Comments on AGM batteries

[Dicky]

2004 350Z 110,000 mls…all car checks OK …. Battery drain with car locked 80 ma, Alternator output just over 14v

I’ve had two AGM sealed batteries Yoasa  and Bosch in the last for years each with a 4 yr warranty and each packed in after two years with the same fault ie the battery not holding charge.

In both cases the suppliers would not replace under warranty saying the cells checked out ok and that's as far as they would go.

After a little research I find the problem seems to be that these batteries don’t like not being fully charged at all times ie if after starting you don’t travel for long enough to replace the starting current then you must put the battery on charge at the end of your journey or drive around a for 30 to 60:mins according to Chat GPT. It would seem that undercharging causes lead sulphate crystals to grow on the cells reducing their ability to hold charge.

 

Anyone else had this problem? If so don’t you think this is a con when you’re not given a copy of the warrant to check when buying and just told it’s a 4 yr warranty end of !!

 

 

 

Edited 3 hours ago by Dicky