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From: (no name) (no email)
Date: Fri Apr 25 2008 - 13:45:10 EDT
Currently we have 100A Balmar alternaters on our Lehmans (don't recall the model number) that have been rebuilt a couple of times. Our battery bank is 1245Ah, so we're short on the 25% rule of thumb (charging capacity = 25% battery capacity) - 300A vs 200A. However, we typically try not to draw down more than 50%, and usually make long runs so figured it wouldn't be an issue.
Last summer we encountered some circumstances that are making us look at our charging system again. We were burning through Ah faster than expected overnight - some load investigation determined that the nasty culprits were our 110v ice maker on inverter (keeping our chest cooler happy with ice) and the heater (September in the PNW can still mean cold nights :)). No problem, we thought, it's a long leg ahead today.
Turns out that our electrical consumption while underway was such that very little was getting into the batteries, most of the available amps were going to loads. Further, it appeared that though the batteries were quite low, the alternators were only chugging along at 50A each or so (based on separate ammeters on the alternator outputs) rather than 80, 90 or (gasp) 100A. The regulators are Balmar MC-612, paralleled through a Balmar Centerfielder.
So that's the backstory, the upshot is we want to increase our alternator output.
One question I have is whether the current alternators are shot - I never see them registering 100A (or even 80-90A) output, which means either the ammeters are inaccurate (they're "homemade" by the previous owner - a shunt matched to a large scale VM), the alternators aren't putting out rated current, or the regulator isn't "asking" for the rated current during the bulk phase. Given that the alternators have been re-wound a couple of times, I suspect them over the other options. However, I do plan to replace the current ammeters with commercial units for piece of mind (and remote viewing, but that's another matter).
I've considered the possibility that the current alternators are good, but are getting de-rated due to heat. However, if that were the case I'd expect to see them start off @ high current and then back off as they get hot.
That leads to replacement options.
Our Lehmans don't have a double belt pulley, and we've been advised by a local Lehman guru (Norm @ Pat's Marine) that putting one on would be a "bad idea" because of additional stresses put on the water pump (if I'm recalling the reasoning correctly). Anyone out there have good/bad experiences with putting a double-belt pulley on the 120?
Assuming that is true, that leaves us with small-frame. I saw one note recently about Zena 150A alternator running on single belt - anyone else have good experience there? Seems like a good option - continuous duty (less likely to burn up the alternators, as we'll still be on the low side of the charge equation) and higher capacity (an extra 100A across the two). What about another Balmar? Not sure if we've had bad luck with ours recently due to poor rebuilds or initial poor design/quality. Are they truly continuous duty?
Thanks for any ideas or experiences shared!
-- Jason Pringle M/V Shibui - 50' OA Mk I www.quartermasteryacht.com _______________________________________________ http://lists.samurai.com/mailman/listinfo/trawlers-and-trawlering To unsubscribe or modify your subscription options (get password, change email address, etc) go to: http://lists.samurai.com/mailman/options/trawlers-and-trawlering Trawlers & Trawlering and T&T are trademarks of Water World Productions. Unauthorized use is prohibited.
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