Sterling Procharge Ultra Battery Charger Problems

I bought a new Sterling Procharge Ultra battery charger, installed it and set it according to the instructions. For the first few months it seemed to charge okay and then it stopped. The charger was on but it didn’t charge voltage and the indicator showed 00. The only way to get it working again was to turn it off and on again.

After going through this a couple of times (each time it was after a month or two of what seemed to be normal charging), I contacted Sterling (the company) and the battery charger was replaced under warranty.

Now the replacement battery charger is going through exactly the same behaviour. It stops charging. Charger is on but doesn’t charge voltage and indicator shows 00. I “reset” the battery charger by turning it off and on and then it goes back to working again.

Does anybody have any ideas as to what the problem is?

Here is a picture of the charger indicators when it stops charging.