High Output Alternators

[dkoenitz]

I would like to put a 250+ amp alternator in my '95. Unfortunately, because she's a 2.5L I'm having trouble finding off the shelf options. LActrical has a 160A on Amazon for pretty cheap ($130) and Mean Green makes a 200A for $400. There are lots of high-output offerings for the 2.5L TJs and of course the 4.0 YJ.

Anyone done this? I'm just trying to work out the cheapest/simplest route to 250A (~125A @ idle), whether it's some custom rewind or modifying a bracket to fit a 4.0L alternator. I'd like to run a large pure sine wave inverter when running tools in the field or accessories when camping. I'll also most likely be installing a second battery at some point (pretty sure I can get it in the engine bay pretty easy)

I *could* just buy a $400 Honda generator as the first comment will indubitably tell me to do (and this isn't totally unappealing as an option), BUT as we all know storage in the jeep is a hot commodity and the inverters are smaller and I'm already wired with a large battery cable with disconnect near the trunk.

 

[Gilaguy23]

Curious what the conversion factor is on a converter going from DC to ac power. We ran them in our work trucks but never paid much attention. So 400 amps DC can supply XX amps A/C. Do they go off watts produced perhaps. 120V into 4000 watts = 33amps a/c er?? if you know,let us know. Knowledge is power as they say.

 

[dkoenitz]

Curious what the conversion factor is on a converter going from DC to ac power. We ran them in our work trucks but never paid much attention. So 400 amps DC can supply XX amps A/C. Do they go off watts produced perhaps. 120V into 4000 watts = 33amps a/c er?? if you know,let us know. Knowledge is power as they say.

A good pure sine wave inverter is close to 90% efficient. It's Watts_AC/Watts_DC (though it does vary with amount of load). It isn't quite as simple as that though. Your battery (or batteries!) are what really has the ability to handle high peak draw. Alternator mostly tops of the batteries. Massive inverters only draw what they are asked to, but if you try to draw more than the battery+alternator can supply, you start blowing fuses. Nothing I want to do requires high continuous current. I really would like to be able to power some of the tools I have that it would be impractical to buy battery-powered versions of. In most cases, it is more practical to just charge your tool battery bank and use cordless tools, but I don't want to buy a $700 battery miter saw, for insurance. I mean, I do, but I can't justify it.

At idle, a 250A alternator gives about ~125A of power. Converted at 90% efficiency and using a large enough inverter gives around 1500W continuous, but assuming the battery(ies) can handle it, the peak draw could be much much higher.

 

[Bucky]

After I put a HO alternator on my 89 4.2 the belt would squeak when battery was low or when I run all my KC Daylighters for a long time. Even after installing new belts. I have to spray belt dressing on it to stop it. I probably should put in dual batteries.

 

[jeepjoe43]

After I put a HO alternator on my 89 4.2 the belt would squeak when battery was low or when I run all my KC Daylighters for a long time. Even after installing new belts. I have to spray belt dressing on it to stop it. I probably should put in dual batteries.

Left my factory Alternator in, and now the belt squeals because of the dual batteries.
If you do go dual, you may have re-arrange a little sheet metal to get it to fit. Mine was a Rugged Ridge kit.

 

[Steel City 06]

I’ve dealt with several HO alternators.

I recommend reaching out to the following three companies:

Singer Alternators

www.singeralternators.com

DC Power Inc. - High Output Alternators!

Whether you’re into racing, off-roading, RVing, or have a 10,000 watt stereo system in your daily driver, you’ve come to the right place. DC Power Engineering Inc. alternators are engineered from the ground up for those that demand the very best. Engineering is more than a word to us – it’s our...

www.dcpowerinc.com

Mechman Alternators | Made in the U.S.A High Output Alternators | Call 1-888-MECHMAN

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Those three companies routinely build alternators up to 370 amps for most cars, and I’ll bet at least one of those companies will build a 370 amp (or smaller) model for your YJ.

I have had great experience with Singer alternators. They rebuilt a fried Mechman 370 amp alternator (Denso core) into a 270 amp alternator that has been flawless for 80,000+ miles.

Note that idle output is always less than cruising output. A 370 amp alternator, for example, generally only does about 220 amps continuously at hot idle. A good rule of thumb is hot idle continuous amperage is about 60% of cold high RPM peak output.

 

[jeepjoe43]

I’ve dealt with several HO alternators.

I recommend reaching out to the following three companies:

Singer Alternators

www.singeralternators.com

DC Power Inc. - High Output Alternators!

Whether you’re into racing, off-roading, RVing, or have a 10,000 watt stereo system in your daily driver, you’ve come to the right place. DC Power Engineering Inc. alternators are engineered from the ground up for those that demand the very best. Engineering is more than a word to us – it’s our...

www.dcpowerinc.com

Mechman Alternators | Made in the U.S.A High Output Alternators | Call 1-888-MECHMAN

mechman, mechman alternators, high output alternator, mechmanalternators, motor swap, universal, custom, car audio, bass, basshead, subwoofer, amps, voltage, alternator, alt,

www.mechman.com

Those three companies routinely build alternators up to 370 amps for most cars, and I’ll bet at least one of those companies will build a 370 amp (or smaller) model for your YJ.

I have had great experience with Singer alternators. They rebuilt a fried Mechman 370 amp alternator (Denso core) into a 270 amp alternator that has been flawless for 80,000+ miles.

Note that idle output is always less than cruising output. A 370 amp alternator, for example, generally only does about 220 amps continuously at hot idle. A good rule of thumb is hot idle continuous amperage is about 60% of cold high RPM peak output.

I'll be looking into them for my dual battery set-up.
Thanks!

 

[dkoenitz]

I’ve dealt with several HO alternators.

I recommend reaching out to the following three companies:

http://[URL]https://www.singeralternators.com/

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http://[URL]https://www.dcpowerinc.com/

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http://[URL]https://www.mechman.com/

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Those three companies routinely build alternators up to 370 amps for most cars, and I’ll bet at least one of those companies will build a 370 amp (or smaller) model for your YJ.

I have had great experience with Singer alternators. They rebuilt a fried Mechman 370 amp alternator (Denso core) into a 270 amp alternator that has been flawless for 80,000+ miles.

Note that idle output is always less than cruising output. A 370 amp alternator, for example, generally only does about 220 amps continuously at hot idle. A good rule of thumb is hot idle continuous amperage is about 60% of cold high RPM peak output.

Thanks. This is exactly what I was looking for! And yes, a good part of the reason I was looking to go 250+ is because that's the only way to get close to what I'd like at idle (at least half of that).

The guy who sold me the Jeep pointed me to a local company that did a HO rewrap for him 15 years ago, but that proved a dead end.

 

[Steel City 06]

This is what Mike Singer quoted me about 2 years ago when I was looking into an HO alternator for my 2006 TJ. Given inflation and COVID related parts costs, I would expect somewhat higher prices now. These are for brand new alternators made from new Denso cores.

 

[Steel City 06]

Also make absolutely sure you do the Big 3 wiring upgrade. This means a bigger wire from alternator to battery positive, alternator/engine case to ground, and body ground to battery.

All parts of the circuit must be able to handle the maximum amperage of the alternator and any potential loads (like your inverter). The biggest alternators can put out enough juice to start a fire on stock wiring.

On my TJ I ended up with a 180 amp factory alternator, so I went with 2 AWG wiring. On my F150 I had a 370 amp (now 270) so I upgraded to 2/0 AWG wiring.

 

[dkoenitz]

Also make absolutely sure you do the Big 3 wiring upgrade. This means a bigger wire from alternator to battery positive, alternator/engine case to ground, and body ground to battery.

All parts of the circuit must be able to handle the maximum amperage of the alternator and any potential loads (like your inverter). The biggest alternators can put out enough juice to start a fire on stock wiring.

On my TJ I ended up with a 180 amp factory alternator, so I went with 2 AWG wiring. On my F150 I had a 370 amp (now 270) so I upgraded to 2/0 AWG wiring.

I was going to ask about smaller pullies to give closer to peak amperage at idle. Glad that's a thing. Yes. A big cable wiring overhaul was in the plans. Thanks so much! Excellent.

On a side note, since you mentioned your f-150, the new f-150 hybrid has an optional 2400W set up (at idle) but you can get also option it with a 7200W set up that can power the tools of a whole construction team. I'm sure it's a $million, but it's certainly a cool concept.

 

[Steel City 06]

Most HO alternators come with a smaller pulley, so you'll need a shorter belt. Fortunately there are hundreds of different serpentine belts available so that becomes relatively easy.

I'm actually ordering a new F150. I totally would buy the hybrid for the inverter, but they only offer it in a crew cab, meaning you can't get it with a standard 8' bed.

The inverters are surprisingly reasonably priced. The charging hardware is already there. On the hybrid they use the hybrid motor generator to generate the electricity as opposed to an alternator.

Even the standard 2.0kW inverter they won't sell with an 8' bed. I can always install a 3kW one myself later down the line.

 

[Jage]

Also make absolutely sure you do the Big 3 wiring upgrade. This means a bigger wire from alternator to battery positive, alternator/engine case to ground, and body ground to battery.

All parts of the circuit must be able to handle the maximum amperage of the alternator and any potential loads (like your inverter). The biggest alternators can put out enough juice to start a fire on stock wiring.

On my TJ I ended up with a 180 amp factory alternator, so I went with 2 AWG wiring. On my F150 I had a 370 amp (now 270) so I upgraded to 2/0 AWG wiring.

Just like to add put a ground from engine to frame.

 

[ranchoazulcolstrip@gmail.]

Curious what the conversion factor is on a converter going from DC to ac power. We ran them in our work trucks but never paid much attention. So 400 amps DC can supply XX amps A/C. Do they go off watts produced perhaps. 120V into 4000 watts = 33amps a/c er?? if you know,let us know. Knowledge is power as they say.

P (watts) = I (current) x E (voltage). I/m assuming you're not running 3 phase AC circuits so the 1.732 (square root of 3) doesn't apply...