Alternator excess charge

[nautibake]

Week before last we went out for a nice 6 hour day-cruise, I noticed the new alternator on the port engine was making 36-37V the entire time. I thought it was supposed to have a high initial charge and then drop off but it stayed up there. I made a note and asked the guys that installed the alternator and they were going to look at it next time they were over (hasn't happened yet).

This morning we needed to pump out so we were headed out again for a picnic cruise and i throttled up after leaving the inlet and the FB helm port engine voltmeter "pegged" at 50V! I throttled back and went down to the PH helm to check the that gauge as well as the separate digital gauge. The readings on the FB were accurate and consistent with the PH gauges. BTW the charger was turned off the entire time. We turned around and idled in. The difference between 900 and 1000 RPMs was an increase from 35 - 40V. If I pushed up any more, the volts would go right on up (once this became obvious I stayed below 1000 RPMS all the way back in).

Is this definitely a regulator problem, or should I start with the new alternator (brand new, under warranty)?

In case it is the regulator, I researched the option of "smart" regulators on this forum and it seems Balmar might be a good option. Most of the postings were a few years old, anything newer or better?

Additional context, I just last month replaced both main battery banks with AGMs and replaced the Charles 9000 with a Newmar 3 phase charger. Also, repaced the 12V bank for the electronics with Mastervolt, and a Mastervolt smart charger. The 12V bank is charged by the starboard engine through a 32>12V converter. I'm concerned about damaging the brand new bank of AGMs by severely overcharging them. Fortunately this morning I was able to catch the high voltage after what I think was only a couple of minutes. It definitely got my attention.

As always, and insights are greatly appreciated.

[MikeP]

I would first check the voltage at the batteries with a multimeter at various RPM to verify that the gauge is giving you valid info. If the multimeter shows the overcharge as well, then I would break/clean/remake all the connections at the alternator; a bad ground can cause overcharging. After that, Obviously the regulator is a prime suspect (whether internal or external). Also, bad batteries can cause overcharging though 50V is mighty high - I've never seen a bad batt cause that much overcharge but I have no experience with AGM batts so I don't know how they might react/affect the charging output.

[scottinsydney]

In boatdiesel.com / Forum DD 71 series last month there is a series of questions and answers between myself and a very knowledgeable Detroit Diesel man called Ron Sparks on this very topic. You may find the answers there.

Cheers, Scott.

[jim rosenthal]

I have Balmar external regulators on both alternators on my engines. At the time, they were the best thing out there, but there are a lot of companies competing for that business now. I would see what's on the market. I would not, however, buy Xantrex. Their customer support is terrible.

If you are going to go to the trouble of installing smart regulators, you should consider a battery monitoring system. Mine is (again) a Xantrex, because at the time, there wasn't much else to choose from. But there are competitors now, and probably something better.

I was under the mistaken impression (when we did the electrical system updates to my boat) that I needed bigger alternators. The company that did them (Yacht Electronics Systems in Annapolis) pointed out that the existing ones were probably big enough, but that smart regulators would make them charge faster and at rates that would keep the batteries up much better. The internal regulators that are fitted into alternators at the factory are evidently not very efficient and can't be adjusted to match the charging profile of different types of batteries. The smart regulators can do this.

My boat is set up with a starting bank that starts both engines. There is a separate battery which starts the generator, and then a house bank which, right now, is two Odyssey AGMs. One engine charges the starting bank, the other charges the house bank. There is also a battery combiner, and a smart charger, which is (again) a Xantrex. When that finally gives up the ghost, I will follow Scott's advice and get a Victron.

Ironically, the Xantrex items on my boat are holding up okay. This is a good thing, because when they don't, their backup of them is such a headache that you just end up buying something else and throwing their item out.

I think Victron also make smart regulators etc but not sure. He has had good luck with them- it would be worth looking to see if they have all the pieces you need.

[nautibake]

I would first check the voltage at the batteries with a multimeter at various RPM to verify that the gauge is giving you valid info. If the multimeter shows the overcharge as well, then I would break/clean/remake all the connections at the alternator; a bad ground can cause overcharging. After that, Obviously the regulator is a prime suspect (whether internal or external). Also, bad batteries can cause overcharging though 50V is mighty high - I've never seen a bad batt cause that much overcharge but I have no experience with AGM batts so I don't know how they might react/affect the charging output.

Thank you Mike - I have a separate digital monitor going to the port battery bank, and it was consistent with gauges at both helms. The alternator is new, as are the batteries and all of the cables. It may still be that there is a connection issue, so sounds like a good idea to double check those (in case something is mis-wired too I suppose).

[nautibake]

In boatdiesel.com / Forum DD 71 series last month there is a series of questions and answers between myself and a very knowledgeable Detroit Diesel man called Ron Sparks on this very topic. You may find the answers there.

Cheers, Scott.

Thanks Scott - I will search for that thread. I spent quite a bit of time over the weekend looking for cranking amps required to turn an 8V71 but didn't have any luck.

[nautibake]

I have Balmar external regulators on both alternators on my engines. At the time, they were the best thing out there, but there are a lot of companies competing for that business now. I would see what's on the market. I would not, however, buy Xantrex. Their customer support is terrible.

If you are going to go to the trouble of installing smart regulators, you should consider a battery monitoring system. Mine is (again) a Xantrex, because at the time, there wasn't much else to choose from. But there are competitors now, and probably something better.

I was under the mistaken impression (when we did the electrical system updates to my boat) that I needed bigger alternators. The company that did them (Yacht Electronics Systems in Annapolis) pointed out that the existing ones were probably big enough, but that smart regulators would make them charge faster and at rates that would keep the batteries up much better. The internal regulators that are fitted into alternators at the factory are evidently not very efficient and can't be adjusted to match the charging profile of different types of batteries. The smart regulators can do this.

My boat is set up with a starting bank that starts both engines. There is a separate battery which starts the generator, and then a house bank which, right now, is two Odyssey AGMs. One engine charges the starting bank, the other charges the house bank. There is also a battery combiner, and a smart charger, which is (again) a Xantrex. When that finally gives up the ghost, I will follow Scott's advice and get a Victron.

Ironically, the Xantrex items on my boat are holding up okay. This is a good thing, because when they don't, their backup of them is such a headache that you just end up buying something else and throwing their item out.

I think Victron also make smart regulators etc but not sure. He has had good luck with them- it would be worth looking to see if they have all the pieces you need.

Thank you Jim, very interesting. Sounds like you have a really good set-up with redundancy. I'm tempted to do something similar when I finally get around to adding the inverter. I'll check on the Victron smart regulator too, didn't even think of that as an option. Thanks again...

[jim rosenthal]

These systems were good when they were installed, but that was thirty or forty years ago on a lot of these boats. Modern smart systems with variable charging curves and high-frequency chargers are a lot better. The smart regulators were a revelation for me- I just figured I needed bigger alternators. Not the case at all, as it turned out.

[jim rosenthal]

I emailed Victron. They do not make alternator regulators- evidently for a while they sold them, but I think they were selling Balmar regulators and they chose not to compete with Balmar sold under their own name.

Victron do have a nice variety of marine products and at least one HOF member swears by them. I would imagine Balmar regulators play well with their equipment, since they sold them in the past.

My Balmar regulators are at least ten years old and work fine, not a peep out of them. Interestingly, one of my reman Cummins turned out to have an alternator that was NF from the factory. We didn't know it until we put in the smart regulators.

[Boatsb]

Jim the regulators do help but keep in mind the alternators are not meant to power the boat instead of a genny.

Yes they will recharge batteries.

Yes they will run more advanced charge curves with smart regulators.

No they are not designed to run at full power for hours to keep up with house and inverter banks. Even adding a 500 amp at to the system will not be as reliable and long lived as running the genny.

[jim rosenthal]

I agree. I don't put a lot of loads on them at all. They only have to run the nav gear and lights etc. Everything else runs off the genset or shore current.

My next charger will also be an inverter, and I will up the size of the house bank, so the fridge will stay cold while I'm running the boat. It isn't a big one and it ought not to strain things.

[davidwigler]

Jim the regulators do help but keep in mind the alternators are not meant to power the boat instead of a genny.

Yes they will recharge batteries.

Yes they will run more advanced charge curves with smart regulators.

No they are not designed to run at full power for hours to keep up with house and inverter banks. Even adding a 500 amp at to the system will not be as reliable and long lived as running the genny.

My port (house) alternator is rated at 60 amps at 32 volts, or 1920 watts. What would you think a safe constant load would be, 50%?

[davidwigler]

I would first check the voltage at the batteries with a multimeter at various RPM to verify that the gauge is giving you valid info. If the multimeter shows the overcharge as well, then I would break/clean/remake all the connections at the alternator; a bad ground can cause overcharging. After that, Obviously the regulator is a prime suspect (whether internal or external). Also, bad batteries can cause overcharging though 50V is mighty high - I've never seen a bad batt cause that much overcharge but I have no experience with AGM batts so I don't know how they might react/affect the charging output.

Mike, I was wondering with your single bank do you have trouble with two operating alternators? Does one of them carry the full load? If you ever need to run on one engine will it harm the non operational alt or the diodes?

Balmar makes a combiner for this purpose but I believe they no longer sell 32 volt equipment at all.

[Boatsb]

My port (house) alternator is rated at 60 amps at 32 volts, or 1920 watts. What would you think a safe constant load would be, 50%?

They are not really designed to run a constant load. At least not over about 50% depending on the unit. If you have heavy DC needs there may be a problem. they were not designed to run large loads full time.

[MikeP]

Mike, I was wondering with your single bank do you have trouble with two operating alternators? Does one of them carry the full load? If you ever need to run on one engine will it harm the non operational alt or the diodes?

Balmar makes a combiner for this purpose but I believe they no longer sell 32 volt equipment at all.

There is no issue running multiple alternators/battery chargers to the same bank. A typical example that exists on the boats as OEM is: any time your generator is running while cruising, your AC powered battery charger is on line at the same time as the engine alternator, attached to the same battery bank.

Whichever charger (either of the alternators or the AC charger) is outputting the most voltage will be the one doing the charging. The others will "sense" that the batteries are fully charged and go "off line." The diodes in the systems prevent current from back-flowing.

[rsmith]

There is no issue running multiple alternators/battery chargers to the same bank. A typical example that exists on the boats as OEM is: any time your generator is running while cruising, your AC powered battery charger is on line at the same time as the engine alternator, attached to the same battery bank.

Whichever charger (either of the alternators or the AC charger) is outputting the most voltage will be the one doing the charging. The others will "sense" that the batteries are fully charged and go "off line." The diodes in the systems prevent current from back-flowing.

Most of the AC chargers shut off with an oil pressure switch on both engines.

[MikeP]

I never looked at the wiring diagram for the original ferro charger so I was not aware that there was a shut off incorporated. But I seem to recall seeing the meter on the LaMarche charger still showing an output when the engines were running and either shore or Genny power was applied. But perhaps I am mis-rembering that...:)

However, you can have any number of chargers operating into a battery and the results are the same -ASSUMING they are all working correctly, they all have voltage settings that prevent any excess charging and they all have diodes/electronic switching the prevents "back flow" of current. The chargers may shift as to which one is charging at any given instant based on their own individual settings - whether set by the user or fixed by the factory.

Our 53 has been running up to three chargers into the battery banks (two alternators and the inverter/charger if the Genny is running) for over 10 years. If concerned, it's easy enough to do a battery voltage check to see if there is any substantial difference in voltage with any/all chargers operating. Obviously, based on manufacturing tolerances, identical chargers/alternators may vary slightly in the output at different RPM. IOW, it's possible that one charger/alternator will be on line at a certain load/RPM and a different one on line at a different load RPM.

[nautibake]

Mike, I was wondering with your single bank do you have trouble with two operating alternators? Does one of them carry the full load? If you ever need to run on one engine will it harm the non operational alt or the diodes?

Balmar makes a combiner for this purpose but I believe they no longer sell 32 volt equipment at all.

I just got off the phone with Balmar, unfortunately David is right, they no longer make any 32V gear. They said try Prestolite / Leece-Neville. I'm still hoping to find a smart regulator for my alternator.