[birko]

Hi,
Just finished my falcon alt conversion but have found that the output from the alternator is gradually increasing the more load is put on it. ie, it runs at 14.4, then with the lights on at 14.8, then lights/ heater fan at 15.2. Any ideas what this is and how to fix it?

[want33s]

I did know what caused this.. Something to do with the stock under dash wiring not being able to pass a current without a voltage drop I think.
The alt senses the drop and compensates by pumping up output.
I think.

[royce]

measure the volatage at teh battery and at the volt sense wire on the alternator (the one with power on it at ignition) they will be probably reading heaps different

[joeblow]

the regulator is not doing its job. sort it out quick before other stuff gets fried.

[birko]

Quote:

measure the volatage at teh battery and at the volt sense wire on the alternator (the one with power on it at ignition) they will be probably reading heaps different

Yep, They are. The wire is reading around 13.5v

Quote:

the regulator is not doing its job. sort it out quick before other stuff gets fried.

Yep i no, im not driving it like this.

[Damo]

birko wrote:

Quote:

measure the volatage at teh battery and at the volt sense wire on the alternator (the one with power on it at ignition) they will be probably reading heaps different

Yep, They are. The wire is reading around 13.5v

So what causes that?

Is it the wire in the stock loom not big enough? Or just something like a bad connection somewhere?

[Rockhopper]

Damo wrote:

birko wrote:

Quote:

measure the volatage at teh battery and at the volt sense wire on the alternator (the one with power on it at ignition) they will be probably reading heaps different

Yep, They are. The wire is reading around 13.5v

So what causes that?

Is it the wire in the stock loom not big enough? Or just something like a bad connection somewhere?

could be both. If you're running stock wiring on the alternator, try running a thicker wire back to the battery. Only way to really diagnose it is to follow the wiring back from the alternator and test it at differant points and find where the voltage drop is

[royce]

nah the ignition sense wire comes from the key via about 12m of wire!!!!! so it drops voltage along the way and from other things loading it up (like lights and stuff)

Nissvit posted about fitting a relay so the standard wire switches a feed straight from the battery so it tracks it better

[birko]

Yep, it got a upgraded charge wire. I will try shorting the sense wire directly to the battery and see what the result is. But yep a relay seems like a good idea

[birko]

Quote:

Nissvit posted about fitting a relay so the standard wire switches a feed straight from the battery so it tracks it better

Searched but couldnt find it

[nissvit]

At the back of the alternator there is two wires, one does the battery light thing, and the other provides the sense voltage (and field excitation current).

Run the sense wire out to the trigger coil relay of a relay (pin 85 or 86 on a bosch relay) run the other side of the relay coil (the other pin of 85 or 86) to earth.

Run a fused wire directly from the battery to pin 30 of the relay then run a wire from pin 87 ( the two switched pins on the relay) out to the sense wire input on the alternator.

this will bypass all of the original under-dash wiring, and now the alternator will see the true battery voltage with minimum losses... so it will provide better voltage regulation..

do not run a wire directly from the battery to the sense input on the alternator, as this will keep the field windings continually energized, which will drain the battery...

[want33s]

Very handy info there Nissvit... Thanks.

[steve]

if there's any chance to run more relays nissvit will find a way, he loves em.

[Saam]

still could be the regulator aswell

[Damo]

steve wrote:

if there's any chance to run more relays nissvit will find a way, he loves em.

I have a similar love of relays. Actually, I love them as much as I hate scotchlocks

Relays FTW!!!

Waiting for Ford alternator to arrive, then i'll give this a crack

[shep]

Damo wrote:

steve wrote:

if there's any chance to run more relays nissvit will find a way, he loves em.

I have a similar love of relays. Actually, I love them as much as I hate scotchlocks

Relays FTW!!!

Waiting for Ford alternator to arrive, then i'll give this a crack

you would have liked my bike then, i recon that it had 30 relays on the thing.

[steak_knife]

shep wrote:

Damo wrote:

steve wrote:

if there's any chance to run more relays nissvit will find a way, he loves em.

I have a similar love of relays. Actually, I love them as much as I hate scotchlocks

Relays FTW!!!

Waiting for Ford alternator to arrive, then i'll give this a crack

you would have liked my bike then, i recon that it had 30 relays on the thing.

Running What??

[Mike]

steknig wrote:

shep wrote:

Damo wrote:

steve wrote:

if there's any chance to run more relays nissvit will find a way, he loves em.

I have a similar love of relays. Actually, I love them as much as I hate scotchlocks

Relays FTW!!!

Waiting for Ford alternator to arrive, then i'll give this a crack

you would have liked my bike then, i recon that it had 30 relays on the thing.

Running What??

the brake light

[Scrawny]

Mike wrote:

steknig wrote:

shep wrote:

Damo wrote:

steve wrote:

if there's any chance to run more relays nissvit will find a way, he loves em.

I have a similar love of relays. Actually, I love them as much as I hate scotchlocks

Relays FTW!!!

Waiting for Ford alternator to arrive, then i'll give this a crack

you would have liked my bike then, i recon that it had 30 relays on the thing.

Running What??

the brake light

Wow!! Where you been hiding Mike??

[nissvit]

Found this pic from another post I put somewhere, but it may be useful if someone is trying to work out which pin on the alt does what...

the alts on the sierra's & the vits have the same pin layout.... on the (mitsubishi manufactured) alt fitted to the falcon the pin functions are stamped L (light) & S (sense) in the ally casing beside the connector block.

but if you have a chinese copied alternator (off ebay of similiar)there will be no stampings...
there were chinese copied alternators for ford probe or Mazda 626 (70 amp ones) on a few sites for while for $89 US, and it looks like these have been brought in and fitted to quite a few vehicles. They are great for use in a zook, but if their reg fails (a rare event) they are just different enough to the mitsubishi that parts are not interchangeable, and a problem to get... bearings in them are the same as the mitsu ones..

[trity]

Can someone pls tell me what type of relay to use? Is it a normally open type?

Ive tried wiring it in but to no luck still reads 15v

[Rossco]

yep, if you've wired every thing in correctly and it still gives a high reading to regulator is probably stuffed and you'll need a new one. thats what happened to mine at least.

[trity]

I ran the sense wire directly to the battery and reads a respectable 14.34v as soon as the relay is put in it instantly jumps to 15.3v so that leads me to maybe the relay

[Reubs]

trity wrote:

I ran the sense wire directly to the battery and reads a respectable 14.34v as soon as the relay is put in it instantly jumps to 15.3v so that leads me to maybe the relay

Is the relay connected properly? You can use a n/o 4 or 5 pin or a c/o 5 pin - but if you use a c/o 5 pin ensure you use the correct pins (not pin87a)!

Run the original sense/ignition +ve wire (black/white) to pin 85, connect an earth to pin 86, connect a wire from the battery (with a fuse at the battery end) to pin 30, connect alternator 'sense' terminal to pin 87.

This runs a fresh wire, fuse & relay to the alternator - removing any voltage drop. I'm not sure about the EL mitsubishi brand alternators but the Bosch one I installed had a 14.4V regulator and there would need to about 1 volt of drop across your wiring, ignition switch, fuse box etc, to the 'sense' terminal to see a 15.3V output at the alternator.

[trity]

Ok what i have is this

Pin 30 direct to battery via fuse
Pin 85 to earth
Pin 86 to original sense wire
Pin 87 to alternator sense terminal

The relay used is narva brand 4 pin normally open type 12v 40amp and states pin 30 power in pin 85 earth pin 86 switch and pin 87 power out acc 1

[trity]

Found the issue a blown fuse was making the reading higher replaced the fuse now all good 14.34v