Bikelights and recgargeable batteries

[lingus75]

I have been trying a selection of good, fairly new re-chargeable batteries on my Blackburn Commuter 4 LED front light. Now, I have one set of basic Panasonic batteries which work fine, but the point of buying some Uniross 2700 mAh bateries (with proper Uniross charger) was to give me more power and longer run time. The batteries are fully charged and power a radio control car for ages untl they run out (the panasonic ones barely run it but work on the light fine) but they will not power the light at all.

I have made sure the batteries are fitted correctly and they are fully charged but I am at a loss as to why they don't work in the light. There is obviously the possibility that they won't work on this light but I have not come across an appliance that won't accept re-chargeable batteries.

Does anyone else have any ideas why this may be the case?

[Moose.]

What's the voltage of the batteries that don't work? It could be your LED light requires 1.5v per cell and the batteries that don't work are 1.2v (total guess here!)

[Parrot of Doom]

The capacity or chemistry of the batteries is irrelevant, all that matters is the voltage and the current that can be drawn from them.

I think Moose is correct. Your 4 batteries will only be producing 4.8V, but your light may require 6V (4 x 1.5V). Your light probably thinks you have flat batteries in there (4.8V is a reasonable cutoff point for a 6V supply going flat).

[lingus75]

Parrot of Doom said:

The capacity or chemistry of the batteries is irrelevant, all that matters is the voltage and the current that can be drawn from them.

I think Moose is correct. Your 4 batteries will only be producing 4.8V, but your light may require 6V (4 x 1.5V). Your light probably thinks you have flat batteries in there (4.8V is a reasonable cutoff point for a 6V supply going flat).

Interesting, I had a look at the batteries and you are in fact correct (both of you) the re-chargeables are 1.2v and the Panasonic's are 1.5v. However, I then put in some 1.2v 1300mAh batteries and it works fine

It's no major issue as the crappy batteries run for a while anyway but it was/is confusing why this happens. Heyho.

[Parrot of Doom]

Check the voltage of the rechargeable batteries when fully charged. I bet they're not 1.2V, I bet they're below that.