Should propane selenoid valve be on starter battery?

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R

Rubyp

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Jun 28, 2019
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Fluid Motion Model
C-302 C
Hull Identification Number
13105G617
Vessel Name
ruby p
Had draining starter battery at anchor because of operator error. TURN OFF PROPANE RIGHT AFTER YOU USE COOKTOP!!
THAT IS WHAT THE SAFTEY SYSTEM IS FOR. Aging AGM batteries, 2016 R31S and inattention saved by parallel switch till I figured it out.
 
yeah its a known thing. always turn this off ASAP
 
So as a safety feature the solenoid valve is powered by the start battery because the house batteries are more likely to be run down and if it was powered by the house the safety shut off system wouldn’t work. Because the start battery should theoretically have power then if gas is detected the solenoid would get shut down. But because the solenoid takes 1 amp per hour and the solar system system is 90/10 house/starter it doesn’t take many days on the hook to run the start battery down and then the safety system wouldn’t work or more likely the propane solenoid would simply shut down if there was no power? This make sense? So if the solenoid shuts down with no power then maybe the solenoid being on the house batteries makes more sense? I’m not exactly sure how the system works so I’m not criticizing or offering boatbuilding advice just pondering.
 
What about two batteries for start system? I like the logic, what about the thruster battery. You need the thruster after the engine starts.
 
Actually, the propane solenoid is “normally closed.” Opening the solenoid so that gas can flow means that there is a constant current flow of approximately one amp till the button is pushed to turn the gas off again. So it is failsafe in the sense that if a wire breaks or the battery voltage gets too low (whether it is your house bank or your crank battery), the solenoid simply will not open. I couldn’t think of a good reason to leave it on the crank battery (I always want to be able to rely on that getting me started) so my solenoid is now switched over to the house bank.
 
That sounds like a very good idea. I have also been wondering about a couple of related battery diminishing possibilities, namely: (1) When the propane solenoid switch is off there is still a green light on. Significant?
(2) The carbon monoxide sniffers are always on. What is their current draw & from which battery?
 
The current draw of CO detectors is insignificant for all practical purposes. The latest ones draw <4mA. So a single 110 amp hour battery could theoretically power it 24/7 for 1-1/2 years before being depleted to half its capacity. (Of course, you would want to recharge the battery long before that even if there were no external current drain.) The propane fume detection circuitry, including the little green indicator LED, draws 55mA in its resting state. This is still a small draw, but more than an order of magnitude greater than the CO detector. By comparison, that same 110 amp hour battery could power it for 6 weeks before reaching 50% depletion. Since my battery banks never go more than a week before being recharged - whether we’re cruising or moored - I don’t give consideration to those things or the other tiny LED indicator lights here and there, but focus on judicious use of the major systems. Like the refrigerators, interior and exterior lights, Webasto ignition and fans, Chartplotter, stereo, inverter (it draws power even if nothing is plugged into it), recharging electronic gear through the house bank (phones, iPad, headsets, vacuum, portable radio, etc.), and yes, remembering to turn the solenoid off when not in use.
 
Thanks for that very detailed explanation of current draw for those devices. I tought the draw might be in mA's. And I see that the carbon monoxide detectors draw from the thruster battery. After a bad starter battery experience with the propane switch being left on while at anchor for a few days, we now religiously turn it off after using the stove - and run the engine for an hour after the 2nd day on the hook.
 
Once more... turn off everything you can think of. Then at the house battery side clamp the positive lead and measure the current being drawn from the house side. This would be your scavenger current used by all the things like monitors and items like radios and plotters that when off are only in standby and use some current. To be absolutely certain that all things are off put a switch on this line and when off you can be sure everything is off! You can decide if you want the bilge pump to be located on the battery post or after the switch.
 
We did the same thing our first time at anchor when our boat was new - depleted our crank battery by leaving the solenoid on for a few days. I didn’t realize that it drew power while it was on. Lesson learned. But I still didn’t like the fact that it was connected to the crank battery. That’s the one I most want to be able to rely on if nothing else works. IMO, that’s what the ACR’s are mainly for - to isolate your “mission critical” battery when the other batteries are being drawn down. So the solenoid is now on our house bank.

Incidentally, if you run your engine to charge the batteries, I have been told that the Volvo diesels do not like idling for very long. I specifically asked about this at a Volvo seminar during a previous rendezvous. The Volvo guy said it was ok to run the engine to charge the batteries but suggested bumping the rpm up to 1500. That was for our D4 but I suspect the D6 is similar. We also got a Honda 2000 generator which we can use to charge the batteries without putting engine hours on the main engine.
 
I also drained my starter and was convinced I had a parasitic draw or that my starter was somehow getting linked to the house. Thanks to this forum discovered it was the solenoid... user error!
BUT I would much prefer to run it thru my house bank then the starter. Does anyone know where the wire terminates and/or the best way to reroute the system through the house bank?
 
tdellaviola":12wwffio said:
I would much prefer to run it thru my house bank then the starter. Does anyone know where the wire terminates and/or the best way to reroute the system through the house bank?
Click to expand...

Our boat is an R-31 but yours may be wired similarly. There is a small fuse block under the cockpit sink with a red feeder cable labeled “Engine fuse block.” There is an output wire from the fuse block labeled something like “stove switch.” Take out the fuse and see if that makes the green indicator light go off on your propane solenoid switch. If so you’ve got the right fuse block. You can detach the far end of that red feeder cable and reattach it to the switched side of the “House bank” battery switch. Since it is now no longer the “engine fuse block,” you should probably relabel it so, way down the line, you or someone who comes after you doesn’t get confused.

One other issue: you may find that the wire to your battery meter also goes to this fuse block. If so, you will need to detach it and run it to the engine battery positive side. You could pick this up at the engine battery switch in the same under-sink compartment. If your boat is wired the same way as ours, and that wire doesn’t get switched back again to the engine battery, you’ll be reading the house bank when your meter says it’s reading the engine battery. To comply with code, you should make sure the battery wire is fused - 1 amp or even less would be fine.
 
Shano":3g9x9hwo said:
So as a safety feature the solenoid valve is powered by the start battery because the house batteries are more likely to be run down and if it was powered by the house the safety shut off system wouldn’t work. Because the start battery should theoretically have power then if gas is detected the solenoid would get shut down. But because the solenoid takes 1 amp per hour and the solar system system is 90/10 house/starter it doesn’t take many days on the hook to run the start battery down and then the safety system wouldn’t work or more likely the propane solenoid would simply shut down if there was no power? This make sense? So if the solenoid shuts down with no power then maybe the solenoid being on the house batteries makes more sense? I’m not exactly sure how the system works so I’m not criticizing or offering boatbuilding advice just pondering.
Click to expand...
Great pondering! So if I don't use the propane how do I disconnect this. Just pondering

Jim
 
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