My Yanmar 3HM diesel engine is equiped with a Delco78 amp alternator supplying power to a battry bank of 4 deep charge batteries of 125 amph each. I understand that batteries can not accept more than 25% of their capacity and therefore, I am planning to upgrade to a 120 amp alternator. What would be the issues to concider in such upgrade and would a car alternator be adequate given that this is a diesel engine? Thanks folks.
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Dave Smith
The car alternator will work find. The batteries will do better with a deep charge and that would be a lower amp charge. However if you want a fast charge then go with a higher amp altenator.If you notice that on any battery charger the deep cycle charge is always a lower amp rating such as 1 or 2 amps and a normal charge is 10 amps. The reson for the high amps of a car or boat altenator is to supply amps for all the electronics and aircondintioning clutch wich is an electo magnet. If you have a lot of electrical devices that you are running onboard then go with the higher amps so you will not drain from the batteries when the engine is running.
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Les Murray
Don't use an automotive alternator
Bert, If you are going to upgrade your alternator, might as well go for one that accepts an external regulator. A good three-stage regulator will help you get the optimum charging regimen for your batteries. You should also look at getting some sort of monitor for your system. I got a Link 10. Check out Hamilton Ferris for a good alternator at a fair price. They helped me redo my electrical power system. I added 2 Group 31 AGMs (105 AH each), a 150A alternator and three-stage external regulator.
Bert, If you are going to upgrade your alternator, might as well go for one that accepts an external regulator. A good three-stage regulator will help you get the optimum charging regimen for your batteries. You should also look at getting some sort of monitor for your system. I got a Link 10. Check out Hamilton Ferris for a good alternator at a fair price. They helped me redo my electrical power system. I added 2 Group 31 AGMs (105 AH each), a 150A alternator and three-stage external regulator.
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John Richard
Make sure the alternator fits your motor
I recently took a diesel class. The instructor said that you need to make certain that the engine's pully system will handle larger alternators. It may be that your particular Yanmar can only accept something smaller than the 120 amp. I'd give them a call first. John Richard s/v Jack's Place
I recently took a diesel class. The instructor said that you need to make certain that the engine's pully system will handle larger alternators. It may be that your particular Yanmar can only accept something smaller than the 120 amp. I'd give them a call first. John Richard s/v Jack's Place
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Rick Webb
Automotive Parts Not Suitable
Although many of the parts on your engine look similar to the ones on you automobile there are big differences. On a diesel there may not be all of the worries that you would have with a gas engine and spark suppression, fuel venting, backfire flame arresting, and so on. But be aware of the differences before you make you decision. It may not matter to you but it may to your insurance company or the folks control boating laws in your state.
Although many of the parts on your engine look similar to the ones on you automobile there are big differences. On a diesel there may not be all of the worries that you would have with a gas engine and spark suppression, fuel venting, backfire flame arresting, and so on. But be aware of the differences before you make you decision. It may not matter to you but it may to your insurance company or the folks control boating laws in your state.
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larry w.
electrics
Bert; IMHO, what you need is a modern, integrated system in which all the parts work together. It makes no sense to have a huge alternator if you can't control it, and be aware that a large alternator takes horsepower to turn. If your engine is small, about ten horsepower, that could be a big factor. Any alternator over 125 amps or so will require a double pulley. Automotive alternators are not suitable, period. Get an externally regulated hundred amp alternator with a three-stage regulator and a monitor. Do it right the first time, you won't regret it.
Bert; IMHO, what you need is a modern, integrated system in which all the parts work together. It makes no sense to have a huge alternator if you can't control it, and be aware that a large alternator takes horsepower to turn. If your engine is small, about ten horsepower, that could be a big factor. Any alternator over 125 amps or so will require a double pulley. Automotive alternators are not suitable, period. Get an externally regulated hundred amp alternator with a three-stage regulator and a monitor. Do it right the first time, you won't regret it.
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Dan
Electric Upgrade
Bert, You are getting some good advice here. We just altered our new 356. We put tow Group 4D AGM house batteries, a Group 27 AGM starter battery, Balmar 100 amp alternator, 612 regulator and Pathmaker combiner. Works great and the alternator brings the batteries back up pretty quick. You may want to do something similar. Since you have 4 house batteries, I'd recommend that you set them up in groups of two, that way you can have 250 amp hour banks and still switch them easily with a standard battery switch. Use the marine stuff, and get the externally regulated alternator and a good multi-stage regulator. You only need the combiner if you don't want to watch the switch positions. We use a Link 2000 for monitoring the two house banks. We do not monitor the starter battery except with a voltage meter in the breaker panel. Dan Jonas (S/V Feije)
Bert, You are getting some good advice here. We just altered our new 356. We put tow Group 4D AGM house batteries, a Group 27 AGM starter battery, Balmar 100 amp alternator, 612 regulator and Pathmaker combiner. Works great and the alternator brings the batteries back up pretty quick. You may want to do something similar. Since you have 4 house batteries, I'd recommend that you set them up in groups of two, that way you can have 250 amp hour banks and still switch them easily with a standard battery switch. Use the marine stuff, and get the externally regulated alternator and a good multi-stage regulator. You only need the combiner if you don't want to watch the switch positions. We use a Link 2000 for monitoring the two house banks. We do not monitor the starter battery except with a voltage meter in the breaker panel. Dan Jonas (S/V Feije)
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