In a couple of weeks time I am going for a 6 day hike. I will have no access to power source to recharge batteries. I honestly don't know how long I will have the camera on each day because It will all depend on the weather conditions. With great conditions possibly up to 2-3hrs a day. I plan to do some long exposure shots as well. I currently have 2 OEM batteries but I have not used the OMD enough to know whether this will be enough.

I think 1 more OEM would be safe.

I've been trying to look for batteries in my area but still no dice. :(

One more than you take with you....

I think it's an impossible question to answer. Will you take 5 pictures per day? 50? 500? How many of those will be long exposure? Will you be using the rear screen a lot, or will you shut it off?

If you expect to use the camera a lot, I think 2 batteries probably won't be enough. And I'd suggest turning it off between shots, rather than relying on the auto time-out feature.

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Nothing worst than carrying a camera that you cannot use.... I also say one more battery to be safe and remember to set to evf prior to hike.

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I ended up using two batteries until dead on a three day trip. I ended up buying a 3 pack of generics on eBay for $31 or so. They fit in the grip too so it makes it easy to swap out as needed. I was doing some longer trip-pod exposures so that couldn't help.

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I know its a hard question to answer, I was hoping for advice from people who had done something similar trip. If I had estimate maybe 200 photos a day, 15% being long exposure. Sounds like I should pick up an extra one. Can anyone comment on the battery life of third party batteries compared to OEM?

As a complete WAG, I would guesstimate that I get about 2/3 the number of exposures from my two Wasabi batteries, relative to my Olympus battery.

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I wasn't hiking, but I took a 4-day trip in a remote area of Bolivia with no chance of charging batteries. I had the E-PM1, which seems to drain batteries at about the same rate as the OM-D. I shot an average of 200-300 pictures a day, and used all five batteries I brought. All but one was a generic, and I suspect they didn't have quite the capacity of the real thing.

So take this for what it's worth . . . may or may not apply to you. But about one battery/day is what I'd take. They're pretty cheap.

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Damn, thanks for the advice Mellow.

I must be shopping that the wrong place. I picked up one at my local store last weekend when I got the HLD 6, it was $90.