, 11:10

Re: Electric Tug Battery Life

Postby GordonT » 23 Apr 2016, 17:25

Chris - fully charged Lipos will normally hold their charge for years. However, if left fully charged, their internal resistance slowly increases, which will reduce their capability to deliver current. You may also find some loss of capacity goes with this and some puffing up of the cells. Store them at 3.8Volts if you possibly can. Most modern chargers have a storage mode which will bring the batteries to the correct level.

MarkDev
Posts: 231
Joined: 19 Mar 2015, 10:41
Location: Dorset

Re: Electric Tug Battery Life

Postby MarkDev » 23 Apr 2016, 19:28

Does this happen with all lipos? Or just poor quality ones or does it apply across the board? What about li ion?


M

GordonT
Posts: 49
Joined: 18 Mar 2015, 11:10

Re: Electric Tug Battery Life

Postby GordonT » 24 Apr 2016, 17:32

Mark - This happens with all Lipos, just that the more expensive ones will probably take longer. The new Turnigy Graphene cells may be less prone to doing it, but they're too new at the moment to know for sure. Li-Ion - not sure to be honest.

Chris Hurst
Posts: 10
Joined: 12 Apr 2015, 17:10

Re: Electric Tug Battery Life

Postby Chris Hurst » 25 Apr 2016, 14:04

Many thanks everybody for the various thoughts. I will progress this over the next few months and let you know where we get to.

David Wilcock
Posts: 11
Joined: 20 Mar 2015, 09:50
Location: Silsoe, Bedfordshire

Re: Electric Tug Battery Life

Postby David Wilcock » 24 May 2016, 22:04

Hello Chris

I hope you resolve your battery life issue. I have very little technical knowledge but this is my experience having done a lot of electric flying in recent years.

I have found a lot of variability in the quality of all the Li-Po's I have used. I store all my Li-Po's at full charge in an largely unheated store. Some survive the winter, others don't, some last years others only months. Some run at low discharge rates in sports models, others get hammered in hotliners for short bursts, it makes no difference.

Capacity-wise, I have found that most batteries lose the ability to deliver their stated capacity quite quickly.

Typically I get 3 to 4 years out of most batteries. The good news is that in every case the battery dies reasonably slowly and I have never lost a model through Li-Po failure as (my radio is always powered by a Li-Po via an ESC BEC or voltage regulator).

However, one thing I have found extremely useful with my FrSky Taranis transmitter is the ability to use the telemetry to see what is happening to one's battery voltages in flight. I set my display to show the total voltage of the battery, the lowest individual cell voltage and the regulated voltage going to the receiver. It's interesting to see how the voltages change under load in the air (handy to have a "Pilot Not Flying" to look at the screen and note the voltages).

I hope this helps.

David


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