Electrical Monitor

I am an engineer, and nothing bothers me more than the inability to know what is happening in any of the systems.  Probably the system I had the least information on was the 12 volt electrical system.  The only information I had on the battery usage was the very coarse indicators on the charger panel.  The LED's here are in 3/4 volt increments and 3 to 100 amp increments.  There was no indicator of actual battery usage.

At an FMCA convention I looked at all the electrical component vendors to see what was available in electrical system monitoring units.  There were a couple small meters that would have done the job by displaying volts, amps and amp-hours.  However I saw one unit that seemed to be built to a much higher standard (and price).  It is the Emon II produced by Ample Power Products, a company specializing mainly in marine power systems.. 

This monitor reads voltage from either battery system, house battery amps in or out, battery temperature, amp hours used or remaining, and a fuel type guage that indicates how full the battery is.  It is set up to operate with solar panels and with an optional  3 stage regulator for the engine alternator.  It will display any single item, scan your selected list of readings, or quickly select any of the 4 most commonly wanted values.  It keeps many totals and allows the setting of a number of alarms.  There is a computer interface and software to allow the keeping of data on a laptop computer.

The battery level circuitry tracks incoming and outgoing amp-hours.  It processes this data through an equation known as Peukert's Equation.  This takes into consideration the rate of discharge.  A battery will produce far fewer amp-hours at a high rate of discharge than at a low rate.  This is all compensated for in this instrument.

Installation consisted of mounting the instrument, installing a current measuring shunt, and running quite a few wires to the two battery banks and the 12 volt panel in the main cargo bay.  I got quite familiar with the way wires are run fore and aft in the center of the coach over the various bays.

I now can keep very close track of my battery usage and level of recharge when I am dry camping.  One thing tht really suprised me was how slowly the batteries recharge while driving.  An all day drive will only replace about 20 amp hours of use.  The charger in the Prosine inverter is very much faster.

This is a very high quality instrument!
 

 

I mounted the current measuring shunt just below the main ground distribution point and connected it with a "Z" shaped copper bus bar.  The battery cable attaches to the other end of the shunt.


I made a new mounting panel for the monitors, inverter panel, and CO detecter.

The Emon II battery monitor is the lower left, and the Foretravel supplied AC monitor panel is the upper right.

AC Power Monitor

Foretravel supplies an AC monitor panel in all their motorhomes.  This panel contains two digital AC voltmeters and two sets of neon bulbs to verify correct connections to the campground pedestal.  In normal usage, where all connections are correct, each bank displays 2 green lights and no red lights.  By the time the rig was about 2 1/2 years old, the green neon lights were flickering fairly badly, and would not light at all at low line voltages.  Foretravel replaced the monitor on warranty, but warned that "they all tend to do that".

Not wanting to have them fail again, I opened the monitor and replaced the light bulb series resistors with ones 10 times the resistance.  If I remember correctly, they were 47k and I changed them to 470k.  This reduced the intensity somewhat, but they are still plenty bright.  Their life should now be extended by a large factor.  It is now over two years after making this change and the lights are still rock solid. 

Note of 3/25/12

It is now almost 10 years since replacing the resistors in the monitor and the lights are still bright and flikker free.  I highly recommend increasing these resistor values as most other Foretravel owners are reporting failure of these light in less than 3 years!  The ForeForums had a very extensive thread on this subject a couple years ago.  I have included a couple of my posts on this subject here:  Both were written on June 15, 2010.

First Post:

Hi all,

I finally found a source for the ne-2g bulbs for our power line monitors!  It is All Spectrum Electronics in Van Nuys, CA (www.allspectrum.com).  Under the topic of NEON LAMPS they list about 10 different size and lead length combinations of the green bulbs.  I would have to open my monitor and measure the existing bulbs to verify the correct one.  Prices run around $0.50 each, varying a little by exact bulb.

Dick


Seacond Post:
OK,  I went out and pulled my monitor out and opened it up.

The steps to open it are:
1  Remove front panel from electrical box - 4 screws
2  Unplug 2 cables from front panel to power supplies
3  Remove 4 hex nuts and remove board from front panel

The 4  NE-2G green bulbs are 6 x 12 mm.  There are also 2 plain NE-2 (amber) 6 x 12 mm bulbs for the open ground indication.  I didn't touch the circuit of these 2 bulbs as they are almost never (hopefully!) lit, and should last forever.

I replaced the original series resistors with 470k for long life and not too dim a bulb for the 4 green bulbs.  Before you change these resistors, you should follow the traces and verify that your board layout is the same as mine (2000 U-270).

The attached photo shows these as well as the adjusting pots to calibrate your volt meters.  Just be careful of the high voltage, both as for shorting anything while it is hot, and coming into personal contact with any high voltages!

Dick








Kitty Liter Cubbyhole

We travel with our cat Muffy.  One problem in a motorhome is where do you put the cat box?  We decided that we could do with only one full length wardrobe.  I had a door made that was the same length as the center doors and mounted it in place of the right hand wardrobe door.  I made a shelf at the bottom of this door.  We now had a shirt length cupboard at the top and an open area at the bottom.  Her litter box fits nicely in the bottom and is well out of the way. 
 
 

The kitty litter cubbyhole takes up the bottom half of one of our full length wardrobes.  The top half is now a shirt length closet.

Satellite Dish and Mount

When we first bought our motorhome, there was no satellite dish installed.  This meant I had to use my tripod and set up the dish on it at each stop.   I modified my portable dish by putting wingnuts on the dish adjustment points, epoxying the bolts that mount the dish to the LNB arm, and  replacing the nuts with wingnuts.  I  installed a short piece of coax to the LNB so there is always a pigtail ready to connect without further disassembly.  I can now very quickly assemble or disassemble the dish and the LNB arm.  The separate pieces store very easily under the couch.

I wanted something easier to handle and sturdier than the tripod.  I desighed a support made of two pieces of telescoping square tubing that will mount the dish at the end of the inner piece.  The end of the outer piece has a flat plate and a bolt tightened  "L" bracket that allows me to clamp it to a flat surface edge.  I can clamp it to the bottom of a square frame member at either side in the rear of the coach, or to the generator mounting rail in the front at either side.  I can also clamp it to a frame member through the front opening of the rear fender well.  This gives me 6 locations around the coach to mount the dish, each of which allows a certain amount of "swing" and in-out adjustment.  The dish is firmly mounted to the motorhome and is not in danger of blowing over in the wind.

Now that I have my roof mounted auto-seeking dish, I still use this mount occasionally when one of my 6 mounting locations gives me a shot at the satellite, but the roof antenna does not.  Of course there are still occasions where I need to set the dish some distance from the motorhome.  I  use my tripod on these occasions. 
 
 

The satellite dish mount can clamp to the edge of any horizontal surface up to about 1/2 inch thick.  The bars can telescope from about 18 inches to about 30 inches long.  It provides a very stable mount for the dish.  As mounted here, the mount can extend over a foot and swing further to the side allowing the dish to point almost due foreward.
Richard Mason, Prescott, AZ 1/15/05

 

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