UK-POLOS.NET - THE VW Polo Forum

Hi,

Not sure if this has already been answered elsewhere but I’ve searched everybody’s favourite friend Google and couldn’t find an answer.

Last week my alternator died on me and I replaced it along with the belt and tensioner. I fitted a 90A alternator but I see some people say it’s a 120A from factory?

Are there any drawbacks from fitting a lower amperage alternator. Everything seems fine, once I’ve started the car. Just wondering if there would be any long term affects.

Car is a 2007 Polo Gti 9N3.

Any help would be greatly appreciated.
Thanks
James

you'll often see a havier alternator in cars with i.e. a trailer hitch

Higher trim level cars tend to have more toys so could possibly need more 12V power, as long as you don't use all that car's toys all the time, it should be okay.

You will find out if it is not okay if the battery does not seem to always stay in good condition.

Been looking into this myself and wondering if I could fit a 110A alternator when I currently have a 90A alternator if I end up fitting a subwoofer just for the extra headroom in terms of load? Both look the same but don't want to start melting wires or throwing error codes.

don't worry you can fit a heavier alternator without any issues.

Thought so as I can't imagine an extra 20A would put out much more heat.

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Thanks a lot for the advice guys.

I can’t imagine it would make a lot of difference myself but just wanted to hear what you guys thought.

The car is pretty stock in terms of ICE. Like I got no aftermarket stereo or sub etc.

Why can’t they just have one rated alternator

Thanks again.

Because VW are Germans and German engineering needs to be precise and thorough.

Jokes aside, all car manufacturers do this.

Also price per unit, higher output will normally cost more, every penny/euro counts in manufacturing.

On the matter of fitting a higher output alternator, again VW Group will have sized/rated the charging leads for the alternator's max output and again possibly saved a small bit of money by using a slighter small cross sectional lead(s) for 90A than 110A applications and the first fuse should also match the rated output.