Passat b6 battery upgrade

[ciacly]

Hi all!

I have a B6 Passat and I'm having some issues with the battery I believe. I can feel some loss in power every time the AC is on. I got some advice that the battery may be too weak, can this be the case? My current battery has 74ah and 680cca and I am looking to get a bigger one to 77ah and 780cca, both Varta. What are your thoughts on this? Thanks!

[phumy]

Really??






Who has told you that?

[ciacly]

I asked the mechanic when I did my annual service. Is not just the AC but that is my main concern because is quite frustrating.

[MatthewH5]

Replacing your battery won't help you here.

A slight power-loss is normal when AC is on, but this is only really noticeable on small engines.

I would be looking at the bearing on the AC compressor pulley if the power-loss is severe. Are there any noises?

[Penelope Stopit]

The majority of manufacturers have compensated for AC dropping the revs, replacing a battery won't fix anything, compressor and alternator load do eat up the horses

[ciacly]

I see, will probably need to check with a different mechanic. I will replace the battery anyway, it looks like it was never replaced or not for a very long time anyway and I can feel it. I will add below 2 link with the current one and with the one I want to upgrade to. Please let me know if any of you saw any difference after adding a higher power battery.

The current one: https://batterygroup.co.uk/batteries-by-applicatio...

The upgrade one which was recommended on Varta website after adding my reg number: https://batterygroup.co.uk/batteries-by-applicatio...

[MatthewH5]

Both batteries are the same physical size (known as 096) so either will be fine.

The CCA rating refers to the starting power at low temperatures. It's unnecessary to go higher than the OEM recommendation, but it's probably worth going for the "Silver" version for an extra £1.50 if your battery needs replacing anyway.

Again, this will make no difference to any of the issues you mentioned above though. A new battery will help your car start more easily and it will hold a charge for longer but you won't notice anything else!

Edited by MatthewH5 on Wednesday 23 June 14:44

[ciacly]

Thank you for sharing your knowledge, one of the other issues I have is slow engine start so as you mentioned, will probably help.