R34 Gtr Battery Voltage

[TommyR34]

Whats the normal voltage to have while driving? 12.6 seems to low to me is this normal

[BrynDETT]

hmm i think a working alternator chargers somewhere around the 14v mark..

[t_revz]

13.8 - 14.4 is ideal. little under is ok but 12.6 is too low. is that the best you get out of it or does it get better with rpm? were any accesories being run like lights or stereo? when you stop the engine and just have the key on what is the voltage? need to ensure that gauge is reading correctly first then go from there.

[jrm]

Test it from the battery - in my experience, the MFD reads slightly low (though, even then seems even lower than I'd expect)

Edit: Just went and checked my MFD - reads 14.1V at idle (and 14.3V directly at the battery) - weird - seem to remember it being out by more (i thought 1V) when I first checked ..

Anyway - hopefully that helps; definitely sounds like you have dramas with your alternator if that's the voltage whilst idling/driving...

[TommyR34]

No lights or stereo being run, without the engine running voltage is 12.4....Same readings from battery give or take .1... Took it to mechanics said the alternator is running and charging ok but its down near 12 and should be up near 14

[TommyR34]

Thanks for the info guys

[R.3.2.G.T.R]

No lights or stereo being run, without the engine running voltage is 12.4....Same readings from battery give or take .1... Took it to mechanics said the alternator is running and charging ok but its down near 12 and should be up near 14

hope u didnt pay him for that advice.. better off taking it to an auto elec, alternator might be on its way out

[mad082]

there is a chance the alternator is ok but the wiring is the problem. check the voltage at the alternator (although i have a feeling that if the earth to the alternator is dicky then it will lower the voltage reading you get there too).

[kane84]

ok im an auto elec...battery volts should be 13.8 - 14.4 with the revs up so the alternator is wroking harder and charging, gauge is always going to get lower as remember there will be a drop is volts in the leads, test the battery with a multimeter and also at the alternator there will be a differents onces again in the cable....if a alternator/ battery is lower then 13.4 running id be getting the alternator rebuild dont go out and buy one cheaper to fix urs

[R.3.2.G.T.R]

rebuild, how does it cost?

[kane84]

what do u mean how does it cost, to pull one down, clean, sand blast, replace bearing, and any other parts to make it new is cheaper the buying one,

we charge $132 plus parts, take half a day or so to do,

[t_revz]

what do u mean how does it cost, to pull one down, clean, sand blast, replace bearing, and any other parts to make it new is cheaper the buying one,

we charge $132 plus parts, take half a day or so to do,

132 for half day is cheap

[TommyR34]

Thanks for all your help guys! Turned out to be alternator 1st mechanic got it wrong or didn’t know what they were doing...won’t be back there again

[jrm]

Glad to hear you got it sorted; Glad we could all help.