RC Car battery question.

[pelle242]

Since I know there are lots of RC folks here I have a question.
Just got a email from my 10year old nepew with his christmas list and he wants a new battert for his RC car.
Its a Traxxas Grave Digger and as far as I can tell it comes with a 8.4V NiMH pack but it has LV detection for LiPO.

Now I have some A123 cells left over and thinking if I can put together a pack for him and get a cheap charger of ebay.

Is this advisable? Does RC car controllers in this price range have current controll or do they count on a specific internal resistance in the battery to not burn up?
The manual says max 2S lipo ie 7.2volts, 2S A123 would be 6.6 nominal. Will that be slow and boaring or will the higher C rate make up for lower voltage?

 

[snellemin]

The 6.6v will work fine. You can gear up to get to the same speed as 7.2v. Or you can do 3s1p A123 in a triangle format.

old vid of my rc pulling my kid with 4s1p A123.

[youtube]I5BXVafQDgw[/youtube]


This is another one on 3s1p A123. Start watching at 1.20
[youtube]TMYv4y2VgIc[/youtube]

 

[pelle242]

Fantastic vids

How would 6.6V A123 compare to 8.4V NiMH? Would it be an upgrade?

 

[snellemin]

If it's a brushless setup, than it can be. If it's a brushed setup, not so much. But as I said before, with the A123's you can gear up to make up for the lack of voltage and not have to worry about stressing the batteries out. I've heated A123's to 193F in my RC toys before, without bursting in to flames and whatnot.