Ammeter installation is driving me crazy!

[P. Vallerie]

Been busy updating and repairing the coach electrical system. Replaced the old converter/charger with a new 35 Amp converter/ 4 stage battery charger. Installed a 12 Volt outlet for a new Magestic 12 volt color TV and power booster antenna. Did a complete rework of a very scary 12 volt outlet that could have burned the entire thing down. I am not an electrical engineer but I have done my fair share of adding circuit branches and electronic widgetry over the years. I am in the process of installing a 6-18 Volt Meter and a 30-0-30 Amp Meter with an INTERNAL SHUNT. Both meters are an analog made by VDO @ a medium price range that typically are used on the front driving dash. I thought I could use them in the coach. I want to monitor the battery voltage as it discharges/charges and measure the current going in and out as we use the appliances. We have one 12 volt 100 ohM battery. Maybe in the future we'll add another. Plain Jane - nothing fancy! Both meters are set up on a temporary test board. The Volt Meter and the lights to the meters are wire with a fused 10 AWG wire to the distribution board. They work beautifully. Here's my dilemma - no matter how I wire the Amp Meter in line to the positive or negative side of the battery it still reads zero when there is load put on it. I have tested all the wires in the circuit with my multimeter = good. What the devil! It's driving me crazy. My question is did I GOOF UP trying to install an internal shunt Amp Meter. Are the built in shunts not rated @ small/ fine enough increments to read the current resistance in the application I am trying to use it in. Should I have purchased a Blue Sea analog meter 50-0-50 external shunt rated @ 1 Milliamperes @ full scale or can I add a 30 Amp, 60 mV external shunt to the amp meter I am trying use?  VDO makes a really nice 30-0-30 external shunt gauge approx $200. Yikes it is a little bit more than what I want to spend to have a matching gauge. Am I on the right track or do I have to rethink this monitoring circuit? I am going to take an aspirin - now I really have a headach. Pamela

[Rich Thomas]

I need to address a mistake I made in posting my reply on your amp meter problem. I was interrupted while writing my synopses (family showed up) and I didn't realize I had posted it. I am sorry for any problems it may have caused, any way from reading your last post it appears you and Dave C. have come up with a solution. Dave's an excellent resource for all things camper.     

[P. Vallerie]

Thought I put closer on this discussion. With a nice hot cup of coffee, feet up and hot roaring fire. Recieved the new 50-0-50 Amp meter. Wired it up and it works like a champ!! Got credited for the defective meter. Nice.Had to make a new panel to accomidate it along with a 1 amp panel fuse. I call it the "Frankenstein Panel". It reminds me of the old 1930 monster movies. The mad scientist looking at the dial meters, throwing switches and laughing a deranged laugh. More power Borus! It is getting close for me to do my annual blog so there will be pictures $ lots of other things. Thanks to all. P

[John "T" Nordhoff]

Congrats on the new meter working. Ive been sort of incognito in and out of internet since we left coldddddddddd Indiana Dec 29. We dry camped the first 8 nights in such places as Flying J,,,,,,,,,,,Church parking lot in High Springs Florida,,,,,,,,,,,,Bushnell Florida,,,,,,,,,,,,,,,,,Zephyrhills Wal MaRT,,,,,,,,,,Craigs in Arcadia Florida for a bluegrass festival,,,,,,,,,,,Avon Park Florida,,,,,,,,,,,,,now at the Florida Flywheelers in Ft Meade Florida for 10 days where Im an exhibitor whewwwwwwwww lol  We have 2 more tractor shows plus 3 more bluegrass festivals to attend. We base camp out of Avon Park and Sebring area but travel around like 2 months much of which is dry camping which necessitates my solar panels and 4 golf cart (460 Amp Hrs) batteries plus 110 gallons of fresh water storage capacity. 

 A few remarks on an Ammeter: True if the voltage potential on BOTH sides is equal theres NO current flow. Current is like CFM of water flow, how many electrons are flowing while Voltage or potential difference  is like water pressure. If the charger is higher voltage then the batteries, current flows INTO them charging them but if youre dry camping then current flows OUT of the batteries into your loads.  

 I have an ammeter that's between my solar charge controller and my batteries so I can see how many charging amps the solar panels are pumping into the batteries. I have a digital voltmeter on my batteries so I can observe their voltage. 12.6 is fully charged while 12 is something like 50% (I didn't take time to look up the exact amount) depleted.

John T  Lake Bonnett Village Avon Park Florida