My Yanmar died and I've ordered a Beta-25 to repower. The Beta-25 will be delivered with a 75A alternator. I understand this alternator cannot be modified with the brush box for external regulation. I have an existing Balmar 614 external regulator that I would like to use to charge my AGM battery banks (currently 220AH house and 80AH starter). What other alternators are available (75A or greater) that either come with external regulation or can me modified for external regulation and will fit the Beta-25?
With such a tight fit on the Beta-25 alternator, I expect my existing alternator off the Yanmar will not fit with enough clearance to the rear terminals. Without dimensional drawings for the Beta, I'll have to wait until it arrives to see. The existing alternator is a CMI-80-ER (a custom high performance 80A alternator from Compass Marine International with a case similar to the Hitachi LR180 series with Yanmar 3.15" saddle mounts).
As for the 75A alternator that will be delivered with the Beta-25, I plan to keep it as back-up when I head off-shore. With internal regulation, it will be a good backup in case of failures with either the alternator or regulator.
Until the guru checks in.... I would point out that besides the 75 amp option, there is a 120 amp option for this engine. I installed a new Betamarine25 in our boat last year, and did go with the 75 amp alternator. upgrade
Our house bank is rated at about 235 ah, and consists of two large GC flooded batteries. Our emergency bank is a single AGM 12 volt sealed battery.
Perhaps the hassle of adapting your old alternator is on a (rough) financial parity with just paying more for the larger factory upgrade. OTOH, you know what output your storage solution requires and what minimum specs you need to adhere to. And of course you know what you want for back-up.
Good luck.
BTW, I have done a lot deliveries in boats with Yanmar's, as well as Universals, and while they all worked well - you will LOVE the peace and quiet of the B-25 engine. Technology has indeed moved forward since my former 1988 Universal diesel was the "latest thing"... !
:)
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40 years of racing, cruising, and deliveries. Enjoying our Ericson-built 1988 Olson 34, #8, since 1994.
Thank you LB-PDX. All good feedback. Yes, I could have (and probably should have) ordered the 120A option. I was thinking I could just re-use my existing alternator by adding a K4 serpentine pulley and shims for the mount. After ordering and the Beta-25, and with it on the way, I took a close look at the engine drawings and realized I may not have enough clearance from the alternator to the heat exchanger. It looks to be a very tight fit even with the Beta provided alternators.
I understand the 120A option alternator can be modified with a brush box, so perhaps that is the right answer. I could then use the Balmar 614 regulator belt load manager to lower the stress on the alternator and belt and still have adequate charge capability. A question for the guru... Does (or can) the 120A alternator come with the K4 serpentine pulley and if not, can I just swap the one from the 75A?
I have a 260AH rated AGM house bank that wants bulk charging of at least .2C (52A) and could handle .4C (104A) just fine. I do a number offshore multiple day races each year that stress the bank in deep cycle operation with charging predominately in bulk mode for efficiency. The 120A alternator does sound like a better answer to minimize run time and lower alternator stress. Sounds like I'm talking myself into it.
I am really looking forward to the new Beta 25. The ease of service is also a big plus. No more bruised knuckles changing the raw water impeller!
I suspect that you will find that your current 80 amp alternator will not fit without major modifications to the engine.
However we do have a very good rapport with Balmar and they have devised a way to use the Balmar MC614 regulator with the 75 amp alternator that we fit to the small engines. We do have these kits with instructions in stock here in NC.
The 120 amp alternator needs a 6K belt to get the output from the alternator so this is not easily changed out for the 75 amp alternator.
Thank you Stanley. That sounds like the 75A modification is the best option. I expect it would not be very economical to upgrade to the K6 belts in addition to a new alternator. In hindsight with my intended use, it might have made sense to have ordered the engine with the 120A alternator.
