Alternator output low

[maldotcom2]

The alternator on my VS was only putting out 13.8v. Obviously it was failing to charge the battery fast enough for normal commuting. So I replaced the rectifier (I believe) on the back and it was then charging at over 14v. After a few drives it's back down to 13.3v. Something is not right, but short of buying a whole second hand alternator, what else could I try?

 

[sxi ss]

Before you buy second hand look at getting yours rebuilt I just has mine rebuilt last week striped cleaned tested new bearings new regulator and the slip rings machines for $210 the wreckers here wanted $195 for a second hand one with no guarantee

 

[maldotcom2]

You've got to be kidding me! And wreckers wonder why people load up their pockets...

Thanks mate.

 

[sxi ss]

Nope well that's in nz anyway but prices may vary in Aussie

 

[RX25SE]

Is the B+ wire at the back of the alternator burnt out?

With the engine running, connect a voltmeter between the B+ teminal at the back of the alternator and the battery postive terminal and measure the voltage drop. Post up the result.

 

[maldotcom2]

Ok finally got a chance to play with it. Voltage drop is 0.4 Volts. That seems a lot just for a length of cable.

 

[RX25SE]

Does seem a bit high.
Make sure the wiring to the B+ is not burned and the battery terminals are clean.
If the wiring is burned you will need to open up the loom and replace the overheated wire. There is a splice in the loom about 300-400mm from the B+ terminal IIRC.

 

[maldotcom2]

Alright I had already bought another second hand alternator so this arvo I replaced the alternator, and the charge cable at once. Voltage drop is now 0.01 volts. That's more like it.

However, the voltage across the battery terminals is only about 14.4 volts, which then drops to around 14 as everything heats up. Isn't it supposed to be 14.7?

 

[axemurderer101]

14v to 14.4v is fine mate

 

[RX25SE]

Charge rate and voltage drop are all good.

Nice one.