Discussion List (Batteries)

[Adam Glatt]

Electric R/C airplanes and helicopters drive the development of better 
batteries for electric R/C airplanes and helicopters.  No other market 
places such a high emphasis on power density and energy density.  
Personal electronics only care about volumetric energy density and 
gravimetric energy density.  Cordless power tools only care about 
volumetric power density.  Any vehicle that operates on the ground 
doesn't care about mass (at least, not enough to pay for the switch from 
round cells to lithiums).

I still haven't heard one report of a Thunder Power Pro Lite 5.3Ah or 
6Ah battery failing in the 10-100 cycle range.  I've heard of a couple 
that fail within a few cycles that are replaced by TP at no charge.  I 
haven't heard of anyone retiring their Pro Lite due to capacity loss 
with high cycles.  In my opinion, Thunder Power Pro Lite cells are 
everything we need to have a great experience with e-pattern.  The only 
downside is cost, which will come down in time.

-Adam

Gray E Fowler wrote:
>
> Richard
>
> I am not a battery expert, but like everyone else on the list that 
> does not stop me from having an opinion about batteries.
> First, electric airplanes do not exactly drive the battery 
> market,......even if 50% of the FAI finalists use them. No other 
> applications
> that I am aware of uses these batteries in the manner that we attempt, 
> which is that massive current draw. What electric planes do
> to batteries is damaging, as demonstrated by your 25 flights.  
> I would not expect the battery market to develop a battery capable of 
> long life and extreme current draw since no one else uses
> batteries in such a manner.
>
> Invest in bottle of Windex, clean the oil.
>
>
>
> In fairness to the manufacturers, I don't think they really understood 
> that
> guys potentially would go out and fly 50+ flights per week.  When I 
> finally
> got all my infrastructure charging act together and made time to
> practice--which wasn't all that much, I still was clicking along at a 35
> flight/week pace right up to our first contest in mid June.   As you may
> recall, I was using 20C 3200s on a shared cost beta program.  At 11 lbs.,
> the airplanes were gobbling up 63-68 amps at times and significantly 
> heated
> the batteries and shortened their lives.  The manufacturer came out with
> some 15C 4000s--but there was still the problem of amp draw and heat.  The
> consensus at that point is the batteries aren't very happy at much 
> over 10C.
> The problem I had/have is anything over the smaller batteries was going to
> blow the weight limit--plus, as more information was coming out from 
> some of
> the top guys that they were getting around 50-60 flights on the larger
> packs.  Since I'm not a top dog, I would pretty much have to foot the 
> entire
> bill to switch to the larger units.  As it appeared to me--the batteries
> just aren't quite up to the task for the average guy--so I made an interim
> decision to go back to IC for the rest of the season--hoping the battery
> guys would come up with something more acceptable for '06.
>
> That didn't pan out very well either, so I was effectively out for the
> season.  (Lots of other contributing factors also)  What I told the 
> battery
> manufacturer was what a guy really needs is five sets of 
> batteries(with the
> then current stuff) and immediate service for turnaround.  Have three sets
> for flying and one or two sets traveling to/from.
>
> I'm sold on electric--particularly for a guy with limited practice 
> time.  I
> could go on and on....
>
> Richard
>
>
>
> Gray Fowler
> Principal Chemical Engineer
> Composites Engineering 
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