Alternator Wiring

[R.3.2.G.T.R]

anyone know if it's fine to wire up positive wire from battery to alternator directly

I already have done the negative wire although it earth via bracket

is fusable link required as mine was chopped off

my issue is the alternator voltage is almost half volt more than at the battery terminals

[t_revz]

Yeah it's fine. Ideally a fuse is a good idea and depending on the car you can but alternators almost never fail to the point of shorting out completely. Just double up alternator cable from alt to fuse panel for extra security. Are you sure the volt drop is in pos cable?

While running, Set multimeter to volts. Go neg batt - neg alternator= neg volt drop.

Pos batt- pos alt = pos volt drop.

You can break it up into smaller sections once you know which side your fault is.

I've left standard wiring, then added 0gauge cable from batt in boot-starter then 2gauge cable from alternator-front fuse box connections. All cables are well secured but I've added an isolator switch just incase

Edited September 25, 2012 by t_revz

[R.3.2.G.T.R]

thanks, the way i tested it, earth to chassis and +ve probe to battery and then compared it to the alternator +ve lug nut.

ill test it your way this arvo and report back

for the alternator cable to fuse panel, is this the one in the engine, do i simply remove it and the cable running to the fuse box underneath will be visible? is the white wire with the blue strip?

[t_revz]

Just looked at mine. Can't see where alt cable goes exactly but it must be joined into main positive from junction box to starter so it's not fused.

[R.3.2.G.T.R]

Yeah it's fine. Ideally a fuse is a good idea and depending on the car you can but alternators almost never fail to the point of shorting out completely. Just double up alternator cable from alt to fuse panel for extra security. Are you sure the volt drop is in pos cable?

While running, Set multimeter to volts. Go neg batt - neg alternator= neg volt drop.

Pos batt- pos alt = pos volt drop.

You can break it up into smaller sections once you know which side your fault is.

I've left standard wiring, then added 0gauge cable from batt in boot-starter then 2gauge cable from alternator-front fuse box connections. All cables are well secured but I've added an isolator switch just incase

just did the test

+ve to +ve 0.22

-ve to -ve 0.02

so i gather an issue with the positive wiring.. instead of running +ve from alt to fuse box, if its alt to battery, will there an issue with this?

otherwise i guess strip the loom and replace the cable incase with heat soak it increases resistance

[t_revz]

Is your batt up front or boot?

I would go alt-battery directly. Just secure it well and away from sharp edges etc

[R.3.2.G.T.R]

Is your batt up front or boot?

I would go alt-battery directly. Just secure it well and away from sharp edges etc

in the front.. i have an earthing kit so will use one of the wires to connect it directly alt-battery

[t_revz]

Sounds good.

[R.3.2.G.T.R]

Sounds good.

with direct wire from battery +ve to alternator +ve 're-did the test

+ve to +ve 0.08v

-ve to -ve 0.02v

so definite improvement there, will take the car for a long run and see if voltages drop after a while

thanks for all your help

[t_revz]

No problem

[R.3.2.G.T.R]

small update on this,, while it fixed my overall low voltages that i was seeing, i still see around 0.5v drop after driving the car onces its all warmed up..

i suspect its my attessa relay that going off every 30sec or so.. so will disconnect the relay and see if it makes a difference..

[t_revz]

Where are you seeing the difference?

Multi-meter to Ecu readout?

Or multimeter across different places?

Or multimeter to gauge etc?

[Beppo]

Sorry to summon an old thread, but I can't find anywhere that tells me what the wires are on my R32 GTR alternator.
I'm putting the RB26 into a BMW, and I get the positive and ground, but there's a small brown plug with 2 tabs sticking out and I don't know where I'm to connect them. Is one to a light and the other to ignition on?

[t_revz]

Probably yes. Are there letters on the alternator near the plug terminals? The letters will explain what they are. Ie I=ign.