Yanmar alternators output

[DerekL]

I have a two year old Yanmar 4JH5E (54HP) engine with a 115amp alternator. On previous boats I have fitted a Sterling advanced regulator to get maximum charge into the batteries with the short engine runs on a decent day's sailing. I have a battery monitor and the usual problem exists with the standard set up - charge rate quickly falls off as the battery recharges (typically to ~15amps after an hour or so). So far as expected - that's why I want to fit and advanced regulator.

However. On one occasion when I was on a long motor and became frustrated with the low charge rate I decided to boost things a bit by shorting out the diode of the split charge diodes which goes to the domestic bank. This did kick up the charge rate to around 45-50 amps (note 125amp rated) but the alternator became scorchingly hot.

While researching the regulator vs DC to DC charger I have come across other references to the temperature sensitivity of Yanmar alternators.

Has anyone fitted an advanced regulator to a modern Yanmar with an alternator of this sort of size and if so is overheating a problem? - either physically or because of current restriction.

I am now starting to wonder whether I need to go the whole hog and install a Balmar alternator and regulator.

The boat has a 320ah domestic bank, 70ah starter and 130ah bow battery. Presently charged through a 3 way split charge diode. It's not what I would have done but it is what was installed with the boat so that is the starting point.

DerekL
"Nightsong"

 

[[2574]]

Derek,

Can't advise on souping up the Yanmar alternator but I have fitted a 120A Balmar alternator and Balmar ARS5 regulator with upgraded Electromaax serpentine belt kit on my 4JH2E so PM if you think I can assist if you decide to upgrade.

Rob

 

[pvb]

It's fair to assume that the starter and thruster batteries will usually be pretty well charged, so your charge current is mainly going into the domestic bank. Frankly, with only 320Ah of batteries, you're unlikely to see much more than 45-50A, regardless of what type of alternator you have. So buying a Balmar system wouldn't be a good use of your money.

You could convert your current alternator to be battery-sensed, and this would enhance the charging current (as you've discovered by shorting out the diode). You could achieve a similar result by fitting a Sterling booster regulator with a temperature sensor on the alternator. You might also consider fitting an engine room fan to exhaust hot air, and arrange a cool air inlet pipe to blow on to the alternator.

Adding more batteries to the domestic bank will help, too. A larger bank can absorb more current and is more efficient.

 

[Birdseye]

This is an issue that I struggled with through three different alternators. I started using a Sterling regulator but eventually the alternator ( standard Volvo) overheated and the alternator place I took it to treated it like a car alternator and bu66ered it. So I got a replace from one of the cheap alternator places, still using the Sterling and soon enough the same symptoms of intermittent output. Alternator no 3 was a 90 amp unit from Prestolite with no Sterling this time yet again it failed. I measured the temperature on the casing when running and it was 88C so a lot more inside on the diodes and windings. I should add that my engine is tightly boxed in. Anyway Prestolite confirmed that the alternator was oversentitive to temperature and refunded. Current alternator is a european made 70 amp job and with some forced air ventialtion into the engine box is doing OK.

In all this saga, all the engine bay wiring was checked out and founfd to be OK. Charles Sterling gave what I think was the likely culprit in that most alternators now are made in China and the solder used isnt silver solder as was the case but a lower melting point conventional solder leading to intemittent contact as the solder overheats and makes a dry joint.

I guess what I am saying is that the cooling of an alternator is sized for its standard output and if you use a digi regulator to increase that output you risk the alternator overheating. Depends obviously on the ventialtion of your engine box. And it could be that Balmar use silver solder anyway. Maybe check the temperature of your existing alternator anyway - they are meant to be too hot to touch

 

[pvb]

I guess what I am saying is that the cooling of an alternator is sized for its standard output and if you use a digi regulator to increase that output you risk the alternator overheating. Depends obviously on the ventialtion of your engine box. And it could be that Balmar use silver solder anyway. Maybe check the temperature of your existing alternator anyway - they are meant to be too hot to touch

Very few alternators ever run close to their rated current output. The add-on regulators simply increase the output voltage, they can't do anything to increase the max current output.

Balmar alternators are made by Prestolite.

 

[RobbieW]

...Balmar alternators are made by Prestolite.

Not necessarily. According to the man at JASM, mine is based on a Denso unit

 

[charles_reed]

I have a two year old Yanmar 4JH5E (54HP) engine with a 115amp alternator. On previous boats I have fitted a Sterling advanced regulator to get maximum charge into the batteries with the short engine runs on a decent day's sailing. I have a battery monitor and the usual problem exists with the standard set up - charge rate quickly falls off as the battery recharges (typically to ~15amps after an hour or so). So far as expected - that's why I want to fit and advanced regulator.



However. On one occasion when I was on a long motor and became frustrated with the low charge rate I decided to boost things a bit by shorting out the diode of the split charge diodes which goes to the domestic bank. This did kick up the charge rate to around 45-50 amps (note 125amp rated) but the alternator became scorchingly hot.

While researching the regulator vs DC to DC charger I have come across other references to the temperature sensitivity of Yanmar alternators.

Has anyone fitted an advanced regulator to a modern Yanmar with an alternator of this sort of size and if so is overheating a problem? - either physically or because of current restriction.

I am now starting to wonder whether I need to go the whole hog and install a Balmar alternator and regulator.

The boat has a 320ah domestic bank, 70ah starter and 130ah bow battery. Presently charged through a 3 way split charge diode. It's not what I would have done but it is what was installed with the boat so that is the starting point.

DerekL
"Nightsong"

Yes, it literally melted.
I'd change any Hitachi alternator for a Magnetti Marelli.

 

[RichardS]

Yes, it literally melted.
I'd change any Hitachi alternator for a Magnetti Marelli.

That's the first time I've ever seen a recommendation for the quality of Italian engineering above Japanese engineering.

Richard

 

[lw395]

If the alternator is overheating, it needs more air or cooler air.
These things commonly run at much more than 45A in cars etc, for long periods.
Just not in an insulated box.....

 

[pvb]

If the alternator is overheating, it needs more air or cooler air.
These things commonly run at much more than 45A in cars etc, for long periods.
Just not in an insulated box.....

Indeed, and often in much higher ambient temperatures - think of Range Rovers in places like Dubai.

 

[snowleopard]

Very few alternators ever run close to their rated current output. The add-on regulators simply increase the output voltage, they can't do anything to increase the max current output.

I have a 345AH domestic bank which should theoretically be able to absorb 100A of charge. I have 2x55A alternators. So far so good. I added an Adverc twin-engine controller so should be able to really shovel the amps in.

The best I have ever seen is 35A when the batteries are well down.

I have a 30A Sterling 4-stage mains charger which does what it says on the box - a steady 30A until the battery is close to full. The difference is that the Adverc works on voltage, holding it at 14.4v, dropping back to 14.0 for 5 minutes in 20. The Sterling works on current, i.e. it tweaks the voltage till it gets the advertised current.

As an aside, one of my alternators developed a fault in its internal regulator and produced over 16 volts which cooked the entire bank by the time I noticed the badly-sited over-charge warning light.

 

[vyv_cox]

I have 330Ah batteries (3 x 110Ah) charged by a standard 55 Amp alternator on a Yanmar 3GM30F with a Sterling regulator. Starting the engine first thing in the morning, fridge running all night, solar panels not yet seeing enough sunlight to produce any power, the ammeter will show about 50 Amps or slightly less for no more than 1 minute. It then reduces quite quickly and is usually down to less than 10 amps within an hour.

A little dodge that can be used with a Sterling regulator at float voltage is simply to stop the engine and re-start it. This sets the one-hour timer back to zero, delivering full current, so far as the battery bank wants it, for another hour.

 

[RichardS]

I have a 345AH domestic bank which should theoretically be able to absorb 100A of charge. I have 2x55A alternators. So far so good. I added an Adverc twin-engine controller so should be able to really shovel the amps in.

The best I have ever seen is 35A when the batteries are well down.

I have a 30A Sterling 4-stage mains charger which does what it says on the box - a steady 30A until the battery is close to full. The difference is that the Adverc works on voltage, holding it at 14.4v, dropping back to 14.0 for 5 minutes in 20. The Sterling works on current, i.e. it tweaks the voltage till it gets the advertised current.

That does seem a bit low Snowleopard. I wonder whether the Adverc is actually doing anything in your set up? We have similar setups except I have the optional 80A alternators on each engine and 600Ah of house batteries and no Adverc. When the batteries are low both alternators will read a maximum of about 65A which then slowly drops over 3 or 4 hours down to about 10 amps.

My Victron 40A mains charger operates the same as yours although the meter on the front reads 50A for the first few hours!. It eventually comes down to about 5A and never seems to drop below that. If I turn off the mains and start the engines at that point the alternators will both show around 5A. However, when running the engines once the batteries are low I've never seen it get down to 5A. Perhaps if I ran the engines for the whole day it might!

Perhaps the Adverc is superfluous where modern alternator systems are concerned?

Richard

 

[RobbieW]

I have a nominal 720Ah house bank, we use +- 100A/day. The solar doesnt keep up so running the engine every so often is a necessity. With a deficit of 100A + the alternator will start at 110-105A and slowly run down to 20 or so over an hour. Thats with a Balmar alternator & external Balmar regulator and using a Xantrex Link20 for monitoring

 

[RobbieW]

....Perhaps the Adverc is superfluous where modern alternator systems are concerned?

The Adverc is arguably superfluous with modern altrnators that already deliver 14+ volts, what the Adverc does is boost voltage to improve the battery charge regime. The 'problem' with internal regulators or charge controllers is that thier standard algorithms are conservative and can be improved on for boat battery charging - hence my choice of Balmar which I can program to my requirement (more or less ). Understanding your own charging requirement and understanding what regime will best support that is key to making a decision on charging systems