Ni-MH Batteries - Discharge Current - R/C model

Any model boaters/flyers/drivers who can answer me this?

I’m renovating an electric R/C model boat that I built in my teens for my son’s amusement. OK, for my amusement too. Almost everything seems to work fine, the motor goes, the radio gear is good (despite all being 24 years old and having spent the last 20 years in a box).

I need to get some rechargeable batteries however. It’s a scale model, it’s only slow, and it has a pretty lazy motor that according to the spec sheet only draws 3 amps at max. efficiency which I understand isn’t much by modern electric r/c standards.

I’ve been looking through catalogues at what’s available. There are sub-c NiMH batteries at around 2400mA/hr and from what I’ve been reading they would certainly be fine.

However, there are a range of AA size cells, some up to 2200 mA/hr. They’re much, much cheaper than the sub-C’s and they’d fit into the available spots in the boat much better.

However, various R/C modelling websites that I’ve found warn you off AA’s because they say they can’t put out high currents. However, nowhere do they say what the heck they mean precisely by “high current”. Other reading I’ve found talks in terms of currents of 15 amps or higher in R/C modelling applications. So it may be that by “high current” they mean waaaay higher than my pissant little motor will draw, and that AA’s would be just fine for my toy.

Anyone know?

Yep. Three amps isn’t what they mean by “high current”. I have some 2/3A (odd size, but popular in model flight) that are rated for 13A, although they’d doubtless prefer to be punished a little less. Good AAs would be OK for up to 18A - and sub-Cs are definitely overkill for a 3A current draw, although they’d give you good duration. There are even AAAs that would see you all right, but their capacity is lower - 650-700 is pushing it.

(I’m surprised you’re only seeing sub-Cs up to 2400mAh. I’ve seen plenty of 3300mAh cells in that size.)

Unit is mAh, no slash; milliAmps times hours, not divided by.

Thanks Malacandra.