Simp's M915A1 Build Thread

Tow4

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Yea i saw that thread a few weeks back. I was able to nag almost a dozen of the Cummins 24v equipment alternators for really cheap awhile back. So i will only be in it $300 for the alternator and the equalizer. The 30si duals arent common by no means
I just checked and the 30si with transformer rectifier is available. My cost is a little under $300 new so you have the same money in your setup. If you are going to be running a lot of 24 volt equipment you are better off with a 24 volt alternator.
 

simp5782

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I just checked and the 30si with transformer rectifier is available. My cost is a little under $300 new so you have the same money in your setup. If you are going to be running a lot of 24 volt equipment you are better off with a 24 volt alternator.
Can i ask what part number are you using? The delco 3603854RX is an obsolete unit.
 

Tow4

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Can i ask what part number are you using? The delco 3603854RX is an obsolete unit.
Its a clone, I noted that in my thread. WAI 7256N, you may also find it listed as WPS (World Power Systems) which is a WAI brand. I did a quick google search and came up with 4 or 5 different listings.
 

simp5782

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Its a clone, I noted that in my thread. WAI 7256N, you may also find it listed as WPS (World Power Systems) which is a WAI brand. I did a quick google search and came up with 4 or 5 different listings.
Thanks. I was using the Delco number to find the clone equivalent. The wilson built unit is $320 thru napa if you have an account. Doesnt seem too bad.
 

simp5782

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Threw some belts on the alternator to see what it was doing and to test the new gauge. Looks like nothing much happening with it.

Installed a boost gauge in place of the original volt gauge spot.

Replaced the solenoid in the dash with a John Deere # RE170320 i had on the shelf for a while now and keep the old one as a spare.

Had to fix a leaking wheel O ring so i checked the brakes as well and they look fine. Did adjust all of them as well.

Measured for 2 of the beacon light plates going to add to also hold rear backup lights as well
 

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simp5782

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Welp. went ahead and figured the alternator issue out. Since someone is a complete moron and installed a 24v AC unit in this truck that pulls around 16amps on max blower. Along with the compressor pulling some amps. Basically the reason I am going to assume that this truck was put out of commission was because it was killing the batteries in the summertime and they could not figure out why. The AC was installed in July 2014 around the time they said it was parked. So yeah. we are going to go with that..... Threw a 30Si with the transformer on it that Tow4 suggested. and it can't even keep up on 24v with the AC on high really. Dash gauge drops to 23.8 at the starter switch reading and battery/alternator are both reading 25.7 so it is struggling.

So the choices will be to just run the AC on 12v and rewire it or go to the 100amp 24v alternator and the equalizer. Or swap the AC unit out for a 12v MCC unit.

Alternator wires just aren't big enough to sustain the power draw either.

Always something but just retarded that they used a 24v unit on a predominantly 12v truck.

Off to my next quest of crap for the day.
 

Tow4

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Welp. went ahead and figured the alternator issue out. Since someone is a complete moron and installed a 24v AC unit in this truck that pulls around 16amps on max blower. Along with the compressor pulling some amps. Basically the reason I am going to assume that this truck was put out of commission was because it was killing the batteries in the summertime and they could not figure out why. The AC was installed in July 2014 around the time they said it was parked. So yeah. we are going to go with that..... Threw a 30Si with the transformer on it that Tow4 suggested. and it can't even keep up on 24v with the AC on high really. Dash gauge drops to 23.8 at the starter switch reading and battery/alternator are both reading 25.7 so it is struggling.

So the choices will be to just run the AC on 12v and rewire it or go to the 100amp 24v alternator and the equalizer. Or swap the AC unit out for a 12v MCC unit.

Alternator wires just aren't big enough to sustain the power draw either.

Always something but just retarded that they used a 24v unit on a predominantly 12v truck.

Off to my next quest of crap for the day.
If you remember, the 24 volt side of the alternator was just to charge the starting series 24 volt batteries. The "Top Charger" that was on my original alternator was made by the company I use to work for. I knew the engineer that designed it and he suggested the transformer alternator. The "Top Charger" was only rated at 10 amps and was a compromise at best. The wire from the alternator as you have noticed is only good for 10 or 15 amps.

I guess the question is would it be better to change the alternator to 24 volts and run a heavier 24 volt wire, install the equalizer etc or change the AC to 12 volt. I agree with you, the person that installed a 24 volt AC didn't know anything about the truck.
 

simp5782

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If you remember, the 24 volt side of the alternator was just to charge the starting series 24 volt batteries. The "Top Charger" that was on my original alternator was made by the company I use to work for. I knew the engineer that designed it and he suggested the transformer alternator. The "Top Charger" was only rated at 10 amps and was a compromise at best. The wire from the alternator as you have noticed is only good for 10 or 15 amps.

I guess the question is would it be better to change the alternator to 24 volts and run a heavier 24 volt wire, install the equalizer etc or change the AC to 12 volt. I agree with you, the person that installed a 24 volt AC didn't know anything about the truck.
Yeah. the 24v ac thing is a real drag on it. Why the other day when i left the GA rally it was just killing the 24v side since I had the AC running to keep the windows unfogged. and that drug them down pretty bad.

So yeah i will go with the 24v unit and go with the equalizer. I can take some power off of the equalizer of some items since all the lights i put on are omni volts. I am planning on doing a military light switch install so i can just repower the headlights with 24v

I didn't think it was a 24v ac unit until i put the digital gauge in and watched it drop like a rock when it came on. There is however almost a 3volt different between the key power at 23.2v with the AC on versus the 25.7 volts at the battery and the alternator. Battery/alt are showing 27v otherwise with no load. 12v side is seeing 14volts at the battery and alternator but the gauge wire i tied into is only seeing about 1 volt less. Will refigure all of that.
 

NDT

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Dont think so. its got a homemade bracket on it. and the AC is a Visionaire out of Ft. Worth. It is non adjustable and not a Red Dot unit.
Nope not a RRAD install.

Remember when during the Gulf Wars, the army came out with a version of the Red Dot HMMWV A/C unit for the 915s. It was 100% 24 volt including those two pancake fans. DUH that promptly burned out all the transformer/rectifier alternators on these trucks and led to the alternator upgrade kit that is similar to the HMMWV.
 

simp5782

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Nope not a RRAD install.

Remember when during the Gulf Wars, the army came out with a version of the Red Dot HMMWV A/C unit for the 915s. It was 100% 24 volt including those two pancake fans. DUH that promptly burned out all the transformer/rectifier alternators on these trucks and led to the alternator upgrade kit that is similar to the HMMWV.
Yeah saw one on ebay for around $375 new in the box. pretty cheap actually.
 

ponway

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Welp. went ahead and figured the alternator issue out. Since someone is a complete moron and installed a 24v AC unit in this truck that pulls around 16amps on max blower. Along with the compressor pulling some amps. Basically the reason I am going to assume that this truck was put out of commission was because it was killing the batteries in the summertime and they could not figure out why. The AC was installed in July 2014 around the time they said it was parked. So yeah. we are going to go with that..... Threw a 30Si with the transformer on it that Tow4 suggested. and it can't even keep up on 24v with the AC on high really. Dash gauge drops to 23.8 at the starter switch reading and battery/alternator are both reading 25.7 so it is struggling.

These were the instructions on one of the 915's we drove in Iraq!
IMG_2708.jpgIMG_2703.jpg
 
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simp5782

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Welp. The rain passed. Pulled the fender again and installed the 33si 24v cummins unit. Ran direct 1/0 wire from the alternator to the battery for ground and positive. Used an old truck power wire for the ground ao i didnt have to make another one. Charging 27.6 just above idle. Like 50rpms above idle so i will bump that up a little bit. Bolted right in. Used the spaced out pulley that came on the stock unit. The spaced pulley is actually Prestolite 34-111.

Planning on installing a throttle lock cable anyway for cold days for warm up.

Installed a new V band clamp on the downpipe since it was broke. Turbo is leaking oil along with a leaking exhaust manifold gasket so i will be swapping that with a new turbo i have in the box this week. It currently has a 4LHR turbo on it.
 

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simp5782

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Got the equalizer installed today. Along with all of the big wires ran and the 24v solenoid installed. Installed a maxi fuse holder on the 24v side. How ever i made go over to a heavy circuit breaker.

Tomorrow i will install the 12v solenoid near the battery box along with that wiring. With a circuit breaker in line for that as well.

Going to.hook a few fuse blocks in right near by as well. One for 24v and one for 12
 

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simp5782

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12v solenoid mounted in the box. Used the 24v energizer to power that contact along with the 24v solenoid under the dash. Putting out good numbers. Even with full loads of lights, Hester, ac on high its 27v and 13.4 with 700rpms. Does need a smaller pulley for the alternator though.

Used Borg Warner S603 for the 12v solenoid continous duty and a Cole Harsee 24063 24v continous duty under the dash.

Swapped all the dash lights for LED. Including the snap in bulbs. Gotta find a tachnograph key to replace those bulbs in there though.

Next project will be to swap cab mounts. All of mine are pretty cracked out and worn slap out. Was able to find them from AstroTex in California for $20 each.
 

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