Swap to NiMH in old SunPak Autozoom 3000 External Flash

[DennisS]

I have an old external flash - SunPak Autozoom 300 - that works quite well with my Nikon D5100 SLR. I am using an adapter on my hotshoe to protect the circuitry of my camera from the high voltage of this old flash unit.

Coming to my question - the manual for the flash recommends 4 AA alkaline or NiCd batteries. So far I have used alkaline but would like to use NiMH rather than NiCD. Is there a downside to this - would this damage the circuity of the flash at all with extended use? I have tried it out and it appears to work just fine although the pulsing sound and flashing indicator lamp - when the capacitor is at full capacity - is more frequent/faster than with the alkaline.

[Vortex]

Coming to my question - the manual for the flash recommends 4 AA alkaline or NiCd batteries. So far I have used alkaline but would like to use NiMH rather than NiCD.

If the flashgun was originally designed to use NiCd cells then using NiMH is perfectly OK. (I assume you are using individual NiMH cells that you charge with the correct type of charger).

Is there a downside to this - would this damage the circuity of the flash at all with extended use?

No...

I have tried it out and it appears to work just fine although the pulsing sound and flashing indicator lamp - when the capacitor is at full capacity - is more frequent/faster than with the alkaline.

The NiMH cells (or indeed NiCd) are able to deliver I higher discharge current, hence the more rapid pulsing of the indicator lamp. I see exactly the same effect on a really old Vivitar 283 that I run on NiMH cells; and that wasn't even designed to use NiCds...

[Kodiak]

To add to Paul's correct answers, when it comes to which electrochemical
compound to use in flash units like it's the case, two parameters are crucial:

• the low inner resistance of the compound —this assures the quick delivery
of current when needed for fast recycling times, and

• the voltage —to make sure that the internal circuitry of the flash will operate
within the manufacturer's required (nominal) tension.

[DennisS]

Thank you Paul and Kodiak. That is a relief to know. Yes, I use the relevant charger for the NiMH batteries - a La Crosse BC1000 charger.