SLROC Forum

Hi Guys,
When i was out at the GRR on Sunday the battery light kept coming on, then after the CV broke i wouldn't start again 
got it going again but the battery light stayed on, i had a look at it today and the lights still on but the batterys (on split charge) are getting about 13v on idle but about 16/17 v while revving,
is this normal? shouldn't it be much lower? And do i need a new alternator?
Any help appreciated.
Thanks 

Hi,

Definitely sounds like your alternators at fault.
Have you tried taking a voltage reading on the AC range on your meter?
You should get a reading of OV or very near 0V. If you are getting AC volts readings the diode bank in the alternator is 'breaking down'.
The voltage reading of  16/17 volts is definitely not right. It should be around 14.8V max.
Hope this helps.
Dave

yep sounds like your alternators on way out and over chargeing witch will nacker ur batterys if u keep useing it it should not be over 14.8 volts max best wat to check voltage is with engine running at fast idle with all lights on heater etc but shouldent be that high as u say

Hijacking the thread - but... How do you test a battery charger is working properly. Mines got more lights than a rally car and all read as they should ....but it does not seem to be putting anything into the battery. I think the battery is OK, but...

Try to get hold of a current clamp meter to test curent is going to battery  while its being charged d.c scale and multimeter set to volts and test across postive and negative looking for above 12v normally 13/14volts. Worth checking battery cells specfic gravity with hydrometer as a poor mix can cause the batteries internal resistance to drain battery almost instantly. For gene . Flying scotsman sounds like your voltage regulator is pumped on your altenator as it should be a max of high 13v range no matter how fast engine is run think there is a tutorial on youtube to change diode packs and voltage regulator for land rover altenator