bypassing the batteries

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Jun 25, 2004
146
Catalina 310 Hilton Head
Does anyone use a transformer ( I know there is a different word for it in the nautical world and its not an inverter) to bypass their batteries and convert shorepower to DC power?
 

arghhh

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Apr 7, 2010
19
House Boat Seattle
You are looking for a Converter, which in it's most basic form is a DC power supply.

There are quite a few brands out there but if you are going to be running electrical equipment off of one it's always good to get one that has a stable output voltage throughout the load range. If something high load kicks on without batteries in the circuit the voltage could drop very low while it tries to keep up.
 

kenn

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Apr 18, 2009
1,271
CL Sandpiper 565 Toronto
Does anyone use a transformer ( I know there is a different word for it in the nautical world and its not an inverter) to bypass their batteries and convert shorepower to DC power?
The term you're probably after is 12 v DC power supply. I have a few, mostly for temporarily powering a single piece of gear when it's on the workbench.

I cannot think of a situation where you'd need a 12 v power supply on a boat, except if you needed to remove the batteries for some reason. It makes far more sense to simply run the 12 gear from the boat batteries, with a shore-powered charger maintaining the battery charge. :confused:
 
Jan 3, 2009
821
Marine Trader 34 Where Ever I am
I can't imagine any reason to do this either. Having said that, our Iota battery charger will power the 12 volt system without having the batteries connected.
 

arghhh

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Apr 7, 2010
19
House Boat Seattle
A lot of battery chargers are also converters / DC power supplies as well. When you are plugged in they keep the batteries charged and provide DC power for all your gear within a tight voltage range.

I used a 12volt 10 amp bench type to power lights when I was rebuilding my DC system and the batteries were removed. It worked but not very good for long term.
 
Jun 25, 2004
146
Catalina 310 Hilton Head
I am looking at this to help prolong the battery life. Either the batteries are bad or the charger failed and they drained and now can't hold a charge for long. Not even 8 hours running the refrigerator. Until I can tell which is the chicken or the egg, I am using a 6am trickle charger that seems to do the job, but I don't run it when I am away from the boat, just in case. Anyway, ProMariner said not to bypass the batteries using their charger. ( I tested it and it put out 14+v when hooked directly to the line, but once i touched it to the battery it dropped to nothing-someone told me it was a "smart charger" whatever that means. Anyway, now I'm looking to prolong the batteries.
 

kenn

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Apr 18, 2009
1,271
CL Sandpiper 565 Toronto
Hi Butch,

Thanks for the reply.

I believe the general wisdom is that lead storage batteries last longest when their charge is kept topped up, and they are not often discharged heavily - eg more than 50% of their capacity.

It would help if you could tell us the problem you're having that causes you to consider a power supply. In the absence of more specific knowledge... all I can say is that when on shore-power, you need to measure and calculate how much current at 12v your boat is drawing while docked, and then you need to select a charger that can put out more than the above current demand, otherwise your batteries will discharge instead of charging.

I wouldn't call 6 amps a 'trickle' charge, BTW ;) Unless your batteries are really big.
 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
Hey, Butch, how's it cookin'??? Some chargers, my Xantrex for one, has a switch to stop the charging cycle but put out a steady 13.5- in reality a power supply. I gather yours does not have this function. If you hook your charger to the battery and get no charger reading, it may be in the mode to measure battery voltage so it knows how much to put out. Leave the VM hhoked up, and you'll probably eventually get a reading.

Actually, what you want to do makes sense, like if the batteries are removed for the winter but you still want to run the ship's equipment in the back yard- or the dock.

Ken, I wonder if Butch's "6am" was millli-amps, and not amps?
 
May 25, 2004
978
Catalina Capri 14.2 1670 Rochester, MN
DC Power Supply

I added a DC power supply to my boat because all overnight time is spent on shore power and I had a weak battery charger. (Finally replaced that too)

My boat only has one battery. It's used for the house and starting the outboard. Between the DC power supply and the new smart charger, my batter stays in much better health.
 

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Weasel

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May 23, 2004
159
Beneteau 331 Iuka, MS
Re: DC Power Supply

Dave:

Just a friendly suggestion but it would be a safer installation to cover the exposed 110 VAC connections above the blue j-box.
Sail safe!
 
Sep 25, 2008
1,096
CS 30 Toronto
Romex a-no-no

Never use Romex (household wire) on a moving object, i.e. boat.

Romex is single core and will break after repeated flexing. You'll get a nasty report on the next insurance survey. Tined multicore cables must be used in humid especially marine environment. And don't just screw the multicore wire to the 110v terminal. They must be crimped to an eyelet first.

Romex will work itself loose due to hot-cold cycle plus vibration. Then it will be a fire hazard.

Be safe.

Dave:

Just a friendly suggestion but it would be a safer installation to cover the exposed 110 VAC connections above the blue j-box.
Sail safe!
 
Jan 22, 2008
1,483
Hunter 37 C sloop Punta Gorda FL
I have heard akk that stuff about romex. Got the shitgram from the insurance company and am rewiring my 31 year old boat. Haven't found any problems with the Romex. Wonder if it's a conspiracy by wire manufaturers?
 
Nov 28, 2009
495
Catalina 30 St. Croix
Most Marina offices run their VHF from a 12volts DC power supply thats' plugged in to an AC outlet. Is that what you need. Careful of the type of wave it puts out though.
 
Jul 25, 2009
270
Catalina 1989 C30 Mk II Herrington Harbour South, MD
DC power supplies should supply flat voltage, there shouldn't be a wave at all.
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Wintertime boat work

I use my TrueCharge40's 13.6 volt power supply feature after I've taken the batteries home for the winter. Since it connects to the common of the 3 way you just have to turn on the charger circuit breaker to have the 12 volt side come alive. Kinda handy for lighting.
 
Jun 25, 2004
146
Catalina 310 Hilton Head
Re: DC Power Supply

Dave, that looks nice-and expensive-and probably complicated. I'll check out NewMar
 
May 25, 2004
978
Catalina Capri 14.2 1670 Rochester, MN
alexco38,
The Romex you see was installed by my Hunter dealer when the AC power was added to my new boat.

Shore power, AC outlets, FM radio, and battery charger were all dealer options for the H260, not factory original.
 
Jun 25, 2004
146
Catalina 310 Hilton Head
ok...replaced the batteries and now charger is not charging, but it is putting out 14+ volts when I test it with the meter. Someone suggested that maybe its not properly grounded. I assume it is grounded were the batteries are grounded and they are generating current. I'll check this out tonight!
 
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