1984 Vogue II - Can you identify what is in the picture?

[Captrv]

I'm trying to figure out exactly what the three items are in the photos. They are located in the engine compartment and are connected to the batteries. Directly or indirectly, I'm not sure. The cables disappear forward of the engine and run along the frame eventually making their way to these things. I'm pretty sure one of them controls the 'boost'. I have always had an issue with the batteries staying charged for very long as well as I noticed the other day when I turned on the headlights with the engine running, the voltage guage dropped when set on the starting battery. I turned off the lights and back on with the switch on house (Aux), and it dropped as well. It seemed like the lights dimmed as I was driving until I turned on the genset. I know I need to do some voltage checking but I would like to start by knowing what the stuff in the picture probably is and why it is wired the way it is, especially the large heatsink box. I have more questions, but I figure this is a good start. Thanks for any help you can provide.

[tompen]

Top right picture is a diode type battery isolator. Alternator power on the center terminal and chassis battery and coach battery on the other two. The bottom one is a circuit breaker. Not sure what the other one is. Where do the wires go ?

Tom

[Blag]

This doohickey looks like a shunt. (used for measuring current)

Measuring RV Battery Current with Shunts

[Blag]

Some illustrations here on how the shunt is connected and the benefits of fitting them...

Adding Shunts to Batteries

[tderonne]

Originally Posted by tompen

Top right picture is a diode type battery isolator. Alternator power on the center terminal and chassis battery and coach battery on the other two. ...Tom

And, curiously, it looks like there's no wire on the middle terminal?

[Captrv]

Adds to the difficulty of figuring out what's going on here.

[YC1]

On the top right is a diode isolator that probably went bad and that is why no wire on the middle. They pulled it and stacked it on the left. That is also why one of your batteries is not getting charged from the alternator.

To sort things out and identify which large wire goes to which battery bank grab a voltmeter and measure the two outside terminals. Go to the batteries and see which voltage is close to the ones you measured at the terminals. Take a digital picture and print it out so you can start writing things down. Put some simple tags using masking tape on the wires. If you don't do this you will have doubts in a few days.

Now you have that part sorted, start the engine and measure the voltage on the isolator terminals again. On the left one you should see 13.5 or more and probably no change on the right one.

Be sure to write your results down.
Now shut the engine off and plug in the shoreline or start the generator. Measure the voltages on those terminals again.

If you report back that the right terminal has 13.5 or more with shoreline and the left has approx 12.5 volts then simply replacing the isolator and moving the alternator charge line back to the middle will solve a lot of issues.

[YC1]

OK, now for the long black thing. I too think it is a shunt. The first thing that comes to mind is the rv may have had a AMMETER versus a voltmeter at one time.

Measure the voltage on each of the posts. If they are very close to the same the thing is probably ok and the only thing you should do is disconnect your batteries and clean their terminals and while they are disconnected (after you take a picture), remove each of the nuts and wires on all of the terminals on those black devices and shine them up. I will see if I have a handy schematic for the diode isolator to post.

[YC1]

http://www.metrotrekkers.org/utility/electrical.htm

Bottom left shows a diode isolator. It has additional functions but the basic picture is accurate.

[YC1]

The bottom right appears to be a solenoid. Zoom out a bit and take in the whole scene so we can see how they are interconnected. A solenoid is a simple on off switch controlled by a low current wire. That solenoid could be used to combine the batteries while the engine is running or as an emergency start function.

Measure the voltage on the large posts of it. Also measure the voltage on the little terminal. Then start the rv and measure again. Then do the same with generator or shoreline running.

Also clean those posts while the battery cables are off.

[tompen]

Originally Posted by YC1

The bottom right appears to be a solenoid. Zoom out a bit and take in the whole scene so we can see how they are interconnected. A solenoid is a simple on off switch controlled by a low current wire. That solenoid could be used to combine the batteries while the engine is running or as an emergency start function.

Measure the voltage on the large posts of it. Also measure the voltage on the little terminal. Then start the rv and measure again. Then do the same with generator or shoreline running.

Also clean those posts while the battery cables are off.

I can't see the picture clearly enough, but it looks to me like there are two wires on the top terminal and one on the bottom. I can't see a small terminal. The wires all seem to be about the same gauge. I would expect to see a smaller wire to the small terminal. That's why I called it out as a circuit breaker. Sorry if I missed it.

Tom

[YC1]

Tom, you could be right. I zoomed in as far as possible and still cannot see a control wire either but the picture is just not clear enough.

[tompen]

And then I missed the missing alternator wire on the diode isolator.
We need to hear back from the OP.

[Captrv]

Thanks for the tips everyone. It will be a few days till I can follow up on your suggestions. Work still getting in the way of the good life.