Like I said a while back, I tried to get it to work on a pretty old battery for about four or five days, and it refused to do anything other than show it was in standby mode.
I kept trying it regularly,(thinking maybe it's the operators failure to comprehend its workings/instructions?)
Anyway it finally then proceded to function correctly of its own accord, so maybe it was my dumbo lack of understanding?
Although I do have a sneaky suspicion that it could possibly of been a sticky relay, as now I can here it clicks occasionally, and with a DVM attached to the battery it shows a constant charge too.
Regardless it has now done a couple of 16v boosts with no problems, and it then automatically switches to a monitored variable 12v charge rate, so I'm happy with it .
It has a five year warranty, so if it keeps performing as it does at present, no worries.
I reckon in mho it's quite a slick piece of kit for £60 or so quid.