schumacher

I've seen some Lithium Polymer Sub C cells that they use that have 5000mAh rating and have 1.3v per cell. whether these would be legal for racing I don't know.

grizzbob, what plane is that for? The systems aboard the Airbus planes are pretty sophisticated, all the engineers I spoke to (mainly BAE) said they were superior to the Boeing equivalent in every aspect but they are biased.


sanj

Grizzbob

iTrader: (2)

Well, the supply I deal with is by Acme. They originally designed it to work with Honeywell's INS, but it's also rated to power most any gauge in the cockpit. I'm sure that's mostly for Boeings, but I'm not sure if any other companies' aircraft use it.....Oh, & the battery packs I mentioned for it cost us about $650 apiece(it's as an assembled unit, with wiring, 9 pin connector & a pack heater with temp sensor installed(so the pack doesn't get cold)....

JDM_DOHC_SiR

iTrader: (31)

Out of my price range

-Dave

NightKidZ

I think the problem with lithium polymer cells is they cannot withstand the high current dischatge rates we are using in RC
I mean, from a electrical efficiency POV, it's stupid to use a low voltage, high current system like what we are using here... imagine the I square R losses
Cheers

dw

Grizzbob (or anybody else). You mention heaters. Do you have any info on the effects of packs getting cold or how warm they need to be kept?
I sometimes race in temperatures around 0 degrees C in the winter. Should I be heating the batteries before charging?
I know 3000's can start false peaking below about 10 degrees C.

JesseT

You definately shouldn't charge at 0 C. It will take all the punch and run-time away from the battery and just builds the pressure up in the cells. It's possible to make the cells vent without being warm at all! Lithium ion batteries are unsuitable for RC because of their high internal resistance. That means that when you start to take current out of the cells the cell voltage collapses.

underdog

Lithium Ion cells are used in R/C applications, but are limited to the low amp areas like park-flyers.

I've heard from someone testing the Lithium polymer cells that they were able to pull over 60 amps with them and they were only warm.

In most races, only NiCd and NiMH cells are leagal.

Grizzbob

iTrader: (2)

dw, as far as the heater for the NiCd packs that work on is concerned, it's set up to activate when the pack's temperature drops below 60 degrees F, but I suspect that the ideal temperature will vary from one type of cell to another(& even from one cell manufacturer to another with the same type & capacity, like the difference between Panasonic & Sanyo 3000's, for example), so what works for those packs I work on may not for others...