The little Black Box

Ken · Post by **Ken** » Thu Jul 24, 2008 7:29 pm

What does the little black electrical box do. I know that it works some what like a battery switch. The boat surveyer told me that I should take it out and put in a regular battery switch. Has anyone done this and if you have how is it done. (should I really do this?)
Thanks

prowlersfish · Post by **prowlersfish** » Thu Jul 24, 2008 9:34 pm

Ken if its the box I think it is It has relays in it used for jumping the Batteries . it works when you use the the emergency start switch (also can be called the parallel switch) I have both the battery switch and the "black box" its nice to be able to jump one battery and not even open the engine hatch .I would not remove it .

g36 · Post by **g36** » Fri Jul 25, 2008 7:46 am

i still have mine and it is very handy as prowlersfish said did the survyeor give some reason as why he thought it should be removed? mine also has the circuit breaker for the head installed on it.

Ken · Post by **Ken** » Fri Jul 25, 2008 2:48 pm

He said that the box has a high rate of failure and that it could cause problems. Is there any away to isolate my boat systems (refrig., light ect)from my starting batteries. I'm not always on a dock with shore power and I don't want to sacrafice starting power if I can avoid it.
Thanks

prowlersfish · Post by **prowlersfish** » Fri Jul 25, 2008 5:30 pm

high rate of failure ? I dont think so can you post a photo so I can see if we are talk about the same thing .

g36 · Post by **g36** » Sun Jul 27, 2008 10:42 am

if its what were thinking its basically a 12v solenoid in the box and a pushbutton switch in the dash, something that if bad is changed out very easily, its sure something i think is great when needed. test it occasionally to just verify operation youll here the solenoid click. you could also check with a multimeter if you wanted.

rickalan35 · Post by **rickalan35** » Sun Jul 27, 2008 10:08 pm

Men,

Please explain this black box situation again.

Do I have one of these black box's on my '74 Tricabin? If so, I haven't seen it.

I do have a small red pushbutton on the "left vertical side" of the helm.... what is that for? I've never pushed the darn thing. I always though it was some sort of fuse.

Rick

obeejr · Post by **obeejr** » Mon Jul 28, 2008 7:55 am

The little black box (or, in my case, gray) has solenoids which combine both port and starboard batteries for starting. According to my owner's manual, it operates every time you hit the starter switch.

If one battery is completely dead, the solenoid won't be energized and the good battery won't be hooked into the starting circuit- hence the switch on the dash, which has two "on" positions. By trying it both ways, you can alternate which battery powers the solenoid, and jump start the engine with the dead battery from the running engine.

g36 · Post by **g36** » Mon Jul 28, 2008 10:57 am

on my 78 f32 my lower helm as switch labeled emergency start. it is a momentary switch meaning it only makes as i hold the switch this is the only time that my batteries are paralled they are not automatically paralled when i start my engines. i may be wrong but i doubt that the manufacturer wired a solenoid to automatically parallel each time a engine is started. sounds like someone may have added something, but you may know better than me. this is definetely a nice thing to have but over the years previous owners may have wired this in different ways. rick if you will open your engine compartment and if it is quiet and push the red button you may be able to here the solenoid make, that may help if you cant seem to locate it. just a thought.

Ken · Post by **Ken** » Mon Jul 28, 2008 8:47 pm

I took pictures but I can't get them on this page. The black box is in my engine compartment. It has two red resets on it and both of my batteries hook into it on opposite sides. I then have my two power leads that go to my solenoids on each motor. My boat survey guy did say that it was part of my emergency engine starting system. It is used in combination with the two emergency switches located on my lower helm station. I hope this clarfies what I am talking about. I will continue to try to load pics. My boat is a 1979 F28.

obeejr · Post by **obeejr** » Mon Jul 28, 2008 10:06 pm

g36-

According to my Trojan owner's manual, the solenoids combine the batteries every time you start an engine. If it is in the manual, it must be stock.

As I explained in my earlier post, the emergency start switch on the dash allows the energizing of the solenoids by either battery. This is necessary because a dead battery can't energize the solenoids, so it can't automatically parallel in the second battery. The two way momentary contact switch allows you to select which battery is used to energize the solenoids. You try it one way, and if that doesn't work you try it the other way.

Eddie-O · Post by **Eddie-O** » Tue Jul 29, 2008 12:06 am

Obeejr that what i read in my owner's manual for my 77 f32 the switch is used to change the coil voltage of the solenoid from the low battery to the good battery so that the relay can parallel the batters when either eng. is started
Eddie-O

rossjo · Post by **rossjo** » Tue Jul 29, 2008 12:21 am

Where is this black box? Previous owner must have removed mine ....

TADTOOMUCH · Post by **TADTOOMUCH** » Tue Jul 29, 2008 7:28 am

Mine sits right behind both battery boxes between the engines.

Ken · Post by **Ken** » Tue Jul 29, 2008 7:22 pm

Where can I find an owners manual. I bought my boat on e-bay and it did not come with one. 1979 F28.

Trojan Boat Forum

The little Black Box

The little Black Box

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black box

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