H340 1-2-Both Switch

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Nichole340

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Jan 12, 2019
101
Hunter 340 Narragansett
My 2000 Hunter 340.....1 - 2 - Both Switch seems to be acting up. Twice now, the number 1 side (start battery) has just shut down. This shuts off all the power to the main panel and anything that's running.
So far it was just my fresh water pump as I was testing the system after the new installed water heater.
The number 2 and Both sides work as they should. I usually start the boat on 1 and then switch to Both.
And to be honest, I usually forget that I'm on Both when I leave the boat and simply start the boat from there.
Any ideas as to why only one side is acting like this?
Thank you for the input.
 
ggrizzard

ggrizzard

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May 27, 2004
1,972
Hunter 30_74-83 Ponce Inlet FL
Corrosion on the contacts or loose connections on the back side of the switch or battery terminal would be my first check. Any fuse blocks in the circuit?
 
N

Nichole340

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Jan 12, 2019
101
Hunter 340 Narragansett
There are two I believe. I'm going to get a photo of the switch, but if my memory is right there is a 50 amp any maybe one other.
The switch feels as tight as it always did when turning it so I don't think it's the knob itself.
 
Last edited:
peacheykeen

peacheykeen

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Dec 8, 2013
33
Hunter / Aragosa 34 / 32 831 Toronto
IF the batteries are electrically separate, not only check the battery posts for corrosion but the ground point also..
 
Ward H

Ward H

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Nov 7, 2011
3,649
Catalina 30 Mk II Barnegat, NJ
Nichole340 said:
The switch feels as tight as it always did when turning it so I don't think it's the knob itself.
Click to expand
Battery selector switches are pretty durable so a bad switch is unlikely.
As the others have said, check for a loose or corroded battery cable connection at or from the #1 battery.
The fact that it is not happening in the Both position really doesn't tell you anything because the #1 battery could drop out and you wouldn't know it because the #2 battery is connected.

We don't know what you have for a #2 battery bank but most likely it will start your engine fine. Try using #2 for a while to see if that drops out. If it does your problem is with a connection common to #1 and #2. If not, the problem is somewhere in the #1 side of circuit.

Here is a link to a good explanation of the battery selector switch with different wiring diagrams and methods to use the switch.
https://forums.sailboatowners.com/index.php?threads/1-both-2-off-switches-thoughts-musings.137615/

If you are not used to trouble shooting marine DC systems, you might want to enlist a dock neighbor who does have experience.
If you want to DIY, pick up a volt meter, learn how to use it and continue to ask your questions here.

Let us know how you make out.
 
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AlexB

AlexB

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Aug 9, 2016
37
C&C 36 Great Kills harbor.
Nichole340 said:
My 2000 Hunter 340.....1 - 2 - Both Switch seems to be acting up. Twice now, the number 1 side (start battery) has just shut down. This shuts off all the power to the main panel and anything that's running.
So far it was just my fresh water pump as I was testing the system after the new installed water heater.
The number 2 and Both sides work as they should. I usually start the boat on 1 and then switch to Both.
And to be honest, I usually forget that I'm on Both when I leave the boat and simply start the boat from there.
Any ideas as to why only one side is acting like this?
Thank you for the input.
Click to expand
You are not suppoused to switch, when engine running, read manual. with simple test ligth you can pinpoint trouble spot and fix it.
 
N

Nichole340

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Jan 12, 2019
101
Hunter 340 Narragansett
Ward,
That was a great article on wiring. Thank you for the link. It's now printed and in my folder for future reference.
I found that I had corrosion on the ground wire post at the switch end. I've since cleaned all the posts/nuts/wires both in the compartment and on the back side in the locker where the wiring from the engine connect. It's just maintenance that you never really do, at least me.
Took to much for granted I guess.

Alex,
I never have switched by going through the Off position. It was always from 1 to Both. I think I better look at that practice also. And just take some days and just charge both banks at the same time while running the engine.

It's a learning process to be sure. Great to have this site and the collective knowledge!
 
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N

Nichole340

.
Jan 12, 2019
101
Hunter 340 Narragansett
I was filling the fresh water tank and opening all the faucets to get the antifreeze out and fresh water through the system. That's when the DC Panel shut off.
The Battery selector was on the Number 1 side, I was running the fresh water pump to pressurize the system. I guess when I said I was testing the water heater it was confusing. But I was checking for leaks, as that is the new connections in the whole system.
Sorry for the confusion.
So, the next time I go to the boat will be a real test to see if all the electrical connections I cleaned are tight and working as they should. The water connections are fine.

I say the next time I go because....the weather here in RI has been awful! Wind (15-25 w/gusts),why not have gusts also, rain, cold. If "they" are going to ruin a day, might as well be all the weather they can throw at us.
They say summer is coming. I'll let you know.
So I am sorry for the confusion, hope this helps clear it up.
Thank you for the help and guidance.
 
jssailem

jssailem

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Oct 22, 2014
21,085
CAL 35 Cruiser #21 moored EVERETT WA
Nichole340 said:
So I am sorry for the confusion, hope this helps clear it up.
Click to expand
No problem.. I am often in a confused state, so say my friends. It sounded to me like you might be testing the heating ability and then your talking about a DC issue. No worries. Happy you found the corrosion and that you are on a path to fun, if the weather would just cooperate.
 
sailme88

sailme88

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Jan 19, 2010
1,171
Catalina 34 Casco Bay
Switching the battery selector between 1,2 and both will not hurt the engine. You can cause alternator damage by switching to OFF when the engine is running.

As for the switch issue, you've been given excellent advise.. I would start with the switch. Inspect the nuts that hold the 2 line feeds ( from a batteries) as well as the load line ( out feed).

I actually have 2 selector switches. Switch 1 for Bank #1 is my starting battery, Switch 2 for Bank 2 is the house.
All nav and electronics are powered by #2. This ensures that should I need to start ( emergency etc) that the radar/chart plotter don't get dumped.

I can charge both banks at the same time by switching to BOTH each switch. I can start or run the house from either bank.
 
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