Alternator...."barely charging"

CardinalFJ60

 
 
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I've been chasing a low-voltage gremlim and while at NAPA last weekend, I had them test the battery to strike that from the equation. They said the battery is more than fine...1000CCA. But when I started up and they tested with "everthing on" they said..."Aaaah, you Alt is barely charging".

How much faith should I put in that test? the meter was hooked up only to the Batt.

Also, I had the Alt. amperage tested about a year ago and it was pushing 70A...could it be the VR?


just grasping at straws over here...any advice is appreciated.


Thanks.
 

Pluton

 
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Oct 12, 2004
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A friend of mine was in the 'alternator-a-month' club for awhile until he discovered that the problem was with the fusible links...that little 3 wire+2 connector thing up by the batt + terminal. Sorry, don't know how to test except by replacing. Not a bad idea to have a spare hanging around though. Cheers.
 

CardinalFJ60

 
 
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Good call...replaced that a few weeks ago...

yeah...I've been going through everything (well, starting to) and I picked one up from CDan a few weeks back. That didn't help.

But thanks for the feedback, everything helps...even if it re-inforces what I've already done...like replace all the grounds, the Pos. cables are next. ON that note, I picked up the batt. cables from Urban LandCruisers...they are saaaw-weeeeet!!!
 

lovetoski

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CardinalFJ60 said:
I've been chasing a low-voltage gremlim and while at NAPA last weekend, I had them test the battery to strike that from the equation. They said the battery is more than fine...1000CCA. But when I started up and they tested with "everthing on" they said..."Aaaah, you Alt is barely charging".

How much faith should I put in that test? the meter was hooked up only to the Batt.

Also, I had the Alt. amperage tested about a year ago and it was pushing 70A...could it be the VR?


just grasping at straws over here...any advice is appreciated.


Thanks.
I think the hookup to the batt is valid. To check alt amperage output, you'd hook to the alt + and ground. They were already hooked to the battery +, which is directly tied to alt +.

You said you have a low voltage problem. Have you tested it with a multi-meter (as opposed to the dash guage). Is it always low, only at idle, only with lot of load?
 

CardinalFJ60

 
 
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All of the above....

L2ski, thanks, and.....all of the above, but most noticeable when at idle. For instance, at highway speeds, my dash meter will read about 12-12.2 and when at idle with nothing on, it'll sneak below 12. When all 'stuff' is on it'll be closer to 10.

I've tested everything BUT the back of the alternator with my multimeter and going from the FSM, I wrote my findings down. (don't have it with me) But the jist is that it's about 1-1.5v too low. IIRC, it doesn't ever read above 13 and will read down to about 10.5 or 11 with all my stuff on - the only add-ons are fog lights, CB and stereo with a smallish amp.

So...I think in the FSM you can test the diodes on the VR...I think I need to do that. Will that help pinpoint the culprit??

Next question: Better to just get a new VR or replace it with a Mean Green?
 
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Card;

I'd get a new or reman Toy alternator and have the old one rebuilt. U should be reading 14 to 15.5 Battery volts withe the engine running.

...
 

lovetoski

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DF is right on with the volts you should be getting. Based on what you've said, a VR is likely to be the culprit. Reman Toy or Mean Green would prolly also solve the problem of course! Whatever you do, don't get a cheapo "lifetime" guarantee alt from a discount house.
 
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Try measuring the voltage at the alternator instead.

Agree re fusible links. I imagine if they look okay and the connections aren't corroded then they will be okay.

Make sure your battery is fully charged, then measure voltage at the alternator. If the voltage at the alternator is different to that at the battery by a significant amount (how long is a piece of string) perhaps approaching 1 volt, then run a new 50A capacity cable direct from your alternator to your battery. Over time, the original cabling between battery and alternator may be suffering from loose joints, voltage drop. Running a new cable direct takes this out of the equation. Leave the old wiring in place.

You can adjust the VR to increase the alternator voltage output if that is the problem, or the problem may simply be worn brushes inside the alternator. I'd be adjusting the VR before ripping out the alternator.

Tim
 

CardinalFJ60

 
 
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I can do that...thanks!

So...I'll run a lead from the Alt to the Batt...

Question:

Wouldn't that bypass the fusible link and increase the chance for a "thermal event" under the hood?
 
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and/or you can always include a fusible link or a fuse in the new cable-- just put in a 30amp fuse in one of those little fuse holders. You shouldn't really have 30 amps going to the battery anyway, especially not if this is an addon to the factory loom

Cheap and easy, give it a try.
 

ivanhoe

 
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north bay, ontario
CardinalFJ60 said:
I've been chasing a low-voltage gremlim and while at NAPA last weekend, I had them test the battery to strike that from the equation. They said the battery is more than fine...1000CCA. But when I started up and they tested with "everthing on" they said..."Aaaah, you Alt is barely charging".

How much faith should I put in that test? the meter was hooked up only to the Batt.

Also, I had the Alt. amperage tested about a year ago and it was pushing 70A...could it be the VR?


just grasping at straws over here...any advice is appreciated.


Thanks.

i would have the alternator rechecked since it's been a year ago. i would say worn out brushes or loose fanbelt.
ith,
ivanhoe
 

lovetoski

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CardinalFJ60 said:
So...I'll run a lead from the Alt to the Batt...

Question:

Wouldn't that bypass the fusible link and increase the chance for a "thermal event" under the hood?
I don't think so. Max alt output is ~55 amps (70 on yours a year ago). Max battery output however is 800+ amps. That's a lot. The straight cable from the alt to the batt keeps system voltage higher - less voltage drop due to a "narrow pipe" that reduces "electrical pressure." The stock harness is still protected by the fusable (which you keep in it's stock location).

The key to the additional wire is that it raises system voltage. It does nothing to amps.
 
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Seems like (based on all the cash you have dropped on the truck already) you should just buy a new alternator and see if that fixes it. YOu can get a rebuilt Denso for about 100$. If it's not it you coudl always take it back and but yours back on. It took me about 10 minutes to swap alternators on my truck and that included drinking a beer! :beer: :cheers:
 
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