Civilian 24 volt alternator install

[cornrichard]

About Thanksgiving time the alternator on my deuce decided to give up. I took it to be rebuilt. I called twice and the rebuilder had not got around to it yet. At the 4 week point I walked in the shop and saw my alternator sitting right where I had left it. I told them I wanted it back and walked out with it. I looked around on the internet and found a 24 volt 70 amp alternator from spider marine for $99. The pulley was $20 more. I had them ship it out. I pulled the old alternator bracket and welded tabs to the angled side of it to match the delco 21si alternator I had purchased. I installed it and wired it up like a 1 wire GM alternator. It works great. I was reading the instruction sheet. It says that the R terminal is 1/2 of rated voltage. Sure enough I put a volt meter on it and got 13.6 volts. The sheet says to not exceed 4 amps draw on this terminal. I wonder if I could use it to charge a small sealed 12 volt battery for light use accessories like my gps? Just a thought. Here are some pictures. Bob the dog was sure it would not fit. He was wrong but it is not his fault, he is just a dog.

 

[jdgreen]

Got a part # or link to the site where u got it?

 

[ODdave]

i like this, nice job

 

[cjtroutt]

look good

 

[cornrichard]

spidermarine.com, delco 21si alternator. I got the one set up for cummins. You have to call the 800 number and ask for the pulley. It is not listed on the website. part no. A8003

 

[tm america]

what welding rod did you use to weld the peices to the bracket?

 

[AceHigh]

Good job! I did the same with my A3, but it was because the alternator tech did not want to mess with the military alternator. He spent a lot of time with me to make sure the new pulley and brackets would fit, still it took some grinding and fitting. Mine does not have the 12 volt post, that looks like a nice feature.

 

[cornrichard]

The bracket is steel so I just mig welded it. I had to cut a tack weld apart and move a bracket. The welds were holding real good.

 

[trukhead]

spider marine

100 NEW Delco 24 Volt 70 Amp Alternator: Alternators &amp Alternator

I cut and pasted above link into google and clicked on it to take me to spider marine

I went to this place to look for a pulley

alternator pulleys, pulleys for alternators

found this part number on page 3
241751


gave it to spider marine and they had one for $14 and they installed it on the alternator befor they shipped .

It is a smaller diameter than the A3 set up but I will find out when I install it on my m35A3

I'll try to supply pictures

 

[davidkroberts]

So the "R" terminal can be wired to a small lawnmower (smaller) type battery for an accessory plug maybe? Thats neat worth doing the changeover IMHO.

Thanks for the link.....

 

[cornrichard]

I am at a week in on my new alternator. It is still working great. Does anyone have any idea how the 12 volt terminal on this alternator works? I am guessing it is just a resister but I hoped some of our more electronics knowledgeable members might have a better idea. I really want to hook up a small 12 battery to this but I don't want to smoke my new alternator.

 

[trukhead]

12 volt

I have no idea of how the 12 volt terminal on the alternator works but I would not hook a battery directly up to it as I am guessing it is not a regulated terminal. I would get one of those trailer battery emergency brake chargers and hook it up to the terminal and then use it to charge the battery. call spider marine, they seem to be helpful.

 

[Terexts]

I'm looking forward to this upgraded. I just order mine from spider marine. Alternator with pulley was just $134 shipped. Hope to have it installed sometime next week. This snow has made a mess down here, so I doubt I'll recieve it this week.

 

[Bill W]

Cornrichard
Do you have the part # for the pulley

 

[cornrichard]

The sku# on my inv. was 113377. MFG SPI. They do not have a part # listed and it is not on their website. They are very phone order friendly. I called they 800 number on the website and they had everything located in 5 minutes. The alternator part # is A8003

 

[panshark]

anybody able to verify if the 12v is regulated or not?

 

[gimpyrobb]

I am at a week in on my new alternator. It is still working great. Does anyone have any idea how the 12 volt terminal on this alternator works? I am guessing it is just a resister but I hoped some of our more electronics knowledgeable members might have a better idea. I really want to hook up a small 12 battery to this but I don't want to smoke my new alternator.

Hook it to a battery and put a 4amp fuse in line. If it pulls more than that, it will blow and save any damage. My .02 anyhoo.

 

[fuzzytoaster]

Just called spider marine co, they said it doesnt support 12v in anyway and if it is producing 12v something is very wrong.

 

[panshark]

thanks fuzzy for getting that straightened out

 

[hoop]

The chinese version of the "21si style" should only put out 1 amp on the 12 volt side.
So do what Gimp said....just put a smaller amp fuse in there.
Should be good for cell phone charger...
Spider is wrong......
IMHO
I have the chinese "27si style" and it puts out 12 volts on the little terminal.
I would not go with the 4 amps that DELCO can and will do.

And FWI for those who do use these chinese alternators....open them up and make sure all the nuts are tight......