Quote:
Originally Posted by Garry Spice
are 3200 lipo packs equal too 3200 nimh cells? or do they work out different?
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I can see your logic, but no. Will try and explain, but please do ask any questions if I don't cover it.
Nimh cells self discharge, so if you charge a 3200 pack to 3400 (200mah wasted in heat and resistance), then by the time you reach the track, that pack may have 2900 or less in it, plus it will consume more mah due to it getting hot during a race.
Just try fully charging your own cells, let them cool, then discharge to 6v at 10amps continous and they won't discharge the full mah capacity that you put in
Whereas Lipos, if you charge 3200, they will have 3200 in them when the car is on the track, a few mah may be wasted in heat but these cells will get no hotter than mildly warm under normal circumstances so there is little mah wasted if atall. They do not self discharge over time either. For example, I went to Belgium last week and while I was setting up, I thought id put a pack on charge which I knew id charged fully a week ago - and they literally went off charge within 5 seconds...... i.e. they hold there charge over long periods.
Realistically, a brushless car with a 6.5R Novak will consume 2000mah over a 330 second race. This is not based on calculation but based on my experience. Therefore, a 3200mah pack is more than adequate.
if you go for a higher C rating pack, then the continous ampage draw is higher and they'll discharge quicker in the car - which will result in a faster car, therefore you are likely to motor down or drive smoother and still only use 2000mah.
A 3200mah 20C Lipo pack, will make the car around 150g lighter (approx'), and the power they give is as good as the first charge on top spec Nimh cells if not slightly better. But this power does not deteriorate, after 6 months your Lipo should (if you haven't killed them by charging wrong/over discharging) be as powerful as the first charge (mine are).