November 30, 2017 at 9:58 am #8909
December 1, 2017 at 8:05 am #8920
I really enjoyed reading the attachment on high output alternators. On our GH we have the 100 Amp Balmer small case alternators with MC614 regulators and a centerfield to help them play well together. I have considered enlarging the alternators but am also looking at adding solar to the Bimini on the flybridge.
When cruising typically 7-8 hours a day the house batteries seem to do fine, for us it’s when we skip a day to and are on the hook or a wall with no power that we would like some supplement charging so we don’t have to run the generator as much (3-4 hours a day). You obviously have more knowledge of the issues than me, I’m curious what you think are the advantages of bigger alternators vs solar based on what I outlined above?
December 1, 2017 at 1:01 pm #8923
We had the 100 Amp Balmar small case alternators on Easy, but using the internal regulators. You’re probably getting more out of your 100 Amp alternators than we did due to the Centerfielder.
If we left a marina, cruised for 8 hours, anchored, cruised for another 8 hours and then anchored, we would lose power in the wee hours of the morning, 2nd night of anchoring, due to low DC bus voltage probably when a compressor, refrigerator or freezer, started. I didn’t have a battery monitor installed at the time so I don’t know the battery state-of-charge (SOC) when the lights went out. I think the voltmeter was a little less than 12 volts.
After I installed the high output alternators, we never lost power during the night. If we stayed on the hook a second consecutive day I had to run either the mains or the generator for a few hours to charge the batteries. I tried to keep them between 50% and 95% SOC.
Do you have a battery monitor? If so what is the SOC when you anchor, and when you get underway? What is the size of your battery?
As far as solar, I don’t have any experience with it on a boat. I think Steve Ehler installed solar on Balena this year. He’s headed for the Bahamas so perhaps he can give you some input.
December 1, 2017 at 10:26 pm #8924
I just spent two days replacing our Balmar MC612s with new MC614. My MC612s died.
As I read your question above, if you are running the engines 7-8 hours a day, I would think your 100 amp alternators have the batteries fully charged . If the problem is when you are anchored or tied to a wall, it now takes running the generator 3-4 hours to bring the batteries up. If your alternators were 180amp, you could charge faster in theory (360 amp per hour) vs your genset pushing the two inverters at 130amp/hr(total 260 amps per hour). To do that, you have to run your mains above 1500 RPM in neutral.
How big is your battery bank? If you added battery capacity, you could use the inverters longer before charging. Are your batteries at full capacity?
What inverter/chargers do you have?
Changing to larger alternators could require different belts/pulleys.
What is your daily amp hour draw?
December 3, 2017 at 10:52 am #8925
Henry, Did you install a Centerfielder with the new Mc-614s?
December 3, 2017 at 11:24 pm #8927
We had a Centerfielder II installed 18 months ago by Charlie Johnson (St. Petersburg). This was done when the Isolator Transformer melted. One of the 11 yr old MC612s had stopped working correctly and was sending 14.6-15.1v to the batteries. Dick Hermann helped tell me how to unplug it. In Stuart, Trinity Marine Systems (EXCELLENT Marine Electrician) thought our Centerfielder II was bad, due to very strange lights.
We had him replace both MC612s. He found the ignition wire to the Starboard alternator was inconsistent 12v. He double wired it and now the Centerfielder is working as planned.
December 4, 2017 at 5:05 pm #8928
Excellent. When you mentioned that you replaced the MC612s with MC614s I wasn’t sure if you had a Centerfielder installed. It is a nifty widget because without it one of the alternators, the one whose regulator puts out the highest voltage, will do most of the charging. Once, I tried to charge the batteries faster by starting the genset while underway. The inverter/chargers each have a 120 volt charger. I thought I would get the charging current from the two inverter/chargers, in addition to the charging current from the two alternators. It didn’t work. As soon as the MC614 regulators sensed the voltage from the inverter/chargers, the alternator output current went about 130 amps each to about six amps. The regulators shut off the field current, maybe switching to float mode. I suspect that the absorption voltage on the inverter/charger was higher than the voltage set point on the MC614s.
December 5, 2017 at 1:15 pm #8932
December 5, 2017 at 1:21 pm #8935
Correction: I wrote: based upon personal experience I would not recommend using a Marc Grasser small case alternator.
I should have wrote: Based upon personal experience with small case alternators, I would not recommend using a Marc Grasser stage one alternator with a large battery bank.
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