NiMH battery charger

[videoguy]

I bought a NiMH battery charger, and it says it shouldn't be used with an extension cord, and the charger should be vertical when being used. Are either of these warnings BS?

[SoToasty]

I would say it depends on the extension cord. Some of the chargers can pull a lot of current. Possibly to much for some of the cheapy extension cords. Also, most extension cords now, have multiple plugs on the end, and might tend to have multiple things plugged into them. I don't think it would hurt the charger, but it might melt an inferior extension cord. I think it is more of them playing it safe. As for the vertical thing, have no idea.

[Lainie]

[insert Rats of NIMH joke here]

[jimmy101_again]

Maybe, maybe not.

A battery charger can draw a fair amount of current. Most household circuits (in the US) are 15 amps and most cheapo (18 gauge) extension cords are supposed to be able to handle that current as long as they are not covered. So an extension cord shouldn't be a problem, but I would avoid using a 99 cent extension cord.

Batteries get hot, sometimes very hot, when charging. Heat is bad for most batteries. The charger may well have been designed for convection cooling based on a particular orientation. Any other orientation may overheat the batteries, or charger, to the point that something is permanently damaged. There is even a chance of an explosion.

Is this a rapid recharger? If it is I would stick with what the manufacturer recommends.

[niner]

Is this a charger with no cord, but simple plugs into the wall? If so, then I'd guess that the two of them are related. If you plug it directly into the wall, you're generally out in an open spot (the biggest risk would be behind curtains, I'd think). Put it on a cord and they fear you could lay it down and put something on top of it, or it could fall between seat cushions, etc. In other words, it's a way of forcing you to not take risks.

This battery site suggests that maximum charging rate of a battery is it's AH rating in amps. The highest AA batteries I have are 2500 mAH, or 2.5 amps maximum charging current. However, that's at 1.5~ volts, which is only about 4 watts of power. Even with 8 batteries, and a 50% power loss, you're only talking about 60 watts of input power - the same as a standard lightbulb. To compare, a 18 gauge wire should carry less than 2 amps, or 4 of the same sized bulbs.

Battery site:
http://www.powerstream.com/NiMH.htm
Site where I got the ridiculously low 18 gauge carrying capacity:
http://www.powerstream.com/Wire_Size.htm

Henry

[videoguy]

Thanks guys.

It has no cord, and is not a rapid recharger.