Electrical experts - Is my battery charger u/s?

[doug748]

I bought one of those cheap chargers from Aldi, but I suspect that it is letting me down.
In particular I worry that it is knocking off before my batteries are charged anywhere near full.

For example, I have a spare 12v battery in the shed. It has knocked around for a number of months and shows around 12.5v or 12.6v or so, with a specific gravity reading of c 1250. The "Ultimate Speed" box switches from charging mode (c13v+) to float mode (c12.9v) after only a minute or so - showing "battery full" By comparison my old Halfords, stone age technology charger will give the same battery a blast of 14v and hold it there.

I have two motorbike batteries (one 6v and one 12v) and I have noticed the same tendency to show battery full after a few seconds, when logic dictates that these units are probably quite drained. This has possibly caused a number of running problems.

After all this stuff, is there a way of a mug like me testing the thing easily and finding out one way or the other?

 

[alahol2]

I only use my Aldi charger during the winter but I always use it on the 'cold weather' setting which sems to charge at around 13.8 to 14 volts.

 

[doug748]

I might give that a go, tho it is not suitable for the smaller batteries I use.

BTW I understand the charger is a rebadged CTEK 3600....

 

[Ruffles]

Try discharging the battery a bit. In my experience an old unused battery can be reluctant to draw current from the charger.