Has anyone managed to do an alternator upgrade from the standard 55 Amp or 60 Amp (A483?) alternator to something bigger. I want to fit a bigger alternator, nothing enormous, just bigger than standard, either 70, 75 or 80 Amp - I have a aftermarket stereo and alarm system fitted and am fed up of these flattening the battery. Does anybody know if the 70Amp unit out of the Volvo 440 1.7 fits or have any other practical experience of upgrading the alternator on their 340 1.7?

I'm not sure on your setup but I really doubt a bigger alternator will help you. Sounds like you need a bigger battery.

A small alternator will cause the voltage to drop below 14v if you draw more than 800w RMS or so, and it maybe damaged, your amp will need a lot of cooling if you use this much, but most silly amps are spec'd as peak, which is meaningless.

If you run the amp on the battery only, a bigger alternator will not help, it will not charge the battery any faster when you put the engine on.

Its possible you have slow charging if you have corroded contacts or something.

You can fit any of the 440 alternators, I upgraded mine many years ago to a 70amp iirc from a 460

By the sound of it either your battery is dead or you have a drainage problem.

My brother has a big audio setup in his 240 and that is fitted with a high output alternator and twin batteries to keep the lights on when the sounds are on!

I will be going to a 7/900 alternator.