2nd alternator on Cummins 5.9

[Rivetboy]

OK here are a few pictures of bolting up a 200 amp alternator in lieu of the second a/c compressor. The plan is to use it to charge agm batteries while driving and also running a small auxillary split system.

And yes, that is a piece of my old garage dooor to hold it temporarily. Will fabricate another one that is more robust and uses both engine mount bolts to secure it. Also had to notch the frame rail a bit for clearance but no biggie.

Finally, if that alternator is going to put out near rated output continously it will probaly need its own a/c duct (only half kidding) and the insulation shroud will have to come off the output stud to make room for a number two cable lug and strain relief.

[EtownAcres]

Did this work?

[Rivetboy]

Originally Posted by EtownAcres

Did this work?

The mechanical part yes it was successfully bolted on but could not get the electrics worked out. Decided to buy a Honda inverter genset instead. Got an EU 2000

[PNW_Steve]

When you get it all figured out....... I could use a hand

I would love to install a 2nd alternator on my 8.3. Unfortunately, my fabrication skills are not up to the task.

[Shamoke]

Did you, or has anyone else figured out how to make this work? I was thinking about a 200 amp alternator to run my mini split and refrigerator while I travel.

[cadillackid]

Native did that on his CAT motor.. the exact thing you want to do.. there are bracket kits made to add a second alternator to most engines.

[RolesvilleMarina]

Originally Posted by Shamoke

Did you, or has anyone else figured out how to make this work? I was thinking about a 200 amp alternator to run my mini split and refrigerator while I travel.

would this work?

How large an inverter then to run a mini-split?

I have a rooftop air con. We have a 1000 watt inverter (leftover from our big sailboat I sold) and so right now when driving I can run the fridge. Currently don't have it hooked into my AC system yet. I have an onan 4k I will be installing so I could run that down the road


I have a space, where originally an Air con system compressor would go. But I was going to go ahead and put in engine driven air con.

however if a 200amp Alt can run a mini-split I imagine it could run the roofshaker?

might be easier to plumb in a spare alternator, and get more out of it than a compressor


just thinking/wondering out loud

[cadillackid]

an engine driven bus A/C system on a single sanden SD7 enhanced compressor (standard ear mount) can give you up to 60,000 BTU.. a minisplit is 12.. a roofshaker maybe 15.. to me the only reason to run like that is if your bus will by hyper insulated and you dont mind being somewhat warm.. or you are hell bent on having only electric A/C and nothingf engine driven.. saving space or aesthetics etc. .. or if you had a bus with factory air and removed one of the 2 systems and want to cool the rear you could run your parked A/C while driving..



having a second alternator has a lot of uses depending on your setup.. more than just running air conditioning..

[Oliveguam]

Wow that is a shoehorn job fitting it in there, good job on the install!!! Is that a factory chrysler alternator? is the trouble in getting power production a lack of regulator? when dodge pcms fail its common to get an 89 back (92 if diesel) off the shelf regulator (try to avoid the chrome ones from napa seems the galvanized ones carry a better reputation) Two bullet wires and a small aluminum bracket to mount it, and your set. (I always liked to make a curved plate so I can mount direct to alternator) The chrysler regulates the ground side of field (fords of the positive side so more to wire up) so energize the regulator and positive side of field through a diode or relay (otherwise could back feed ignition) or run direct power through a hobbs switch off oil pressure line. (so its self energizes as soon as engine running, and vice versa) Also of note these work very well for underhood welders (larger case leece neville/prestolite cases are nice but I doubt will fit here). run power lead first to a battery bank isolator (marine barrel) switch then hot and ground wires to weld lead quick connects two way toggle directy ground of field winding vs regulator path and a hand throttle to work amps up or down. Will burn 3/32 rod all day and 1/8 with low duty cycle. run a thin stretch of cable by your stinger as a safety as it should get uncomfortably hot to use before your alternator gets too hot.

[Shamoke]

Originally Posted by RolesvilleMarina

would this work?

How large an inverter then to run a mini-split?

I am still trying to work out all of the details and I need to research on converting dc watts to ac amps, I am not sure if dc and ac amps are the same rating but I think they are. If they are then my 12k btu mini pulls 10.6 amps max at 120 volt ac and that means 1272 watts. A 200 amp alternator at 12 volts dc should be 2400 watts, so unless I am missing something here it should power the mini split, the refrigerator, a few led lights and have power left over for some battery charging through a charge controller.

Using the guide on power consumption for household item found here: https://www.daftlogic.com/informatio...onsumption.htm
I believe that this is workable. Maybe someone here can tell me if I am mistaken anywhere.

[Native]

On our setup, I installed a PenTex 350A 12V alternator. This charges the house batteries. I put a GoPower 3000W inverter charger which runs our Coleman Roughneck III (13.5KBTU) rooftop air conditioner.


When the compressor is running, the load at the inverter is just under 120A (12v). This is what the inverter is pulling from the house battery. In truth, that 120A is provided by the alternator.