Alternator "field" Disconnect For Deep Water Fording

[Mr.510]

In the "New Nissan Parts" thread an alternator relocation bracket was mentioned. Something to put the alternator where the A/C compressor was. I assume that people are frying alternators fording deep water and moving the alternator up would obviously help.

 

My question is: Has anybody run a Field disconnect switch on a Pathfinder? 20-some years ago I built a Baja out of a '71 Datsun 1200. I fried alternators fording creeks *all* the time. I re-wired the Baja to run internally regulated alternators as I worked for a Japanese engine importer and got used ones free. I carried a spare alternator bolted to the roll cage in the trunk and used it often to get home.

 

What I eventually figured out was that if you break the "Field" wire no current goes to the stator through the brushes, the outer windings do not produce AC current, the diodes aren't charged, and deep water doesn't hurt anything. I put a toggle switch on the dash that broke the connection of the Field wire and never fried another alternator. When approaching a creek or deep puddle I'd flip the switch. The "Charge" idiot light came on (of course) and I'd go about splashing around. After exiting the water I would leave the Field disconnected for a few minutes and rev the piss out of the the motor a few times to blow dry the alternator. Then flip the switch turning off the idiot light and getting the alternator back to work charging the battery.

 

I've been 'wheeling Unimogs for the last 15 years and with their waterproof electrical systems I'd nearly forgotten the old Field disconnect trick. Now that I'm playing with my Pathfinder in the woods more I think it's time to install a switch in the Field wire. I guess I'm wondering if anyone else has done this? I'm looking at the charging system diagram in a '91 FSM right now and see no reason not to install a switch.

Thoughts?

[MY1PATH]

So you run your engine purely off battery while crossing water... interesting, you suffer any power loss from going to a battery only system?

 

I have been thru water many times (almost to the mirrors on a few ocasions)and never had an alty fail from it on my pathy. its usually being mud packed that causines an alty to over heat rather than short out that makes a problem for most people.

 

 

[Mr.510]

There's no difference in running off the battery for a few minutes. I'd kill the lights and any other high-drain accessories if possible and don't turn the engine off (if possible) before giving the alternator a chance to catch up.

 

 

So it's packing them full of mud that typically kills Pathfinder alternators? I guess relocation makes a lot of sense then. I always carry a big pressurized water fire extinguisher in my Unimog to blast the mud out of the radiator when things get really deep and soupy. We used it on both Mogs after playing in this hole:

 

 

Guess I should add one to the Pathy's gear list as well.

[MY1PATH]

I guess relocation makes a lot of sense then. I always carry a big pressurized water fire extinguisher in my Unimog to blast the mud out of the radiator when things get really deep and soupy.

I think it takes more than one trip to pack it with mud @ least for me that is. every time my engine gets muddy I let it cool down and then I start it and hose it down while running. everything gets splashed down while its still cool and then I direct spray the radiator and alty.

[headpeace]

interesting. If you do it, do a write up, I like the idea. Man I have wanted a Mog or Pinzgauer ever since I saw the first Mog I'd seen locally.

[Dowser]

Ya I mentioned the Alty Relocation Bracket in the New Parts Thread, and its never really been about water crossings, its always been big soupy mud holes. And I love mud holes. I've sprayed water in the all manner of crap in the alty to try and clean it out after a pretty messy trip. Although I'll admit that peeing in it didnt work as well as I had hoped. I've always wanted to attempt a relocation bracket and theres even a GREAT write up on the forums for one with pictured even from someone doing it. I believe its been done for a R50 as well. I just have never really had the tools at my disposal to make little useful things.

 

I think this is one of those things man that if you fit it right, get it measured out, you could make a ton of these so easily and people would buy them. I know I sure would. Especially if you come up with the AC relocation bracket to the Alty position as well since I'm one of those softies that likes AC in the Hot Humid Southern Ontario Summers. haha. But regardless, I'd way rather have my AC compressor get clogged with sh!t and stop working then my Alty. Even though an AC compressor is more expensive then an alty, I can live without AC. Hard to get your Junk home without a Working Alty and replacing on the Trail after going thru a bunch of mud isn't the most pleasant of experiences.

[kiwipete]

I'd way rather have my AC compressor get clogged with sh!t and stop working then my Alty. Even though an AC compressor is more expensive then an alty

Um, the AC compressor is a sealed pump with a clutch pulley. Hardly the stuff to get clogged with mud as the pulley is spinning all the time when the engine is running.

[MY1PATH]

Even though an AC compressor is more expensive then an alty, I can live without AC. Hard to get your Junk home without a Working Alty and replacing on the Trail after going thru a bunch of mud isn't the most pleasant of experiences.

 

 

I'd rather cary a spare alty then have to replace my compressor every time it got too muddy. Oh and for the record my ford alty(rebuildble with basic hand tools) did not short out when I played in the water @ reiter. And if I cook it, its much easier to fix and more cost effective than buying a new one.

[GrimGreg]

Yeah, our alternators do just fine soaking in water, it is more the break down from both heat and (mud is full of dirt...) dirt grinding away the bearings and such that kills the alts.

[Mr.510]

Dowser said:

I've always wanted to attempt a relocation bracket and theres even a GREAT write up on the forums for one with pictured even from someone doing it.

 

I did a search and didn't find it. Got a link? I'd like to see how someone else did it before I go re-inventing the wheel...

[Dowser]

Um, the AC compressor is a sealed pump with a clutch pulley. Hardly the stuff to get clogged with mud as the pulley is spinning all the time when the engine is running.

 

Your right, what I wrote didn't make very much sense since the Compressor is a sealed unit. I should have been more specific in this sentence. What i was trying to get across was that i would rather have my AC compressor in the Alternator spot since all the Grime, Goop and mud would effect it far less then the alternator. Thanks for bringing that to light. Sometimes I don't think before I type when I'm in a hurry.

 

I'd rather cary a spare alty then have to replace my compressor every time it got too muddy. Oh and for the record my ford alty(rebuildble with basic hand tools) did not short out when I played in the water @ reiter. And if I cook it, its much easier to fix and more cost effective than buying a new one.

 

I doubt you would have to change a compressor after every wheeling trip. I doubt you would have to change one at all unless it malfunctions due to issues not having anything to do with going thru a mud hole.

 

 

As for finding the thread that talked about it.... I've been looking. I've found a couple that refer to it. But none of them are specific like the one I was talking about with the images. Keep in mind that as mentioned on some of these other topics you need to have something in the place of the old alternator spot since the belt runs other things like the water pump.

 

here's the only semi descriptive thread I've found so far.

 

Relocation topic

 

Upon further searching I'm wondering if the images I remember were for a bracket designed to fit a Maxima/Quest Alty in the Stock Alty position without having to modify the Alty's.

 

bracket modification for stock location.

 

Hmmmmm Either that or I saw it on another forums cause I cant seem to locate it. I thought for sure I would have had something like that bookmarked. Perhaps someone else will have more luck then I. Also doing this search has brought something else into the light that i didnt think of. Instead of making a bracket to fit an ordinary pathfinder Alty to be used in the AC position, we should be thinking about making a bracket for a Maxima/Quest alty to fit I'm thinking since everyones trying to get rid of the low amp Alty's we came with. Just athought.

 

And finally... I'd like to add at this time, That Simon is a champ for having to reply the same basic answer about mud being the primary destroyer of alternators in MANY MANY posts over a LARGE amount of time. I think I must have glanced at about a dozen different topics that hes had to mention it. His ability to not tell people they are morons and to use the search function is uncanny! Congratulations Simon.

Edited December 7, 2009 by Dowser

[Precise1]

Instead of making a bracket to fit an ordinary pathfinder Alty to be used in the AC position, we should be thinking about making a bracket for a Maxima/Quest alty to fit I'm thinking since everyones trying to get rid of the low amp Alty's we came with. Just athought.

Yes, at least the maxima alternator as they are 90 amps and cheaper than the stock pathy alternator IIRC. Try to make sense of that...

 

B

[MikeV]

Yes, at least the maxima alternator as they are 90 amps and cheaper than the stock pathy alternator IIRC. Try to make sense of that...

 

B

Picked up my Maxima alternator at Autozone & it was 95 amp

5 amps is 5 amps!-)

Haven't had one die yet but it was screaming that it had sand/grit in it.

[MY1PATH]

I doubt you would have to change a compressor after every wheeling trip. I doubt you would have to change one at all unless it malfunctions due to issues not having anything to do with going thru a mud hole.

not the whole compressor but im sure the bearing for the compressor clutch would not like the dirt as much. or if it got sutck engaged or stuck dis-engaged. I had the clutch bearing start draging whenever it was disengaged and it made a horrible squeal untill I sprayed some lube@ it.

[SamTex]

I put a 125A Quest alty in mine. It's noisy if I get it dirty, but no issues yet.

 

Whats the difference between a sealed unit and one that is open? Is there a reason they need to breath? If mud is such an issue and they do need to breath, could you put cloth bag over it in some fashion? Like the outer wear of an intakes cone filter?

[Kingman]

The spinning rotor and stator inside the alternator generates a lot of heat as it passes electrons, so a fan is needed to cool it so it doesn't have a melt down.