Generator or Alternator Regulator?

[lawrence_craig]

Hi all,

I have a Paguro 4000 generator that currently isn't working. An engineer had a look, stripped it, serviced it and still can't get it to work. I am going to look into a second opinion but also looking at other options.

I mainly use the generator to top up the battery bank (1 hour a day/70aH roughly when solar isn't sufficient) and to run my 230v watermaker (1.5kW).

I have a 115amp alternator on my Volvo Penta D2-55D. I also have a 3kW inverter so I could possibly run the watermaker off the battery bank.

I am wondering that rather than spend £££ on my generator, is there anything I can do to my alternator to satisfy my energy needs? Should I consider an additional HOA?

Any advice would be appreciated. Thanks.

[lawrence_craig]

EDIT: for info, I have 540aH flooded sealed batteries. Appreciate this might be part of the decision process. Inverter is a 3kW/120a inverter/charger.

[JimsCAL]

Does the alternator have a Balmar or other good external multi-stage regulator? If so it looks like you could get away without the generator. Run the diesel to charge the batteries and the water maker rather than the generator.

[lawrence_craig]

Thanks Jims.

I have the following alternator - A003TR0091ZT (Mitsubishi). It was on the boat when I bought it. I don't have a regulator. Can I add a multi-stage regulator to this alternator?

Thanks.

[smac999]

The reason people run gens is they are cheaper to fix / repair / maintain then your main engine.., plus they are smaller so you can Actully load them up. do you really want to run the main engine for an hour a day? With no load it is horrible for it. Replacing the gen today is cheaper then replacing the main down the road.

[JimsCAL]

Don't know if that alternator can be converted to an external voltage regulator. Here's a link to several good articles about alternators and regulators.
https://marinehowto.com/category/alternators/

[kenbo]

That alternator is a good small case alternator and can be converted to external regulation but Volvo's ECM is touchy about that.

I agree using the main engine under low load is not good for its long-term health. Are you open to a portable generator like a petrol Honda?

[Cheechako]

I always ran my main engine with a good alternator and an external regulator as my main electrical source. I had engine drive water maker, but running your watermaker while the engine is running is a similar situation it seems to me. Often I would run the water maker while motoring, even if just the last few miles getting into port. So for simplicity and as just an extra generation system I dont see why not run your main engine.
My impression is what destroys marine engines most is not enough use rather than over use.
The "low load" myth has been debunked many times.... as long as that's not it's only use. An alternator will not be low load on a smaller engine anyway...

[noelex 77]

The problem is that the watermaker will consume all of the output from your alternator, and then some. So your engine run time will be the watermaker run time plus the time taken to charge the batteries.

[Cheechako]

Originally Posted by noelex 77

The problem is that the watermaker will consume all of the output from your alternator, and then some. So your engine run time will be the watermaker run time plus the time taken to charge the batteries.

Yeah good point, I forgot he's got a big AC watermaker.
I converted my 1.5 HP AC watermaker to engine drive...

[lawrence_craig]

Thanks all. Helps clear some things up. Considering 2 things:

- See if I can get the generator working. Its an issue probably with the timing wheel so although not cheap, Im hoping it should be fixable.

- If I have any issue with my current alternator, change it for a Balmar small case alternator and put some external regulation on it (I dislike the fact the current alternator is inefficient and if I am motoring somewhere which is often the case in Greece, the batteries don't get the most benefit).

[kenbo]

Originally Posted by Cheechako

The "low load" myth has been debunked many times.... as long as that's not it's only use. An alternator will not be low load on a smaller engine anyway...

I respectfully disagree. Cat, John Deere, and other manufacturers list low load operation or wet stacking as one of the most significant causes of premature engine failure. They recommend less than 20% wet stack time on the engine to reduce carbon build-up on the rings, valve seats, and glazing of cylinder walls not to mention the coking of exhaust mixing elbows.

So do the math, an hour a day or more to charge the batteries is 7 hours per week. Is that more than 20%, will you run your engine at full temperature and load for 28 hours every week? If so then great but that's not the typical use case for most cruisers.

Do many get away with the practice, sure. Is it good for the engine, no.