I am still trying to figure my electrical system for my new 343. I want to upgrade the alternator to help my 400 amp hour battery bank. I would like to use a 100 amp alternator but am concerned if that size can be used with the 3/8" inch belt? Will this size rob to much horse power from the engine? I would appreciate hearing from anyone that has made this upgrade. Thanks.
alternator upgrade
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I am still trying to figure my electrical system for my new 343. I want to upgrade the alternator to help my 400 amp hour battery bank. I would like to use a 100 amp alternator but am concerned if that size can be used with the 3/8" inch belt? Will this size rob to much horse power from the engine? I would appreciate hearing from anyone that has made this upgrade. Thanks.
You don't need an alternator upgrade,
you need a regulator upgrade. The Hitachi alternator is quite capable of charging your batteries. I used mine for one year before converting it for use with a balmar three step regulator. You would have to have very dead batteries to need the extra 30 amps from the Balmar alternator. I never saw amperage readings over 50 amps. Jim
you need a regulator upgrade. The Hitachi alternator is quite capable of charging your batteries. I used mine for one year before converting it for use with a balmar three step regulator. You would have to have very dead batteries to need the extra 30 amps from the Balmar alternator. I never saw amperage readings over 50 amps. Jim
You don't need an alternator upgrade,
you need a regulator upgrade. The Hitachi alternator is quite capable of charging your batteries. I used mine for one year before converting it for use with a balmar three step regulator. You would have to have very dead batteries to need the extra 30 amps from the Balmar alternator. I never saw amperage readings over 50 amps. Jim
you need a regulator upgrade. The Hitachi alternator is quite capable of charging your batteries. I used mine for one year before converting it for use with a balmar three step regulator. You would have to have very dead batteries to need the extra 30 amps from the Balmar alternator. I never saw amperage readings over 50 amps. Jim
huh?
A specific rated alternator is rated based on it's max output. A different regulator isn't going to somehow increase that max rating. Presuming you have the stock internally regulated alternator, changing the regulator to a 3 stage ext unit will allow you to change the charge rate somewhat but to significantly decrease the amount of time required to recharge a 400 amp bank which is 50% depleted, you should do as you plan and install a larger alternator. A 100 AH rated one will allow you to recharge that half-depleted bank to 85-90 percent full in around 3 hours depending on how you set the new regulator. You can use up to a 100 amp alternator without having to change the drive belt to a double belt.
A specific rated alternator is rated based on it's max output. A different regulator isn't going to somehow increase that max rating. Presuming you have the stock internally regulated alternator, changing the regulator to a 3 stage ext unit will allow you to change the charge rate somewhat but to significantly decrease the amount of time required to recharge a 400 amp bank which is 50% depleted, you should do as you plan and install a larger alternator. A 100 AH rated one will allow you to recharge that half-depleted bank to 85-90 percent full in around 3 hours depending on how you set the new regulator. You can use up to a 100 amp alternator without having to change the drive belt to a double belt.
huh?
A specific rated alternator is rated based on it's max output. A different regulator isn't going to somehow increase that max rating. Presuming you have the stock internally regulated alternator, changing the regulator to a 3 stage ext unit will allow you to change the charge rate somewhat but to significantly decrease the amount of time required to recharge a 400 amp bank which is 50% depleted, you should do as you plan and install a larger alternator. A 100 AH rated one will allow you to recharge that half-depleted bank to 85-90 percent full in around 3 hours depending on how you set the new regulator. You can use up to a 100 amp alternator without having to change the drive belt to a double belt.
A specific rated alternator is rated based on it's max output. A different regulator isn't going to somehow increase that max rating. Presuming you have the stock internally regulated alternator, changing the regulator to a 3 stage ext unit will allow you to change the charge rate somewhat but to significantly decrease the amount of time required to recharge a 400 amp bank which is 50% depleted, you should do as you plan and install a larger alternator. A 100 AH rated one will allow you to recharge that half-depleted bank to 85-90 percent full in around 3 hours depending on how you set the new regulator. You can use up to a 100 amp alternator without having to change the drive belt to a double belt.
Take your alternator
to a rebuild shop and have it boosted. They can increase a 100 amper to about 125, then, with an external smart regulator, you should expect to run your engine about an hour to keep the bank between 50 and 80%, which is where you'll stay when out cruising. Three hours to recharge a battery bank with your main engine is nuts; an alternative is a small generator. I have a Honda 2000 and I love it.
to a rebuild shop and have it boosted. They can increase a 100 amper to about 125, then, with an external smart regulator, you should expect to run your engine about an hour to keep the bank between 50 and 80%, which is where you'll stay when out cruising. Three hours to recharge a battery bank with your main engine is nuts; an alternative is a small generator. I have a Honda 2000 and I love it.
Take your alternator
to a rebuild shop and have it boosted. They can increase a 100 amper to about 125, then, with an external smart regulator, you should expect to run your engine about an hour to keep the bank between 50 and 80%, which is where you'll stay when out cruising. Three hours to recharge a battery bank with your main engine is nuts; an alternative is a small generator. I have a Honda 2000 and I love it.
to a rebuild shop and have it boosted. They can increase a 100 amper to about 125, then, with an external smart regulator, you should expect to run your engine about an hour to keep the bank between 50 and 80%, which is where you'll stay when out cruising. Three hours to recharge a battery bank with your main engine is nuts; an alternative is a small generator. I have a Honda 2000 and I love it.
recharge time from alternator
Three hours isn't "crazy". I'd agree that it's too long though. As an example: 100 amp alternator, once hot, will produce anywhere from 30 to 80 amps depending on engine speed. At close to idle, more like 30 amps. With a 400 amp bank half depleted, you need to replace 200 amps which would, even at full rpm, require over 2 hours to produce anywhere close to 150 amps except any regulator will cut back after the battery voltage decreases such that the last 15-20% requires significantly longer. A 100 amp alternator will not produce 100 amps for a prolonged period so unless you drastically increase the alternator size with the attendent belts and larger bracket, you are looking at a lot of motoring.
Three hours isn't "crazy". I'd agree that it's too long though. As an example: 100 amp alternator, once hot, will produce anywhere from 30 to 80 amps depending on engine speed. At close to idle, more like 30 amps. With a 400 amp bank half depleted, you need to replace 200 amps which would, even at full rpm, require over 2 hours to produce anywhere close to 150 amps except any regulator will cut back after the battery voltage decreases such that the last 15-20% requires significantly longer. A 100 amp alternator will not produce 100 amps for a prolonged period so unless you drastically increase the alternator size with the attendent belts and larger bracket, you are looking at a lot of motoring.
recharge time from alternator
Three hours isn't "crazy". I'd agree that it's too long though. As an example: 100 amp alternator, once hot, will produce anywhere from 30 to 80 amps depending on engine speed. At close to idle, more like 30 amps. With a 400 amp bank half depleted, you need to replace 200 amps which would, even at full rpm, require over 2 hours to produce anywhere close to 150 amps except any regulator will cut back after the battery voltage decreases such that the last 15-20% requires significantly longer. A 100 amp alternator will not produce 100 amps for a prolonged period so unless you drastically increase the alternator size with the attendent belts and larger bracket, you are looking at a lot of motoring.
Three hours isn't "crazy". I'd agree that it's too long though. As an example: 100 amp alternator, once hot, will produce anywhere from 30 to 80 amps depending on engine speed. At close to idle, more like 30 amps. With a 400 amp bank half depleted, you need to replace 200 amps which would, even at full rpm, require over 2 hours to produce anywhere close to 150 amps except any regulator will cut back after the battery voltage decreases such that the last 15-20% requires significantly longer. A 100 amp alternator will not produce 100 amps for a prolonged period so unless you drastically increase the alternator size with the attendent belts and larger bracket, you are looking at a lot of motoring.
Be Careful
A few seasons ago I upgraded the alt/reg on my 331. Your first problem will be trying to find a belt that will fit. The 100A alternator will be considerably larger than the stock alternator. When I found a belt that would fit, I would have to take the Alt off completely to install it. When I got the 3 stage reg and the alt working, the belt would slip under a full load from the alternator. My 27hp Westerbeke couldn't handle the bigger Alt. The directions called for detuning the alt through the programmable regulator until the belt stops slipping. I ended up detuning the alt from a 90A to a 55A. I didn't gain any reduction in the time it took to recharge the battery bank. Even after the detuning, it would still slip whenever I used the electric windlass. I got so fed up with the setup that I scraped the whole thing and reinstalled my original 50A alternator. I have a 300A battery bank and I haven't had any problems since. Read the fine print in the instuctions before you decide to go ahead with the installation. For a 27-30hp motor, you're right at the available horsepower limit for making this setup work. My advice would be to stick with what you have.
A few seasons ago I upgraded the alt/reg on my 331. Your first problem will be trying to find a belt that will fit. The 100A alternator will be considerably larger than the stock alternator. When I found a belt that would fit, I would have to take the Alt off completely to install it. When I got the 3 stage reg and the alt working, the belt would slip under a full load from the alternator. My 27hp Westerbeke couldn't handle the bigger Alt. The directions called for detuning the alt through the programmable regulator until the belt stops slipping. I ended up detuning the alt from a 90A to a 55A. I didn't gain any reduction in the time it took to recharge the battery bank. Even after the detuning, it would still slip whenever I used the electric windlass. I got so fed up with the setup that I scraped the whole thing and reinstalled my original 50A alternator. I have a 300A battery bank and I haven't had any problems since. Read the fine print in the instuctions before you decide to go ahead with the installation. For a 27-30hp motor, you're right at the available horsepower limit for making this setup work. My advice would be to stick with what you have.
Be Careful
A few seasons ago I upgraded the alt/reg on my 331. Your first problem will be trying to find a belt that will fit. The 100A alternator will be considerably larger than the stock alternator. When I found a belt that would fit, I would have to take the Alt off completely to install it. When I got the 3 stage reg and the alt working, the belt would slip under a full load from the alternator. My 27hp Westerbeke couldn't handle the bigger Alt. The directions called for detuning the alt through the programmable regulator until the belt stops slipping. I ended up detuning the alt from a 90A to a 55A. I didn't gain any reduction in the time it took to recharge the battery bank. Even after the detuning, it would still slip whenever I used the electric windlass. I got so fed up with the setup that I scraped the whole thing and reinstalled my original 50A alternator. I have a 300A battery bank and I haven't had any problems since. Read the fine print in the instuctions before you decide to go ahead with the installation. For a 27-30hp motor, you're right at the available horsepower limit for making this setup work. My advice would be to stick with what you have.
A few seasons ago I upgraded the alt/reg on my 331. Your first problem will be trying to find a belt that will fit. The 100A alternator will be considerably larger than the stock alternator. When I found a belt that would fit, I would have to take the Alt off completely to install it. When I got the 3 stage reg and the alt working, the belt would slip under a full load from the alternator. My 27hp Westerbeke couldn't handle the bigger Alt. The directions called for detuning the alt through the programmable regulator until the belt stops slipping. I ended up detuning the alt from a 90A to a 55A. I didn't gain any reduction in the time it took to recharge the battery bank. Even after the detuning, it would still slip whenever I used the electric windlass. I got so fed up with the setup that I scraped the whole thing and reinstalled my original 50A alternator. I have a 300A battery bank and I haven't had any problems since. Read the fine print in the instuctions before you decide to go ahead with the installation. For a 27-30hp motor, you're right at the available horsepower limit for making this setup work. My advice would be to stick with what you have.
dual belts required
Pat brings up a good point - if you go with a 100 amp alternator, it will require not a bigger belt but dual belts and probably a replacement mount arm to accommodate the larger size. On an engine with only 27HP, simple Wattage/HP conversion indicates you would lose a serior portion of the engine's rated power just driving the alternator.
Pat brings up a good point - if you go with a 100 amp alternator, it will require not a bigger belt but dual belts and probably a replacement mount arm to accommodate the larger size. On an engine with only 27HP, simple Wattage/HP conversion indicates you would lose a serior portion of the engine's rated power just driving the alternator.
dual belts required
Pat brings up a good point - if you go with a 100 amp alternator, it will require not a bigger belt but dual belts and probably a replacement mount arm to accommodate the larger size. On an engine with only 27HP, simple Wattage/HP conversion indicates you would lose a serior portion of the engine's rated power just driving the alternator.
Pat brings up a good point - if you go with a 100 amp alternator, it will require not a bigger belt but dual belts and probably a replacement mount arm to accommodate the larger size. On an engine with only 27HP, simple Wattage/HP conversion indicates you would lose a serior portion of the engine's rated power just driving the alternator.
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