Alternators.... (1 Viewer)

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mobydick

mobydick

Joined
Sep 14, 2009
Threads
94
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Location
Medford, Oregon.
OK, may be needing a new one. Is there anyone local who does a quality rebuild of my existing or, if not, your suggestion on where to get a good replacement ASAP?? :meh:
 
New brushes?? Paint store......?

Truck wouldn't start after I pulled over on a trip yesterday to look at a pile of yard sale leftovers. No dash lights at all, nothing...total dead. Got a jump but it ran crappy all the way home with volt gauge around 10-12 volts max. Today I went to Bi-mart and swapped out my 10 month old battery fro a new one(n/c) but even with the new battery it wants to die and volt gauge is still way too low. Don't have power for headlights etc. and gotta use the hand throttle to keep RPMs up above 1500 or it wants to die. Your diagnosis please??.......:hmm::meh:
 
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I use cliff's auto electric at 1311 n riverside in medford....just before the mall. Nice guy, fair price and he knows his s***. Can rebuild an alternator with his eyes closed.
 
jamister1 said:
I use cliff's auto electric at 1311 n riverside in medford....just before the mall. Nice guy, fair price and he knows his s***. Can rebuild an alternator with his eyes closed.
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x2 He has fixed a couple of my old ones.
 
OKee Dokee....!:cheers:
 
A&A off of Table Rock is great too- DO NOT get a Kragen/SChuck's or Napa... You will be getting an inferior unit vs. rebuilding your old one, it is probably just brushes but might as well replace bearings, etc.
 
My 89 FJ62. I like the idea of rebuilding my existing unit locally, bearings and all. Rather than popping a rebuilt one from who knows where. Keep the local economy healthier. Maybe that guy Jesse recommended needs a pair of glasses and we can work out a trade. Only thing I don't like is not learning the job myself. I'm sure I could do it if properly taught. I just never have the time or the money to risk screwing around with that stuff myself. Many an attempt to save the family a few bucks has backfired on my azz! :p

'less of course someone in the club knows how to do a full job on that alternator themselves and would rather have me enrich them while they show me how to strip it out and rebuild it?? Payday is Thursday and I still haven't had time or $$ to go get those bolts Jesse talked about for the bumper either...?? Let me know-:meh:
 
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OK, I've now had Phil's and AA tell me essentially the same thing. my alternator is fine but there is about 3/4 volt drop between it and the positive post on the battery. Should be no more than .2 - .3 volt drop so there is something along the line that is drawing off some voltage and it's just enough to cause the battery to never really get the 14.5-14.7 volts it needs to fully recharge. Probably corroded connections somewhere on the firewall or the fuse box. While the voltage drop needs to be addressed Brian at AA said I could run a separate charge wire off the back of the alternator straight over the the battery to keep the battery from getting shot like the last one. 10 months was a short life for the old battery but he said sounds about right for one not really ever fully charging up. :meh:
 
Someone on the 80's forum did just that, run a seperate run for both the positive off the alt, and a new run for the ground. They ran them side-by-side to the original wiring.

Make sure you have a fuse on whatever you run....
 
Ebag333 said:
Someone on the 80's forum did just that, run a seperate run for both the positive off the alt, and a new run for the ground. They ran them side-by-side to the original wiring.

Make sure you have a fuse on whatever you run....
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What rating would be best for that fuse??? I think Brian said 10 gauge wire should work....you think??
 
100 amp would suffice and give you plenty of head room.

I know people have used 1/0 welding wire. I think 10 gauge would be very small for running between the alt and battery.
 
I run a 10 gauge directly to the battery of the pig. Granted, its a chevy 1 wire 100 amp alternator but it doesn't require much to do its job correctly. Think about how small the wires are on a normal battery charger and are there any on the back of an alternator that are bigger than 10? Nope! No sense in going completely overkill.
 
jamister1 said:
I run a 10 gauge directly to the battery of the pig. Granted, its a chevy 1 wire 100 amp alternator but it doesn't require much to do its job correctly. Think about how small the wires are on a normal battery charger and are there any on the back of an alternator that are bigger than 10? Nope! No sense in going completely overkill.
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Well, it all depends on how many amps you're pushing and how far the run is. I've seen 10 gauge rated at anything from 50 to 100 amps (though far more sites reference 50-55 amps, only one said 100 amps), so if you're running a 55 amp alt, shouldn't be a big deal.

That being said, do you really want to run 100% capacity on a wire?

Additionally, as heat rises the rating decreases. So since you're running over the temps wiring is rated at, you're supposed to decrease the load (or oversize the wiring).

Figure you want to run at 80% capacity due to temps, and then 80% capacity of that to keep from maxing out the load. That 50 amp wire is now 32 amps.


Battery chargers can get away with smaller wires because they are only supposed to be used for short periods of time, have short wire runs, and often have temp sensors that cut power if they overheat. So it's not apples to apples when comparing to an alt that will push out a higher load for long periods of time, and have no overheat protection.


My thought is, why save a few bucks by using a thinner wire and run the risk of either lighting the truck on fire (worst case scenario) or causing yourself problems down the road (failure, etc)? Going with heavier wire costs you what, exactly? $100 instead of $60?

Check out this thread where a guy did a rewire similar to what you're looking at on his 3FE. He used Flux 4awg.

https://forum.ih8mud.com/80-series-tech/525391-battery-rewire-finished-results.html

One thing that thread brings to mind is it could be a bad ground in your case. He was seeing a huge voltage drop when running lights or accessories that largely went away after replacing the ground.
 
The draw on a battery is through the battery cables, not through the wire to the Alt. Stock size or a hair bigger will be fine. Yes, upgrading the battery cables can be a big help, but that does not sound like the issue here. It sounds like the charge wire is partly shorted out somewhere, or just corroded so bad that the voltage drop is too much...
 
Thanks guys, some good info on that thread. If I pick up the wire, etc. you think we could make quick work of it after the meeting at Jesse's?? :confused: Don't want to push my luck though as I will be bringing the bumper/winch for possible assembly. I still have to get the bolts for that. Maybe have to make a run for them after we get the stock bumper off and take a look at what we need. :popcorn: Can I bring some snacks Jesse ??
 
I've got some 8 and 10 gauge wire laying around from my bumpin car stereo days. Just need some crimp on or solder on connectors for it. We can take a look and worse comes to worse we can run a wire but my first inclination would be to attempt to find the bad connection. Snacks are always welcome.
 
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