DIY Power Pack for Sigma EF-500 DG Super?

Hey all,

So I've been reading up a lot lately on quantum units and such, and was thinking about building my own. It would be for use with 8 or 10 AA Rechargable NiMH and would plug in via a coaxial port that I'll install in the flash as well. I read an article about doing it with sealed lead acid batteries, but I kinda would like to explore the versatility of using AA's instead. I would connect 4 or 5 of them in series, then parallel that with another 4 or 5, respectively. The port would feed right into the soldered connection for where the normal internal battery connections are soldered, and there would be a switch on the camera to change between the battery pack or internal batteries. Or perhaps using the 4 internal batteries as well would increase the current even more? Because from what I understand, the easiest way to increase the recycle time would be to up the current.

So how feasible is this project? Any advice to me as I try this out? Would it just completely not work? Am I misunderstanding how you add current to a system? Forgive me if my understanding of current is all wrong. I took one Electrical Engineering class in college and I don't really remember much of it anymore.

Never done it myself. but I have thought about it.

Some of the things I've put on "the list" to consider for such a project.

1. "Dummy" AA batteries to get power into the flash.
2. Sigma prints ZERO spec. on input voltage, so sticking to 4 AA (6v) or equivalent input voltage is a must. Technically you could probably get away with 5 NiMH, but I wouldn't go any higher.
3. Higher current (for faster recycle) would require decent wire or it would be self limiting.

The coaxial power jack has merit, and the base has a nice open flat spot that would be great. I know the 580EX can use internal, external or both for recycle but I believe it has a custom function to select operation which means Canon has internal circuitry to handle odd situations. If you built the pack with banks of 5 batteries I don't know that you would even draw current from the internal batteries since they are at a lower voltage. You may even end up charging them unless you add a blocking diode, so its probably safest to operate from just one source with a DIY mod like this one.

What has always put the project on the backburner for me is the Sigma spec. on maximum number of continuous bursts. At only 10 full power shots before they recommend letting the flash cool for 10 minutes I'm not sure how useful a battery pack would really be when all is said and done.

So, feasible - yes. Practical - maybe. But since it sounds like you have limited electronics knowledge I would tread carefully unless destroying your $200 flash is acceptable result. Batteries can be dangerous things because of the amount of destructive energy they can deliver in a very short period of time when used incorrectly.

mbellot, thanks for the input.

The dummy aa, batteries, i didnt really like that idea because it looks sloppy and you'd have to make a hole for the wire to come out... of course I'd be drilling a hole for the coaxial jack, but that will look cleaner, hopefully.

I was planning on sticking with the 6v...or 4.8v. If I did 8 batteries, it would get me my 4.8v in a parallel connection. Likewise, 10 batteries would get me my 6v. If I did 8 batteries, that would allow me to use the internal batteries as well.

The reason I want this mod done is because I do a lot of event photography. I use my flash for indoor photography, rarely ever full power. But having the faster recycle time would be great for those moments during a performance or something where I want to take a lot of pictures, but am limited by Sigma's recycle rate. It wouldn't be used for full power shots into umbrellas for portraits or anything like that. I remember reading that in the manual when I bought it. Thanks for reminding me of that.

If I go through with it, I'll be sure to write a detailed DIY guide.

Did you ever try it Vermin?
I wound up frying my 500DG with a 6-volt battery...evidently I did not do something right...

irishguy_wi wrote in post #11316618
Did you ever try it Vermin?
I wound up frying my 500DG with a 6-volt battery...evidently I did not do something right...

Yep! I had no problems with the mod...I think I did overheat it at an event using too many full power shots though.

https://photography-on-the.net/forum/showthre​ad.php?t=322674