lithium polymer batteries

[gponder]

I was reading about the lithium polymer batteries in a recent Flying Models magazine. Supposedly they have better "energy density." According to the verbage in several of the monthly columns, they behave differently than Ni-Cads with respect to both charging and discharging. They need a different charger, and the cells were referred to as "not cheap." I called one of the distributors (FMA Direct) and their prices range from $4.95 for a small one, to about $28 (I think) for one in the range of 3000 mah. I'm not sure what the "official voltage" is but it's in the range of 3-4 volts. I'm not sure about the weight.

So here are my questions for you electrical experts. Are these potentially suitable for electric control line? If so, what would be a likely combination to start with for a speed 400 or a speed 600. If these batteries really don't match up with a speed 400 or 600, then what motor might be suitable for these batteries if they offer an improvement over Ni-Cads.

thanks, glenn

[jrb]

Hi Glenn!

Simple answer: Yes.

But there's a bit more to it than that.

Also, a bit more to ECL than regular EP.

And, unfortunatley not many frequent here.

Here's the forum that got all the battery info: http://www.rcgroups.com/forums/forumdisplay.php?forumid=129

It would be nice if some more ECL activity was posted.

[steve lewin]

Li-poly are indeed special, 3.7V nominal, and much lighter than NiCd/NiMH for the same energy capacity. Unfortunately they are still a bit fragile and not yet too good at high currents though getting better, almost by the minute.

If you have anywhere that will let you fly C/L indoors they are great with GWS motors and similar and they seem to be usable up to about S400 but not really much more. They also do indeed need special chargers and can't be charged very fast (about an hour is as good as it gets AFAIK).

ATM I'm only playing with the small Li-polys, mainly for FF and indoor R/C. I'm still using NiCds for my C/L experiments.

Steve