Cummins alternators - change?

[Piers]

Play d'eau has twin Cummins 6CTA 8.3 M3 engines (CPL 2172), fitted with their original standard alternators.

Given all the nav kit we run, the DC demand is much higher that when she was built in 2002/3. I also suspect the regulators are 'dumb'. Each engine sharges its own battery bank although it's possible to join them. Port alternator only charges the engine starting bank, the starboard alternator only charges the house bank which runs everything.

Two questions: If I was to fit heavier duty alternators - which ones? if I was to fit intelligent regulators - which ones?

All the best - and thank you....

 

[swifty]

Have a look at the Merlin Smartbank System.

 

[bristoljim]

Also consider Prestolite 8LHA series, almost indestructible,24 or12 volt very easy to fit Adverc smart regulators to.Do not have the "Marine" price tag. Available from The Starter Motor & Alternator co at Plymouth.You will need a double A pulley.
Jim

 

[jfm]

Most OEM alternators from the engine manufacturers are a bit wimpy. I strongly recommend and have had great service from a couple of 150 amp mastervolts with 3 stage charge regulators that also sense the battery temp. These deliver 5hp ++ apiece at cruise rpm but you could get pulleys that make the alternators do 4x the main engine rpm instead of the usual ~3x, to get more power at lower rpm. Because of the torque you might need to upgrade your engine pulleys to multigroove but that isn't too difficult. You may also need to fit chunky 24v cabling to take the 150 amps, etc. About £2k per side.

 

[Piers]

Most OEM alternators from the engine manufacturers are a bit wimpy. I strongly recommend and have had great service from a couple of 150 amp mastervolts with 3 stage charge regulators that also sense the battery temp. These deliver 5hp ++ apiece at cruise rpm but you could get pulleys that make the alternators do 4x the main engine rpm instead of the usual ~3x, to get more power at lower rpm. Because of the torque you might need to upgrade your engine pulleys to multigroove but that isn't too difficult. You may also need to fit chunky 24v cabling to take the 150 amps, etc. About £2k per side.

Thanks John. I've asked my Cummins guru the qustions re pulleys and multigroove. Sounds good to me.

 

[Piers]

The stbd engine charges the services battery bank whilst the port engine charges the engine strat bank. Hence, and without thinking about redundancy, it's only necessary to upgrade the stbd engine alternator. The Mastervolt Alpha Compact 24/150 with the Alpha Pro III regulator, multigroove pulley, seems the perfect fit.

However, I'm also advcised the Mastervolt will need a bracket fabricated to hold it. Any suggestions of suitably calapble fabricators?

 

[burgundyben]

The stbd engine charges the services battery bank whilst the port engine charges the engine strat bank. Hence, and without thinking about redundancy, it's only necessary to upgrade the stbd engine alternator. The Mastervolt Alpha Compact 24/150 with the Alpha Pro III regulator, multigroove pulley, seems the perfect fit.

However, I'm also advcised the Mastervolt will need a bracket fabricated to hold it. Any suggestions of suitably calapble fabricators?

Surely there's a fabricator on Guernsey?

Are you trying to fix a problem that does not exist? Is the stbd battery bank running down when underway because all the nav kit etc is pulling more than the alternator can deliver? If that's not the case, then surely the only issue is that of lifetime of the alternator, which in a marine leisure application is hardly likely to be an issue?

(Sure I have said this to you before, probly more than once, but I love the Flemming, I was crew on a 55 from Hamble to Oslo and back in 1991. A boat called Ozmaiden, she is still on the Hamble, I happened to see her ashore a year or so back and noted she has stabs now. On the trip to Oslo, we had Tony F onboard, smashing chap, I was talking to him about the fold down table in the saloon, he said 'for every problem there is a simple solution, if you find a complex solution, then you need to keep looking. I also recall him telling me that as a young man he rode a motorcycle across the USA, sold the bike, bought a light aircraft and flew back across to where he started, left an indelible mark on a 20 year old me)

 

[Piers]

Surely there's a fabricator on Guernsey?

Are you trying to fix a problem that does not exist? Is the stbd battery bank running down when underway because all the nav kit etc is pulling more than the alternator can deliver? If that's not the case, then surely the only issue is that of lifetime of the alternator, which in a marine leisure application is hardly likely to be an issue?

Can I answer this in two section? Yes, I suspect there's a fabricator in Guernsey but I was hoping (expecting?) there to be a standard issue bracket somewhere without having to have one made.

When bought in 2003, the 'normal' battery bank was only 2 x 8DL and the nav kit was limited. Now it's 4 x 8DL and there's considerably more nav kit. Hence, the current (no pun intended) alternator cannot cope. Well, it can, but it really struggles and runs warm to hot. It's been serviced and found to be within spec, so the next step is to upgrade it.

 

[burgundyben]

When bought in 2003, the 'normal' battery bank was only 2 x 8DL and the nav kit was limited. Now it's 4 x 8DL and there's considerably more nav kit. Hence, the current (no pun intended) alternator cannot cope. Well, it can, but it really struggles and runs warm to hot. It's been serviced and found to be within spec, so the next step is to upgrade it.

Ok, so it is a lifetime issue and with no proper data to tell you the effect of elevated temperature on lifetime, then sensible course is to upgrade.

 

[Piers]

Ok, so it is a lifetime issue and with no proper data to tell you the effect of elevated temperature on lifetime, then sensible course is to upgrade.

Thanks for this. Yes, it's purely that it takes an age for the voltage to rise, the alternator getting really hot, the additional 8DLs, and the somewhat extensive nav kit.

Have a great Christmas.

 

[burgundyben]

I was just musing....and I might not be right.

But...if you fitted a smaller pulley it would run faster, so for any given output each rotation would be doing less work, so perhaps run a bit cooler.

 

[Boat2016]

I was just musing....and I might not be right.

But...if you fitted a smaller pulley it would run faster, so for any given output each rotation would be doing less work, so perhaps run a bit cooler.

I thought that could be possible but then thought it would be same temp as you would still be pulling the same power from it. Again just thinking it over and not sure how accurate this theory is.

 

[burgundyben]

I thought that could be possible but then thought it would be same temp as you would still be pulling the same power from it. Again just thinking it over and not sure how accurate this theory is.

Yes, indeed, same power. Power = I * V, in this case both controlled by the draw from batteries and whatever kit is being used, but capped by the alternators ability.

But...my thought is that the pulley has a fan on it, so, assuming the fan pushes more air as it gets faster, then alternator would be creating same power, but with more cooling, hence run cooler.

 

[Boat2016]

Yes, indeed, same power. Power = I * V, in this case both controlled by the draw from batteries and whatever kit is being used, but capped by the alternators ability.

But...my thought is that the pulley has a fan on it, so, assuming the fan pushes more air as it gets faster, then alternator would be creating same power, but with more cooling, hence run cooler.

Good point about the fan. Could be worth trying a new pulley and a test run with the infrared thermometer first to see if it could work.

 

[Piers]

Hi burgundyben and Boat2016. After taking advice, I believe there are three potential issues with existing alternator. If the pulley its reduced in diameter, the existing alternator would spin too fast at max rpm; being unintelligent, the alterator only delivers its full output at a higher rpm that my cruise rpm; the extra 2 x 8DLs and my nav kit demand more charging that its able to deliver. Combined, it's like asking a 100hp outboard to drive Play d'eau!