Making a voltage/current control panel...

[Terry G]

I made this control panel using some parts I found online from a company called LightObject. It gives me real time monitoring of battery voltage and current. The big 50 Amp toggle on the left (from AutoZone) disconnects the battery ground from the system. I installed it because I found that the propane detector will drain the battery when the trailer is in storage. There's a small LED next to the switch to tell me that my battery is connected. The smaller toggle in the center turns the meters off when you're not using them. The unit is mounted on the back of my partition which keeps the wire lengths short.

Some of the stuff I've found out is interesting, like that my Revolution LED bulbs take .12 Amps while the incandescents they replaced drew 1.2 Amps each. My furnace fan is about 3 Amps and my water pump is about 5. Nice stuff to know when you're boondocking.

I used the following components from LightObject:
1) 3 1/2 digit 20V voltage meter
2) 3 1/2 digit 20A current meter
3) 20A current shunt
4) 12V to 12V isolator module (needed for current meter)

Total cost of everything was about $40 and the skills necessary are just simple wiring and soldering. Now the company has new models of meters which give 4 1/2 digit resolution for those people who like to get down into the Milli-Amps. If anybody's interested, I'd be happy to make up a schematic and post it.

[goosler]

Well done. Clean Install!

[Larry C Hanson]

Terry,
Nice job! Your installation looks very professional. I visited the parts web site and found
many interesting items at good prices. Thanks for sharing your project. A schematic
would be great.
Larry H

[Terry G]

Originally Posted by Larry C Hanson

Terry,
Nice job! Your installation looks very professional. I visited the parts web site and found
many interesting items at good prices. Thanks for sharing your project. A schematic
would be great.
Larry H

It'll take me a couple days, but I'll get you something.

[Ron F]

Nice job! I look forward to seeing the schematic.

Ron

[Matt in SV]

I want two sets so I know how much voltage the ammeter drops, and how much current the voltmeter draws!

[Rick G]

[QUOTE=Terry G;231132]I made this control panel using some parts I found online from a company called LightObject. It gives me real time monitoring of battery voltage and current. The big 50 Amp toggle on the left (from AutoZone) disconnects the battery ground from the system. I installed it because I found that the propane detector will drain the battery when the trailer is in storage. There's a small LED next to the switch to tell me that my battery is connected. The smaller toggle in the center turns the meters off when you're not using them. The unit is mounted on the back of my partition which keeps the wire lengths short.

QUOTE]


Did you really make the big toggle switch to disconnect the battery ground rather than the positive 12V wire? If so, why did you choose to do it that way? It makes me nervous that you could become the path to ground in wet weather.

Rick G

[Terry G]

Originally Posted by Rick G

Did you really make the big toggle switch to disconnect the battery ground rather than the positive 12V wire? If so, why did you choose to do it that way? It makes me nervous that you could become the path to ground in wet weather.

Rick G

Rick, my cables from the battery to the switch are short and inside the trailer. My reason for disconnecting the negative is that all the instructions on jumping batteries say to connect the negative last and disconnect it first. If that's how you're supposed to do it working outside in the weather, then it seems like it should be pretty safe doing the same thing indoors with a switch.

[Terry G]

Originally Posted by Matt in SV

I want two sets so I know how much voltage the ammeter drops, and how much current the voltmeter draws!

Matt, I can save you some money. According to specs, the shunt for my current meter drops 75 mV when passing 20 Amps and each meter draws a maximum of 75 mA. However, I've wired it so the current for the meters doesn't register on the shunt.

[Bill F.]

Originally Posted by Terry G

I made this control panel using some parts I found online from a company called LightObject. It gives me real time monitoring of battery voltage and current. The big 50 Amp toggle on the left (from AutoZone) disconnects the battery ground from the system. I installed it because I found that the pro
pane detector will drain the battery when the trailer is in storage. There's a small LED next to the switch to tell me that my battery is connected. The smaller toggle in the center turns the meters off when you're not using them. The unit is mounted on the back of my partition which keeps the wire lengths short.

Some of the stuff I've found out is interesting, like that my Revolution LED bulbs take .12 Amps while the incandescents they replaced drew 1.2 Amps each. My furnace fan is about 3 Amps and my water pump is about 5. Nice stuff to know when you're boondocking.

I used the following components from LightObject:
1) 3 1/2 digit 20V voltage meter
2) 3 1/2 digit 20A current meter
3) 20A current shunt
4) 12V to 12V isolator module (needed for current meter)

Total cost of everything was about $40 and the skills necessary are just simple wiring and soldering. Now the company has new models of meters which give 4 1/2 digit resolution for those people who like to get down into the Milli-Amps. If anybody's interested, I'd be happy to make up a schematic and post it.

It's nice to know what amps each appliance draws but I was more interested in knowing how many amp/hours(% battery) were left at bedtime so I could be sure the furnace would run all night. Because I wasn't smart enough to build something to do all that I think it cost me close to $200 for a Trimetric 2020 monitor and shunt to get the info. Since you already have amps and volts from the shunt can you now add the ability to keep track of amp/hours?
Bill

[Michael Pupeza]

I bought a Xantrex Link 20 Battery Monitor that does all of the above, and then some, for my 2 batteries that gives far more than that info. It also memorizes the maximum draw-down of each battery and the efficiency of recharge for each one. There's a Link 10, for 1 battery, on ebay now.
In my opinion, there's hardly a better system to keep track of your 12V system. A marvelous gadget!
In my case, it was less than $150 new, old stock.
Mike 1993 Bigfoot 17CB, 2003 Honda Odyssey

Originally Posted by Bill F.

It's nice to know what amps each appliance draws but I was more interested in knowing how many amp/hours(% battery) were left at bedtime so I could be sure the furnace would run all night. Because I wasn't smart enough to build something to do all that I think it cost me close to $200 for a Trimetric 2020 monitor and shunt to get the info. Since you already have amps and volts from the shunt can you now add the ability to keep track of amp/hours?
Bill

[Terry G]

Originally Posted by Bill F.

It's nice to know what amps each appliance draws but I was more interested in knowing how many amp/hours(% battery) were left at bedtime so I could be sure the furnace would run all night. Because I wasn't smart enough to build something to do all that I think it cost me close to $200 for a Trimetric 2020 monitor and shunt to get the info. Since you already have amps and volts from the shunt can you now add the ability to keep track of amp/hours?
Bill

Sorry, Bill, mine is just a simple system with no microprocessor.

[Terry G]

Here's the schematic for the system.

[Dave Bese]

Fine job; could you list part numbers? I checked the site and there are several variants of parts.

[Byron Kinnaman]

Originally Posted by Terry G

Here's the schematic for the system.

Great job. I would make one suggestion, put a .1ufd ceramic capacitor across the shunt. This should eliminate the possibility of ground noise getting into any audio/video equipment you might want to use.

[Terry G]

Originally Posted by Dave Bese

Fine job; could you list part numbers? I checked the site and there are several variants of parts.

Dave, This is a suggested parts list using 4 1/2 digit red panel meters from http://LightObject.com. Stock and availability seem to fluctuate a bit so I would suggest calling the company and asking them about what you want to do before you order. Different sizes and LED colors are available but not always listed on the site. The meters I used are no longer available.

4 1/2 digit red 20A current meter EPM-8145R20A
4 1/2 digit red 20V voltage meter EPM-8145R20V
20A Shunt (Must match meter.) ES20A
12V to 12V isolation module EPS-1212CSW2

And some other notes:
1) The panel is a 10" x 4" piece of .032 brass available at many hobby and hardware stores. The meters snap in place, so I had to use a nibbler to rough cut the openings and then a file get the exact fit.
2) The frame for the panel is a simple box out of 1 x 2 stock. I fastened it to the partition with small "L" braces.
3) The wire from the battery to the shunt and power switch should be fairly big. 8 gauge is recommended.
4) The current meter will be destroyed if it is not isolated. Make sure you use the module.
4) Electronic parts hate to be wired wrong and this will usually turn them into useless hunks of smoking junk. Check your work carefully.

Hopefully this helps. If you have any more questions, let me know.