Interested in upgrading the 55 amp alternator to a Balmar 90 or 120 Amp unit. Does anyone have experience with a larger alternator on this particular engine model? Thanks Grant Ziebell
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What About 75amp Info?
I've got a 75amp Balmar on our 3GM30F hooked up with the ARSII three-step regulator and it has worked perfectly for over ten years. The load center consists of four golf carts and the match is fine. The batteries all have double-0 cables up to the selector switch with #2 from the alternator to the selector switch. The ground conductors are double-0 up to the common point and then to the engine. The manin selector switch was upgraded to a Blue Sea high-amperage. The ARSII three-step regulator really works fine with about a 45 second delay after starting the engine before starting the charging. The main thing I would be concerned about is belt slippage as this will (1) wear the belt out, and, worse, (2) ruin the alternator via the heat generated from the slipage. The higher the amperage of the alternator the greater the potential slippage. Plan B is to go with two V-belts but this ratchets up cost and complexity. Another factor to consider in your design is the acceptance rate of the batteries and the output curve of the alternator. When the Balmar alternator is cold it will have an output significantly higher than it's hot rating. For example, my 75amp was bench tested at 135amp cold. The batteries will have a high acceptance when charging is first started but as time progresses the acceptance rate will decline. Bottom line, a really large alternator will not really do much for a battery bank like mine. I also have a group 27 start battery but it is seldom discharged much. Also, the Hitachi 55 amp is rated cold (read: maximum output when first started) where as the Balmar is rated hot. Therefore if I had a recommendation it would be to go with a smaller alternator, avoid the belt slippage problem, use a multi-step regulator, and have a carefree system. Hope this helps. Any questions?
I've got a 75amp Balmar on our 3GM30F hooked up with the ARSII three-step regulator and it has worked perfectly for over ten years. The load center consists of four golf carts and the match is fine. The batteries all have double-0 cables up to the selector switch with #2 from the alternator to the selector switch. The ground conductors are double-0 up to the common point and then to the engine. The manin selector switch was upgraded to a Blue Sea high-amperage. The ARSII three-step regulator really works fine with about a 45 second delay after starting the engine before starting the charging. The main thing I would be concerned about is belt slippage as this will (1) wear the belt out, and, worse, (2) ruin the alternator via the heat generated from the slipage. The higher the amperage of the alternator the greater the potential slippage. Plan B is to go with two V-belts but this ratchets up cost and complexity. Another factor to consider in your design is the acceptance rate of the batteries and the output curve of the alternator. When the Balmar alternator is cold it will have an output significantly higher than it's hot rating. For example, my 75amp was bench tested at 135amp cold. The batteries will have a high acceptance when charging is first started but as time progresses the acceptance rate will decline. Bottom line, a really large alternator will not really do much for a battery bank like mine. I also have a group 27 start battery but it is seldom discharged much. Also, the Hitachi 55 amp is rated cold (read: maximum output when first started) where as the Balmar is rated hot. Therefore if I had a recommendation it would be to go with a smaller alternator, avoid the belt slippage problem, use a multi-step regulator, and have a carefree system. Hope this helps. Any questions?
Slippage.
John's note about slippage needs to be well heeded. Especially if the same belt also drives the engine water pump. Anything over 75 amps is going to take a lot of horsepower to turn. And you do not have a lot of horses. When you tighten the belt to prevent slippage you put a lot of unwanted sideways torque on the waterpump shaft. The pump won't go too long before the seals and bearings let go. You could add a second shaft pulley and offset the pump onto its own belt. Some Yanmars come from the factory like that. But you will still be taking a lot of power from the engine when charging. I have a 37' boat with 300 amp hours in the house bank and the Hitachi 55 is just fine.
John's note about slippage needs to be well heeded. Especially if the same belt also drives the engine water pump. Anything over 75 amps is going to take a lot of horsepower to turn. And you do not have a lot of horses. When you tighten the belt to prevent slippage you put a lot of unwanted sideways torque on the waterpump shaft. The pump won't go too long before the seals and bearings let go. You could add a second shaft pulley and offset the pump onto its own belt. Some Yanmars come from the factory like that. But you will still be taking a lot of power from the engine when charging. I have a 37' boat with 300 amp hours in the house bank and the Hitachi 55 is just fine.
Ed, What about this....
I'm in the process of upgrading my batteries from 100ah to 320ah on an H34. The engine is a 20hp Yanmar 3GMF. The way I understand Nigel Calder's calculations I need a 100 amp alternator. After reading through the archives and then posting a question about this it seems not to many peole are following his example (take the bank ah, multiply by .25, add 25% to that number, then add the ah while under power). Your one of the people that I read all your posts. I'd be interested in your advice here. Thanks, Joe Mullee
I'm in the process of upgrading my batteries from 100ah to 320ah on an H34. The engine is a 20hp Yanmar 3GMF. The way I understand Nigel Calder's calculations I need a 100 amp alternator. After reading through the archives and then posting a question about this it seems not to many peole are following his example (take the bank ah, multiply by .25, add 25% to that number, then add the ah while under power). Your one of the people that I read all your posts. I'd be interested in your advice here. Thanks, Joe Mullee
Joe's dilemma.
Like most sailors I also rely on Nigel Calder's book. But we need to remember that he is optimizing the systems. And cost is no inhibitor. Given his recommendations I would first replace my 2QM20 with a new turbo four cylinder Yanmar. Then I could drive a big alternator and increase my house bank to about 800 amp-hours. The $300. for the most recent waterpump was a big deal. I already have the parts to separate the pump belt from the alternator belt. I have a good three-stage battery charger tied to shorepower. Since my boat spends at least five days a week tied to the dock I cannot justify an electrical system that will charge the batteries to 100%. My 300 aH house bank easily lasts me a long weekend. And given the amount of motoring we do between anchorages and on windless days I will always have enough battery. They will never discharge to over 50%. I also carry a Honda 2000 generator. This makes a nice backup but it is mainly so that I can run the A/C when away from shorepower. When you think about it that generator only has a charge rate of about 20 amps per hour(2000 watts divided by 110 volts). That's less than 30 minutes of motoring with my 55 amp Hitachi alternator.
Like most sailors I also rely on Nigel Calder's book. But we need to remember that he is optimizing the systems. And cost is no inhibitor. Given his recommendations I would first replace my 2QM20 with a new turbo four cylinder Yanmar. Then I could drive a big alternator and increase my house bank to about 800 amp-hours. The $300. for the most recent waterpump was a big deal. I already have the parts to separate the pump belt from the alternator belt. I have a good three-stage battery charger tied to shorepower. Since my boat spends at least five days a week tied to the dock I cannot justify an electrical system that will charge the batteries to 100%. My 300 aH house bank easily lasts me a long weekend. And given the amount of motoring we do between anchorages and on windless days I will always have enough battery. They will never discharge to over 50%. I also carry a Honda 2000 generator. This makes a nice backup but it is mainly so that I can run the A/C when away from shorepower. When you think about it that generator only has a charge rate of about 20 amps per hour(2000 watts divided by 110 volts). That's less than 30 minutes of motoring with my 55 amp Hitachi alternator.
More power
Ed, Actually you will get a bit more than that out of the Honda generator. That is 20 amps at 110 volts, or about 180 amps at 12 volts. I could run my 100 amp charger off that 2000 watt generator at full power. Thats a lot more than the 55 amp Hitachi will put out. Interestingly, the Honda only puts about about 8 amps on the dc side for direct charging if I remember right. Dan Jonas (S/V Feije II)
Ed, Actually you will get a bit more than that out of the Honda generator. That is 20 amps at 110 volts, or about 180 amps at 12 volts. I could run my 100 amp charger off that 2000 watt generator at full power. Thats a lot more than the 55 amp Hitachi will put out. Interestingly, the Honda only puts about about 8 amps on the dc side for direct charging if I remember right. Dan Jonas (S/V Feije II)
Ratings ....
The Hitachi with it's inflated cold rating of 55 amps is puting out much less when it warms up. My manual is on board but it wouldn't surprise me if it was in the order of only 35 amps hot. For info, the Honda EU2000i is rated at only 1600 watts for continuous service.
The Hitachi with it's inflated cold rating of 55 amps is puting out much less when it warms up. My manual is on board but it wouldn't surprise me if it was in the order of only 35 amps hot. For info, the Honda EU2000i is rated at only 1600 watts for continuous service.
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