Amperage

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I'm still running the stock alternator on my 85 and have noticed it runs right around 13 amps. When running the head lights, front & rear wipers and the rear defroster it drops to 11-12 amps. When the front two Piaa's come on it is right at 10-11amps.

So far the battery hasn't failed, but as I understand it you need at least 12amps to recharge the battery when running.

Question is do I need a bigger alternator. Looking at a 300 amp Mean Green but don't want to throw down $500 for that right now.
 
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It's volts that the gauge on your dash shows, not amps. You need *more* than 12 volts to charge your battery.

Are these readings you refer to at idle or at higher engine speeds.

Mark...
 
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If it is an amp gauge then I suspect the Piaa's are wired direct to the rear of the alternator and the drop in amps is from the Piaa's sucking all the available current and the 10 is all that is left over

Remember for every 100 Watts of light out the front the alternator has to find 8.5 amps. Dual filament bulbs in the Piaa's and its 34 amps before the main headlights, tail lights, dash lights, ignition system, stereo, blowers, etc ,
Don't take much to hit the 45 amp barrier of the std unit.
 

Tapage

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Ok .. keep in your mind to things ..

AMP and Volts ...

So if you have lights, and converters and and and ... you have many " things " that need amps .. ! so with you have all on and hteir consumption goes more than you alternator can produce, your electrical system get more Amps from your battery.

More amps .. are good .. but you relly need it .. ? and how much .. ?

Some Hyundai gallopers and terracan suvs uses 115 AMP alternator with vaccum pump attached ( that I need for example )
 

lovetoski

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Cookiemonster said:
I'm still running the stock alternator on my 85 and have noticed it runs right around 13 amps. When running the head lights, front & rear wipers and the rear defroster it drops to 11-12 amps. When the front two Piaa's come on it is right at 10-11amps.

So far the battery hasn't failed, but as I understand it you need at least 12amps to recharge the battery when running.

Question is do I need a bigger alternator. Looking at a 300 amp Mean Green but don't want to throw down $500 for that right now.


As Mark W said, your gauge reads Volts, not amps. They are related, but not the same. At idle I get pretty similar numbers to yours above. Especially if my idle is leaning down towards 650 rpm. Sometimes my idle is more like 800 rpm, and this makes a lot of difference in the output of the stock alt. Over 1200 rpm, I can run everything, and the volts don't drop below 13.5.

So, four suggestions:
1. Confirm that your numbers above are at idle, and that above idle, your volt meter reads much higher.
2. Use a multi-meter to measure the voltage at idle, and with diffferent loads applied. The multi-meter is much more accurate than the dash meter. Compare the two to get the dash "calibrated."
3. If based on the above you are still worried, go to an auto parts store, most will do a free load test on your alt. If you decide to buy a new alt, don't buy one from a discount Schucks type chain - even with a "lifetime" warrenty, they tend to fail often. Get a NAPA/Meangreen/etc.
4. In the FAQ section, there are some threads on maximising the performance of the stock system. Some of this might be helpful.

HTH
 
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Unlike most vehicles today - the 60 series has a volt meter, not an amp meter. I gaurantee that your lights alone take more than 12 AMPS. The amperage output of the FJ60 stock alternator is adequte, but not generous. Many people have rewound or replaced their alternatord for more amperage to run lights, amps, winches, etc.

Mike S
 
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Ya that's the ticket volt meter.

The Piaa's are wired direct to the battery not to the alternator.

I've been needing to p/up a multi-meter. As a general contractor I do do general wiring but trouble shooting is not my thing. And as far as the combustion engine well that's a whole other story.


No question about it. I do need to replace the alternator. Today at idle I watched it surge from 10-14 as the front wipers ran on the delay cycle. As it stands I can't run my laptop on trips (kids use the dvd feature).

Next question is which Mean Green? MAF has the 200amp but I figure what the heck I can buy the 300amp direct from MG. Any suggestions?

I really want to mount a minigun on the roof for the wife so I'm thinking the 300. Nothing like overkill.
 
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Ya what I said above, minus her log on. :doh:
 
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Explore rewinding and rebilding your current alternator - this is a good less expensive solution. You do not need megaamps to run your cruiser...

M
 

Tapage

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Mike S said:
Explore rewinding and rebilding your current alternator - this is a good less expensive solution. You do not need megaamps to run your cruiser...

M

is a good advice ..
 

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