AGM battery lifespan

**Gutoneto** · 14-02-2024, 12:00 PM

Originally Posted by DV52

@gutneto: Hi.

When you say " I installed a new about 3 years ago" - did you replace like-with-like? Or, the question asked another way - was this car factory fitted with an AGM battery, or with a EFB battery?

And perhaps the even more critical question to ask is: when you installed the new battery "about 3 years ago" - did you tell the car's Energy Management System (EMS) about the change by re-coding the Gateway module with the new battery's details ?

Don

@gregozedobe:Hi. Yes, 101% correct!!

But and with absolutely no offense intended - how does the EMS charging regime in mk7s/7.5s (which as you correctly say reserves 20% of the battery's capacity for regenerative braking) affect battery longevity (AGM and EFB battery technologies don't have a memory problem AFAIK)? What have I missed?

Don

Hi Don,

To be very honest I really don't remember which battery was installed on the car and the shop advised me to get an AGM battery.

I did code the battery corrected to the car at the time as the shop said that only needed to reset the battery with his scanner and it would be fine, so, as soon as I get home I code correctly using VCDS.

**Gutoneto** · 14-02-2024, 01:56 PM

OK,

I went to a Super Charge reseller and he told me that the battery was dying and from its original 720cca it was only reading just over 230cca, and to my no surprise he said that it was out of warranty. He thinks because the car was parked for a long period last year because the engine swap (about 5-6 weeks) might have caused some damage and made the alternator to charge it harder as it had some oxidation (that I haven't noticed before) on the positive.

Needed to get a new battery straight away as I almost ended up not able to crank the car after driving for about an hour.

The new battery is a Delkor (they had on special) and it's an EFB this time and comes with a 30m warranty. They told me the EFB it's the type that comes from the factory in VWs.

I tried to code using the OBD11 that I have in the car but it didn't allow me to select EFB or EFB+ and still coded as fleece. I'll try later with the VCDS or ODIS.