If it's the one that came with the alternator then it's just a "dumb" automotive type regulator. It will just put in whatever the batteries will accept. As I understand, and no doubt I will be corrected if incorrect, the big issues are:

1./these regs do not float the batteries at a proper voltage of 13.2 to 13.6 volts when they are finally charged, instead it will keep them at around 15 volts. This causes gassing, sulphation and excess water usage.

b./they do OK in bulk phase charging but don't properly handle the absorption phase.

Basically they don't know how to properly charge and maintain deep cycle batteries.

With 484 amps in your bank and a 50 amp alternator, if that's your only source of charging it will be a slow haul depending on what your consumption per day is.

[QUOTE=kenstrom;8869]I am upgrading my battery system to four 6v Interstate 2300S 242 Amp Hr batteries 2 in series and then paralleled to provide a single house bank with 12v 484 Amp Hrs. I'm following the Emerg Starting Batty Project notes by Bruce Lansberg in the Upgrades section. I've studied and read about also possibly upgrading to a differnt regulator and/or a larger alternator, as the OEM alterantor is only 50 amps. I'm trying to determine exactly what kind of regulator the OEM has. I understand the need to charge the batteries at a higher amperage rate when the battery (SOC) State Of Charge is low and the danger of charging at too high a rate when the SOC is high. Can anyone tell me what kind of internal regulator my OEM alternator equipment has? Is it constant voltage, constant current, a multi-step regulator or what? I'm trying to determine my alternator charging capability, typical re-charge time and if there is an advantage to replacing the OEM regulator while keeping the OEM 51 amp alternator . I understand that if I upgrade to say a 90 amp alternator, that I should then purchase an external multi-step regulator. I've searched the c36ia forum, M35 engine owners manual, and internet, looking for spec info on my OEM regulator, but cannot find anything.
Thanks for any help here.[/QUOTE]

To gain a better understanding of your regulator and smart ones please feel free to read this:
[B][URL="http://forums.sbo.sailboatowners.com/showthread.php?t=125392"]
Musings On External Regulation (LINK)[/URL][/B]

Ken,
New or old, a "dumb" regulator is not adjustable. Your alternator will put out 40-50A for a short time into deeply discharged batteries, and then drop down to 30ish amps, then down to 20ish amps. It will take you a LONG time to recharge your batteries at that rate. I've read that it's possible to convert the OEM alternator to be externally regulated, but haven't done it myself. Besides MaineSail's excellent article (link above), here's another source of info that you should read:
[URL]http://amplepower.com/primer/index.html[/URL]
Hope this helps.

Ken,
The North Channel is one of the nicest cruising grounds anywhere, but you should be anchoring away from shore power for multiple day stretches. We changed over to the four 6v battery plan and also changed over to the Leece Neville 90 amp alternator. The case is the same as your stock alternator and it is a real easy change out. Initially I just used the stock regulator but then went to an external regulator. Can't say I noticed much difference in charging times between the regulators, but the difference between the stock 51 amp and the 90 amp was huge. 1 to 1.5 hours of engine time covers a typical days use of electricity. Much better than spending half a day listening to the engine when you could be hiking in the Benjamins! For what it's worth, I didn't buy into the extra starting battery and instead bought one of the emergency starters.

Ken,

Last year I changed over to the 4 X 6V for the house batteries and 2 X 12V for my starting batteries. Both batteries are connected to the alternator via a battery isolator which monitors the voltage in both banks and accordingly doles out what each bank needs without either taking from each other. I mostly day sail so I use one bank one day for the engine and the next day out use the other bank giving both an equal amount of usage (As suggested by the owner of the American Battery Store I purchased the batteries from). Up until a couple of weeks ago I had the original 55 amp 13.6v Motorola alternator.

Two weeks ago I installed a 90 amp Leece-Nevile alternator using the dumb regulator. I also updated/upgraded my wires to 2 gauge from the alternator to the - ground engine block and to the + battery isolator. I also upgraded the wires from the battery isolator to the + battery posts on each bank with 2 gauge wire.

I have a BEP digital meter that measures the two battery banks for volts, amps and amp hours. Prior to the upgrade the BEP meter measured a slight amp charge and in most cases a discharge with a 13.6 volt reading when I was motoring out to the bay using either bank. It should be noted I have a Raymarine Chartplotter with several added ST60 monitors and radar. After the upgrade to the Leece-Neville 90 amp/14.4 volt alternator I noticed a positive amp charge offsetting the electronics and a steady 14.4 volts on my BEP meter when the engine is running.

Additionally last year I had to replace the motor on my windlass (years of salt water took its toll and the motor rusted through). Prior to the upgrade the windlass was struggling to pull up the anchor. After the upgrade the motor pulled the anchor without any labor... I even noticed the engine making a funny sound I had never heard. I increased the RPM which smoothed out the noise. I took a look at the BEP meter and noted the BEP amp meter showing the alternator pumping out a whole lot of amps to offset what I had just used to pull up the anchor a couple of times.

All in all the upgraded Leece-Neville 90 amp alternator along with the 2 gauge wire was definitely worth the effort.

At this time I am going to stick with the dumb regulator. After talking with the tech at Gen Star in Oakland and especially after reading the article from Practical Sailor I seen no need at this time to pay the $200 + for something I don't think I need. At this time the dumb regulator is doing it's job. Too many times I have opted to upgrade to something that costs a lot of money taking me a long time to install for a minimal amount of improvement.

Chris

I also upgraded to four 6v batteries plus a dedicated start batt, last winter.
I installed a Balmar alternator and external regulator (alt.=712-80; reg.=ARS-5-H). Their alternator will fit perfectly, is 80 amps and combined with their regulator seems to work well. The reg. is adjustable in many functions including max output. This is apparently important in that the small pully and belt will not support even 80 amps of output and thus the reg. needs tp br adjustable in order to de-rate the out put. This is easily done on the reg during initial programming.
If their product is interesting to you in any way, then I suggest you call their product support and discuss your needs. I think I recieved patient and knowledgable advice.
In any event it is an option worth looking at before upgrading.

New wet cells?

[url]http://c34.org/bbs/index.php/topic,6353.0.html[/url]

The one downside of internal regulators is that you can't do a Small Engine Mode with them: [url]http://c34.org/bbs/index.php/topic,4669.0.html[/url]

Ken,
I purchased the new alternator from a nearby alternator shop about 5 years back. Turned out the owner has a C36 and had this alternator on his boat. He said he thought external regulation was a waste of money, so I initially installed it out of the box. This was an easy change over except for the time studying wiring charts to get the tach working. I had them install a machined pulley. The next year I decided to go ahead and add the external regulator (Balmar ARS 4). I ordered the external regulator plate from the same shop. It is the same shape as the stock regulator, but with two terminals on the back. The stock regulator fit just fine, but the terminal posts on the external plate just hit the engine. My solution was to leave it off and just plug the connectors from the wiring harness directly to the internal terminals on the alternator. I would not do this with a gasoline engine (explsive vapors). We extended the wiring harness a couple of feet and mounted the Balmar behind the long cabinet door undert he sink. I don't have any record of the part number for the alternator, but we are heading out for a couple of weeks of cruising this Friday. If you send me your email I can forward the part number and some pictures when we are up at the boat. I put the same setup on my Catalina 34 except back then it was still a Motorola alternator and in both cases it has worked just fine. This is a great upgrade if you are going to rely on the engine to charge your batteries.

[QUOTE=kenstrom;8879]Mike -- It probably is worth getting the higher amp alternator now and tie it in with the rest of my battery upgarde. Do you have the M-35B engine if so, what was the part number / model of the alternator you used that was a direct fit replacement? Did you have to go to a new belt?
Thanks for all the information links and input here guys.
Ken[/QUOTE]

Ken: Did you every go ahead with the alternator upgrade? We have very similar setup and not far away. I've got 2004 TM w/ wing keel, keeping it in Milwaukee. Also planning on North Channel this year. Planning on bow thruster installation this spring which seems like something you had considered in the past also.