Alternator upgrade for 3GMF30

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A

André R.

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Jun 3, 2004
54
Hunter 34 Lake Champlain, NY
I found out thrue this site that the 55amps alternator would only give out around 35amps normally with the use we have of our engine. I'm looking to upgrade my alternator for 90-100amps.

I will be leaving for a one year sailing period, the boat will be equipped with a ST6000 autopilot, radar, computer with navigation software, recent fridge, ham radio, etc.

I will have 2 solar panels of 130W with MPPT controller and maybe a small wind generator.

Any one out there have upgraded their alternator ? I didn't find anything in the archives. , I am open to any suggestion or comments

Thanks in advance

André
 
chuckwayne

chuckwayne

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Mar 20, 2004
1,746
Hunter 356 and 216 Portland, ME
Balmar makes a high performance alternator and external regulator kit that should work on your engine-we've had on on our 3gm for 5 years now and it works really well. You just have to keep an eye on belt tension (we use a notched belt for less slip). recharges our agm main bank much faster than the stock alternator. 70 amps (it's the "real" hot rating for the balmar, not the meaningless cold rating used on the stock alternator) is about as large as you can go without changing to dual belts.
 
B

Benny

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Sep 27, 2008
1,149
Hunter 320 Tampa, FL
Check the archives on this topic. A larger alternator may not do much for you unless you have a large battery bank or AGM batteries. One thing that is mostly overlooked when considering an upgrade is reliability. Your factory alternator is quality unit but some of these replacement units are not built to the same standards. They do compensate by offering a good replacement warranty but when you are out to sea and the alternator fails somehow that warranty may seem hollow. Start by working a power survey to size your battery bank, factor in your recharging alternatives and then decide if it is necessary to upgrade the alternator. Do your homework as there are pros and cons to such a conversion.
 
shemandr

shemandr

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Jan 1, 2006
7,651
Slickcraft 26 Sailfish
I am considering an upgrade for my alternator. I think it rated at 35 amps which isn't very useful for charging my 400 ah battery bank (AGM,s). One reservation I have is how much engine power I would lose from, say, a 70 amp alternator. I already think my boat is a bit underpowered with the 3GM Yanmar. So what say you Chuckwayne? Do you notice a decrease in rpm, power or speed?
 
shemandr

shemandr

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Jan 1, 2006
7,651
Slickcraft 26 Sailfish
Was the Balmar for the 356 numbered "70-YP-80-KIT ." That's a 3.15" saddle mount with a 1/2" single groove pulley, wiring harness, external voltage regulator and battery and alternator temp sensors. The price is a bit dear but being able to charge the batteries at anchor could change the way we use the boat.
 
Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Boat power usage spreadsheet

I have an excel spreadsheet that lets you enter the loads and battery bank capacity then play with the recharge schedual and means.
email me at william-roosa@us.army.mil for a copy and instructions
 
B

Benny

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Sep 27, 2008
1,149
Hunter 320 Tampa, FL
Current diesel engines do not take well to idling at low RPMs with light loads for long periods of time. It induces carbon build up and running problems down the line. These engines have mechanical control components which do not offer "smart" tuning adjustments and are designed to run at high RPM under load and do a poor job of properly burning fuel at iddle speeds. It all boils down to looking down the line at costly repairs and more frequent breakdowns. I would rather expend and replace a portable generator a few times than having to prematurely repower the boat.
 
chuckwayne

chuckwayne

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Mar 20, 2004
1,746
Hunter 356 and 216 Portland, ME
Andy, I couldn't locate the exact model number here but that sounds probable-it's a 3.15 dual foot, single 1/2 pulley 70 series alternator with an mc-612 external regulator.
And yes, it's only a couple of horsepower but I did notice a loss of motive power if the batteries were down but it hasn't been a problem, you can select a less aggressive rate if you want. I added a field coil cutout switch just in case (Balmar's suggestion) but i've only used it when first heading out into a strong river current. Well worth adding to your 356, and sometimes it's worth spending more for known quality-it's run flawlessly for 6 years now.
Chuck
 
A

André R.

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Jun 3, 2004
54
Hunter 34 Lake Champlain, NY
chuckwayne said:
Balmar makes a high performance alternator and external regulator kit that should work on your engine-we've had on on our 3gm for 5 years now and it works really well. You just have to keep an eye on belt tension (we use a notched belt for less slip). recharges our agm main bank much faster than the stock alternator. 70 amps (it's the "real" hot rating for the balmar, not the meaningless cold rating used on the stock alternator) is about as large as you can go without changing to dual belts.
Click to expand
Would you know the part numbers ot that alternator and the external controler ?
Thanks
André
 
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