Battery or Alternator

[VTcommodore1998]

I recently changed the battery, and the battery seems to be flat after a few days.

I tested the voltage across the terminals on the battery at ~13.88 V when the engine is idling. However when I rev the engine, the Volts drop to around ~13.6.

I thought the opposite should happen as you rev the engine. Is this something wrong with the battery or alternator?
Car is VT 98 Commodore. Non S/C

 

[accentstencil]

I would say the alternator as it should be around 14.4 to 14.8 with the engine running regardless of RPM.

 

[dirty hands]

regulator fault in alternator if all wiring/fuse/earths is correct

 

[Tasmaniak]

Brushes to be more specific.

 

[dirty hands]

oh good ..had me worried for a moment .. you can buy either type ...under $ 200

http://www.ebay.com.au/sch/i.html?_...nator&_nkwusc=vt+commadore++alternator&_rdc=1

 

[VTcommodore1998]

I would say the alternator as it should be around 14.4 to 14.8 with the engine running regardless of RPM.

This says 13 to 14.5 the alternator is in good shape.

How to Check an Alternator: 9 Steps (with Pictures) - wikiHow

this video says. 13.8-14.8 for a good alternator.

https://www.youtube.com/watch?v=Bzz7P3qNHcE

 

[Immortality]

You'll find most alternators have a minimum given voltage at a given RPM. Idle RPM voltage isn't a great guide, especially if you have a bit of load on.

I would say the alternator as it should be around 14.4 to 14.8 with the engine running regardless of RPM.

Should be. I'm yet to see a V6 engine with an alternator that actually puts out 14.4 volts especially at idle or low revs. I see some places are even selling voltage upgrade kits for the V6 engines. Basically it's just a diode which is fitted into the battery voltage sensor wire and raises the output by 0.6 volts approx.

Not that I recommend this supplier Increase the Voltage on your Car by 0.5-0.8 volts depending on electrical loadand engine rpm. Good for those with Big Stereos or High Wattage Lights which place extra strain on the Altenator and Battery. This Voltage Increase Kit will Boost ...

If someone was real keen on doing something like this they would be much better of going and buying the bits from jaycar or some place similar. Should cost about $3 total.

 

[Tasmaniak]

There is a guy named Leigh over at Pradopoint who builds them into an actual fuse. So you pull your alternator fuse, drop this bad boy in its place and off you go... It still has a fuse in it also.

 

[Immortality]

There is a guy named Leigh over at Pradopoint who builds them into an actual fuse. So you pull your alternator fuse, drop this bad boy in its place and off you go... It still has a fuse in it also.

That's not a bad idea actually.

edit: I'm assuming you talking about one of the fusible links?

 

[Tasmaniak]

No. The Excitor fuse.