What's the largest/best alternator I can put on my '89 36 Catalina with the 23hp diesel? Thanks for your help.
Alternator Upgrade
- Thread starter cappra53
- Start date
It depends on the engine, how much space you around it, if anyone makes a kit to fit that engine if you are not able to engineer one yourself.
We have a Hunter 356. It has a Yanmar 3GM30F , with 27 HP. I'm told above 80 Amps it is best to change the engine pulleys to use two belts or a flat belt as a single drive belt is not strong enough. I installed a 140 Amp alternator with a flat belt kit on our engine. It was an easy bolt on kit. The kit came from Electromaax. The company gives great support.
Bob
I should also add, unless you going with all AGM batteries an alternator over 80 is probably bigger than you need. We have 410 Ahr AGM bank. I have watched it suck up 153 amps from this alternator.
We have a Hunter 356. It has a Yanmar 3GM30F , with 27 HP. I'm told above 80 Amps it is best to change the engine pulleys to use two belts or a flat belt as a single drive belt is not strong enough. I installed a 140 Amp alternator with a flat belt kit on our engine. It was an easy bolt on kit. The kit came from Electromaax. The company gives great support.
Bob
I should also add, unless you going with all AGM batteries an alternator over 80 is probably bigger than you need. We have 410 Ahr AGM bank. I have watched it suck up 153 amps from this alternator.
Attachments
What is your budget?
What size & type of bank are you feeding?
With the standard belt you can drive about 80A which means a 110A+ alternator de-rated to 80A.... With absolute perfect alignment, perfectly clean pulleys etc. you can eek out 90A but will have belt dust...
With a Serpentine pulley kit you could go to 190A which is the upper allowable limit from Universal.... Unless you have Li batteries you won't need anywhere close to 190A...
Maine, how about alternator drag? The numbers tell me that the drag induced by a larger alternator is not that much more than a stock one but how does it affect in practice? Have heard comments of sailors that indicate their boats seem to have lost
significant power. I would imagine the smaller the engine the larger its percentage of horsepower needed to run the alternator.
significant power. I would imagine the smaller the engine the larger its percentage of horsepower needed to run the alternator.
If can certainly be noticeable.. Whenever a large amperage alternator is installed on a small diesel AUX engine their should also be a regulator cut switch which disables the regulator so you can have more power in an emergency.
Usually it is not noticed under normal motoring but with batteries in bulk, while fighting a current and headwind you'd be happy you installed a regulator cut off switch at the engine panel.
I have 3 cyclinder Yanmars running 165A + alts and the owners rarely if ever need the cut switch but it is there.. I run a 160A alt on our Westerbeke but it is derated/limited to about 120-130A. I don't ever need the cut switch, even when driving the engine driven refrigeration and the LiFePO4 battery bank, but we have a 4 cylinder 40+ HP engine...
Good post. I have the Yanmar 2GMF20 with the stock 35 amp alt. I have seen a 105 amp but that seems like overkill for my budget [both usage and wallet], and I was concerned about drag and wear and tear on the pulley system. I used to see a 65 amp alternator and thought that might be a useful upgrade. Now I don't see that unit anywhere. Is a 30 amp upgrade significant enough to warrant the expense?
The problem with all Yanmar/Hitachi alternators, except some very old models, is that they can lead to chronic under charging and extremely slow bulk & absorption charging. Why? These alternators have a built in thermal protection system that works by lowing the target voltage point as the alt heats up.
Most of the Yanmar/Hitachi alts begin temp compensation at 20C / 68F and drop the voltage by 0.01V for every degree above 68F. When you consider that most of these alts will run at 210-220F+ in bulk that means:
220F - 68F = 152 degree difference
152 X -.01 = -1.52V drop in the alternators max voltage output at 220F.
The specs will also say things like 14.4V (+/-0.3V) for the regulated voltage. Let's assume your reg was producing the spec of 14.4V and your alt is now running at 200F.
That is a 132 degree rise above 68F so 132 X -.01V = -1.32V
14.4V - 1.32V = 13.08V at the batteries :cussing::cussing:
This is NOT INCLUDING ANY VOLTAGE DROP IN THE WIRING
Lowering the voltage point reduces accepted current by the battery bank and allows the alt to cool... It is a safety feature for the alternator but a death feature to your batteries...
Any upgrade beyond a factory Yanmar/Hitachi alt is a good one....
Mainsail
What is the best way to install one of these cutoff switches for the alternator
and I saw a 80 amm Hitachi alternator on E-bay for just $99 and thinking it may be a good spare and minor up grade for my 60 amm alternator,I have 2-195 solar panels and Gen so I don't really need one of those big alternators.
Nick
What is the best way to install one of these cutoff switches for the alternator
and I saw a 80 amm Hitachi alternator on E-bay for just $99 and thinking it may be a good spare and minor up grade for my 60 amm alternator,I have 2-195 solar panels and Gen so I don't really need one of those big alternators.
Nick
I too checked ebay and to replace my Hitachi, I found a slew of 35 amp replacements but only 1 upgrade, a 105 amp at about $100, which, from what I am reading, would also require me to change pulleys, belts and possibly requiring a more robust mounting arm. I am charging my house bank of 2 group 31 AGMs directly from the alternator and if I read Maine correctly, am actually undercharging them with the 35. The 80 amp Seadaddler describes seems like a very good compromise that would allow my to keep the same pulleys [watching the belt carefully], but I suspect that one replaces a different alternator used on his 36'.
Matching#
I found the alternator on ebay matching the # in my 3YM30 manual as the optional 85 amh alternator.
Suppose to be delivered soon
Nick
I found the alternator on ebay matching the # in my 3YM30 manual as the optional 85 amh alternator.
Suppose to be delivered soon
Nick
Thanks for the replies everyone, I guess I would have been more correct to ask whats the highest amperage battery I can safely use. Sorry bout that. Now that use guys have answered that one, whats a moderate/good size battery bank to have? I currently have two (2) Group 34 AGM batteries on board, I don't want to go crazy but would like a sufficient amount of power. I know this depends on a million different things but say just an average size battery bank.
In order to properly size a battery bank, you need to do an Energy Budget.
http://c34.org/bbs/index.php/topic,3976.0.html
http://c34.org/bbs/index.php/topic,3976.0.html
Don't get me wrong but that's like asking "how long is an average piece of string". As Stu suggests you really need to know how much power you use to know what you need / want to be able to store to have a "sufficient" supply.
What is the amp hour rating of your batteries?
I would say you are well below the "average" for a 36' boat. A group 34 AGM (likely Deka) is a 55Ah battery.
Most C-36's & C-34's I know of are running house banks of 200Ah - 450Ah.... You have 110Ah if those batteries are in parallel for a house bank and 55Ah's if one is start and the other is house......
install
Hey Bob
Did you do the alternator upgrade yourself. Was it an easy switch. Whats the gadget in the pic with wires attached overtop the engine. Our H356 had a newer yanmar 3ym30 engine installed by the previous owner.
Thanks
Richard
Hey Bob
Did you do the alternator upgrade yourself. Was it an easy switch. Whats the gadget in the pic with wires attached overtop the engine. Our H356 had a newer yanmar 3ym30 engine installed by the previous owner.
Thanks
Richard
alternator
Hey Nick
Did you get that new alternator. Any issues with it?What it a good deal. Do you recommend it. I am thinking of upgrading my alternator.
Thanks
Richard
Hey Nick
Did you get that new alternator. Any issues with it?What it a good deal. Do you recommend it. I am thinking of upgrading my alternator.
Thanks
Richard
Nick, I asked the ebay alternator seller whether the unit he 80 amp unit recommended would substitute for mine:
"In looking at your item number 400327040255, it does not refer to the usual alternator numbers associated with the Yanmar 2GM20F engine, which are 128171-77200, 581200-3411, 128270-77200, 128270-77200. Do you feel that the 400261126428 will replace these without having to modify anything?"
He replied:
"What is the part # that is actually on your old unit ?? part no 128270-77200 is in this listing and title and is completely interchangeable with 128171-77200. Thanks, Jay "
I haven't had the chance to check the part number on my current alternator.
"In looking at your item number 400327040255, it does not refer to the usual alternator numbers associated with the Yanmar 2GM20F engine, which are 128171-77200, 581200-3411, 128270-77200, 128270-77200. Do you feel that the 400261126428 will replace these without having to modify anything?"
He replied:
"What is the part # that is actually on your old unit ?? part no 128270-77200 is in this listing and title and is completely interchangeable with 128171-77200. Thanks, Jay "
I haven't had the chance to check the part number on my current alternator.
Richard, I did the install myself. It was not hard to do. I bought the kit from Electromaax.com, they supplied everything. The box above the engine is a Sterling external regulator, it has a temperature probe on the alternator and battery bank.
Regards, Bob