Where can I buy the jack or plug that plugs into the E-M5 grip providing external power? I already have the AC-3 power adapter but for timelapse, would also like to be able to power the camera with an external battery after stepping the voltage down to 9V. Thanks.
You can't, it's proprietary to Olympus! Two options: - cut the AC3 cord and put a jack so you can unplug the cable from the AC3 and plug it into the voltage regulated battery cable. - assuming you're talking about a 12v car battery just use an inverter and plug the AC3 into that.
Thanks, you're right. Cutting the AC-3 cord and putting in a jack as you suggested looks like the best option. A few days ago I tried an inverter and had problems because of interference. It's not a true sine wave inverter and ran the camera OK but caused the monolight flash I'm using to trigger itself every few seconds. The monolight can also be run off of DC so I ordered a connecter to hook that to my battery, too.