The BP-511 battery packs for my Canon EOS D30 digital camera died one by one over the last ten years. The last two of them are extremely weak and are about to die. So I've been thinking of alternative power sources, rather than buying more BP-511 battery packs. One such alternative source is the R/C battery packs. However, using the R/C battery pack is quite cumbersome, unless you've been doing it for years as a wedding photographer. I would like something that fits inside the vertical battery grip.
The Experimental Canon BP511 Dummy Battery Interface gave me an idea. Why not use a 9-volt battery? Attach it to the BP-511 dummy battery and you are done.
However, the Canon EOS D30 is rated for 7.2v to 8.1v. Will 9-volt work? It might burn out the electronics and damage the camera. Taking a risk on the Canon EOS D30 is worthwhile, because it's extremely old and I'm ready to upgrade to a Canon EOS 5D, 60D, or a 5D Mark II.
So I attached a 9-volt battery to the BP-511 battery pack and plugged it into the Canon BG-ED3 Battery Grip (see photo below) and turned on the camera.
Quite surprisingly, the Canon EOS D30 worked with a 9-volt battery. But not every type of 9-volt battery. See below for details on each type of 9-volt batteries.
I found that it worked best with the NiMH rechargeable battery. The ones I got are rated at 200 mAh. Compared to BP-511's 11 mAh capacity, they don't last too long. They do come in handy in an emergency.
It seems that it's not a good idea to leave the NiMH 9-volt batteries inside the Canon EOS D30 when not in use. The Canon EOS D30 seems to drain the battery even when it is off. I put one in before noon and shot a few photos. When I came back to use the camera in the afternoon, it's already out of battery. The battery seems to last more than a few shots of photos when just inserted and I keep shooting.
Alkaline 9-volt batteries doesn't seem to work as consistently as the NiMH. And the brand may make a difference. The Energizer ones lasts a few minutes, before the battery indicator started blinking. The Sunny Select Alkaline Premium Long Lasting batteries from Lucky supermarket doesn't work at all; they give the flashing battery indicator right off the bat. They even make the digital camera display Error 81 some times.
The 9-volt battery is smaller than the BP-511 battery pack. Therefore, they will fit in a hollowed out BP-511 battery pack. This means that it will work in the Canon EOS D30 directly without the vertical grip. Or you can put two of them into the BG-ED3 vertical battery grip.