CAT 3208 HIGH OUTPUT/AMP ALTS!!! :)

[Scottwb96]

Hey everyone out there with CAT 3208 diesels that have been struggling to find high output alts that will fit into that ridiculously small space... After years of looking for alt options, serpentine belt options, brackets, pulleys, ect... I had pretty much given up and thought I was just going to have to accept the OLD Balmar 91-150 that I had on the port side and the 95a Leece-Neville I had on the STBD side (both externally regulated WS500's and pointed at my LiFePo4 house bank). My Balmar would MAYBE hit around 90-95 amps when cold and during a WOT carbon burn on the engines (for a few mins) but never over 100a and would usually settle at right about ~80a. The L/N did a little better and would also settle at about 80-85a.
I somewhat recently stumbled across Mechman Alternators (I have ZERO affiliation) and after playing 20+ questions w/ their techs/service department, I decided to pull the trigger on 2x 240a alts. They dyno'ed at ~256-ish at 1,800 (engine) RPM which is my perfect, "not in a hurry, but not trying to conserve a ton of fuel" cruising RPM... The alts have the (+) coming out of the bottom vs. the back like both of my other ones (mm's from the block!) So that right there made for a much better/safer fit! I requested them both to be setup as externally regulated, I also requested dual-v 1/2" pulleys. My plan was to derate them down to about 200a to start and see how everything worked (belt slippage/dust, etc). So far, these things have been AMAZING!!!
My output:
~600RPM = 50a each
~1000RPM = 100a each
~1500RPM = 150a each

For comparison, my other alts were putting out about 15-20a each at idle!!!

Here's the "cons"-
1. Even though I requested 1/2" double-V they sent me 3/8" D/V more annoying than anything, because I hadnt noticed until I was LITERALLY bolting them up (OOPS!)
2. The directions in the box as far as wiring/labels was basically non-existant
3. Even though it was setup as E.R. there were no outputs for stator/tach. This one pissed me off that that was not mentioned AT ALL during the pre-sales barrage of questions I had asked! My WS500's use the stator wire to get TACH info and also display that on my N2K network...
4. The wiring "plug" on the alt is a simple red/black (2 wires) being so used to field wires always being blue, that one had me spinning a bit (I was TIRED at this point 11pm)

Here are the ones I picked up... lol, "pro-tip" if you put it in your cart and wait ~24 hours you'll get an email w/ a 15% discount to come "complete your cart"... If you don't wait, you will get a 10% one from the "chat-bot"...

240 amp racing alternator - BLACK

Shop Mechman 240 amp racing alternator - BLACK 7127240B, best prices, fast ship time & top notch customer service! @ Mechman Alternators

www.mechman.com

If you have any questions, feel free to shoot me a message, happy to help/answer any questions you might have...

 

[tiltrider1]

This is good information for us 3208 owners.

 

[Diep]

Very Interesting. Might work on a Cummins 6BT as well.

 

[Crux]

I would suggest being sure to use matched, premium quality belts.......Gates Green Stripe and they will be physically paired

 

[twistedtree]

That's a great improvement, but I don't understand why a 250A alternator is only putting out 150A at 1500 rpm.

Did Mechman ever say what their sustained, continuous output rating is? In other words, what derating is required to keep it from overheating?

 

[Scottwb96]

I would suggest being sure to use matched, premium quality belts.......Gates Green Stripe and they will be physically paired

Thats exactly the belts I am (and have always) using!

 

[Scottwb96]

That's a great improvement, but I don't understand why a 250A alternator is only putting out 150A at 1500 rpm.

Did Mechman ever say what their sustained, continuous output rating is? In other words, what derating is required to keep it from overheating?

I have the alts derated from their dyno rated speed of ~256a down to 200a currently. Thats why the 150a at 1500rpm. I am using Wakespeed WS500's on both my engines/alts. The WS500's have alt temp sensors to keep the units within predefined temp ranges so they dont get damaged by long sustain high amp output. 400a feeding into my LiFePo4 house bank through a REC Active BMS that uses a 500a contactor, and I didn't want to max out the contactor for the BMS.

 

[heysteve]

Good stuff. The double belt setup seems like a challenge. On my engine, the outside belt is for the raw water pump so I'd presumably need to add the Cat two belt extension on the damper pulley. But then the alignment would be off on the alternator.

Could you describe what you did and maybe include a pix?

 

[Mac2]

Do you think they have a 24v version? I will call them next week if you don’t know and report back. Im already setup for the dual 1/2 belts, so this would be a dream come true if they have the 24v version. My two alternators are doing nothing to charge my house bank.

 

[luna]

I had a look at Mechman website, lots of glitz with not a lot of details.

Do you have any info. regarding the following:

- Are there brushes in this alternator?
- Any idea on the efficiency of the unit.
- You have your regulator protecting the alternator from an overheat. What is the Temp. rating of the alternator and your regulator's Temp. setting?
- 200A from a pair of 3/8" belts is pushing it. Any belt dust? You may quickly loose the belts due to the 1/2" crank pulley.

 

[twistedtree]

I have the alts derated from their dyno rated speed of ~256a down to 200a currently. Thats why the 150a at 1500rpm. I am using Wakespeed WS500's on both my engines/alts. The WS500's have alt temp sensors to keep the units within predefined temp ranges so they dont get damaged by long sustain high amp output. 400a feeding into my LiFePo4 house bank through a REC Active BMS that uses a 500a contactor, and I didn't want to max out the contactor for the BMS.

Do you need both the derate and the temp sensing? You derate to indirectly control temp, but isn't that what temp monitoring/limiting does directly?

It's just interesting to see the different output curves. I get essentially full output by 1000-1100 rpm out of a max 1800. But I have space for large frame alternators.

 

[twistedtree]

I had a look at Mechman website, lots of glitz with not a lot of details.

It's so frustrating that modern web sites have become like this. All nebulus platitudes, and no actual information. All you can infer is that if you buy their product you will be happier, younger, and better looking than you are today.

 

[Mac2]

OP: I hope you keep us posted on your real life experience with the alternator. Only time will tell. Luna mentioned belt dust. This is a big one for me. A cruising season should give you an indication of wear. How long have you been running the alternator?