where to put volt/amp meter in circuit

[patfraley]

looking to install meter near WFCO. Currently, it is wired with RED & White into meter > WFCO and only reads AMPS when plugged into shore. Can someone please look at circuit diagram and tell me which wires to tap into to read volts/amps off 12V battery only (no shore)

thanks in advance!

[Harvey51]

It seems the Chinese put the shunt between the negative terminals. A "shunt" is a short piece of wire with a small resistance so current going through it causes a small voltage across it. The rest of the ammeter is just a voltmeter to measure the small voltage. Meters with higher amp ratings will have an external shunt so only the small voltage need go to the meter through light wires. On ebay ammeters be careful to make sure it says the shunt is included or built in - often it is not. The current flowing from input minus to output minus terminals will be measured. You could cut the wire to the battery negative and insert the meter in line.

Or more practically unhook the wire from the negative battery terminal and connect it instead to the ammeter output negative. Run a new wire from the meter input negative to the negative battery terminal. I have a "battery monitor" in that same box. I broke a terminal connecting a 12 gauge wire so I recommend using 14 gauge. If the #14 wires are short and the current under 15 amps it should not overheat or cause a troublesome voltage drop. You will also need a connection from battery positive to one of the meter positive terminals, just one since the two positive terminals are just connected together in the meter box. This connection just powers the meter electronics so only a light wire is necessary.

When you charge the battery via converter, current will flow backwards through the meter. I wonder what it will do? If it can show reverse current that feature will be listed in the ad. If not hopefully nothing will happen. I think it will be okay. Current going through the shunt backwards will just put a tiny reverse voltage on the electronics of the meter display so no danger of fire anyway. No loss if it does kill a chip in the meter - it wouldn't be useful for monitoring the battery anyway.

Please post what happens and a link to the ebay item so others will know what to expect if they buy it. We work together to get value out of these bargains.

[tenbear]

patfraley, are you still here? Did you get your meter to work?

[Oldme]

I recently added a digital DCV meter to my 12volt distribution panel.
I Simply went from the (+) side of the meter to the (+) on the
feeder line on the panel. Did the same with the (-) on the panel.

[tenbear]

Reading the post I referenced above, it appears that the battery should be connected to the input, both positive and negative. The battery negative is not connected to the frame. The output+ would be your red wire and the output- is connected to the frame.

Edit: corrected output-.

[tenbear]

Here is a link to an old post you might be interested in.

[RoyB]

I was just going by what was listed on the ebay seller's page



Have no idea how this is wired up on the inside of the box... I'm thinking now he blown REVERSE POLARITY fuses as he probably had the battery terminals removed when connecting up.

Roy Ken

[tenbear]

It seems to me that your input would be your battery and the output would be your red wire. This should read the battery voltage and current. So, disconnect the red wire from the battery and connect it to the output +. Connect the battery + terminal to the input +. Connect both - to the frame.

Just my guess.

[RoyB]

ALso be sure the battery is connected up properly. It is so easy to reverse the connection. FInd the WORD "NEG" or the symbol "-" on the battery case and make sure the lead from this terminal is going to FRAME GROUND.

If you go the terminals swapped just for a sec the REVERSE POLARITY and IN-LINE fuses (ALL THREE) will blow. Correct the problem first if they are blown otherwise the new fuses will just blow again on you.

Roy Ken

[RoyB]

Is there something you are suppose do when you want to monitor DISCHARGING or CHARGING modes.

Perhaps you have to also move the battery load somehow. The battery is connected to all your trailer loads via the 12VDC Distribution panel. The battery should connect to this panel normally at the same point the converter connects to 12VDC Distribution panel. Perhaps the REVERSE POLARITY FUSES BLEW ON YOU. They are the two large 15AMP fuses off to them self on the 12VDC board.

One good check is see if your 12VDC ceiling lights works OK when you are NOT on shore power. We may have interrupted the path from the battery positive lead to the 12VDC Distribution Panel somehow by going thru the new meter. ???

Roy Ken

[patfraley]

RoyB wrote:
My guess would be disconnect the RED WIRE line coming to the converter from the battery and connect it to the input + as shown in the below ebay diagram for the DCN 9030C unit. The - connection would go to frame ground.

Then connect a new short lead from + OUTPUT terminals to the converter terminal that used to connect to the battery POSITIVE terminal. The - lead goes to frame ground again.


This DCM9030C meter has to go in series between the converter and the battery. This means your total current load goes thru the meter panel which is only rated for 30AMPS I guess it is...

When your converter is producing charge current it is already connected up like the CHARGING diagram shows on ebay so I assume it work just fine with no changes anywhere.

To me that is alot of current to be running through those 10-32 screw heads on that terminal board??? Must be OK as that is the way the DCM9030C simple diagram shows from the ebay page.

I would make sure there is an 30AMP IN-LINE FUSE right next to the battery terminal. I'm pretty sure your battery is capable of producing more that 30AMPS in the case of a short circuit. It should have this in-line fuse there already just check and make sure.

I would just ignore the other battery leads that will also be connected to the same positive battery terminal. One is for emergency brakes and another maybe for your slide I see you have. Those other Positive + battey leads will just not be monitored...

This is pure guessing hehe... If it blows up on you I know nothing as Sergeant Schultz says on METV Hogans Hero's

I would run all of this by the ebay seller and gets his comments back...

Roy Ken

pretty sure what you suggest is how I have it now and it only reads A when shore is connected

RED > + INPUT METER > + OUTPUT METER > CONVERTER
WHITE > - INPUT METER> - OUTPUT METER > CONVERTER

is this what you describe above?

[RoyB]

Let me know if it works - I like the meter readout and the price is right. I might try it on my 200A setup in my OFF-ROAD POPUP for monitoring 4 batteries...

I see the ebay seller has several different current meter models for sale...

Roy Ken

[RoyB]

My guess would be disconnect the RED WIRE line coming to the converter from the battery and connect it to the input + as shown in the below ebay diagram for the DCN 9030C unit. The - connection would go to frame ground.

Then connect a new short lead from + OUTPUT terminals to the converter terminal that used to connect to the battery POSITIVE terminal. The - lead goes to frame ground again.


This DCM9030C meter has to go in series between the converter and the battery. This means your total current load goes thru the meter panel which is only rated for 30AMPS I guess it is...

When your converter is producing charge current it is already connected up like the CHARGING diagram shows on ebay so I assume it work just fine with no changes anywhere.

To me that is alot of current to be running through those 10-32 screw heads on that terminal board??? Must be OK as that is the way the DCM9030C simple diagram shows from the ebay page.

I would make sure there is an 30AMP IN-LINE FUSE right next to the battery terminal. I'm pretty sure your battery is capable of producing more that 30AMPS in the case of a short circuit. It should have this in-line fuse there already just check and make sure.

I would just ignore the other battery leads that will also be connected to the same positive battery terminal. One is for emergency brakes and another maybe for your slide I see you have. Those other Positive + battey leads will just not be monitored...

This is pure guessing hehe... If it blows up on you I know nothing as Sergeant Schultz says on METV Hogans Hero's

I would run all of this by the ebay seller and gets his comments back...

Roy Ken

[patfraley]

RoyB wrote:
I see this item is available on EBAY with SELLER elite.element

Perhaps you might want to contact them for additional info on how to connect the unit up... The write-up says it has a built-in SHUNT so probably just connects between the converter and battery bank like shown in their simple application. Perhaps the INPUT goes to BATTERY Connection and OUTPUT goes to Converter connection...

This would not be wise in my battery connections where I deal with up to 60AMPS or so of DC Current. My 1500WATT INVERTER is fused at 175AMPS DC current

Not real sure what you have here.... May be too small values to use in your RV setup.

DCM 9030C

Just my thoughts
Roy Ken

thanks Roy. I'm just in a small pop up. No more than 20A if everything was running...not even that

[RoyB]

I see this item is available on EBAY with SELLER elite.element

Perhaps you might want to contact them for additional info on how to connect the unit up... The write-up says it has a built-in SHUNT so probably just connects between the converter and battery bank like shown in their simple application. Perhaps the INPUT goes to BATTERY Connection and OUTPUT goes to Converter connection...

This would not be wise in my battery connections where I deal with up to 60AMPS or so of DC Current. My 1500WATT INVERTER is fused at 175AMPS DC current

Not real sure what you have here.... May be too small values to use in your RV setup.

DCM 9030C

Just my thoughts
Roy Ken