New Alternator for New Batteries

[MeiWenti]

We are about to replace our old, nearly expired, 420Ah flooded LA battery bank with new 660Ah bank of AGMs.

To keep them properly charged, in addition to 400W of solar, we are looking to upgrade the Yanmar 4JH5E engine's stock 80A Hitachi alternator which, because of alternator temperature regulation, rarely delivers more than 20-25A into the batteries during extended motoring.

With a large AGM bank we want to go to the largest alternator that we can fit. After a lot of research, to keep with a small frame size alternator that we know will fit, it looks like being either the Balmar AT-165 or the Mark Grasser (DC Power Solutions) Stage One 180A alt, together with a serpentine belt/pulley conversion and Balmar MC-614 regulator.

The temptation is to go for the Mark Grasser on the basis that it is larger, but is there any good reason to go with the lower powered Balmar AT-165?

Assuming both alternators are sensibly belt limited and temperature regulated, is the MG 180A alternator always going to deliver more power that the Balmar, or is the design of the Balmar AT better able to handle high temperatures and therefore in the end able to deliver more power?

[MBWhite]

Is it possible to fabricate a mount and fit a second alternator? That will give you the best of a couple different scenarios. Plenty of charging amps and also redundancy should one fail at some inopportune time. Additionally neither is working as hard as it can so internal heat goes down and longevity goes up.

[Maine Sail]

Originally Posted by MeiWenti

We are about to replace our old, nearly expired, 420Ah flooded LA battery bank with new 660Ah bank of AGMs.

To keep them properly charged, in addition to 400W of solar, we are looking to upgrade the Yanmar 4JH5E engine's stock 80A Hitachi alternator which, because of alternator temperature regulation, rarely delivers more than 20-25A into the batteries during extended motoring.

With a large AGM bank we want to go to the largest alternator that we can fit. After a lot of research, to keep with a small frame size alternator that we know will fit, it looks like being either the Balmar AT-165 or the Mark Grasser (DC Power Solutions) Stage One 180A alt, together with a serpentine belt/pulley conversion and Balmar MC-614 regulator.

The temptation is to go for the Mark Grasser on the basis that it is larger, but is there any good reason to go with the lower powered Balmar AT-165?

Assuming both alternators are sensibly belt limited and temperature regulated, is the MG 180A alternator always going to deliver more power that the Balmar, or is the design of the Balmar AT better able to handle high temperatures and therefore in the end able to deliver more power?

Mark builds a great alternator and is a great guy to boot. I run a Mark Grasser 160A current limited to 120A on my own boat. It is driven by an MC-614 and feeds a LiFePO4 bank.. Both the AT and Grasser alts are excellent but Marks alt is a lot less money.. The AT would likely put out a bit more at idle...

[Finistere]

Just a note of caution, I installed a 100 amp Balmar on 3jh5e and since the tach is driven by the alternator it reads about 500 rpm high. Yanmar techs are not adjustable for the number of poles on an alternator. The Balmar is down to 35 amps pretty quickly when charging to a 400 amp agm bank.


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[Maine Sail]

Originally Posted by Finistere

Just a note of caution, I installed a 100 amp Balmar on 3jh5e and since the tach is driven by the alternator it reads about 500 rpm high. Yanmar techs are not adjustable for the number of poles on an alternator.

Some Yanmar tachs are adjustable but it is a menu system you need to get from VDO or Yanmar for the Yanmar specific tach.. Otherwise throw a Faria tach in there..

Originally Posted by Finistere

The Balmar is down to 35 amps pretty quickly when charging to a 400 amp agm bank.

Most likely an installation issue or temp compensation... The other possibility is your bank is not drawn as deeply as you think.

With less than a .25C charge current an AGM bank (especially if Lifeline or Odyssey) sould be in bulk from 50% SOC to approx 80% SOC..

[Fuss]

Originally Posted by MeiWenti

We are about to replace our old, nearly expired, 420Ah flooded LA battery bank with new 660Ah bank of AGMs.

To keep them properly charged, in addition to 400W of solar, we are looking to upgrade the Yanmar 4JH5E engine's stock 80A Hitachi alternator which, because of alternator temperature regulation, rarely delivers more than 20-25A into the batteries during extended motoring.

With a large AGM bank we want to go to the largest alternator that we can fit. After a lot of research, to keep with a small frame size alternator that we know will fit, it looks like being either the Balmar AT-165 or the Mark Grasser (DC Power Solutions) Stage One 180A alt, together with a serpentine belt/pulley conversion and Balmar MC-614 regulator.

The temptation is to go for the Mark Grasser on the basis that it is larger, but is there any good reason to go with the lower powered Balmar AT-165?

Assuming both alternators are sensibly belt limited and temperature regulated, is the MG 180A alternator always going to deliver more power that the Balmar, or is the design of the Balmar AT better able to handle high temperatures and therefore in the end able to deliver more power?

Well, I assume that you didn't replace 420ah with 660ah for no good reason.
The more amps rammed in under engine the better in my opinion, its a sailing boat, not a motor sailer right?, you're going to be using amps for other things besides charging when running the engine for a short time, so stick on the alt with the most amps possible that does not compromise or damage the rest of your mechanical installation.

Why belt limiting...a double pulley or serpentine will have no problem with 180amps at 12v.

Can't answer the temperature question, but I wouldn't stick any alternator on my boat that couldn't handle high temperatures.

Make sure you set the regulator to the new battery manufacturers specs.

[MeiWenti]

Thanks for the replies. We have decided to go with the Mark Grasser alt.

I don't think we can fit a second alternator in the engine compartment.

Fuss - I tend to agree with your view on belt limiting. If the belt system can take the load, which the serpentine system certainly should be able to, the concern should be not to allow overheating of the alternator with extended high load running. The alternator temperature sensor and MC-614 regulator should take care of that.

Finistere - I know we might have to recalibrate the tach. It is a VDO unit (I think).






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