How about one of these:
http://www.wiggle.co.uk/lezyne-macro-drive-duo/?lang=en&curr=GBP&dest=1&sku=5360657176&kpid=5360657176&utm_source=google&utm_term&utm_campaign=UK_PLA_Accessories&utm_medium=base&utm_content=mkwid%7CsYWwKvMpF_dm%7Cpcrid%7C67090793462%7Cpkw%7C%7Cpmt%7C%7Cprd%7C5360657176uk
The exposure link + looks like the don in terms of battery power and life. However you can get spare batteries for the lezyne and it's cheaper.
Just need to make up my ****ing mind!
@GreatSince78 started
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How about one of these:
http://www.wiggle.co.uk/lezyne-macro-drive-duo/?lang=en&curr=GBP&dest=1&sku=5360657176&kpid=5360657176&utm_source=google&utm_term&utm_campaign=UK_PLA_Accessories&utm_medium=base&utm_content=mkwid%7CsYWwKvMpF_dm%7Cpcrid%7C67090793462%7Cpkw%7C%7Cpmt%7C%7Cprd%7C5360657176uk