New Jaycar 16amp 4 stage charger

Hi

I bought it and am keen for advice from anyone that has it. I put it on a number of batteries at home last night and it never got off the flashing red "Refresh" button. No error buttons flashed. After testing it on 4 different batteries, one probably buggered, one near full, one definitely full, and one agm (note this unit charges at a peak of 14.8v so probably not to be considered if you have AGM's).

So i thought it was a dud.

However, put it on our Echo's battery this morning which is almost always nearly fully charged, and after about 5 mins of red light flashing it did actually go to the green light of fully charged.

So is this normal behaviour from this unit ?

I'd like to think it was processing the condition of the battery but last night it was put on a relatively new Exide Extreme that was holding charge at 12.75v and for a good 20min the "refresh" red light flashed which didn't make much sense.

The instructions are cr#p and talks about what red flashing light means but doesn't say which red flashing light.