15KW Westerbeke Gen issue

Ok... I have Never run a Cabo and I am not familiar with their set up BUT generally speaking battery chargers almost always have lower output than alternators installed on mains...

I can't imagine a Cabo using that much DC Power that stock alternators can't keep up and need to rely on the battery charger.

I would NEVER buy a boat where you must rely on the charger to keep batteries charged... That is a lousy setup as if the charger fails it s game over and you have to come home.

As to chargers conflicting with alternators, it may be an issue on some older set ups (not sure how old is the raritan charger mentioned ) but once the alternators kick in the charger will sense the higher voltage and back off. Heck even my old Pro mariner does this on my 40 year old Hatt!

Up with some coffee. Sorry about my babel last night. Also sorry I can't find the delete option. However, I think you kids did pick up on my thoughts.
Chargers and alternators are always fighting each other if they both are on. Sometimes you can see it on a bouncing volt meter, sometimes not.

And yes, That has to be a lot of current draw to bring down the batteries while the mains are running. Are we talking about a common battery bank for the gen-set, house & main(s) electric needs?

Gen-set alternators don't have a lot of charging current to offer, maybe 15 amps. Usually plenty to recharge the battery, keep a run solenoid, fuel pump, blower & other things running. I think Skip has the newer MANs that have large alternators. Needs them to keep the engine computers going.

Here is that thinking while I type thing again, If The MANs are running, the batteries can't be dead.

Quite common setup on sportfish boats, genset runs off the house bank and mains have one or two bankc for themselves often 24VDC while house is 12VDC. House bank is usually charged by a dedicated 120V charger and/or the genset alternator and most leave the AC charger on when running the genset with no issues using modern alternators and chargers.

What it sounds like is the genset alternator failed or the fuse/breaker controlling it's voltage regulator has opened. If you always use the charger you will never know if that's happened though (a lesson I learned the hard way!).

From looking at their schematic's there is an 8 amp fuse in the DC control circuit and the fuel solenoid provides excitation to the voltage regulator. The first two places I'd look.

Indeed with the mains running the start batteries and hopefully the house bank will be kept charged BUT on most boats *, the genset has it s own dedicated battery which typically is isolated from the other banks.

* by most boats, I meant to excluded entry level smaller boats where the genset is sometimes started by one of the engine or house batteries

So ASSuning Cabo did it right and installed a dedicated battery for the genset, if the small genset alternator fails, voltage will go down until shutdown. That said, again ASSuming it was done right, the genset battery should also be charged by a charger. Unfortunately, very few people check the genset alternator output by occasionally turning the charger off which means that you can be running just fine for months without realizing the genset alternator is dead, until one day the charger craps out or is left off

So, the big question in this case are

Does the genset have it s own start battery?
If so does it also have its own charger?
If not, which battery is used to start the genset?
Does each engine has its own start battery?
Does the boat have a dedicated house bank?

Maybe it's a sportsfish thing but on a cruising boat, using the house bank to start the genset is plain dumb. If you re on the hook on a cool day and run down the house bank, you can't start the genny.

Recharging a larger housebank with a smallish genset alternator doesn't make much sense either... I prefer having an isolator on the mains so that the mains charge the house bank with their bigger alternators

Doesn't this generator have its own alternator and starting battery?

If so then the boat's DC system is irrelevant.

Agreed seperate banks for house and genset starting is desirable but I can't say I've seen a single sportfish done that way. If the mains are the same voltage (12/24) it's a simple matter to install an emergency parallel switch to the house/genset so you can bring to bear their larger alternators to replentish a bank. If it's differing voltage you can still tap off the low side of the 24V bank for long enough to get the house back up and running without causing equalization problems with the mains.

Except for some tuna chunkers in the Northeast who want dead silence to get a bite, most sportfishers don't lay on the hook with a genny off. None have battery capacity sufficient to run AC compressors nor do many have inverters.

Most sporties now have a pair of AGM's (or 8D's) for each main, a pair for the house and one on the bridge for electronics. Quite a bit different from a 47' trawler yacht I was just on that had six 8'd's for house and a single group 31 on each main and one more for genset starting!

So Skipr

What did you find?

It's been a long while since I've been on a 43' Cabo, but the batteries go like this. 1 bank of 2 group 31's per engine, 1 group 31 for the gen, 2-3 group 31's for the 12 volt house bank. Generator alternator has a battery isolator for charging gen starting battery and 12 volt house bank, gen alternator not really large enough to run nearly 25% of the house load capability. Boat is designed for the house bank to be charged by the battery charger at all times. I think 12 volt electronics come off of gen battery, but could be house bank cannot remember. Can run the boat with very light loads on the house bank and not have it go dead in an emergency with engines and generator running and no battery charger. Can also hit parallel switch and it will jump start gen battery from 1 of the engine batteries. Most sportfish rely on small battery banks with crossover capability (for emergency starting), and are done this way.

It might not be an electrical issue.

When a Kohler shuts down with the "UU" code (Under Voltage), in my experience, more times than not, was it caused by dirty fuel filters. In one case an owner supplied a non OEM replacement fuel filter. Then Gen would shut down frequently with no rhyme or reason. I replaced the filter with the proper Kohler Filter and it's been fine ever since. Good Luck.

Why would they use the genset alternator to charge the house bank? Any idea? I just can come up with a good reason... If anything it s forcing the small genset alternator to run at max output which isn't ideal. Much better to have isolators on the mains to charge the house bank

Do fishing boats run extra pumps for bait tanks, that s extra amperage on the house bank

Uh Oh; So the gen-set battery is charged by the mains alternators. Means gen-set battery did not die.

The engine banks are 24 volts, and usually on Cabo's the generator battery is 12 volts as is the house bank (12volts) (sometimes it's a shared bank depending on boat size). The alternator from the generator puts out 12 volts (on most cabo's) and will charge the house bank but not with enough AMP's to keep it up if you're putting more than minimal loads on it. You cannot charge a 12 volt house bank with 24 volt alternators from the engines.

Most all sportfish are this way as Bill mentioned. I ran a 2004 54' Hatteras and it had 2 -8d's for each engine (24volts), 1 8D for generator and house 12 volts and that was it.

Well Cabo and Hatt are more or less the same company nowadays aren't they?

24v house and mains is a much better option than 12v house and 24v mains.

This is what happens when bean counters start building boats...

So, what happened to Skips generator. Any thoughts on my last thought? Gen-set cranks off the bottom 12vdc of the mains starting battery, Mains can not run with out DCv, Gen-set can not run with out the bottom 12 of the mains DCv. If mains run, then loss of DCv is not the fault.
My theory is the crm Mans need allot of DCv to run. They would alarm or fault if the batteries were low.
Further I believe were back to a low DCv at the gen-set or another problem.
OR, The gen-set has is on another battery bank separate from the mains.

Well if the mans and genset are on the same bank (lousy set up...) then Cabo's suggestion that the issue was low DC voltage due to the charger being off goes down the drain... Not a surprise.

Could have been a sensor triggering a shut down (heat, low oil press) or a fuel problem.

Back to basics... How old are the primary AND secondary?

Whenever machinery shuts down, i like getting down there right away and check what s going on, make sure it s not a serious condition. Keep an IR thermometer on board and if it happens again, check coolant temp right away at the tstat housing

Try to restart right away. If it has to cool off, it may be the high temp alarm

How is the water flow out the exhaust? I always check on start up. Sometimes reduced flow will not trigger a shut down till fully loaded (AC compressors kicking in at the same time). Any steam out the exahust under load?

Also, check the vac gauge on the Racors if you have one...