Using a common automotive alternator with external regulation

[Reefmagnet]

Hi all. Im looking for a common automotive alternator to replace the existing stock 50 amp internal regulated model on my motor. Reason being I'm a cheapskate, habe agm's and have had the unfortunate experience of being stuck in the middle of nowhere with a failed alternator and no chance of a nearby sourced spare. As we intend being in the middle of nowhere quite often in the not to distant future, I'm keen on a roll your own solution that can use readily available spares at budget pricing.

Output between 70 and 120 amps is acceptable. I'd like to retain the existing single vee belt power transmission, but can add a second vee belt if applicable for larger output unit. The alternator mount is the Hitachi type and, as I'm in Australia, likely candidates, i think, are most probably units from Japanese four wheel drive vehicles. The more common, the better and no issue changing the pulley or adding an external regulator as long as it's doable.

Any suggestions welcome!

Sent from my SM-G900I using Cruisers Sailing Forum mobile app

[Island Time O25]

I had an old (1990s) external regulated Powerline (Motorola based I think) but they're out of business and Motorola's version was about $700. So I was advised by my marine pro buddy who is a maintenance manager for a large sailing club to order the cheap 110amps internally regulated Chinese knock off from ebay for $70 which they buy at his club. So far going on the 3rd season without issues. But then again I don't run the engine for charging batteries that often since I installed 420W of solars.

Don't know though what it'll cost you for delivery down under but in US the delivery was included. And I figured that even if I have to replace it every few seasons I'd still be ahead compared to spending $700 to begin with.

[svadagio]

I have 2 2800JB LN alt. Both were bought internal reg. The local alt rebuilder simply opened them up and added a wire inside. That is all that is needed. He said any alt can be changed. Try going to a place that rebuilds alt for cars. I assume you have that down under.
Bob

[Reefmagnet]

I like the idea of a knock off. We have solar and a genset with Stirling 50 amp charger. So engine alt is for motoring snd perhaps rapid charging as tequired. Interesting they can be easily modified. Of course, any modification should be doable onboard with basic tools.

Sent from my SM-G900I using Cruisers Sailing Forum mobile app

[UNCIVILIZED]

Most automotive alternators, for cars, aren't designed to produce anywhere near their "rated" output, for significant periods of time. Particularly as the (electrical) power use profile of a car doesn't demand it.

You're probably better looking at vehicles which have a consistently higher electrical draw. Such as various types of trucks & commercial vehicles. Though as to recommendations, sadly, I'm a little out of my depth regarding specifics.
Perhaps vehicles which have to provide power for refrigeration uints?

[wsmurdoch]

I have been using a Chinese knock off of a Delco CS-130 alternator with its field + wire brought out for about 8 years without a failure. It charges three group 31 and one group 24 battery every morning over the course of an hour while my engine drive refrigerator freezes its holding plate. I bought two of them new from Starters, Alternators and more for Cars, Trucks, Tractors and ATVs for about $75 each and did the modification myself. It involved some heavy soldering and a little titchy work because they were not really made to be taken apart. One is still an unused spare and the other has never failed. For the last 8 years we have spent around 150 days each year on the boat primarily in the Bahamas and almost never with shore power.

Irish Eyes to the Bahamas

As part of the refrigeration compressor installation, my Yanmar 3HM35F engine was modified to use a one bolt alternator, so this is not too useful to you, but my alternator is like one on a 1988 Chevy Caprice 5.0l engine, has a 1V 67mm pulley, and is Lester numbers 7808 or 7888. It is rated at 105A and is controlled by an external Xantrex regulator with temperature sensors both on the alternator and on one of the batteries. The internal regulator is still present, I carry the plug that fits the alternator, and I could use it if the Xantrex regulator failed.

When running at a low engine speed, in warm weather, and delivering over about 75A, the alternator will overheat and the external regulator will drop to about 50A output until the alternator cools. It then jumps back up. In cooler weather and with a cruising engine speed, it will not overheat. The alternator puts a pretty good load on a single 1/2" belt, and I have dusting and have had occasional belt failures.

The alternator does develop 105A gross output, but the engine controls, the regulator, and a few other things on the boat use about 10A all together leaving a bit less to go to the batteries. In a typical daily hour run with the batteries at 12.3V, the initial charge rate is 85A into the batteries falling to 15A over the hour. The alternator has the battery voltage up to 14.6V in about 15 minutes where it stays for the rest of the hour.

My bet is that the CS-130 is one of the most common alternators and I could pick one up at any auto supply store or junk yard.

[jimbunyard]

My vote is for a Delco 10SI or 12SI alternator. Have been using them for 30+ years, they're robust, simple and can be rebuilt with no soldering on your kitchen table in about 30 minutes with 2 nut drivers and, if you need to replace the front bearing, an allen key and a 15/16" wrench. Plus a fairly complete rebuild kit with bearings can be had for less that 20.00...

[Wanderlust]

As Uncivilised said, most car alternators are not designed for the continued high power generation required to charge a house bank, and that would apply more so for AGM batteries.

When I bought my previous boat it had a standard Bosch 80 amp alternator out of an early Commodore (different mount to yours). It produced close to its rated power for just a few minutes, but quickly ramped down to about 30 amps, so not much use for a large house bank. So I had it converted to external regulation. That was still not ideal because it got too hot, so I needed to adjust its output down. I still cooked a couple of alternators, but at around $30 each from a wrecker it was viable.

As I was mostly only using the boat on weekends, I just left the solar panels to finish the job during the week. One of my projects had been to cool the alternator by routing a bilge blower to it, but sold the boat before getting around to it.

So from my experience, if you are going the ex automative path, I would look for one that has a reasonable frame size, and give it some forced ventilation. With the regulator, get an alternator temperature sensor.

[four winds]

I believe you have the dual foot mount Hitachi, correct? It's either 3.15in. Or 3 1/4 inch depending on who's doing the measuring. Either work fine in my experience.

Anyway the Chinese knockoff 80 amp version was my backup alternator while using a rebuilt factory 80 amper. The rebuilt ate it's bearings within one year and the knockoff has worked fine for several years. Until a couple of weeks ago it became intermittant.

Turned out the brushes were worn past the limits, so I installed the used brushes from the old alt and it's back in service.

The knockoffs can work fine, but others report inconsistent quality. There are a couple of different manufacturers. Mine has AH in the part number and identifies the maker.

My knockoff starter is the same maker and has worked fine for years, I start my engine daily. Both are in the 80-100 dollar US range. EBay and Amazon both sell them.


Here's an alternative from API. A modified Delco that will fit your mount. 94 amp and probably a better alt than the Hitachi. Though $200.

Yanmar, Perkins & Many Small Diesel Auxillary Engs. 12V 94-Amp with a 3-1/4" Saddle Mount | API Marine Inc

[wayne.b]

Originally Posted by Reefmagnet

Hi all. Im looking for a common automotive alternator to replace the existing stock 50 amp internal regulated model on my motor. Reason being I'm a cheapskate, habe agm's and have had the unfortunate experience of being stuck in the middle of nowhere with a failed alternator and no chance of a nearby sourced spare. As we intend being in the middle of nowhere quite often in the not to distant future, I'm keen on a roll your own solution that can use readily available spares at budget pricing.

Output between 70 and 120 amps is acceptable. I'd like to retain the existing single vee belt power transmission, but can add a second vee belt if applicable for larger output unit. The alternator mount is the Hitachi type and, as I'm in Australia, likely candidates, i think, are most probably units from Japanese four wheel drive vehicles. The more common, the better and no issue changing the pulley or adding an external regulator as long as it's doable.

Any suggestions welcome!

Sent from my SM-G900I using Cruisers Sailing Forum mobile app

===

The Delco CS-144 is a very good choice - rugged, lots of power, easy installation and relatively inexpensive. It can be modified for external regulation. I've had one on my starboard engine for over 3,000 hours of operation with no issues other than belt wear and replacement.

https://alternatorparts.com/cs144-se...lternator.html

[jeepdoesrubicon]

I use a 160 Amp dual winding truck alternator. Have had only one fail in nearly 15 years of service. It does need a serpentine belt and I carry two spares. I have a fall back single winding 80 amp unit but have never had to use it. The truck unit costs about $600 USD but easy to get at truck stops.
P

[sailm8]

You might find this informative.
Automotive Alternators vs. Deep Cycle Batteries Photo Gallery by Compass Marine How To at pbase.com

[lorenzoj]

I am using Delco Remy 12SI alternators with a Balmar ARS-3 external regulator. The alternator output is 100 amp and the alternator will provide full output at 900 engine RPM.
The Delco 12SI is a very popular alternator, available almost worldwide. It costs less than $100 and parts are readily available. This alternator has been in use for many years, and is bulletproof. It will run on 1 drive belt, but 2 would be better. 100 amps is close to the limit for a single belt.
I have a twin engine powerboat. One Balmar external regulator controls both alternators. A fuel pressure switch disconnects the Balmar regulator from the alternator when the fuel pressure is low (engine not running). A Yandina 100 amp battery combiner parallels the two banks when voltage on EITHER bank reaches 13.3 volts, and disconnects the parallel connection if BOTH batteries fall below 13.2 volts. This allows automatic charging of the house bank aftter the start battery is more than 80% charged (13.3 volts) and prevents accidental discharging of the start battery. All automatic operation with no switch turning needed.
This arrangement has worked without problems for the past 15 years. Every 600 engine hours, I remove the alternators for internal cleaning and brush replacement.
The 12SI is a single wire self regulated alternator, but can be converted to external excitation by replacing the regulator with an adaptor. The external regulator provides full 4 stage charging, soft start, battery temperature monitoring, etc. In an emergency, the alternator can easily be converted back to self regulated.

[fdr14127]

Yo;
Here is what you should research....
https://en.wikipedia.org/wiki/Leece-Neville

These folks are quite common (on eBay for instance) and they can be found in the junkyard where old police cruisers go to die. Given the load the police place on the vehicle with all the lighting and communications requirements, the officer's ride will often come equipped from the factory with this upgrade so I would assume the local dealer may have a part number to support your cause. These Prestolite units are also used in the trucking industry.

I know Leece/Neville catalogs spark suppressors for many of their models as they are OEM suppliers to the Marine industry. They are required by the Coast Guard in the USA, and I would think for a reason. Therefore whatever you do, I would investigate the availability of these additional parts and retrofit them before leaving the dock. Just sayin............

Drove by the factory in Arcade yesterday on my way to Pancakes and Maple Syrup. Must be spring and boatyard weather......

[Nanamuk]

I see you have a smaller boat so your engine compartment probably gets up close to the temperature of your thermostat after many hours of running - at least way hotter than would be seen in any car. From my experience any automotive alternator, even the marineized Powerline 100amp, based on a Delco body has a nearly solid back plate and will not allow enough of the hot air to flow through the alternator and you will melt the grease out of it and burn up the stater windings. After going through far too many alternators and rebuilding the Powerline 3 times I bought 3 Bosch 85 amp alternators in Darwin - wanted spares that could be swapped with no need to change belts or mount arms - they have a very open body, you can buy an easily installed clip to change to external regulation and are inexpensive at an automotive parts store. That was in 1999 and the 1st one is still working after the completion of our trip back home to B.C. Canada.