I actually did that with my 285HV speedlites, using a 7.2v SLA Deep Cycle wheelchair battery from eBay. For your purposes, a couple in parallel would work quite well. I actually drilled small holes in the battery cover of my flashes, and wired up dummy batteries, and used RCA connectors hooked up to the batteries. Was a pretty slick setup.
Originally Posted by frotog
You could also do Lithium or NiMH battery packs, if you want to save weight. I considered doing something similar to old MTB head lights-- a NiMH battery pack mounted in a bike water bottle, and then clamping a water bottle cage to my light stands. Never got around to it, though, as I don't do product photography much anymore.
I already know it is...I have replaced the batteries in my Quantum 2, as well as in two Quantum Turbos, using the Powersonic 832.
Originally Posted by mgb74
As a long time Metz 60 user I've grappled with battery issues for years but I've never tried the Lithium batts which might be the best option. https://www.flickr.com/groups/421691...7612486080070/ discusses the Lithium batts and they seem to recycle faster than the Sonnensheins.
The last 2 new Sonnensheins that I bought from an Australian distributer performed WORSE than my old batteries with only about (approx.) 3/4 of the capacity. Maybe they where stored too long before I got them, I don't know, but I will never buy Sonnensheins again.
For MANY years I've used external 6 volt 12AH gel batts attached with fly leads on 2 of the 5 Metz 60's that I regularly use. These have much greater capacity and are extremely cheap to replace but are quite heavy (although this doesn't matter much in my line of work, and some times the weight is an advantage). The fly leads that I use are shielded well to avoid shorts and are heavy duty. Over approx. 5 years of use they have never been a problem, have never developed a poor contact, shorted or come loose.
One disadvantage that I've noticed with some batteries is that their internal resistance might be slightly higher so the recycle times can be a little slower, enough to matter anyway. My external batts take approx. 2 secs longer to recycle at full power. The Sonnensheins seem to recycle faster, but they are still not worth the money IMHO. If I ever have to replace them I will go all Lithium.
I would guess that the issue with your Sonnensheins was, as you suggested, that they sat too long on the shelf without being charged. From what I've read, the design life for SLA batteries is much longer when used with a float charger.
Here's an example of a DIY LiPo conversion: http://andycaus.wordpress.com/2013/0...po-conversion/ With LiPo batteries, you can specify discharge rate. But it might be best (for the life of the flash) to keep the discharge rate within the SLA spec.
In the end, a lot depends on how you plan to use the flash. LiPo batteries might be best for infrequent use or if you walk around with the power pack. But if, like me, you're planning to use this as a portable monolight for amateur use, it's tough to beat the inexpensive SLA batteries.
If you choose to use an old battery case, an alternative would be an old Metz 402 Nicad case, as these are the same shape and you can easily take them apart.