£22 in maplins - same as the one you show but B grade and in stock.
I have this one was about £25 at the time (£39 now) and does the job....they have 3 in stock at Exeter...looks just the same as the toolstation one except mines yellow...
-- Edited by jt on Sunday 6th of March 2011 07:20:59 PM
You press a button to check the state of the internal battery- the 3 lights are low - medium-high.
After about 36 hours of charging the lights didn't change on either of the two boosters. The Low light is a bright yellow and the other two glow green. I assumed this meant fully charged but one booster turned the Jag over slowly - not fast enough to start it and the other only just lit up the boot light
My guess is that these machines are all made by the same factory and just slotted into different carcases so hopefully someone will have another model can say how the lights work on theirs