HMMWV alternators

[richingalveston]

I have been reading the HMMWV tm's about the alternators. I am looking to increase the electrical output on my cucv. I am considering a HMMWV 200 amp alternator but it appears they do not put out much power at low rpms. A lot of my wheeling is done at low rpms and apparently if you are only running 1500 rpms the 200 amp alts put out less than 50 amps.

Am I reading the TMS correctly. IF this is the case. I think I need to find a different alt.
you have to be in the 5000 rpm range on the alt to get to the 160 - 200 amp range.

I have found new model alts that can do 200 (12v) amps at idle so I may be better off at staying with the two alt system and adapting a new alt. to my cucv.
Thanks for any input.

 

[papakb]

Hello Rich, You didn't state why you feel you need more alternator power and at their high costs unless it's really necessary it's hard to justify the cost for a 200A setup. What are you thinking of running in your CUCV that needs that much power? Especially since the HMMWVs almost never run at 5K RPM.

 

[hrbergeron]

You may want to consider staying with a stock cucv charging system. The 200 amp alternator puts out 200 amps 24 V, DC. Last time I checked, the 12V DC output on it was only around 40 amps. On my cucv, I have dual 60 amp alternators that have run all my accessories without issue, most notably my period correct lightbar which uses electric motors and halogen lights that have a huge draw.

 

[richingalveston]

I am looking to run an inverter for electric AC and I have a lot of lights some radios and eventually want to power a portable fridge. From what I have read the 27si alts on the cucv put out 100 amps each which give you either 100 amps at 24 volt or 100 amps at 12 volt. For every 12volt amp you use you loose one amp at 24volt.
I have found some high output 12volt alts that I will probably use one of these along with the stock 27si for my 24 volt. I can do this for less money than the HMMWV alt and not have to change brackets. I am looking for a 3 belt power steering pump pully so I can use the hmmwv water pump and crank pully's to enable the high output alt to use two belts.

 

[Milcommoguy]

What do you have that is 24 volts?

The CUCV's I have owned, 24 volt for the starter and any left over military radio needs (RT524) If you think about it even the glow plug system was 12 volts.

IMO, Half assed way to meet military needs (remember CUCV) for 24 volts to haul around an extra battery and alternator just to play radio or start A / the truck.

Swap the starter to 12 volts, bypass the start relay circuit, ditch the glow plug ballast resistor, rewire alternators for parallel operation (now you got 200 amp for a piece of wire), parallel up the batteries, add 12 volt meter for cool factor.

Any civilian 12 volts accessories, lighting, radios, doodads... 200 amp of charge, 1000's of amps of battery, no issues. NO MORE 24 volt headaches. with one dead battery.

Inverters DC to AC still going to draw down when approaching maximum wattage outputs.

IMO, I wouldn't even think of dropping in a HUMV alternator. Too much mechanical mickey mousing, too much money for less and weights too damm much.

DO you really need a 24 V slave outlet? Something to think about... Go 12 volts, CAMO

AND you might not be able to close the hood, LOL

 

[richingalveston]

I have some lights that are 24 volt and I plan to use a 24 volt inverter. I believe I will keep the 24 volt system so I can use the same wiring and not have to upgrade a bunch of wires. I just need a little more power. I am planning to upgrade the 12 volt alt to a 200 amp minimum alt. this will give me a full 100 amps at 12 and 100 at 24. I will add a second belt by using the hmmwv pully's for the crank, water pump and hydro pump the new alt I get will have a double pully. The only change I will have to do with the mounts is move the passenger alt out because it will use the 4th belt groove on the water pump and crank pully's. I think this is the easiest way to get the power I need and the most economical. I have a newly rebuilt 24 volt starter and a fresh rebuilt 24 volt spare starter along with 3 spare rebuilt 27si alts. I also have two brand new batteries and all new oversized battery cables.
After looking at the HMMWV alts, I have decided going with a new 12 volt alt is the best choice.

 

[Mogman]

I know this is an old thread but can you tell me what TM you found that info in? also are you sure they are talking about engine RPM and not alternator RPM? the alt runs much faster than the crankshaft and the 6.5L will not twist anything near 5 grand.

 

[Gcelevator]

I know this is an old thread but can you tell me what TM you found that info in? also are you sure they are talking about engine RPM and not alternator RPM? the alt runs much faster than the crankshaft and the 6.5L will not twist anything near 5 grand.

Same i thought, diesel engines (most of them) by nature are low RPM.

 

[Mogman]

OK I found the data you quoted and it plainly states alternator RPM not engine RPM, big difference!

The stats show the combined loads, at 1500 alternator RPM it will make a min 90A without any load on the 14V side etc.
I will have to check but I would not be surprised if the alt is not turning at least 1200 RPM at idle.