Originally Posted by RichardV6
Originally Posted by Leroy
Reckon I need a new alternator for my roadster. Got around to purchasing a multimeter today and checked the charge with the engine running. 13.5v.
As the engine is from an ST220, will an ST220 alternator be the same, or will it be different?

Is it a simple enough job to replace? TIA

13.5 volts into the battery is low but remember the alternator is only regulated to give a maximum of 14.4 volts or thereabouts. To a large degree the battery itself dictates the voltage and only reaches alternator regulated voltage when close to being fully charged and with engine well above idle. Given a depleted battery it may take some time to reach this voltage especially in the winter with lighting, wipers, heated seats etc. to contend with.

Worth checking this out before replacing alternator. Ensure battery fully charged then at the end of a good run check battery volts with an accurate voltmeter and engine running at least 2000 rpm.

I had been out earlier today, and the battery put back on its charger so it would have been full. Would 13.5v normal at idle? Engine was still a bit warm.


2004 Series 1 Roadster