Alternator advice

[questionmark]

Hello all,

On our way back from the Channel Islands on Friday our alternator decided life was no longer worth living. I pulled it off to replace and now find myself in a quandary. Any and all opinions are welcomed.

The alternator is a modified Delco 12SI-94. A previous owner way back had the electrical redone, and the electrician cracked the case, removed the internal voltage regulator, and machined in terminal studs for external regulation and the tachometer. The external regulator is an older Heart Ideal.

Our plans are to spend this next season cruising the Sea of Cortez for six months. So whatever I end up with I’ll grab a spare. So my choices seem to be:

Rip it all out and throw in a Ballmar alt and regulator. They make one that will fit the bracket. But, if I do end up a spare it’s going to cost at least $1500 to go this route, maybe even $2k. That’s a lot of cheddar. Almost the cost of the new arch I’d rather get.

Pay an auto electric shop to rebuild what I have. And have them make the same modifications to a new unit. I’ll put the new alternator in place and keep the old as a spare. This is the ~$500 option.

Or, what I’m kind of leaning towards, buy a pair of new alternators and modify them myself. This is a fairly common mod and there’s multiple sets of instructions and videos online showing the process. I can buy the pair of alternators for $130 and I have all the bits to mod them laying around (except for a trio of insulated spacers which I’d have to find/fab but that’s like $1.) If I go this route I plan to lead the wires out rather than machine insulated studs through the case.

I have the time and the shop/tools to do the work, as I can do it after hours at my place of employment. If I have to spend money on the charging system I’d rather dump it into solar. I plan to run the engine an hour or so every other day just for hot water, so whatever I decide will get use.

Thoughts?

Josh

 

[DavidM]

Your 12si alternator probably failed because you increased its load with an external regulator and it couldnt handle it. So dont rebuild it. Start with a 22si alternator and modify it yourself.

David

 

[kchace]

I like David's idea and also I'd talk to the guys at the auto electric shop. Chances are they can give you good advice about what can be done and how well it's likely to work.

Ken

 

[questionmark]

Your 12si alternator probably failed because you increased its load with an external regulator and it couldnt handle it. So dont rebuild it. Start with a 22si alternator and modify it yourself.

David

Thanks. This setup has run for at least twenty years before I showed up, and I didn’t adjust it in any way. Oddly enough I was surprised to find the 94amp rated version, as the most I’ve ever seen in bulk mode was 50 amps, so I’m guessing they had the field turned down because it’s a single pulley set-up. I think it just got tired and the bearings cried Uncle.

While I’d love to mount a bigger alternator, I don’t think I’m ready to swap out all my pulleys so I can dual belt it. The engine is an Isuzu 6BD1, so the alternator runs on a belt with the the alternator and an idler pulley where the radiator fan would be in an industrial/automotive install. The belt is inboard of the belt that drives the raw water pump. I’d have to modify the raw water pump mounting as well if I added a second belt for the alternator. I just pulled the raw water pump off also (since I had the access) and I’m going to swap it out and rebuild the old one for a spare.

Josh

 

[kchace]

Thanks. This setup has run for at least twenty years before I showed up, and I didn’t adjust it in any way. Oddly enough I was surprised to find the 94amp rated version, as the most I’ve ever seen in bulk mode was 50 amps, so I’m guessing they had the field turned down because it’s a single pulley set-up. I think it just got tired and the bearings cried Uncle.

While I’d love to mount a bigger alternator, I don’t think I’m ready to swap out all my pulleys so I can dual belt it. The engine is an Isuzu 6BD1, so the alternator runs on a belt with the the alternator and an idler pulley where the radiator fan would be in an industrial/automotive install. The belt is inboard of the belt that drives the raw water pump. I’d have to modify the raw water pump mounting as well if I added a second belt for the alternator. I just pulled the raw water pump off also (since I had the access) and I’m going to swap it out and rebuild the old one for a spare.

Josh

Actually about 1/2 rated output for any period of time is about what a light duty alternator can do. So if you were happy with the way it worked before, a rebuild could be just fine.

Ken

 

[Xsbank]

I'd do it myself; if you have the time, go for it.

 

[FF]

Visit a large truck parts house.


A new Leece Neville , now under another brand name should cost about $135.00 for a large frame unit of about 130 amps.
It will already be wired for an external regulator , use your favorite.


The PIA of reworking the alt mounts will be made up by probably never having alt problems again.They can handle high output on a cont. basis.



The drive pulley and cooling fan will be a bit extra , be sure to get the fan for the direction you will spin it.

 

[Maerin]

There are less costly alternatives to the Balmar solution. The plan should start with an accurate assessment of the load requirements. Any alternator that's externally regulated and charging a bank vs. a start battery is going to be operating well beyond the parameters of its OEM design, so start with an alternator that's capable of operating under the conditions your system requires. Add to that the rest of the SYSTEM parameters, and you'll come up with a solution that will be less subject to cascading problems/failures. An external regulator like the Balmar 614 provides temperature protection for the alternator as well as custom programming that can be tailored to your system. Zena alternators offer a marine configuration built for continuous duty. Other options are available, but whatever option you choose should be one that is built for continuous duty rather than OEM use that is essentially designed to replace mimimal starting current loads. Either way, look beyond the alternator alone and consider the entire system for the most trouble-free solution.

 

[sunchaser]

Josh
My dos centavos worth-

Have you looked at solar water heaters. For smaller needs they work great in the Baja winters.

As previously mentioned, keep your alternator choices simple and maintain your current pulley and alternator frame size. BTW, Prestolite makes very good alternators. Cost effective and found everywhere. They own Leece Neville.

 

[Tator]

One option to dual pulleys is to run a 5/8 belt and pulley. I've been doing that for 12 years on each of my 150 amp Zena alts still w/the original belts after 3k hours. I usually run them at 120-125 amps.

Tator

 

[CMS]

Hello all,

On our way back from the Channel Islands on Friday our alternator decided life was no longer worth living. I pulled it off to replace and now find myself in a quandary. Any and all opinions are welcomed.

The alternator is a modified Delco 12SI-94. A previous owner way back had the electrical redone, and the electrician cracked the case, removed the internal voltage regulator, and machined in terminal studs for external regulation and the tachometer. The external regulator is an older Heart Ideal.

MarineHowTo.com offers a number of externally regulated "affordable" alternators. A 2" foot Delco can easily be built.

A more versatile solution would be the CMI-90-ERM shipped with the 2" fit kit. This is a 1" foot alternator with universal adjuster ear and a 1" to 2" fit kit. It can replace 2" foot Delco units or 1" foot Motorola units.

Something to gnaw on anyway...

 

[sdowney717]

I have two 12SI setup as 1 wire alternators. Only minimal disadvantage, engines need to be sped up for them to turn on. They are 80 amps each.

I put 80 amp fuses on their outputs. I have never seen the ammeters go anywhere near that high, but have seen it get to 60 amps.

12SI are internally regulated and have a battery sense wire for setting voltage remotely to the proper level , some are 1 wire. What is the problem, why do they need to be modded for external regulation?

 

[JDCAVE]

Adding another belt is no big deal. I did it and it cost me about $150 for a shop to machine a fitting for the water pump. My mechanic advised me that I needed another belt and pulley on my alternator as it was too large for a single belt. I’d start with a “shop” that deals in alternators and starter motors and ask them for advice. There’s a place in Richmond BC, called “Brighouse Electric”. Fabulous guys. They knew my mechanic, talked with him to confirm what he wanted and put another pulley on the alternator for $25. Mechanic sent me to his “go to” place for aluminum fabrication. 2 days later and I had my new “fitting” on the water pump. Done. No new mounts or anything. I have an “Amptech” 125 and a Balmar 612 regulator. Adequate for my needs. My mechanic told me to install the alternator myself.

Get some advice from an alternator place where you live. Hopefully you can find a “Brighouse” equivalent.

 

[questionmark]

A quick thank you and update:

I rebuilt the alternator myself after watching a few videos on YouTube. It turned out to be WAY easier than I thought. I ended up using the old case and just swapped out all the internals. When I get back from our next trip I’m going to have a spare built, as I’ve found a local auto electric shop that’s super reasonable.

Thanks everybody!

Josh