Cliff's Long GoPro Timelapse page

All About GoPro Batteries 

Once there were dry cells then NiCads then sealed lead acid and a few others but then we moved on to Li-Ion. These promised light weight, higher capacity and an output which stayed up for a long time at around the required voltage. Li-Ion batteries have however been iknown to get very hot so avoid them!

 

Lithium Iron Phosphate (LiFePO4) now seems to be the state of the art - high power ratings, lightweight, compact size and safe to dispose of. These however have their own problems, most notably damage through over discharge.

 

If weight and size are of no concern a decent  car battery provides a relatively cheap and effective solution. This one cost me AU$133 but you should be able to source something similar for less cost. Just click the picture.

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For my application I purchased two Shorai LFX18A1-BS12 12V 18 A-h LiFePO4  motorcycle batteries which with the matching charger cost me around $400 including the exorbitant cost of postage to Australia, but you don't need to spend anywhere near as much as this. 

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You could also try cheap 12V sealed lead acid cells such as the Panasonic LC-R127R2P. These weigh about 4 times as much as the LiFePO4 cells above.

 

Whatever you choose, buy two or more. One can be supplying power while the other is on charge. If you are using either of the Cam-Do intervalometers, do not concern yourself over swapping batteries in the middle of the time-lapse cycle. Leave the camera running and just unclip the leads from one battery and clip them onto the new one. The inervalometer described later will just power down then power up and recommence the cycle. At worst you might lose 1 frame from your timelapse, although if you monitor the activity light on the back you can even avoid this.

 

My first attempt with the LiFePO4 cells came close to being very very expensive, as at that stage I did not know that a 12V battery could actually be flat at 12.86V. A fully charged 12V LiFEPO4 battery should read around 13.4v or up to around 14.3V with no load connected. When modern batteries discharge they supply power continually but the voltage actually drops very slowly. A 12V battery charged to 13.9V may have as little as 20% of its capacity remaining while the battery still reads 12.8V, but you will have had a lot of power to use before you get to that point. 

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See these spreadsheets for amazing info showing actual tests on how various types of batteries discharge over time. If you didn't understand it before, you will now.

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Battery Discharge Test in .xls format

 

 Battery Discharge Test in .xlsx format

 

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