a general charging query

[mattJT]

Hi all

Having gone from a brushless to a brushed set up (club rules for mardave and tam mini's)

Have ended up with a couple of nicad batteries - a 1600mah and 2000mah, the query I have is a small one and I'm sure I know the answer too.

I have a core udc20 (5amp max)....can I safely charge the nicads at 3.2a and 4a respectively (effectively 2c I think?)

Just that takes soooo long to charge them at 1.6a and 2a, even longer than my lipo's did


Many Thanks

[sosidge]

Good quality NiCd's could take that charge rate. Check the temperture as you charge.

[Col]

Leave the prehistoric stuff where they belong!
Lipo's can be had for pennies these days if you know where to look...

[bodgit]

If the rules wont let you use lipo,s then have a look here
http://stores.ebay.co.uk/vapextechbatteriesandchargers

Those nicads are old and I would not risk charging them at 2c
Get some new ones for next to nothing.

[Holeshot]

One thing to remember aswell is that nicads are prone to a "memory effect" or "voltage depression" and it is a good idea to fully discharge them before recharging or storing them.

[mattJT]

Cheers for replies guys

Basically I can use a brushless esc and 2s Lipo's, but can't use brushless motors and have a 20t limit.

Somewhere else someone said that wasn't much point using brushed motors and lipo's, so thought would go back down the nimhs route (only have the nicads as came with car) as did find nimhs to be good in the first car I had.

Essentially running an mtroniks rv15 with hpi saturn 20t in the mardave and an LRP ai runner reverse with 23t in the tamiya mini, both pretty basic combo's but for the car's scale and the rules, work out quite well, just need to sort out some 3000 ish minhs for both

[mattJT]

Originally Posted by Holeshot

One thing to remember aswell is that nicads are prone to a "memory effect" or "voltage depression" and it is a good idea to fully discharge them before recharging or storing them.

cool, cheers for that mate, didn't realise nicads were like that

[sosidge]

Originally Posted by mattJT

Cheers for replies guys

Basically I can use a brushless esc and 2s Lipo's, but can't use brushless motors and have a 20t limit.

Somewhere else someone said that wasn't much point using brushed motors and lipo's, so thought would go back down the nimhs route (only have the nicads as came with car) as did find nimhs to be good in the first car I had.

Essentially running an mtroniks rv15 with hpi saturn 20t in the mardave and an LRP ai runner reverse with 23t in the tamiya mini, both pretty basic combo's but for the car's scale and the rules, work out quite well, just need to sort out some 3000 ish minhs for both

There seems to be this idea floating around that LiPo batteries are incompatible with brushed motors, and vice versa.

Which is nonsense.

The battery simply supplies a voltage. Granted, the 2s LiPo has a slightly higher nominal voltage but that does't make any difference to quality electronics.

Since you already have the charger, I see no reason to get a NiMH when there are plenty of decent LiPos around. I have a Much-More Impress LiPo stick in my Mini. Power and usability is not an issue.

[mattJT]

Originally Posted by sosidge

There seems to be this idea floating around that LiPo batteries are incompatible with brushed motors, and vice versa.

Which is nonsense.

The battery simply supplies a voltage. Granted, the 2s LiPo has a slightly higher nominal voltage but that does't make any difference to quality electronics.

Since you already have the charger, I see no reason to get a NiMH when there are plenty of decent LiPos around. I have a Much-More Impress LiPo stick in my Mini. Power and usability is not an issue.

Thanks for this sosidge, but, pretty sure that both esc's don't say that you can't use lipo's with them, defo the mtroniks one, not too sure actually about the lrp one.

But then, from what your saying, this shouldn't matter tho, (as if I've understood you right), then at the end of the day, the ultimate ouput of either a 7.2v nimhs or 7.2v lipo, is actually the same as far as the esc is concerned.

[sosidge]

Originally Posted by mattJT

Thanks for this sosidge, but, pretty sure that both esc's don't say that you can't use lipo's with them, defo the mtroniks one, not too sure actually about the lrp one.

But then, from what your saying, this shouldn't matter tho, (as if I've understood you right), then at the end of the day, the ultimate ouput of either a 7.2v nimhs or 7.2v lipo, is actually the same as far as the esc is concerned.

I said quality electronics...

The only possible issue you can have is overdischarge of a LiPo due to the lack of a cutoff in most brushed ESCs. But as long as you stop running the car when it slows down noticeably, you'll be fine. Most racers won't even come close to dumping a LiPo in 5 minutes. I'm probably taking 800mAh out of the pack in mini class.

[mattJT]

Originally Posted by sosidge

I said quality electronics...

The only possible issue you can have is overdischarge of a LiPo due to the lack of a cutoff in most brushed ESCs. But as long as you stop running the car when it slows down noticeably, you'll be fine. Most racers won't even come close to dumping a LiPo in 5 minutes. I'm probably taking 800mAh out of the pack in mini class.

(the mtroniks one came with the car)

Cool, well maybe try it on the lrp one then. Cheers for the advice mate