I scrapped a BMW a while ago, but kept the small torch out of the glove compartment. Now I want to charge it up, but I've discovered that the bulb is 2.2v, which means it's transformed down from 12v, but is this done in the car or the torch itself? I don't want to give it 12v and trash it since it's very convenient. Anyone know about this? Also, the terminals are not marked
TIA
Steve
A normal AA battery is 1.5v - a NiCad AA rechargeable battery is 1.2Volt - so two AA batteries = 2.4V
I am at a lose ???
Andy
You sowed the seeds of doubt there, so I went and checked. It's definitely
2.2v, 0.25a. But I still don't know whether it is fed with 12v and cut down to 2.2v in the torch, or fed with 2.2v from the car.Steve
Chances are it's 2 AA NiCad's. You often find torches with the bulbs slightly under rated for the batteries. It makes the batteries appear to last longer though obviously not the bulb which has its life considerably shortened by over voltage. Anyway what I would do is to use a voltmeter and measure on the input socket. With any luck there won't be any diode protection and you can measure which pin/hole is + and which is -. You can then trickle charge them by putting a resistor in series with the + pin and taking the - to earth. Probably 120 ohms or a bit more would be right for a
10 hour recharge.
Inside the torch body you will find 2x DEAC batteries. (Flat round NiCd of approx 500mAh capacity rated at 1.2V each). The charging from the 12V car supply is via a dropper resistor in the glovebox socket. It's a pity there's no room for AA cells in the moulding as I was going to convert mine to LED with NiMH cells.
JB
It's got two Ni-Cad cells, which would be nominally 2.4 volts in series.
I'd guess the charger is not part of the torch. Maplin might sell one, but it would be cheaper to buy a new rechargeable torch with charger.
I'm surprised it's that crude. Given the tiny current allowed to trickle charge Ni-Cads of this size without damage continuously, I'd have thought it would take ages to re-charge one after use. Or does it only charge with the engine running?
Mine still works on a '97 car - so the charger certainly must be either intelligent or at something like the 30 hour rate.
No intelligence in the charging at all as far as I can see. Just as you say, a low charge current. Mine is still ok even after 12yrs.
JB
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