Thank you, I have posted my questions at Seaboard Marine, and hope they might have an idea for a conversion kit.
Cummins N855 alternator upgrade
- Thread starter woolf
- Start date
The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
If you have answers, please help by responding to the unanswered posts.
Thank you, I have posted my questions at Seaboard Marine, and hope they might have an idea for a conversion kit.
C lectric
Guru
The new alternator is driven by the crankshaft with no other loads on it???
Have you considered a Timing belt or Synchronous belt drive. It's been a long time since I had anything to do with them but they can handle a lot of power since it is NOT friction drive, rather the actual cogs on the belt matching up with the cogs in the pulleys. They are a positive drive. They too are available in many different sizes and at least the ones I had to fool with used taper bushings to adapt to a straight shaft but I know other drives are available..
A means of tensioning will of course be needed but they do not need to be TIGHT the way a V belt does. Just take the shake out of them and ensure the belt and pulley cogs fit.
Often called synchronous belts. Dodge belts and drives?
Talk to a belt and/or a bearing specialty house OR industrial drives house. It's been almost 40 yrs since I last played with them so cannot remember all the details.
THere were a couple different mfgrs. and of course the cogs did not match so you had to have the proper belt. Carry a couple of spares just in case as they will not be common in boats so marine repairs shops may not know what they are. Any good industrial repair shop should though and maybe larger boat repairs shops
https://www.baldor.com/brands/baldo...ical-drive-components/belts/synchronous-belts
dodge synchronous belt drives, dodge sprockets drives, dodge timing belts, dodge sprockets catalog
Have you considered a Timing belt or Synchronous belt drive. It's been a long time since I had anything to do with them but they can handle a lot of power since it is NOT friction drive, rather the actual cogs on the belt matching up with the cogs in the pulleys. They are a positive drive. They too are available in many different sizes and at least the ones I had to fool with used taper bushings to adapt to a straight shaft but I know other drives are available..
A means of tensioning will of course be needed but they do not need to be TIGHT the way a V belt does. Just take the shake out of them and ensure the belt and pulley cogs fit.
Often called synchronous belts. Dodge belts and drives?
Talk to a belt and/or a bearing specialty house OR industrial drives house. It's been almost 40 yrs since I last played with them so cannot remember all the details.
THere were a couple different mfgrs. and of course the cogs did not match so you had to have the proper belt. Carry a couple of spares just in case as they will not be common in boats so marine repairs shops may not know what they are. Any good industrial repair shop should though and maybe larger boat repairs shops
https://www.baldor.com/brands/baldo...ical-drive-components/belts/synchronous-belts
dodge synchronous belt drives, dodge sprockets drives, dodge timing belts, dodge sprockets catalog
Last edited:
Thank you C lectric, I had not thought about this option, will look into it. If I cannot find a multigroove set that fits, my next step if unsuccessful would be to contact an industry supply specialist for belt drives.
The crankshaft drives the hydraulic pumps only, you can see the orange flex coupling in the pictures. Above that is a separate PTO: the inside belt drives the water pump, one out is the twin belt pulley for the alternator. On top is a spare single pulley, not used by us today.
The crankshaft drives the hydraulic pumps only, you can see the orange flex coupling in the pictures. Above that is a separate PTO: the inside belt drives the water pump, one out is the twin belt pulley for the alternator. On top is a spare single pulley, not used by us today.
sunchaser
Guru
- Joined
- Apr 9, 2008
- Messages
- 10,197
- Location
- usa
- Vessel Name
- sunchaser V
- Vessel Make
- DeFever 48 (sold)
Woolf
The water pump belt is the most important one on the engine. Whichever modifications you make for driving the alternator keep in mind the ease of changing out the water pump belt. For sure put a new pump belt on when accessible.
The water pump belt is the most important one on the engine. Whichever modifications you make for driving the alternator keep in mind the ease of changing out the water pump belt. For sure put a new pump belt on when accessible.
Ski in NC
Technical Guru
Cog belt drive is worth looking into. They can handle much more load than vee or serp belts. But I doubt there are any ready made pulleys to go that route. You would need to buy the pulleys and have a machine shop adapt them to a machined aux drive pulley. Alt pulley should be simpler.
I had to design a cog drive belt system for another application. The belt vendors (e.g., Gates, Dayco) have a lot of information available to help the design process. Also have generic pulleys available designed to be easily adapted by a machine shop to all sorts of apps. May also be helpful if you chose to go serp belt.
I had to design a cog drive belt system for another application. The belt vendors (e.g., Gates, Dayco) have a lot of information available to help the design process. Also have generic pulleys available designed to be easily adapted by a machine shop to all sorts of apps. May also be helpful if you chose to go serp belt.
Thank you, very good point - currently it is easy to change the cooling pump belt, just release tensions and remove the alternator belts. Will see to keep it that simple, whatever the final chosen setup.
twistedtree
Guru
Where have you guys found efficiency numbers, or preferably curves, for alternators? The Prestolite (Leece Neville) web site has a bunch of info, but I'm not seeing efficiency numbers for the various large frame alternators.
If they really are in the 80-90% efficiency range vs the 50-70% range that I thought, it changes a bunch of my thinking around power generation while underway.
Attached is the paper from Delco Remy that I've been going on, if anyone is interested. It does a good job of breaking down the power losses.
If they really are in the 80-90% efficiency range vs the 50-70% range that I thought, it changes a bunch of my thinking around power generation while underway.
Attached is the paper from Delco Remy that I've been going on, if anyone is interested. It does a good job of breaking down the power losses.
C lectric
Guru
T.T.
Thank you for the white paper.
I was perusing the Delco Remy site a few weeks back and seem to recall that some of their larger units were rated at higher efficiency than 50%. I will have to go back. For me this will just be an exercise, hopefully, but I have been mildly looking at bettering my 22SI. Either Remy or Leece Neville.
THat paper may be helpfull or confusing to me though. I will find out.
O C Diver
Guru
- Joined
- Dec 16, 2010
- Messages
- 12,878
- Location
- USA
- Vessel Name
- Slow Hand
- Vessel Make
- Cherubini Independence 45
Woolf, this probably isn't going to help you with your current configuration, but just shows an alternative mount system for driving an alternator off the crankshaft.
https://www.trawlerforum.com/forums/members/1458-albums983.html
Ted
https://www.trawlerforum.com/forums/members/1458-albums983.html
Ted
twistedtree
Guru
Thanks. I hadn't heard of APS before. It's a bit hard to tell, but they seem a bit like Balmar, packaging up stuff for specific applications. My guess is that like Balmar, they are more or less stock LN alternators. Their 42i sure looks a lot like mine... Nothing wrong with that, just not likely to yield any magic with respect to efficiency.
Interestingly, their "large frame" alternators are 50% efficient, your 55i is listed as 87%, and the 42i is 70%. That's quite a spread. I also expect the efficiency number in the data sheet is best case since it is otherwise unqualified.
The APS 55i was installed on Volvo Ocean racers, where efficiency and low weight is paramount. That's how I found them, and they looked like a good fit for our application.
I bought them from Bruce Schwab at OceanPlanet Energy in Bath ME, who is doing some interesting electric installations, mainly on sailboats.
I bought them from Bruce Schwab at OceanPlanet Energy in Bath ME, who is doing some interesting electric installations, mainly on sailboats.
ryanleestma
Member
- Joined
- Oct 15, 2022
- Messages
- 15
Hi there - VERY interested in your setup as I would like to do the same - biggest downside I’ve heard regarding this sort of PTO High amperage DC Alternator output is belt slippage - I must confess I’m not great mechanically I just had the idea - what pulley / belt system did you use to avoid slippage? I am in Muskegon
Ryan
Ryan
The missing information on most alternator brochures is the actual output in a 120 deg engine room at cruising rpm. 60% is pretty efficient for an alternator, and a 6 kw output alternator is generating 4 kw of heat or 14 KBtu. About the same as a diesel furnace in a package the size of a football. You can let it fry, or temperature limit it with an external regulator that derates on temperature, the inevitable result is you don't get 6 kw output.
Making things worse, if you are running a 1600 rpm cruise and a 2.5:1 belt ratio - just some typical numbers, the alternator cooling fan is running at about half speed.
APS says "at ambient conditions" which I assume might be standard atmospheric, 68 deg F. It will run about 50 deg hotter in a typical engine room, by the time you derate for that your output power will be significantly off.
Making things worse, if you are running a 1600 rpm cruise and a 2.5:1 belt ratio - just some typical numbers, the alternator cooling fan is running at about half speed.
APS says "at ambient conditions" which I assume might be standard atmospheric, 68 deg F. It will run about 50 deg hotter in a typical engine room, by the time you derate for that your output power will be significantly off.
