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ddp 08-18-2008 12:10 PM

High-output alternators
We're new owners of a 1999 PSC40. As part of our DC overhaul, we'd like to add a 2nd high-output alternator for a 4x 4D AGM house bank and isolate our existing Hitachi 80-amp alternator to charge a Group 27 or 31 AGM cranking battery. The local shop is recommending an AmpTech 125, but I originally wanted to use a much beefier Balmar. However Yanmar apparently doesn't recommend adding a dual-pulley to our 4JH2-TE engine, so that leaves out all of the 9x series Balmar.

Does anyone have any experience or recommendations on this topic?

camaraderie 08-18-2008 12:58 PM

I suggest you replace your Hitachi with the Balmar and keep the Hitachi as a spare. Dual pulleys and high side loads on the ENGINE bearings that result are not good for small diesels. You mitigate this somewhat with dual alternators as close to 180 degrees opposed as possible but there is NO need for a separate alternator for the starter only as VERY few amp hours are used in starting...high amps for a few seconds do not matter much and you can either get a dual output regulator (3 stage of course) or simply echo charge the starter battery. We did 4x8d's and a starter battery with a single 110A Balmar and it all worked out fine. You will have approx. 300ah's available for house amps and this means you will run your engine for 2-3 hours every 2-3 days to get back to 90% charge levels given a 100-150ah per day use.
Of course this is not good for your engine but many do it and alternatives are quite expensive. A lot depends on your cruising plans and how many years you plan to be out for.

LittleWingCA 08-18-2008 02:34 PM

On my Orion 27, I use an echo charger off of the main house bank to charge the starter battery as needed. This keeps the two banks isolated, and charges the starter battery when needed. I agree, you probably don't need a alternator just for charging your starter battery.

niftynickers 09-06-2008 03:28 PM

On our C37 NiftyNickers we have a Beta 37.5 hp engine which I ordered with dual pulleys to drive a Balmar 140amp alt. for the hse batts and I use the 65amp stock Beta alt to charge the Optima start batt.-Using a parallel switch I have the ability to charge either bank with either alternator if one alt should quit.Redundancy is GREAT.The Balmar is mounted on a bracket which we fabricated from 1/4" steel below the crankshft pulley and in front of the oil pan.The bracket is attached to the front engine mount bolts.
Dianne and Chuck Burke S/V NiftyNickers C37 #139

arisatx 09-07-2008 12:00 PM


I don't profess to have any expertise in this area but had these posts bookmarked for future reference:

Dual Alternator Ideas:

SSCA Discussion Board :: View topic - Yanmar 4JH4 second alternator kit for sale

Mack Boring sells the Yanmar kit on page 9:

Fellow forum member Halekai36 has a cool website of his boat projects including upgrading his Hitachi to a Leece-Neville


ddp 09-08-2008 09:24 AM

I decided to take the advice here and just go with a single 140-amp AmpTech. The hot specs have it slightly better than the equivalent Balmer and the local folks told me that Yanmar was recommending the AmpTech 125 for my particular engine, so this is just a little beefier than that. I have a Xantrex Freedom 20 onboard, so I'm going to use the echo charger that's built into it and I'm installing a Link 2000R for the AmpTech.

sachemgfp 09-13-2008 12:09 PM

Link Installation
Would be interested to see your link 2000 installation. If you have any pics you could sent to me.

arisatx 09-14-2008 09:39 AM

How is your single working out?

I came across some more info on the dual alternator kit for the Yanmar, so I thought I'd post it here for future reference.

There is a kit offered by Peter Kennedy Yacht Services.

ddp 09-17-2008 10:23 AM

sacemgfp, what are you wanting to see? How the display was mounted? I completely cheated in that there was an existing Xantrex battery monitor already installed which turned out to be the same size as the 2000R display. I'm happy to show you how it came out though but I can't PM until I have 10 posts. Sigh. I'll try to remember to take a picture today and see if I can post it to the member gallery...

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