You mean these? http://www.exposurelights.com/cycle-lights/batteries-and-chargers/support-cells
Yes, he took those, unsure which capacity but I'm probably going to see him at the pub later in the week if you have any specific questions.
You can also get the light's internal battery replaced by Exposure (or there is a DIY guide to do it somewhere...)
@atk started
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You mean these? http://www.exposurelights.com/cycle-lights/batteries-and-chargers/support-cells