Single Wire Alternator Question

I'm sure it's been covered a number of times, but having an issue finding just what I'm looking for using the search function. My 70 CJ has had the engine swapped (PO) with based on block numbers is a 77-78 even fire 231. I would like to move to a single wire alternator as I'm deep into a re-wire. I think Delco S10 or S12 at 63A would be the best choice, but thought I would put it out there to see if there is a preference one over the other?

 

Thanks Fino, this helped a bunch, I hadn't seen the MAD info yet. Based on the fact that I'm running a large electric fan, I'll probably go with a 94A S12. Much appreciate the feedback, now just have to find one online , don't feel like going to my local shop, last time I was in there, no one wearing masks, no social distancing, etc..

 

Avoid connecting any factory ammeter with these high-amp alternators. Send the charging current directly to the battery through a fusible link. Connecting the 3-wire is trivially easy to me, though some still like the 1-wire. Mad Electrical has an article on how to choose a 10SI or 12SI alternator from the parts store. Click here --> Catalog Apparently the largest you can get in a 10SI is 63 amp. The 12SI supports higher amperage and functions the same, but is physically larger. Don't worry about the clocking; you can clock these to any direction you want.

Put in the part number at RockAuto: RockAuto

 

If you are considering going with the 3 wire electrical arrangement as apposed to the single wire, you may want to consider using a Delco CS series alternator. Example: A CS130 alternator (found everywhere) has an output capacity of 105 amps and it will produce 80 amps at engine idle. Neither the 10si nor 12si will do that.

 

Just to add to the above good info... A three wire will give you the advantage of remote sensing in addition to a dash warning light if you want one. As mentioned MAD has a good article on that which may inform how you wire things since you're in the thick of it.

Edit: In the spirit of safety I thought it was worth mentioning that you may want to consult a good AWG chart or two, if you're making your own harnesses. With a high output alternator you need to upgrade your wiring. I have a 140amp unit and run a 2g charge wire. Make sure your circuits are protected and have the appropriate size wire for the current/load. I think it's a good idea to fuse a bit lower than the current rating for a given wire size. Circuit breakers work well for the heavier circuits (eg: a primary wire to a fuse box).

Here's one. I like the Blue Sea stuff. CHART

 

Thanks for the feedback all, looks like I have a bit more to think about. PO had installed a new harness (wasn't painless, but another source). PO had about 60% of the work complete, but as I started tracing stuff (just to make sure), I found a few errors, which made me want to basically start over. Was just planning on single wire to get rid of the regulator and clean up a bit. Thanks again.

 

I have a Marine grade 10SI that is rated at 105amps single wire.

 

OK, I think I might know why I've been a bit baffled. Part no. from existing alternator is 1102480 (which according to Delco site is an obsolete 10SI). If someone would, please confirm that this is internally regulated? PO had it wired to an external regulator. It sounds a bit crunch when I spin it by hand, so will be replacing anyway (will replace with 3 wire based on comments from this thread), so not a huge deal, just wanted someone to confirm. Thanks again

 

It's a 10SI. They are all internally regulated.

This is covered in any '75-on TSM.



Look at the '76, '77 or '79 TSM on the Tom Collins site. Or take it to your local parts store and ask them to test it.

It's either a case of DSPO or it's broken and somehow rigged to work with an external regulator. If broken, just replace it - not economical to repair it these days. Discard the external regulator.

 

Thanks Timgr, at least I can pull out the regulator/wiring associated with it. I'm sure that will help clear things up a bit. Not sure why PO installed with external.

 

NP. DSPO, most likely.

 

The alternator on my 198 was giving me fits. Couldn’t figure out if the problem was the alternator, the regulator, the exciter wire, or the idiot light. Ended up scrapping everything and replacing with a tuffstuff one wire alternator and all has been well since then. https://www.summitracing.com/parts/TFF-7127