High Output Alternator Upgrade - Has anyone done this?

[ghhardin]

I am new owner of a 40C with the Cummins 380 and I am holistically looking at power systems. Being an EE this is my first intrigue with the rig..



As I look at Batteries, Charging, Generation, Inverting & Consumption I am thinking one of lynch pins is the Alternator.


The stock alternator is 160 Amps which is fine. But I would like to be able run House AC units as I am driving without running the 10K Generator.


I have done some research and there are high-output Alternators in the 300+ Amp range..


Questions:
I have not been able to find the make and model of the current alternator - Does anyone know what it is?



Has anyone installed a Hi Output Alternator?


Thanks in advance...
g

[mwdilday]

An RV A/C would need 177 amps at 12 volt DC thru an inverter. That is just for the A/C. That is a lot of amps.

[bubbles]

Huh?

[ghhardin]

I just did the math (worst case):
The AC unit is on a 15 Amp circuit
120VAC * 15 Amps = 1800 Watts AC


Converting that to DC:
1800W/12VDC = 150 Amps DC


Granted the efficiencies of the inverter will not be 100% but this is close...


My thinking, all things being equal, by upgrading from a 160 A alternator to a 340 alternator I have about 200 extra amps...

[IsleDog]

you can look and see if your chassis was ever available with a twin alternator setup. this is fairly common in the car audio world and with ambulance packages.

[Chuck_S]

Beat me to it.

Common on boats as well.

Alternators in trucks and cars don't power much. AC is engine powered for example. Audio, medical equipment, and marine electronics suck up a lot of current. Alternators seem to work best at no more than half their rated maximum power outputs.

-- Chuck

[D W]

I'm sure there's a 350A alternator out there for that engine. I would contact Freightliner Custom Chassis Corporation to find the exact details of what the integration of a 350 amp alternator entails.

[Maxwell D Pratt]

Do you think that would be a good idea . As converting back to 120 volts from 12 volts DC . You lose about 30% doing that . Do you think it would be worth the money .

[ghhardin]

LOL - not sure if it is a good idea....


I am planning on significantly upgrading the batteries to LiFePO4.. At a minimum 8 batteries, for 800 AH of stored power.


But that means I can also charge at 800 Amps per hour..


Having a high-output alternator will allow me charge much faster as well...


Using the same math (w/o the AC being turned on), I could use the extra 200 Amps to charge the entire battery bank in 4 hours of drive time.

[ghhardin]

oh, then I should be able to run an AC unit for about 5 hours

[Maxwell D Pratt]

I was just wandering why you would want that much DC charging capacity. Just a novice when it comes to electric . Do understand the basic . That’s why I was wondering if the price was worth the end result. Good luck on you endever. I worked 30 years in the water & sewer industrie as service tech.

[Larry-NC]

Originally Posted by ghhardin

I am new owner of a 40C with the Cummins 380 and I am holistically looking at power systems. Being an EE this is my first intrigue with the rig..

As I look at Batteries, Charging, Generation, Inverting & Consumption I am thinking one of lynch pins is the Alternator.

The stock alternator is 160 Amps which is fine. But I would like to be able run House AC units as I am driving without running the 10K Generator.

I have done some research and there are high-output Alternators in the 300+ Amp range..

Questions:
I have not been able to find the make and model of the current alternator - Does anyone know what it is?

Has anyone installed a Hi Output Alternator?

Thanks in advance...
g

As another EE, let me remind you of the equivalence:
746 watts = 1 horsepower.

You're gonna have some effect on driveability and fuel economy when you turn on all the loads.

Larry

[ghhardin]

Thanks thats' a good number to know... Nothing is for free...


I am a Telsa owner... I live by those numbers... My number is 400 Watts/mile..



I am still trying to see if I can get a Tesla Wall under the rig ;D

[Steelhorzz]

Originally Posted by ghhardin

oh, then I should be able to run an AC unit for about 5 hours

You need to check the amp output at various RPMs.

Don't think that just driving down the road a 200 amp alt is putting out 200 amps.

First, it depends on how fast it's spinning. (It is in fact an electrical motor generating power.) the faster it spins the more power is generated.

Secondly, ( it depends on how much power is required during normal operation).

Even if you were traveling fast enough to spin the alternator at maximum power output, the regulator only turns on and allows the battery to be charged after there is enuf power available to supply whatever requires power during operation. (Lights, heater, AC, radio, cameras, etc.)

If there is not enuf amps available, the battery does not get charged).

This is simplefied, but You need to be aware.

It's not just "plug and play"

Example, in my case I had an original 60 amp alt and
I added some additional options.
Led headlights, heated seats, electric radiator fans.

I replaced the alt with a 100 amp unit. (More than enough power to supply my vehicle and all the options). So I thought. .....

I forgot about idling at stoplights, intersections and driving in slow traffic.

My vehicle kept overheating.
The radiator fans were not getting enuf electrical power, (amps) to spin fast enuf to pull air thru the radiator.

I had to upgrade to a 200 amp alt to be able to generate enuf amperage at idle.

Problem solved.

Just need to know your numbers on the output curve...

Good luck!!

[Oscarvan]

With a LARGE bank and a LARGE alternator observing all the usual rules it will keep up....

But everything has to be multiples of the load. If you need 100A to keep the AC going, you need a bank sized to feed that, and you need an alternator that will provide the charge on average over a broad RPM spectrum, not exceeding the safe charge amperage of the bank.

So electrically it may work.

Mechanically is another story. Aside from the HP loss (which you are going to incur one way or the other whether out of your main engine or out of your generator) there is also a seriously increased load on the BPS. (Belt Pulley System). The resistance on the belt from an alternator trying to crank out 300A versus 50 (The 160 that's on there only puts that out for a few minutes after starting) is substantial. You may need a wider belt, a larger pulley with longer contact or more acute angle, and you my need to evaluate increased stress on all the other items on the belt, the tensioner, the idler pulleys, control of the belt oscillations and on and on. Or, you may need an additional pulley on the crank shaft and a separate belt to the HD alternator, and I am not sure which coach you have but if it has a rear radiator there's very little room.

Then there's the additional heat generated by the engine keeping up with this while you're still trying to do 65mph in the desert heat..... Is the cooling system compatible?

You're an EE, but you'll need an ME with engine specialty to figure all this out. In the marine environment we dealt with the Balmar company. They did the high output alternators and the application solutions.

And, as someone pointed out, there's a LOT of loss going from various voltages through inverters etc etc.

Now, if all you're after is running the AC while driving you could also consider adding another compressor, or finding out how vehicles with multiple AC's (Suburan) solve for this with a single compressor.

But I'll be following this with interest. I have solved the heat part of the equation with my cabin heater (see my blog) and not having to run the generator in the AC season would be cool.

[ghhardin]

I am understanding how the alternator load affect engine load and the RPM's required to generate current.


This is the Alternator I have been using as a reference...


370 amp high output alternator 06-09 Dodge Ram 5.9L Cummins Diesel



The Elite series alternators offer the highest possible amperage and durability available in standard fitment "direct bolt in" automotive alternator. 6 phase technology, combined with massive twin rectifier assemblies and 12 diodes make these alternators totally durable for daily use. This alternator will easily produce 200+ amps output at engine idle RPM, with 370+ amp output at normal cruising speed.



https://www.mechman.com/high-output-alternator-dodge-ram-diesel-370-amp-cummins/

[ghhardin]

I have already ordered and will be installing three Mircro-air EasyStart Soft Starters to help normalizing the inrush current requirements for three AC units (two have heatpumps)

[daveinthekeys]

Is there any chance that engine allows for a PTO, or has one?

There is at least one manufacturer of PTO powered generators. I think it was 3 or maybe even 8 KW. Perhaps a range of generators with several KW offerings.

Sorry I can not remember more. The idea was emergency power, construction sites,
etc. Using HD pickup truck diesel engine's with PTO.

[daveinthekeys]

here is a link to the PTO generator idea for diesel pickups. But with the right bracket any PTO would work. (I assume)

https://www.integrelmarine.com

[ghhardin]

What is a PTO generator?
A Tractor Power Take Off (PTO) generator is one of the quickest ways to turn your most trusted piece of farm equipment into a mobile power plant. PTO generators convert the energy from the output shaft of your tractor into electricity with minimal loss.