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Minor disaster averted / brain teaser

Jun 25, 2004
282
Hunter 306 Pasadena MD
In the spirit of NPR's Car Talk puzzler, here's a puzzle for you:

Just started a week-long cruise in which I'll be solo for the first 3 days, before picking up my wife on Oxford, MD. Day 1: Rock Creek (Pasadena MD) to West River (Shady Side, MD). Great sail for 4 hours, wind averaging maybe 12 knots gusting to 22, with some reasonable waves (2-3 feet), but very nice and cool temps. Eventually had to motor into the wind for a few hours. Anchored in W. River with no drama. Today, West River, crossing the bay to go south of Tilghman Island, and then was planning to round the point and come north to Dun Cove. Just as I was getting to the turning point around Tilghman (S to N), I went below and noticed that the new USB port w/ digital voltage readout said something like 12.4V. Now the engine was running all day today, because there was no wind, so it should be more like 13.9 or 14V. Crap! I figured I blew the diode in the voltage regulator. Engine is running like a kitten, but not charging! Minor disaster on the 2nd day of a cruise! The other thing is that I had just now figured out why the (separate) GPS unit which feeds my C80 plotter has been losing fix every now and again for many years. It's very sensitive to voltage, so if the voltage is low, everything else onboard is working fine, but the GPS is unhappy and quits on me.

So I quickly looked up repair places in Oxford, and called Hinckley Yacht Services, which was 2 hours away (gulp: Hinkley). They were great, and promised to fit me in on short notice. The GPS continued to work fine for 1 1/2 hours, despite a battery that was getting weaker. Then the GPS died (no disaster: iPhone backup plotter program, and I'm in the Choptank, so there are day markers). I'm just rounding the corner (N to E to S) to come into Oxford, when I glance down, and see what the problem is. What was it?
 

Mr Fox

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Aug 31, 2017
204
Marshall 22 Portland, ME
I vote yes on smokey73’s answer if, and only if, the position of the key was obfuscated by some inky shadows.
 
Jun 25, 2004
282
Hunter 306 Pasadena MD
Dang it! That's it! The problem is, the key is always on when the engine is running, but every now and then, something hits it (it's in a seatback), and it gets shut off. I eventually looked down and wondered "hey: why is the tachometer showing 0 RPMs when the engine is running beautifully?". I immediately turned it back on and ducked down to look at the voltage meter: it was 13.5 and rising... Called Hinkley to cancel, and they were very gracious about it.

These things are actually a bit complicated, and generally not covered in the manual! For example, I had to figure out using a (portable) voltmeter: are both house and starting batteries always charging when we're on shore power, or does it somehow depend on the battery selector switch? Turns out that they're both charging all the time (and I always leave the battery switch on OFF when I'm not on the boat). OTOH, I was quite aware (from experimenting) that the battery selector switch DOES matter as far as which battery is charging off the running engine. I start it on #1 (the starting battery). Then if I've been at anchor and have run down the battery, I then change it to #2 (going from #1 to both to #2) to charge #2 (the house battery). The engine will bog down as it goes to BOTH, and even more when it goes to #2 (if the engine is only idling), so clearly the switch matters for engine charging. But I had never realized that the on/off switch controlled engine charging as well... And I've had the boat for 15+ years.
 
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Jan 7, 2014
236
Beneteau 45F5 51551 Port Jefferson
Wire the alternator directly to the house (or start) and install an ACR and you won't have the problem
 
Jan 7, 2014
236
Beneteau 45F5 51551 Port Jefferson
An Automatic Charge Relay. When it detects a voltage above a set point ( I think 13 volts or so) it opens a relay to share the charge across the banks. When the voltage drops below a set point it closes to isolate them again. It will share the charging from the alternator so you don't have to remember to parallel the batteries but will never drain the start. I have an inverter bank, house bank and start bank. I never parallel the start unless the start died of old age.

 
Jun 25, 2004
282
Hunter 306 Pasadena MD
An Automatic Charge Relay. When it detects a voltage above a set point ( I think 13 volts or so) it opens a relay to share the charge across the banks. When the voltage drops below a set point it closes to isolate them again. It will share the charging from the alternator so you don't have to remember to parallel the batteries but will never drain the start. I have an inverter bank, house bank and start bank. I never parallel the start unless the start died of old age.

Good to know: thanks. Don't know that I'll do it (sounds like a hard DIY project), but maybe some day. I'd like a battery monitor and a 2nd house battery first. Maybe first I can rig something to protect the key from these inadvertent bumps. A seatback is no place for an engine panel...
 
Jan 7, 2014
236
Beneteau 45F5 51551 Port Jefferson
If both your house and start charge when on shore power regardless of switches but not from the alternator, maybe your charger has dual charging output.?

In June, I pulled my Invertor/charger cause the batteries died after a night on shore power with the charger on. I shipped it off to invertor service center for a repair. They tested it and it worked fine. Turns out I never turned the battery switch to invert/charge when in the marine. I learned my lesson.
 

RoyS

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Jun 3, 2012
1,153
Hunter 33 Steamboat Wharf, Hull, MA
Wire the alternator directly to the house (or start) and install an ACR and you won't have the problem
Not necessarily. His boat needs the key on to excite the alternator. Agree with alternator output to house battery and ACR for start battery.
 
Jan 7, 2014
236
Beneteau 45F5 51551 Port Jefferson
Not necessarily. His boat needs the key on to excite the alternator. Agree with alternator output to house battery and ACR for start battery.
I did not know that about the ignition. I have to check that on my boat. thanks .
 
Jun 25, 2004
282
Hunter 306 Pasadena MD
After mulling this over, I'm thinking the easy(ish) short-term fix would be to make a small, hinged plexiglass panel to cover the hole for the key. Since the key protrudes a bit, I could make a slot at the angle for "on", so the panel would essentially lock the key in place. It would also keep most of the rain off the panel.
engine_panel.jpg
 
Jun 25, 2004
282
Hunter 306 Pasadena MD
Not necessarily. His boat needs the key on to excite the alternator. Agree with alternator output to house battery and ACR for start battery.
Yep: I think the AC powered charger hooks up to the batteries directly, charging each one independently of the battery switch. But the output of the alternator must go through the battery switch, as it only charges the selected battery(s). Separately, the alternator charges nothing if the engine panel key isn't on (apparently).
 
Oct 22, 2014
15,785
CAL 35 Cruiser moored EVERETT WA
If a key is not a necessity than a simple on off switch and a push to start button would seem a simple solution.