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ALTERNATOR shut down switch (water crossings)

H

HaZakated

NAXJA Forum User
Location
Fairfield OH
A guy in this thread just brought up an interesting idea that I have never heard before. He suggested having a switch hooked to the ALT that when fliped, shuts down the alt while going into deep water. We all know that XJ alt's are prone to death by water crossing. I would hate to relocate the alt due to time consumption.

My questions to this matter are: Would this mod stop the alt from getting fried? Is this mod possible to begin with? how exactly would this mod be set up? I have some ideas as to how it can be done, but other people's perspectives would be great.

Here is the thread link............http://www.naxja.org/forum/showthread.php?t=52592&page=2&pp=15
 
I drove about 30 miles on straight battery on the way home from KY wheeling last year. It was dark so I had the lights on as well. Sounds to me like a great idea. I dont know alot about electrical systems though so dont take it from me.
Brian
 
I've had water in my alternator a lot of times, with no adverse effects I could see. It's when mud/dirt/muddy water get in there and get on the bushings/turning parts that creates a problem. Every time I take my jeep to the car wash I always blast my alternator with water to get the dirt out.

Get a protective shield (even the little rubber one that comes stock soemtimes) to keep mud away from your alternator and other things on your belt system.

A friend did this mod and has not had trouble since:
http://www.jeepinohio.com/viewtopic.php?t=320
 
NO WAY (outside of some AC compressor type mod) to shut down a moving alternator. You can disconnect it from the circuit with a bypass switch but that wouldn't keep it from producing just from providing current to the system.
 
HaZakated said:
A guy in this thread just brought up an interesting idea that I have never heard before. He suggested having a switch hooked to the ALT that when fliped, shuts down the alt while going into deep water. We all know that XJ alt's are prone to death by water crossing. I would hate to relocate the alt due to time consumption.

My questions to this matter are: Would this mod stop the alt from getting fried? Is this mod possible to begin with? how exactly would this mod be set up? I have some ideas as to how it can be done, but other people's perspectives would be great.

Here is the thread link............http://www.naxja.org/forum/showthread.php?t=52592&page=2&pp=15
Click to expand...


I believe the major problem with the alt is getting debris in it therefore having it mechanically lock up. Once this happens, your in trouble, cause the belt will burn and you loose all your accessories, including you water pump. Turning it off electrically, just don't see an advantage to that, cause water usually will not short it out, and if it does, no harm done, quickly dried out. Best insurance is to carry a spare when mud running..........................
 
jfiscus said:
Get a protective shield (even the little rubber one that comes stock soemtimes) to keep mud away from your alternator and other things on your belt system.
Click to expand...
Try the fatory rubber splash gard (i paid $30 for mine) and the factory front engine skid and that should help alot.
 
My original splash guard was too torn up, so I pulled it, but I plan on replacing the front of it at least with some aluminum flashing I've got lying around and some self tappers to hold it on. I also will eventually build a front skid, but I figure that the aluminum will hold up fine for water, mud, and any gravel that gets kicked up on roads (don't want it hitting any of the lines that run down there).
 
Rocketman said:
NO WAY (outside of some AC compressor type mod) to shut down a moving alternator. You can disconnect it from the circuit with a bypass switch but that wouldn't keep it from producing just from providing current to the system.
Click to expand...
Cut Field power, and alt. stops producing.....Just coasting along.

Now, will this save your Alternator? Probably not.

I can see it stoping arcing across the brushes, but mud is mud...It kills everything.
 
Water won't usually hurt an alternator. They produce some heat, and along with the air flow through it from the fins they will dry out pretty quickly. Getting mud and debris in there is another story.
 
I made an hour drive home from a wheeling trip with the alternator producing 9v. As soon as I went through the last puddle and onto the road the voltave meter droped into the red. Measured voltage and it was producing 9v at 2000rpm. I drove it an hour home that way. All non-essential electric circuts where turned off ie: radio, HVAC, turn signals. Got an new alternator from Autozone with a lifetime warrente and its been fine since.

I agree that just turning it off wont really save it, as mud and debris are what kills it.

AARON
 
I'm thinking of using a window screen for a debri blocker. I'll just mount it where the stock rubber shield used to be. This way the engine will stay cool and most all debris will stay out.

Brian
 
Shutting down the alternator is easy - interrupt the field current. Put a switch in (probably thru a relay) to cut off the field current, and the alternator output drops immediately to zero.

This, however, does nothing to stop the unit from spinning - not much else you can do there without putting a clutch on it or something. Dunno what to do there just yet.

5-90
 
I agree with the field current. I think the trick is to develop some sort of "filter" around the alt while its closed. And when you think about the size of debris that it would take to get in the bearings and brushes, well window screen isnt gonna cut it. Your talking about micro sized fragments. Your alomost talking about a complete compartment around it with ventilation and that could get tricky, along with the price it would take to build it... just burn it, then buy one with a lifetime warranty.
 
I think that I would rather try and re-locate it up to where the A.C. compressor is....and if I HAD to keep the air....I'd move it down to where the alternator was.....and I'd just find some longer lines for it if necessary. I've been thinking about possibly trying this out on my XJ. I realize that I'd have to fab up some brackets....but you've already got the factory brackets on the engine to start out with, so, it wouldn't be too terribly difficult to do. IMO anyways.

Aron
 
seems to me there isnt enough room to accomodate anything larger and longer than the altenator down there. I have a feeling it wont clear the oil pan (not sure going from memory here), and you certainly cant move it away from the engine as the the alternator barely clears the frame rail. If you were ditching the AC would you just install some form of idler pulley down there? If so wouldnt you end up having to replace the bearing in the pulley just as often? Hope I'm not being to discouraging and negative but Ive rolled this problem around in my head for a while and keep coming full circle with no solution that makes me happy. I wonder if the engineers that designed it drove themselves nuts over this? :)
 
for $100 you can keep an extra on in the back.... Mine makes some noise and i think its a junkyard one replaced before I got it, I think i will replace it and keep the core charge as a trail spare...
 
weapon said:
seems to me there isnt enough room to accomodate anything larger and longer than the altenator down there. I have a feeling it wont clear the oil pan (not sure going from memory here), and you certainly cant move it away from the engine as the the alternator barely clears the frame rail. If you were ditching the AC would you just install some form of idler pulley down there? If so wouldnt you end up having to replace the bearing in the pulley just as often? Hope I'm not being to discouraging and negative but Ive rolled this problem around in my head for a while and keep coming full circle with no solution that makes me happy. I wonder if the engineers that designed it drove themselves nuts over this? :)
Click to expand...


I'd probably just ditch the A.C. and get a smaller belt :D
Aron
 
HaZakated said:
I'm thinking of using a window screen for a debri blocker. I'll just mount it where the stock rubber shield used to be. This way the engine will stay cool and most all debris will stay out.

Brian
Click to expand...


That's a great idea!
 
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