HI - I have a Yanmar 2GM20F, 18hp, in a 2000 Hunter 320. I think the alternator is a 55amp. Can I run a 100amp alternator (or bigger) alternator off this 18 horse engine? I'd like to speed up the charging process. My concerns are about the alternator taking up the engine power leaving little to move the boat. Any make/model recommendations for hi output alternators for a 2GM20F would be appreciated.
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I Use 80Watt on 3GM3F
I have an 80watt Balmar on a 3GM3F, which is a 20hp Yanmar and have had no problems with it. You may be able to go up to a 100w unit, however, I would not go any higher. For me I felt the 75-80 watt range was best and this is what was recommended by Balmar. Call Balmar and talk to then. They are very helpful and know exactly what will fit on your engine. I ended up purchasing the unit new on e-bay at a good discount, but it took a while to finally find and bid on the unit I needed.
I have an 80watt Balmar on a 3GM3F, which is a 20hp Yanmar and have had no problems with it. You may be able to go up to a 100w unit, however, I would not go any higher. For me I felt the 75-80 watt range was best and this is what was recommended by Balmar. Call Balmar and talk to then. They are very helpful and know exactly what will fit on your engine. I ended up purchasing the unit new on e-bay at a good discount, but it took a while to finally find and bid on the unit I needed.
I don't think that there is any problem at 100 amp
Bob: I don't think there is any problem going upto 100 amps on the alternator. Once you exceed this level you probably need a new setup for your belts (double). There are several companies that make aftermarket unit including Balmar. These unit normally do not kick in until the engine is up to speed, so you will not be loosing much if any usable H.P. Check out E-marine Inc for another source for power.
Bob: I don't think there is any problem going upto 100 amps on the alternator. Once you exceed this level you probably need a new setup for your belts (double). There are several companies that make aftermarket unit including Balmar. These unit normally do not kick in until the engine is up to speed, so you will not be loosing much if any usable H.P. Check out E-marine Inc for another source for power.
Most would say 100amp too much....
...80 is more like it. The problem is that if you use more than 80 you either have to change to a double belt or a bigger belt. Otherwise it will slip. Don't forget, the regulator is more important than the alternator. I installed a Balmar small frame 80amp alternator with one of their multistage regulator (ARS 5) on my H36. Also keep in mind some would argue that you are not going to get much more charging with your stock vs Balmar. If your batteries are 50% it does make a difference...but if they are already 85% it probably wont. good luck abe
...80 is more like it. The problem is that if you use more than 80 you either have to change to a double belt or a bigger belt. Otherwise it will slip. Don't forget, the regulator is more important than the alternator. I installed a Balmar small frame 80amp alternator with one of their multistage regulator (ARS 5) on my H36. Also keep in mind some would argue that you are not going to get much more charging with your stock vs Balmar. If your batteries are 50% it does make a difference...but if they are already 85% it probably wont. good luck abe
I agree...
...with Abe. I went through a similar upgrade last year on my H33. The problem with the stock alternator is a weak internal regulator. I had upgraded my battery bank to gels and the charging voltages were all wrong. A new small frame alternator from Balmar and a multistage, programmable regulator and everything was fine. On my engine 80 amps was the limit before you were required to up the belt size or change to a two belt system.
...with Abe. I went through a similar upgrade last year on my H33. The problem with the stock alternator is a weak internal regulator. I had upgraded my battery bank to gels and the charging voltages were all wrong. A new small frame alternator from Balmar and a multistage, programmable regulator and everything was fine. On my engine 80 amps was the limit before you were required to up the belt size or change to a two belt system.
J
Jeff
How much is too much?
You may want to check with Yanmar. They have a N.E. office in Middleborough, mass@mackboring.com, if they can't answer it, try lberlin@mackboring.com, Larry is their Director of Training and has seen it all.
You may want to check with Yanmar. They have a N.E. office in Middleborough, mass@mackboring.com, if they can't answer it, try lberlin@mackboring.com, Larry is their Director of Training and has seen it all.
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