[mannesty]

... that today's modern electronic wizardry can't deal with the differing potentials of various battery types.

I've recently bought a Pentax AF500FGZ flash complete with its TR Power Pack II. I've found a manual for the Power Pack online and looking through it I discovered that NiCd batteries are not compatible and presumably NiMh aren't either. The same is true for the original TR Power Pack for the AF400FTZ hammerhead flash.

My surprise was to learn that NiCd, and presumably NiMh, batteries are not compatible with the newest TR Power Pack III for the AF540FGZ flash either.

These Power Packs take 6 x C cell batteries so I know that the total voltage is 9V for Alkalines (1.5v/cell) and 7.2V if NiCd/NiMh (1.2v/cell) were used.

I just don't see why the difference can't be dealt with by the electronics, as most devices that use 4 x AA/AAA cells can deal with it.

Any of you electronic techies out there care to educate me?

Has any of you tried these Power packs with NiCd/NiMh batteries with any success, albeit with reduced recycle times and perhaps fewer flashes per charge?

[hoanpham]

I have mod these flashes. The NiCd cells will melt down the battery package, only if you use it at full power shots within a short timeperiod.

The NiCd/NiMh charges quick, and the current is powerful. The internal cables are not dimensioned for this kind of use.
What I did is replace these cables, find spare parts for power packs, ie metal springs for batteries. I also create an external power cable using harddrive power sockets to feed DIY battery pack.

However, the best way is to use the unit at 1/2 power as max to prevent heat/melt down the plastic of the power pack.
Now, if i need more power, I just bundle several units, but they too at 1/2 at max.

and be careful when you open up. high voltage, danger, very danger.

[mannesty]

Thanks for the info hoanpham. So are you saying that it is the current that NiCd/NiMh batteries can deliver that makes them incompatible?

That being so, why haven't Pentax simply fitted thicker internal cables, especially as they've now had three models to perfect it.

[hoanpham]

I think pentax support want to be in a safe side by saying 'not compatible' to prevent you and me putting NiCd/NiMh in their flashes. If we do, we are on our own. No guarantee. I replace the electrical/power wire with either thicker, or better, multiple thread type for maximum flexible and softness.

It's not only the cable. The plastic cannot stand the heat from the batteries. The springs in my power pack is totally deformed and had no tension left when they have been heated up.

I have a dozen of cheapmanual flashes with radio receivers, so the need of one big flash is fallen away. Also the trigger cable of these models are quite expensive and hard to get. My radio transceivers costs 15 usd each from ebay/hongkong. My manual flashes cost 10-15 usd each on used market. The most expensive part is the batteries. I bought 50 pieces 2700 mh a year ago, and still have some spare.

[mannesty]

Thanks for the explanation. Most helpful.

[sterretje]

If I recall correctly, Metz advised against non-alkaline batteries for their 45 CT1 when not using their dedicated rechargeable battery pack.

And thicker cables cost more money, by the way Other parts in the flash might also need to be supersized adding again additional costs.