Counting Amps

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How many amps does a stock alternator put out and how long can I get away with running a stock alternator if I add aux lights drawing 10-20 amps each? At what point do I upgrade?
 
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The stock FZJ80 needs 10amps to run the engine. The lights (stock) will pull ~10-15 amps. That leaves u with around 50-60 amps that the alternator can handle safely. Adding 20 amps for extra lights brings the alternator down to ~30-40 amps. Any more load than that and u would have to consider finding a 100amp alternator [not easy].

...
 
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My alternator shop told that while my nippondenso is rated at 80 amps the nippondensos typically are overbuilt whereas domestic alternators never exceed their rating. Though we didn't put it on a tester he said that 100 amps would be no surprise.
 

Romer

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Chad,
I have the stock alt with Dual batteries

I run PIAA lights, an engle, CB, and a Ham Radio and so far have had no issues.

Don't run the lights much.

Might be better money spent to go with Dual batts.

I notice from the indicator the only time the Hellroaring seperates them is when I run the winch, but then I switch over and force them to be tied together.
 
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I'm not far from adding a winch, so a dual battery set up will certainly go with it. I like the Hellroaring, but may try to do something like Kevin's set up.
 

alia176

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You don't need a larger alternator. You do, however, need a larger reservoir - one large battery or two batteries for the additional load. As long as you put in more than you take out of the battery system, that'll all that matters.
 

Romer

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You don't need a larger alternator. You do, however, need a larger reservoir - one large battery or two batteries for the additional load. As long as you put in more than you take out of the battery system, that'll all that matters.

Now here is a guy with more toys on his truck than you can shake a stick at. he would know:D
 
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Chad might have a valid point for why he is looking for a higher capacity alternator. Given the alternator might not put out 80 amps at idle or low crawling RPMs, it might be wise to consider a higher capacity alternator.

IIRC correctly, the 80 amp output from the alternator is at engine RPM of over 2k. Between 1-2KRPM range, the output of the alternator is probably closer to 60 amps.


10 amps to run the engine
20 amps for headlight on high beams
20 amps for aux lights
10 amps for aux accessories such as CB, radios, and fan
60 amps total usage.
 
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You don't need a larger alternator. You do, however, need a larger reservoir - one large battery or two batteries for the additional load. As long as you put in more than you take out of the battery system, that'll all that matters.

Correct. Auto electrics don't run off the alternator directly. A healthy alternator is just one component of a good electrical system. You need a good battery. I have the Odyssey PC1700MJT in mine along with my stock alternator and upgraded wiring/connectors.
 
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My experience

JC,

It depends would be my answer to your predicament. The issue with dual batteries is that when you add additional cells for holding current (two batteries) you introduce another problem into the system. The alternator stock was charging one battery but now it's being double loaded by charging two. Granted there is an isolator relay in the middle but when those batteries get drained it still has to charge them up. It's like putting a bandage on a broken leg.

With that being said, a lot of people run that setup very succesfully without upgrading their alternator and just running two batteries. The reason being is that they hardly every tax both batteries simultaneously that much or with that much consistency that their alternator will have a significant load.

My suggestion to you, if you want to do it right with a dual battery setup for longevity is first having your alternator rewound by Havana Electric (Aurora, CO), they'll use the same housing and charge I believe around $100 (I did mine about a year ago on my other car so the rate may have changed, call and check). Second would be going to complete drycell batteries like the optima. You should use redtop for the engine and a yellowtop for the accessories.

Lastly, if you need a deal on the battery/batteries let me know I will take care of you out of my store. Also, if you need 0/1 gauge wire, i have a huge bunch that i can take care of you on and also connectors (no crimping required).
 

alia176

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Another thing to throw (muddying the issue as always) in is that re-winding an alternator for a higher output often reduces the longevity of the unit. Higher output = higher heat, which *could* shorten the lifespan. I'm not saying that this will happen but just keep that in mind. A stock alternator with good set of brushes, clean vents will often run a very long time w/o any issues.

Also, it's a good idea to either replace the alternator output heavy gauge wire with a fresh one or run another #4 gauge positive wire in parallel. The original wire can lose its conductivity through all those heating/cooling cycles and may become brittle. It's also a good idea to run a fresh ground wire as well. Basically, let the alternator push the amps out to the battery w/o having to work really hard; similar to a fire hydrant pushing water through a garden hose concept.

Cheers.
 
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Alternator Rebuild

Ok,

I should've posted this earlier with my earlier comment. Any how, here is the link to these guys. Alia is right that it may effect the longevity but it's still better than stock. Anyhow, here is the link for Ohio Generator that can custom make one for your rig. These guys are very well known for their alternator setups and can help you with the proper one for your needs. FYI this option may be more than you may want to spend.

http://www.ohiogen.com
 
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Lastly, if you need a deal on the battery/batteries let me know I will take care of you out of my store. Also, if you need 0/1 gauge wire, i have a huge bunch that i can take care of you on and also connectors (no crimping required).

Hijack...

Colorado80, are you on the Rising Sun 4x4 forum?

www.risingsun4x4.org

If not, you should be and post up in the Vendor are where your store is at and the kind of deals you can get for the members :D

Hijack off
 
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I would say spend your $ on a dual battery set-up first. Include a seperator. Then, if and when your alternator dies. Address it. Practically, a dual battery set-up will be able to easily provide the reserve most need. The alternator is always running and the voltage regulator is constantly turning the charging circuit on or off to keep a strong charge while preventing overcharge. A good seperator simply redirects the charging from the alternator, that is already running, to the other battery when the primary doesn't need it any more.

Use good deep cycles such as Optima or Odyssey. I'm thinking that your stock alternator will be capable of easily doing the job with the right storgage system.
 
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Practically, a dual battery set-up will be able to easily provide the reserve most need.

FWIW, I have found that a good single battery does quite nicely as long as all your components are up to the task. Conceptually I like the idea of multilpe batteries, but I have seen several dual setups fail. I like to keep things as simple as practical for each system.
 

Grench

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Second would be going to complete drycell batteries like the optima. You should use redtop for the engine and a yellowtop for the accessories.

IMHO if you're doing dual batteries, do them both Yellow tops matched in type and age. The Yellow/Blue tops are rated as both starting AND deep cycle.

And... if you want overkill.. The D31A fit for me. Some people have some cable length issues though as they are center top posts.

YMMV.
 
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optima batteries

IMHO if you're doing dual batteries, do them both Yellow tops matched in type and age. The Yellow/Blue tops are rated as both starting AND deep cycle.

And... if you want overkill.. The D31A fit for me. Some people have some cable length issues though as they are center top posts.

YMMV.

Yes, I would do the same also. But the only thing is that the yellow top is not warranteed by optima if it is used as a starting battery. I have seen some go bad within six months (not many, but some). And on those unlucky few, we couldn't warranty swap them. At my store we do the warranty swap over the counter, no questions, just a battery load test.

So, the only reason i recommended the yellow for accessories and red for starting was because they both are designed for a specific purpose and will be able to retain their warranty this way.
 

Grench

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Yes, I would do the same also. But the only thing is that the yellow top is not warranteed by optima if it is used as a starting battery.

Funny, they advertise it as a starting and deep cycle battery.

From http://www.optimabatteries.com/publish/optima/americas0/en/config/product_info/commercial.html
"There's not another battery in the world that works as hard as the OPTIMA battery. Especially against the number one enemy: vibration. The unique SPIRALCELL® Technology used in the construction of the OPTIMA YellowTop group 31 battery makes it an excellent power source for demanding heavy duty engine starting and deep cycle applications."

Another difference... The D31A has a different warranty than most Yellow tops with 24mos instead of 12.
http://www.optimabatteries.com/publ...ig/product_info/commercial/warranty_info.html

I've had good luck with mine and have not had to look for warranty replacements. They are outside of warranty now, so I probably just cursed myself. YMMV
 

alia176

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I've managed to abuse my Yellow top (aux batt) quite regularly and they've held up great. By abuse, I mean running low drain devices for a long time; ie Engel, laptop, CB, HAM, cell charger, backup lights while setting up camp, etc. They haven't really been tested for heavy winch pulls much but once I measured the amp draw to be around 550 amps :eek:. This occurrence is few and far between for me.

One could just have a mondo single battery like this Odyssey http://www.odysseybatteries.com/battery/pc2150.htm and be done with it!

Cheers. :beer:
 

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