Is there a way to increase alternator output??

[Loobed]

Is there an easy way to increase alternator output (amps) myself cheaply?

The only thing I can think of is to get a smaller pulley to increase the units RPM.

Can more windings , or stronger magnets increase the output?

 

[tomcat27]

You've got it. Smaller pulley helps at lower rpm. Find a local alternator shop about rewinding for more output.

 

[Tempest]

What do you need more power for?

 

[JimPghPA]

Or a larger drive pulley.

 

[Loobed]

Originally Posted By: Tempest
What do you need more power for?


A second battery

 

[TallPaul]

Are you limited by the speed the alternator is turning or by the upper limit of the output voltage regulator? Or is it more amps he needs and that is independent of the voltage regulator? I don't half know what I am talking about here, but maybe will jog some thoughts that help.

Don't they have these HD alternators for police vehicles that have a lot of electronic devices drawing off the battery. Or check what they do for motorhomes where the alternator charges both the engine battery and the house (coach) battery.

My motorhome has a solenoid that kicks in once I crank the engine over to send charge back to the house battery. But when I turn the starter only the engine bay battery acts.

 

[440Magnum]

Careful... re-winding for more peak output will REDUCE low-RPM output in most cases. If you look at, say, a stock Nippondenso 80A alternator and compare it to their 120A model, they didn't just change the windings. They made the whole unit larger. Back in the bad old days, Chrysler (to pick on my own favorite car brand) kept upping the peak output of their "squareback" alternator all thru the 70s, but more and more there were issues with discharge at idle because they were just changing the winding count and using heavier wire, not re-designing from scratch.

You can achieve a higher peak amperage by putting fewer turns of heavier wire on the alternator stator windings. That reduces the winding impedance and lets more current flow, provided you have enough changing magnetic flux to excite the windings. But low RPM performance goes in the tank because there's less changing mag flux. More windings of finer wire make better use of the lower mag flux.

 

[mechtech2]

Alternators produce Amps on DEMAND.
A smaller pulley on the alt will help only at idle and low speeds.
A larger capacity alt is what you need. Like a 95A instead of a 75A [whatever is more than you have.]

 

[Dave Sherman]

Rewinding is only part of the problem. Not enough of a stator core, and the core will saturate, limiting how much power you can get from it. Don't forget the rectifier diodes can only handle so much current, and the more current through them, the hotter they get. Rewinding won't help much if you end up burning the rectifiers.

mechtech2 is right, you need a larger capacity alternator.

 

[Loobed]

Originally Posted By: TallPaul


Don't they have these HD alternators for police vehicles that have a lot of electronic devices drawing off the battery. Or check what they do for motorhomes where the alternator charges both the engine battery and the house (coach) battery.



They use to make one for an Ambulance that I could have used, but I can't find it anymore. A police alternator should work. Most of their charging is at idle or low speed driving.

I would be drivign short distances (30 miles), then run accessories (lights, laptop, etc) with the engine off for several hours (6+). I don't want to drain my main battery. I would like a second one. Maybe a deep cycle. I was thinking about somehow just adding a second alternator.

 

[Loobed]

Originally Posted By: mechtech2
Alternators produce Amps on DEMAND.
A smaller pulley on the alt will help only at idle and low speeds.
A larger capacity alt is what you need. Like a 95A instead of a 75A [whatever is more than you have.]


I have a 105 amp one now.

 

[stockrex]

Just get a used or remand high output alt. Why do u need mire juice?

 

[Phishin]

A deep cycle battery would be good option. But be careful what you get. I think Optima's are junk.

If you could fit a size 31 under your hood, I'd get a Trojan battery. I use these in my musky fishing boat. They run my trolling motor all day in the high winds on Lake St. Claire and last for years. Bass Pro Shops re-labels Trojans as their own brand, and sometimes you can get these cheaper.

Have you thought about wiring in a big capacitor? This could help too. You can get a 1-4 Farad capacitor for fairly cheap.

 

[wrcsixeight]

I've got 2 extra deep cycle batteries, at 62 lbs each.

I've significantly upgraded the charging circuit with 2 awg cable
I've reduced the size of the Alternator pulley. It is rated at 130 amps.

I have a digital ammeter that has shown 120 amps with a cold alternator and 3500 engine rpm, but back down at idle speeds the amps taper to 62 when still cold and mid to high 20's when hot.


Once your vehicle's voltage regulator approaches its max setpoint, the alternator only produces enough amperage to hold that voltage. Once this threshold is reached, a higher rated alternator will do nothing unless you are also running 70 amps of driving lights.

On my Vehicle, this can be as low as 7 amps to hold 14.5 volts, even with depleted deep cycle batteries. If I shut the engine off at this point, and hook up a grid powered battery charger, the batteries will accept 30+ amps.

Alternator charging just does not work that well, Despite what many people think. It takes time to charge a battery, especially the last 20%. No way around it.

 

[Loobed]

Originally Posted By: Phishin


Have you thought about wiring in a big capacitor? This could help too. You can get a 1-4 Farad capacitor for fairly cheap.


I could get some larger ones for free. Can you go into more detail? I know Capacitors are DC, but some of the ones I could get say 120v AC or 240v AC. I can't remember for sure but that's what I think they are listed as.

 

[GMBoy]

We put 160amp alternators on every Tahoe/Suburban/Yukon/Yukon XL/Denali/Escalade...all engines 5.3 and 6.2. The Police Tahoes even with dual battery option still get the 160amp. Only exception to this rule is the 3/4 Suburban/Yukon XL 6.0L without electric fans - these get a 140amp and a fan clutch.

So I would assume if your alternator would be fine charging an additional battery if its 100amp or more...you are not fully charging 2 batterys but merely topping them off.

The best way is to just upgrade your alternator because it may be almost as expensive to modify yours.

 

[eljefino]

Back in the bad old days of v-belts you could add a 2nd alternator with a little fabbing of brackets. Now, not so much.

There are plenty of diesels clattering around with two starter batteries and no isolation or fancy alternators. I'd hook up a heavy duty relay, like a ford starter solenoid, to your 2nd battery, and trigger it with, say, your daytime running lights. This will leave your 2nd battery out of the mix if the e-brake is on or if you're running headlights (they kill DRLs). Then run all your gear off the deep cycle battery. Get in the habit of using the e-brake and taking a few seconds after starting before releasing that brake.

 

[GMBoy]

Originally Posted By: eljefino
There are plenty of diesels clattering around with two starter batteries and no isolation or fancy alternators.


Good point. I remember having a 1984 Seville with the 5.7 Diesel and dual batteries. It only had an 80amp alternator and did just fine. I think I was the only guy who never had a lick of trouble out of one of those Olds Diesels!

 

[bullwinkle]

You might be surprised by what your standard alternator is capable of doing-both of my old IDI diesel trucks have 1000 CCA dual batteries & the factory 100 amp alternators have no problems keeping them charged.

 

[440Magnum]

If you've got a 105A alternator, and your only concern is re-charging batteries (not a continuous load higher than 105A) then I don't think you need a bigger alternator.

Batteries will only "accept" so much charging current before their terminal voltage reaches the ~13.8V setpoint of the charging system. For a few seconds after you start charging a dead battery, it might draw 100 amps, but that very quickly tapers down to maybe 30A per battery. So if you've got dual batteries, you're going to have 60A charging current leaving 45A remaining to run everything else.

Now my numbers are just a WAG, so they could be off a bit. Some battery designs have higher and lower continuous charging current capabilities. But I think you're barking up the wrong tree looking for more than 105A.

However- if you are looking for a bigger one, you drive a GM vehicle. More parts available for that than any other brand on the planet. Find the equipment list for the same model you have, but with every power option on the planet, tow packages, etc. and see what alternator it uses. Then buy that, and any brackets needed to install it.