GolfGTIforum.co.uk

Model specific boards => Golf mk7 => Topic started by: Catnapper on 09 October 2021, 15:08

Title: AGM battery replacement
Post by: Catnapper on 09 October 2021, 15:08
I've just changed my battery from EFB to a AGM.
All other specs the same.
Voltage now when running is 12.6V. Previous reading around 13-14v.
Any thoughts or is this right
Title: Re: AGM battery replacement
Post by: Finglonga on 09 October 2021, 15:24
Have you coded it using VCDS or OBDEleven, as it must be coded to tell the charging system the type of battery.
Title: Re: AGM battery replacement
Post by: Catnapper on 09 October 2021, 15:29
Yep coded with carista. May try recoding it
Title: Re: AGM battery replacement
Post by: mustard on 11 October 2021, 08:23
Mine is the same, coding will tell the system that it does not need to put as much charge into a new battery as an old one
Title: Re: AGM battery replacement
Post by: JamesR27 on 11 October 2021, 10:20
I wonder if my battery has issues, it’s the original EFB but when the car is started is running 14.7v. When turned off it’s showing 11.2v.
Title: Re: AGM battery replacement
Post by: clubsport on 11 October 2021, 10:57
I wonder if my battery has issues, it’s the original EFB but when the car is started is running 14.7v. When turned off it’s showing 11.2v.

A static battery showing 11.2v is too low, you need consistently above 12v to have confidence in the battery. As it gets colder, it is likely the 11.2v falls a bit and the car just won't have enough battery power to turn over and start.

The reason it shows 14.7V is that the healthy alternator is partly sending power back to charge the battery, the fact that the battery only holds 11.2v after receiving this top up charge suggests it's on the way out.
With winter coming, I would change the battery now, before it lets you down.
Title: Re: AGM battery replacement
Post by: Catnapper on 11 October 2021, 12:57
sorted...... recoded it as I didnt increase Ah from 69 to 70. Now reads 13.6v
Title: Re: AGM battery replacement
Post by: JamesR27 on 11 October 2021, 13:34
I wonder if my battery has issues, it’s the original EFB but when the car is started is running 14.7v. When turned off it’s showing 11.2v.

A static battery showing 11.2v is too low, you need consistently above 12v to have confidence in the battery. As it gets colder, it is likely the 11.2v falls a bit and the car just won't have enough battery power to turn over and start.

The reason it shows 14.7V is that the healthy alternator is partly sending power back to charge the battery, the fact that the battery only holds 11.2v after receiving this top up charge suggests it's on the way out.
With winter coming, I would change the battery now, before it lets you down.

Thanks Clubsport I suspected it was on its way out so been looking online to get a new battery. Was tempted with the Halfords one but they want £182 with £25 fitting. So looking to see how I can do the battery replacement coding myself.