Carver Owners Forum

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So, on this new-to-us 2004 466, 'discovered' this Newmar box mounted on the forward engine room bulkhead, switched 'off'.

Previous owner says he has no idea what it is! I'm wondering if any other Carver owners might have one onboard & can enlighten me.

It says it is a DC-to-DC converter, and the labeling seems to indicate it steps up 12v to 24v at 6 amps, doesn't it?

I thought it might be somehow related to charging the 24V thruster battery bank from an engine alternator - but can find no wiring connections to support that theory.

(And, I also learned in the process btw - the thruster battery bank does not get charged when engines are running! Only when generator is running or shore power connected, and the thruster battery charger is powered on [:-( )

The two 2-conducter cables that connect to this Newmar box run off into wire bundles and I haven't been able thus far to completely trace them out, except to see that one runs forward & one runs aft.... No DC voltage registers on the box terminals with engines not running.

So while this is an ongoing search, thought I'd ask to see if others recognize this and possibly have one in use that you could describe. Any thoughts would be greatly appreciated!

Thank You....

Some online references pointed that is used to power "communication/ navigation equipment, on negative ground systems. Ideal for powering voice, data and navigation transceivers in mobile and marine applications".

Maybe as a voltage stabiliser, to reduce interference with communication devices?

Tbw5959 wrote:Source of the post I thought it might be somehow related to charging the 24V thruster battery bank from an engine alternator - but can find no wiring connections to support that theory.

(And, I also learned in the process btw - the thruster battery bank does not get charged when engines are running! Only when generator is running or shore power connected, and the thruster battery charger is powered on [:-( )

That is a reasonable conclusion.....if your thrusters are the only 24volt hardware on board. Like a lot of things, there is no free ride maybe it worked at some point but not that well and was abandoned or they just did not notice the failure then sold the boat.....keep following wiring and it should explain itself.

I know there used to be a bunch of Raytheon nav equipment that ran on 24vdc. IIRC there was a converter like that to run the radar array.

Thanks Gents, appreciate the inputs.

The nav equipment, including a Raymarine radar, is original equipment on the boat and all operates normally.

Now I'm starting to wonder if maybe this Newmar box is related to or was used by the satellite phone/tv system the original owner had installed, way back (unfortunately the owner is long gone now, and no subsequent owner used that equipment).

When you write "No DC voltage registers on the box terminals with engines not running", did you mean to imply that there IS voltage there when the engines are running?

If there IS voltage there when the engine(s) are running, but NOT when the genset or shore is available, then that would (obviously) mean that device is sourced from the engine electrical (are both your diesels 12V motors?). That would suggest they were using that to charge a 24V system (the thruster) while the engines were running.

When the DC-to-DC converter is running, what is the actual output voltage? If you measured exactly 24VDC (+/- .5 or so), then it was likely for running some type of equipment. If it was more like 25.2 to 28VDC then it was used to charge/recharge a 24V battery system.

Thanks km1125. I need to get down there & measure voltage on the terminals with the engines running. Will do soon. What I did do previously - was check the voltage on the thruster battery bank with the engines running -- and saw no difference vs their voltage when not being charged by the shore power AC charger -- and that was with this DC-to-DC converter box switched 'on' and 'off' -- no difference.

I also pulled out the 2 fuses in the Newmar box & checked them, they were fine. And noted the 'On' indicator light on the box doesn't light up, with engines on nor off....

Tbw5959 wrote:Source of the post
...I also pulled out the 2 fuses in the Newmar box & checked them, they were fine. And noted the 'On' indicator light on the box doesn't light up, with engines on nor off....

Whereever that feed comes from, the wire should be protected with a breaker or a fuse.

One thing that you could do -as a test- is remove the "input" DC wires from the box (and tape them so they don't short anywhere) and run some temp wires from any 12VDC source (could be existing batteries on the boat, or even a portable "jump start" box if you have one of those) directly to the Newmar box to see if the light comes on. If it does, then again check the output voltage and see what you have. If you have >25.2 then recheck the bow thruster batteries to see if that is charging them.

Tbw5959 wrote:Source of the post I also pulled out the 2 fuses in the Newmar box & checked them, they were fine. And noted the 'On' indicator light on the box doesn't light up, with engines on nor off....

It may as simple as the box is just no good, internal fault.