I read in an archive post a while back where someone had mentioned that a VHF radio should never be wired downstream of the battery isolation switch i.e. when the batteries are isolated, no power goes to the VHF. I did some more looking and could not find a good explanation as to why? Could someone please explain it? It would be nice when I leave the boat for the weekend to flip the isolation switch to off and not have to worry if I accidentally left the radio on and would return to a dead battery. Does it have something to do with the radio electronics? I have read most of Nigel Calder's book "Boatownwers Mechanical and Electrical manual" and I haven't found yet where he indicates not to wire the VHF to the isolation switch. Or is it something more simple like when you are out at sea in a storm and you have an electrical fire and you isolate all batteries to stop it, but now you don't have power to your VHF to call for help? But I suppose if you wired the VHF directly to the isolation switch output (with a fuse of course), you could stop the short causing the fire by opening all your breakers. You would still have power to the radio and any shorted circuit downstream of the breakers would have been removed by opening the breakers. Thanks.
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Jim Covey
Have mine on a switched circuit
I wired mine into an AUX switch on the fuse panel and I shut off all switched except the bilge pump when I leave the boat. Maybe some VHF radios will lose their programming when removed from power? Mine doesn't, I have scanning set to CH 16, the local WX, and our clubs working channel but never lose the scan from memory. That or your theory above would be the only reasons I could think of to have the radio hard wired. Jim Covey
I wired mine into an AUX switch on the fuse panel and I shut off all switched except the bilge pump when I leave the boat. Maybe some VHF radios will lose their programming when removed from power? Mine doesn't, I have scanning set to CH 16, the local WX, and our clubs working channel but never lose the scan from memory. That or your theory above would be the only reasons I could think of to have the radio hard wired. Jim Covey
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Ken Palmer
Good question
I don't remember reading that past post. I also have never heard of having to run the VHF directly to the DC source. Modern VHF radios have memory that doesn't require external battery power to retain the programmed channels in scan, etc. I wired mine through the main battery switch, fused between the switch and the radio. Read your instruction manual on your VHF and see if it has any special installation instructions. Ken Palmer, S/V Liberty
I don't remember reading that past post. I also have never heard of having to run the VHF directly to the DC source. Modern VHF radios have memory that doesn't require external battery power to retain the programmed channels in scan, etc. I wired mine through the main battery switch, fused between the switch and the radio. Read your instruction manual on your VHF and see if it has any special installation instructions. Ken Palmer, S/V Liberty
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Tom Ehmke
VHF radio wiring
Anthony, There are at least two issues here. One is safety and the other is electrical noise interference. The radio should never be directly wired to the battery w/o an inline fuse. One reason for directly wiring to the battery using an inline fuse is to reduce interference from other onboard AC electrical or electronic equipment. OK as long as the line is fused. Wiring the radio through the breaker panel serves the same purpose as far as safety goes, but then you may have to deal with interference from other devices wired into the panel. There are ways to reduce that interference at its source by using capacitors which will cause AC current to flow to ground while allowing DC current to flow w/o interference through the system. My hunch is that most boats have a hybrid wiring system composed of both in-line fuses and a breaker or fuse panel FOR SAFETY. For NOISE SUPPRESSION there are capacitors on some equipment but probably not all. Safety first, then deal with noise interference and suppression or elimination. Which is better for the VHF radio? My radio is wired to the battery through the battery switch. If I turn the battery switch off when I leave the boat, all systems except the bilge pump are off. If I shut off all the breakers (SOP) the radio circuit is still active and it could still be on so I always check it. By the way I sometimes hear interference from the depth sounder on the FM radio. Although the FM radio is also wired direct, the transducer cable for the depth sounder passes behind the radio in its cabinet. Always something... Now I have a question. Does anyone reading know what the ABYC recommendations are for wiring, i.e. does it recommend that everything be wired through the panel?
Anthony, There are at least two issues here. One is safety and the other is electrical noise interference. The radio should never be directly wired to the battery w/o an inline fuse. One reason for directly wiring to the battery using an inline fuse is to reduce interference from other onboard AC electrical or electronic equipment. OK as long as the line is fused. Wiring the radio through the breaker panel serves the same purpose as far as safety goes, but then you may have to deal with interference from other devices wired into the panel. There are ways to reduce that interference at its source by using capacitors which will cause AC current to flow to ground while allowing DC current to flow w/o interference through the system. My hunch is that most boats have a hybrid wiring system composed of both in-line fuses and a breaker or fuse panel FOR SAFETY. For NOISE SUPPRESSION there are capacitors on some equipment but probably not all. Safety first, then deal with noise interference and suppression or elimination. Which is better for the VHF radio? My radio is wired to the battery through the battery switch. If I turn the battery switch off when I leave the boat, all systems except the bilge pump are off. If I shut off all the breakers (SOP) the radio circuit is still active and it could still be on so I always check it. By the way I sometimes hear interference from the depth sounder on the FM radio. Although the FM radio is also wired direct, the transducer cable for the depth sounder passes behind the radio in its cabinet. Always something... Now I have a question. Does anyone reading know what the ABYC recommendations are for wiring, i.e. does it recommend that everything be wired through the panel?
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Bill Lucin
Safety First in an Emargency
Anthony I have my VHF connected directly to my battery with an in line fuse for electrical safety. I feel that if you need your VHF to call for help in an emergency situation the last thing you want to be doing is looking for a switch to turn the power on. Seconds can count if you need to get a call for help off during a disaster. As for leaving the radio on and killing you battery I can understand your concern. (speaking from experience) I have generated a simple checklist which I am now in the habit of using. The list consists of only the "not so obvious" items that I have found I tend to forget when leaving the boat. Bill Lucin
Anthony I have my VHF connected directly to my battery with an in line fuse for electrical safety. I feel that if you need your VHF to call for help in an emergency situation the last thing you want to be doing is looking for a switch to turn the power on. Seconds can count if you need to get a call for help off during a disaster. As for leaving the radio on and killing you battery I can understand your concern. (speaking from experience) I have generated a simple checklist which I am now in the habit of using. The list consists of only the "not so obvious" items that I have found I tend to forget when leaving the boat. Bill Lucin
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Tom M.
Wiring...
Now that you guys mention it, on my breaker panel (h260) there is a bilge pump switch that you can push to the 'manual' side which is a momentary contact switch. I have always assumed that if I turn off the battery switch that I would have no bilge pump power, so I am in the habit of leaving the battery switch on when gone from the boat. I guess that i'll have to crawl back there to the bilge pump and see if it operates with the battery switch off when I lift the float switch. Can't think of any other way to test the theory. On the other hand, I leave the battery switch in the 'on' position to keep the solar panel connected. I have a two battery system with a combiner. I usually switch back and forth between the batteries every couple of weeks or so during the season. Don't know if the combiner works with the solar panel but it does with the engine alternater. Should I have the solar panel connected directly to the battery(ies) and hope the combiner works or what? Wire the batteries in parallel with the panel maybe? What do you think/how does everyone else do it? Please excuse the digression, interesting thread. Thanks. Tom M.
Now that you guys mention it, on my breaker panel (h260) there is a bilge pump switch that you can push to the 'manual' side which is a momentary contact switch. I have always assumed that if I turn off the battery switch that I would have no bilge pump power, so I am in the habit of leaving the battery switch on when gone from the boat. I guess that i'll have to crawl back there to the bilge pump and see if it operates with the battery switch off when I lift the float switch. Can't think of any other way to test the theory. On the other hand, I leave the battery switch in the 'on' position to keep the solar panel connected. I have a two battery system with a combiner. I usually switch back and forth between the batteries every couple of weeks or so during the season. Don't know if the combiner works with the solar panel but it does with the engine alternater. Should I have the solar panel connected directly to the battery(ies) and hope the combiner works or what? Wire the batteries in parallel with the panel maybe? What do you think/how does everyone else do it? Please excuse the digression, interesting thread. Thanks. Tom M.
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Jim Covey
Tom
Tom, I have a H26, if you turn off the battery switch you won't have any power to the bilge pump as it's wired to the fuse panel which is wired thru your battery switch. So, I leave the battery switch on and just make sure I turn off all the switches at the fuse panel. 1st thing I do when we go out is turn on the switches for the radios and depth finders. I wired my solar panel to the "C" position on the battery switch and select A, B or Both when I leave the boat depending on which battery I want to charge. Probably not the best way (without a combiner) but with just a couple of group 27's I figured why get too fancy. Jim Covey
Tom, I have a H26, if you turn off the battery switch you won't have any power to the bilge pump as it's wired to the fuse panel which is wired thru your battery switch. So, I leave the battery switch on and just make sure I turn off all the switches at the fuse panel. 1st thing I do when we go out is turn on the switches for the radios and depth finders. I wired my solar panel to the "C" position on the battery switch and select A, B or Both when I leave the boat depending on which battery I want to charge. Probably not the best way (without a combiner) but with just a couple of group 27's I figured why get too fancy. Jim Covey
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Tom M.
Thanks Jim,
I though that was the case with the bilge pump. Sounds like we have similar set-ups (two gp 27 batts) however my battery switch has only A-B-BOTH. Also sounds like we have the same arrive/leave procedures too. Guess I'll just keep doing it that way. Thanks again Jim. Tom M.
I though that was the case with the bilge pump. Sounds like we have similar set-ups (two gp 27 batts) however my battery switch has only A-B-BOTH. Also sounds like we have the same arrive/leave procedures too. Guess I'll just keep doing it that way. Thanks again Jim. Tom M.
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Tom Ehmke
To Tom from Tom
Tom, I've had a WM C-50 battery combiner onboard for a couple of years. As long as the leads are properly hooked up to the battery, it doesn't matter what the charging source is. I have an AC charger hooked up along with the alternator, and the combiner works fine. I would think that the same would be true for a solar panel. The combiner simply determines which battery needs the charge and diverts it from the source. My mistake has been, at times, to leave the battery switch on at the "both" setting. This means that the batteries are paralleled, and if one of them has a bad cell, it will draw the charge off the good battery. The batteries will eventually BOTH discharge, and the surprise comes when, after being gone for only a short time, the engine battery won't start the boat,and there is no reserve capacity from the house battery. Lesson: 1) Check your batteries 2) Turn the battery switch to the "off"position when you leave the boat, or 3) if that's not workable, leave the switch at 1 or 2 to operate on board systems that you may need. I learned this lesson the hard way by having to carry my car battery on board a few times to start the engine. Come to think of it, sometimes the lessons learned REALLY well generally come from EXPERIENCES that are a pain in the a--!! Happy Holidays Tom
Tom, I've had a WM C-50 battery combiner onboard for a couple of years. As long as the leads are properly hooked up to the battery, it doesn't matter what the charging source is. I have an AC charger hooked up along with the alternator, and the combiner works fine. I would think that the same would be true for a solar panel. The combiner simply determines which battery needs the charge and diverts it from the source. My mistake has been, at times, to leave the battery switch on at the "both" setting. This means that the batteries are paralleled, and if one of them has a bad cell, it will draw the charge off the good battery. The batteries will eventually BOTH discharge, and the surprise comes when, after being gone for only a short time, the engine battery won't start the boat,and there is no reserve capacity from the house battery. Lesson: 1) Check your batteries 2) Turn the battery switch to the "off"position when you leave the boat, or 3) if that's not workable, leave the switch at 1 or 2 to operate on board systems that you may need. I learned this lesson the hard way by having to carry my car battery on board a few times to start the engine. Come to think of it, sometimes the lessons learned REALLY well generally come from EXPERIENCES that are a pain in the a--!! Happy Holidays Tom
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