Converting a gel cell torch to Nicads or NIMH

[Robin Colbourne]

I seem to be surrounded by large torches with 6V gel cell batteries which have died.

Having accumulated (groan) drawers full of nicads and other batteries over the years, I thought about converting some of these torches to run on them.

The issue as I see it is that a fully charged 6V gel cell battery will be around 6.36V, whereas five nicads would be about 7V. Is there a simplish way of limiting the fully charged voltage so it doesn't blow the bulb and without a resistor wasting all the excess as heat?

I do appreciate that I will need a different charger for nicads as opposed to the lead acid gel cell.

Any advice will be gratefully received!

Edited By Robin Colbourne on 18/11/2016 17:01:41

[Denis Watkins]

The forward voltage drop of Diode is 0.7 volts Robin, which is in your ballpark, or just put 2 in series for 1.4v drop.

Edited By Denis Watkins on 18/11/2016 16:50:11

Edited By Denis Watkins on 18/11/2016 16:59:46

[Don Fry]

Try it without, I doubt if the bulb is that voltage sensitive

[Don Fry]

But have you not heard, the world had moved on. I bought a blinding white workshop lamp, LED, works off some AA batteries, £4.50p.

Edited By Donald Fry on 18/11/2016 17:15:01

[Frank Skilbeck]

I've done this in the past with a gel cell bike light, worked well with a 5 cell Nimh pack. I don't use it anymore as I use LED lights now.

[Robin Colbourne]

Hi Denis,

Thanks for the reply. Does that mean I just put a diode in series with the bulb?

Cheers Robin

[Denis Watkins]

Yes Robin, in series. Diodes are listed in watts (W), like our leccy stuff,

[Robin Colbourne]

Thanks Denis, I'll give it a go.

Donald & Frank, I do have some LED torches, but I find the type of light from them in certain applications isn't as good as a filament bulb; generally if I'm looking where the dropped washer or nut went when working on the car.

Plus as I've got the big torches and the nicads it seems a shame not to use them.