Here's a good rundown on the Hitachi alternator, and the 'super-dumb' regulator they utilize:
https://marinehowto.com/automotive-alternators-vs-deep-cycle-batteries/ You might want to consider changing your setup so that the alternator charges directly to the house bank. Your house battery is going to have far more potential to be deeply discharged than your start battery. And take the opportunity of replacing alternator to make sure you have the battery banks fused properly, and consider doing so for your starter circuit as well, and a disconnect switch mounted between alternator and battery bank. On Sun, Aug 13, 2017 at 8:54 AM, Dave S via CnC-List <cnc-list@cnc-list.com> wrote: > Thanks matti and graham- > Seems like a fairly routine failure, and it looks like I can order a > replacement fairly inexpensively and then rebuild the existing as a spare. > Any sort of upgrade seems to be of limited benefit. > Added to my project list: convenient test probe sockets for each bank to > plug in a vom for troubleshooting purposes. > Thanks > Dave. > > Sent from my iPhone > > On Aug 13, 2017, at 6:09 AM, Matti Airas <mai...@iki.fi> wrote: > > Hi, > > I just had a similar charging issue. The motor is a Yanmar 3gm30f. The > alternator was not original. With Nigel Calder's "Boatowners Mechanical and > Electrical Manual" (highly, highly recommended!) I was able to trace the > issue to a faulty charging regulator. We weren't close to home at the time, > so I had call in a boat electrician to have it replaced. He just replaced > the old alternator with a little-used second-hand Hitachi one. Couldn't > really be picky at that point. > > As far as I understand, with ACRs, even any automotive charger from a car > parts store would do, as long as it mechanically fits and the RPMs are in > the correct ballpark. With your biggish house bank, you might want to get a > slightly heftier alternator while at it. > > Cheers, > > Matti > C&C 36 "Hurma" > Helsinki, Finland > > > On 13 August 2017 at 06:38, Dave via CnC-List <cnc-list@cnc-list.com> > wrote: > >> Good evening all, >> >> A new one on me, my batteries no longer appear to be fully charging via >> the alternator, while they do fully charge via shore power. Specifically, >> the (new) start battery sees only 12.56v while the engine is running, this >> is not sufficient to close the ACR, and the house bank (2 ea, also new, >> group 31 @ 130a/h ea). therefore receives no charge at all. Surprise! >> I believe this means the stock Hitachi 55a alternator is failing. >> Any thoughts on this and any recommendations on a replacement alternator? >> >> Thanks! Dave. >> >> Windstar, 33-2 with yanmar 2gm20 >> >> >> >> Sent from my iPad >> _______________________________________________ >> >> This list is supported by the generous donations of our members. If you >> wish to make a contribution to offset our costs, please go to: >> https://www.paypal.me/stumurray >> >> All Contributions are greatly appreciated! >> > > > _______________________________________________ > > This list is supported by the generous donations of our members. If you > wish to make a contribution to offset our costs, please go to: > https://www.paypal.me/stumurray > > All Contributions are greatly appreciated! > >
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