[aceplant00]

I have a 75 watt p;wer invertor that plaugs into the ciggeratte lighter port in my car. I would like to know if this can be used safely to charge my battery packs and radio on the ay to the field. I guess more so to top them up after a few hours of being off the charger.

[igor_throw_the_switch]

Most chargers work on 12VDC. I don't understand why you'd want to invert it, then transform and rectify it back down to 12VDC. A 75W inverter will give you about 5A DC @ 12 V - figuring in losses in the charger.

Brad

[Dennis 9412]

Brad:

I think he wants to use his wall wart plugged into the inverter.

Dennis

[moo]

Originally Posted by aceplant00

I guess more so to top them up after a few hours of being off the charger.

You want to charge them because they've been away from the charger, and not used?

Bad Idea. Reduced battery life.

[igor_throw_the_switch]

Guess I misunderstood this one. I can't see a radio wall wart drawing 75W, so it should be okay. What I'd be concerned about is that the wall warts are trickle chargers - it'd take quite a while to top up the charge. It would be a lot better to have a proper charger that can dump in a few C worth of current - and it would plug into the ciggie lighter, or clip directly onto the car battery.

Brad

[moo]

Yes; but the faster rate heats and ages batteries.

The way I understood it was I charge overnight, but I want to charge on my way to the field using my standard charger.

Either he has a really long drive (a day or two), or he's wasting his time and money on an inverter.

Batteries won't drain significantly while stored in the car waiting to drive to the field, if they do you need new batteries.

[igor_throw_the_switch]

Ahhhh - I see now what you're saying. I need to up my caffeine intake I think

I know that a number of people *do* charge their batts on the way to the field, but this is risky. Even with NiMH or NiCad batts, there is a small chance of something going wrong during the charge, and the distraction caused while driving could be disasterous to say the least. Yeah, a lot of people get away with it, but why chance it?

BRad

[aceplant00]

Ok I will clarify this a bit. I charge my batteries for my plane at night. I go to work and they sit off the charger for 8-10 hours. I go to the field. The field I fly at isn't near my house thus I go after work ( A lot closer. I have a second pack I can put into my plane. I fly on #1 pack for say a hour or so then switch packs. Battery pack #2 sits on the power invertor with wall plug in charger plugged in to keep topped up. I am not using this to charge more so just top up the decrease from sitting all day.

[rscamp]

NiCds and NiMHs will provide higher voltage on discharge and maintain their capacity better if you peak charge them just before use. I don't recommend repeatedly charging them (topping them up). You definitely won't get the best performance if you try to slow charge them to top them up. This will depress the discharge voltage. A reduced discharge voltage results in less power available at the prop.

Do you peak charge the night before? If so, don't. To save time, you can partially charge the night before but don't peak and don't try to put in 100%.

Do you peak charge at the field? If so, this is the best place to charge or complete the charge.

Rob