Use Petzl Myo XP Gen. 1 with 4 NiMh?

I have modified a Petzl Myo XP Gen. 1 to work as a bicycle light. This means that I use the light for about 2 hours and then charge the NiMh batteries between the bicycle rides. I use NiMh batteries since the light is unregulated and I want to have fresh batteries for every ride to get as much light output as possible during the 2 hours.

The problem is that the light is dimmer with 3 NiMh than with 3 alkaline batteries, due to the lower voltage of the NiMh I would guess. I was therefore wondering if I couldn't use 4 NiMh instead to get the light as bright as (or even brighter than) the light running on alkalines. The problem is that i don't know if the slightly higher voltage (4,8 V) would damage the light.

1. Do you know if using 4 NiMh (4,8 V) instead of 3NiMh (3,6 V) or 3 alkalines (4,5 V) would damage the light?
2. If yes, is there a way to avoid that, by adding a resistor or similar, to avoid damaging the light?

I know that you're not supposed to use NiMh batteries in the Myo XP, but I've done that almost daily for more than a year without any problems.

Thank you.

ah! the plights of resistor driven lights!
1. Possibly. One cannot know till he's tried....many variables here. the key issue what the volatge of the 4Nimhs will be under load and if this will atch the alkalines under load. The question is what will happen if you have 4Nimhs in the low mode where the ir voltage drop will be less.

2. It may but you will be adding one more mouse trap (more resistors) into the system.

I guess you could try with fresh Alkalines, measuring their combined voltage under load with the light on. Then you will have to replicate the load (off headlamp) on Nimhs to see their voltage drop. Then cover the voltage difference with a resistor.