D1 Alternator discussion

[d1driver]

Ok, I have cooked two alternators now at the Wilds. Last year, using all my lights, which are too many I guess. This year, used my winch for about 10 minutes straight.

Can I use an alternator out of a P38? Should I just plan on a dual battery setup?

What is the cheapest solution?

 

[crown14]

p38 alternator

 

[p m]

+1.

But regardless of alternator capacity, something is wrong with your electrical system.

 

[garrett]

Yeah winching for 10 min should not kill an alt. If you're really pulling for 10 min straight you're going to kill your winch eventually.

 

[fishEH]

What mods are needed for the P38 install? I'm assuming it puts out higher amps?

 

[crown14]

Yes the massive electrical system of the P38 calls for a higher output alternator. I have installed them on D1s and D90s in place of the original units.

 

[crown14]

I have not installed a Bosch D2 alt (130A) or Bosch P38 alt (150A) on a d1 but the factory D1 alt is only 100A I believe.

 

[p m]

I've installed P38A alternators in both GEMS D1 and late Classics. Haven't even bothered to replace the main feed wire from the alt to the battery - that said, the D1/Classic pulley was larger than P38's, so most likely the alt is going to perform exactly in the same way as stock 100A unit. I thought it would be nice to have a potential capacity margin, even if I didn't use all of it.

Can't say much about winching - I only used mine once for a 20-second straight pull.

 

[lunchbox]

I went to Oreilly and picked up a Rangie alt for an air suspension equipped truck. It's 120amp. Has a lifetime warranty. I give it a good workout, and it's holding up. I do have dual yellow tops though.

 

[Jake1996D1]

I went to Oreilly and picked up a Rangie alt for an air suspension equipped truck. It's 120amp. Has a lifetime warranty. I give it a good workout, and it's holding up. I do have dual yellow tops though.

Same, except a single red top ran winch and 4 100w lights no problems

 

[d1driver]

I think my problem is mainly with the alternators themselves. The regulators I cooked both were used and had unknown mileage. Lets just see if I burn up the one in there now, which is a rebuilt from Advanced. I won't hold my breath on it though. I am sure all the muddy water in them cannot be good for them either.

As far as an electrical problem, I am not so sure. This truck has never given me any electrical problems over the years.

 

[fishEH]

I've installed P38A alternators in both GEMS D1 and late Classics. Haven't even bothered to replace the main feed wire from the alt to the battery - that said, the D1/Classic pulley was larger than P38's, so most likely the alt is going to perform exactly in the same way as stock 100A unit. I thought it would be nice to have a potential capacity margin, even if I didn't use all of it.

Can't say much about winching - I only used mine once for a 20-second straight pull.

I'm not following this. Are you saying the P38 will not put out the capacity its rated for if used on a D1?

 

[Busted_D1]

I think my problem is mainly with the alternators themselves. The regulators I cooked both were used and had unknown mileage. Lets just see if I burn up the one in there now, which is a rebuilt from Advanced. I won't hold my breath on it though. I am sure all the muddy water in them cannot be good for them either.

As far as an electrical problem, I am not so sure. This truck has never given me any electrical problems over the years.

I went through 5 Lifetime warranty alternators from O'Reilly's before I got one that has been going for 4 years solid with no issues. The first five would last less than a year before I started to get the bouncing tach. Thankfully they are a 10 min. change.

I talked to Wrangler Power and they have 200 amp units for the D1 (they just don't list them) they arent cheap though.

 

[p m]

Looks like GM versions might work for a Disco. Just keep in mind extra load on the serpentine belt.

 

[listerdiesel]

Something to remember about winches on DC:

When you turn the winch off, there is a big reverse-voltage pulse from the armature or the field of the motor or both.

This can be a few hundred volts and can quite easily kill the rectifier diodes in the alternator which are only rated for 100V or so.

We killed our charger in the trailer at Nuenen this year, we were using the winch to load the engine and the mains supply to the charger was on.

What you can do to help is to fit an inverse diode across the battery, so that it acts as a surge suppressor.

The diode should be rated at least 400V PIV or Vrrm (Peak Inverse Voltage or Voltage Repetitive Reverse Maximum)

The diode should be connected with its POSITIVE terminal onto the positive of the battery and the NEGATIVE terminals to the negative of the battery. That means it is reverse-biased and will not conduct.

Should anything come along across the battery that is reverse polarity, the diode will conduct and look like a short-circuit to the pulse (In fact it is not quite a short-circuit, there is a forward voltage drop of 0.7V approx)

Diode rating should be something like 6A - 40A, almost anything in that range will do the job.

A decent 40A stud diode with positive on the tag and negative on the stud would be ideal as it could be bolted to the body.

Fairly simple thing to do, just make sure you get the polarity right!!

Peter

 

[p m]

The diode should be connected with its POSITIVE terminal onto the positive of the battery and the NEGATIVE terminals to the negative of the battery. That means it is reverse-biased and will not conduct.
<snip>
Fairly simple thing to do, just make sure you get the polarity right!!

Peter, give me a fucking break. Reread what you wrote.

 

[p m]

... on top of that:
- What Peter suggested is shorting a battery through a diode. It won't damage the battery because the diode will evaporate in a hurry, so not much harm and some entertainment (as long as you don't ignite anything else with it in process).

- as far as "flyback" diode action (which would be if the diode were connected with anode to the ground and cathode to the battery +12V post), the alternator diodes are more than capable of doing that. In fact, the diode bridge in the alternator is probably good for close to current surge twice the rated alternator output.

- flyback diode does not prevent overvoltage. If you are so concerned about it, use a high-power 16-17V Zener diode, or a "crowbar" overvoltage protecting circuit (both will need a fuse rated above the stall current of the winch).

- most of the time, the battery will easily absorb the voltage spike due to disconnecting of the winch motor. You can also add a capacitor across the battery terminals to take up the highest slew rate of the voltage spike, but most likely will not need it.

 

[Robbie]

not sure if they still make them, but I have a Mean Green alternator for my '95. Puts out 200amps. I have winched for 10+ minutes through the mud using my slow ass Pierce 12.5k on a normal diehard battery. No issues whatsoever.

 

[listerdiesel]

Guys:

If you don't understand the principal of an inverse reverse-biased diode, then I apologise for posting the information.

There is nothing wrong with the connection data, but there are instances of incorrect labelling of diodes on the web.

The Cathode or silver ring on small diodes goes to the positive and the anode or unmarked end on small diodes goes to the negative.

Peter

 

[p m]

Guys:

If you don't understand the principal of an inverse reverse-biased diode, then I apologise for posting the information.

There is nothing wrong with the connection data, but there are instances of incorrect labelling of diodes on the web.

The Cathode or silver ring on small diodes goes to the positive and the anode or unmarked end on small diodes goes to the negative.

Peter

Peter,

the diodes are always marked the same way, have been for many decades now. That said, you are the only person I ever knew of calling cathode a positive electrode and anode - a negative. Chalk it up to semantics.
That said once again, the diode bridge inside the alternator will do the same, and it is by far better suited to that than a 6A-rated little diode.