Modifying Delco-Remy Alternator for Manual Field control

[WillieC]

I have a 10SI alternator among the piles of junk I have accumulated for refreshing my Volvo Penta engine and lo, here is a 10SI alternator! Since I can spend a thou on installing a $50 fuel tank access panel (look up the word "hyperbole") I can blow some cash playing with this alternator. Like maybe $950.

I understand the principle of controlling the field voltage with a rheostat so as to control the output voltage and thereby actually charge one's marine use deep cycle batteries. I downloaded a copy of Volt Doctor's Handbook, a veritable encyclopedia right there, but I would like to see exactly how it is done. Specifically, how the internal regulator wiring is interrupted or attached to in order to wire in a cobbled together, farmer regulator. (No offense to real farmers.)

My 10SI is a 70 A unit, a bit of a rarity as I read, only one source acknowledges its existence in the pantheon of alternators despite the "70A" stamp right on it. This alternator needs new bearings, though they would work for my fooling around phase. I know there are issues with these alts, specifically about cooling, especially if one overrides the internal regulator which might require monitoring with temp sensors and ammeter. I ditched the original 30A ammeter when I installed the 60A alternator during my wiring upgrade a couple years back. The electrical system on the boat is almost all original in terms of loads and we use the boat mainly as a daytripper, but leave it on the mooring ball in the summer with no shore power. I hope to do more serious traveling this summer when we get the new(er) engine installed, if it ever quits raining here.

The point is, for our uses, I can most likely stay with my antiquated system. We pull the boat at least once a month at which time I throw on the Sears automotive battery charger, yet another violation of all things boaty-electrical, and we have never had trouble starting the engine. For serious voyages, this system is lacking, though the Swedes seemed to have no problem with it back in the day.

I know I need to spend $600 on a Balmar and another $300 for a regulator and $300 for a system monitor, heck lets throw in a serpentine belt mod for a grand and THEN we can upgrade to AGMs, don't forget solar, which will prolly be the smartest thing i can do given our circumstances.

BUT, before all you geezers out there leave this sod, young A28 skippers excluded, surely one of you can dig back in your memory banks and pass on your wisdom of how this was done back in the good old days.

I know this is a long shot and nobody actually risks burning their babies to the waterline by actually cutting and soldering wires God never intended anybody to even see, so let's just treat this as a history lesson. Anyone, anyone, Buehler?

[Beta Don]

If the Delco series fits your engine, the 10DN alternator is the externally regulated version, used on cars from 1961 to 1972 when they went to the 10SI with the internal regulator. You can but a brand spanking new 10DN 63 amp alternator for $75 with free shipping on eBay and an 80 amp for $100. Why mess around rebuilding an old one when they're that cheap??

http://www.ebay.com/itm/NEW-ALTERNATOR-FOR-AMC-BUICK-CADILLAC-CHEVROLET-GM-AND-MORE-1962-1971-10DN-/361185452875?hash=item541854a34b:g:NAEAAOSwLnBX4veI&vxp=mtr

Here's your regulator - http://www.ebay.com/itm/Marine-Advanced-Alternator-regulator-with-upgraded-software-90201-/200923664443?hash=item2ec7fbd03b:g:WVAAAOxyVLNS5mAc&vxp=mtr

If you want to stick with a 10SI with it's internal regulator and 'piggy-back' an external regulator on it, here's one designed for that - http://www.ebay.com/itm/Sterling-ProReg-BW-Advanced-Alternator-Regulator-100-Amp/171771756153?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D20131003132420%26meid%3D5d064a96cd104b0fb4be3a141b6ec01b%26pid%3D100005%26rk%3D2%26rkt%3D4%26sd%3D200923664443

You really don't have to spend big bucks to have an effective charging system - Old style alternators are CHEAP!

Don

[WillieC]

Thank you, again, Don. I thought of the older style external regged units but didn't quite put two and two together. And that is an excellent price for the regulator. I like the simplicity of it all. Back when I rehabbed my electrical, I didn't have a clue what would fit the Volvo Penta. It turns out the large frame 10SI I have, about an inch larger in diameter easily fits the brackets and tensioner, with slight modification.

Your answer was exactly what I have been pondering. I could spend a lot on bells and whistles and end up with expensive bells and whistles, or do as you suggest and cut more holes in my fuel tank. Ha! Thanks!

[Beta Don]

IMO, the older, externally regulated alternators were all 'overbuilt' and will put up with lots of abuse - You can really push them with aftermarket regulators and almost never burn them up. For diesels which use the single foot mount, the Delco 10DN is a great choice - Rebuilders can push that frame up over 100 amps by replacing the internals, but a stock 63 or 65 amp one will reliably give you 50 amps for many hours, and you seldom need more than 50 amps on most powerboats

If your diesel uses the two foot mounting style, the same can be said for the old Hitachi externally regulated alternators found on many '71 thru '77 Japanese cars. I ran one of those at a steady 50 amps for many hours, recharging the 800 AH battery bank (four L-16's) on my sailboat using a 'smart' regulator. Rebuilt units were only $30 or $35 from Autozone, so I always carried a spare

The secret is using high quality belts, making sure the belt alignment is correct, checking the tension and readjusting it regularly and using a smart regulator. I found that paying a little more for a 'wrapped' belt really extended belt life. Wrapped belts are just a tad wider than regular belts. What kills belts is when they drop low enough in the pulley groove where the belt touches the bottom of the groove. They begin to slip at that point no matter how tight you adjust them and don't last much longer. The slightly wider wrapped belts ride higher in the pulley groove and last lots longer. Keep the belt tight and don't worry about bearing wear - In my experience, heat from a slipping belt will do in the bearings lots faster than a tight belt

Don

[WillieC]

Interesting info on belts, Don. I am currently working on coming up with a mount for an all bronze centrifugal water pump that was used for antifreeze side of HX on the "spare" engine. My original MD3B came with the piggyback style pumps, and I obtained another basketcase piggyback pump with the "montana" MD17C. These pumps are driven off the camshaft. These dual pumps are nearly impossible, at least I have struck out, in finding a replacement shaft. Short of making one, and that is not cheap.

The mount I am having pretty good success with utilizes the starter bolts. A DPO rigged it up using a couple bolts from the exhaust manifold (and cross threading 5/16-18 into the metric threads, thank you very much) and the thermostat bolts. So replacing the thermostat was like tearing the whole thing apart. Anyhow, the pulley on the pump and the double pulley that bolts onto the flywheel have the same belt angle, but are vastly different in width. The belt that came with the whole mishmash setup is what I will start with and, to your point, the belt is almost at the very top of the pump pulley and well off the bottom of the drive pulley. Thanks for your pointer about belt heat.

I wish I had been smarter on the alternator stuff earlier, but hey, I am learning. I really like the simple approach you advocate with the older heavy duty 10DN alternator. For a boat like ours, the way we use it, with a decent Mark Grasser regulator, we will be in hog heaven. I remember Dad ripping the covers off those old regulators, filing the points, bending the spring mount prong, stretching or shortening the spring. All by eye and feel. He didn't need no stinking gauges. Then when I started my electrical apprenticeship, he was really upset. "Good way to get killed!" He was NOT an electrician. But one hell of a machinist.

[sail149]

image.jpeg

Hi WillieC,
Don is way smarter than me on this stuff but you might be interested in this set up that came with my boat.
I can't say much about how it works as I'm still dry land locked.
I did find a manual for it on a sailboat forum .
I also heard using a 110v old type dimmer does almost the same job....
Cheers Warren

[DesertAlbin736]

Warren,

Hey, one of those AutoMAC units came with my boat too, although the face plate on mine looks a little different. I removed it when I re-did my electrical system & replaced it with the Mark Grasser DC Solutions Smart-Charge-One external voltage regulator due to switching from FLA batteries to AGM's.

Rick,
If you're interested in the AutoMAC unit, original instruction pamphlet included, for any reason, you can have mine free of charge (no pun intended).

The thing seemed mysterious to me so I never messed with it or turned it on. But I found this description of how they work posted on a sailboat owners forum

"The trick with the Automac is to use it manually just like the three stage chargers do automatically. Start with the rheostat turned down and the switch off. When your engine starts, the alternator is going to want to put out as much as it can because it sees the batteries need to be charged (unless you’ve just disconnected your shore power and the batteries are fully topped off.) Don’t turn the Automac on just yet; you don’t want to immediately load your alternator. In fact, the amperage output may be pretty high to begin with, all by itself. Wait until the amperage goes down a bit after you start the engine.
After the initial startup, say about five minutes, and only after you’re running the boat at cruising speed, start the Automac. The reason you want to wait until you’re motoring at cruising speed is simply to avoid having to constantly change the Automac settings, which change at different engine, and therefore, alternator RPMs.) Turn the switch on with the rheostat still turned all the way down. What you (personally – so much for “Auto…”) need to do is balance the voltage and the amperage. The volts should be on your electrical panel, or have a voltmeter connected to the batteries. Slowly turn the rheostat up until you get to 14.0 to 14.2 volts on the voltmeter. As you are doing this, both the voltage and amperage will be rising. Watch the amperage rise. Do the voltage adjustment first and watch the amps rise in this order for this reason: the Automac will automatically shut off if you exceed the preset (but adjustable) voltage setting. The adjustment on the Automac is most likely set for 14.2 or 14.4 volts. [The manual includes instructions as to how to adjust it. Don’t bother with this yet, and you may likely never have to.] So, the trick is to set the Automac based on voltage, with the resultant rise in amperage. Don’t set the amperage first, because the voltage rise may cut it out automatically.
So let’s say your batteries need to be charged. Run the Automac to maximize the charge amperage starting with the 14 point something voltage. You will see that the Automac raises the amperage once you reach that voltage. To see the effects, turn the AutoMac on and set it, then turn the switch off. You’ll see the amps drop and the voltage, too. Then switch it back on! What it is doing is “fooling” the alternator’s output signal and increasing the amperage. The trick to charging batteries is balance BOTH the voltage and amperage.
As the batteries get charged while you are motoring, the voltage will continue to rise because of the “inflated” amperage you are giving them thru the Automac. You’ll need to keep checking and slowly turn down the rheostat to keep the voltage near 14. This will reduce the amperage, too. Do it or else the Automac will turn itself off as the voltage rises above the preset 14.something volts. That’s why the three stage chargers are better because you don’t have to continually manage the charge.
Once you’re fully charged, don’t forget to turn the Automac switch off. It draws 2 amps whether the engine is on or off. Doesn’t matter what position the rheostat is in, but I got in the habit of turning it counterclockwise and off as a matter of habit. "

Just reading through this enlightening description, it seems that the AutoMAC (somewhat of an an oxymoron, maybe it should have been named "ManualMAC") is somewhat obsolete compared to other automatic digital "Smart charge" external regulators now on the market.

[WillieC]

DA, your comment on the "enlightening description" sounds like you're describing me!

"(oxy)moron...somewhat obsolete to (what's) now on the market".

That said, I'll take it! Big electrical upgrades will wait for now, but this could be a huge part of my education. Besides it seems easier than rebuilding an MD17C, and more onerous, all that goes with that project.