Battery Voltmeter Installation Question

You can connect where you like. It will read voltage at the point of connection. If all is good then all points have pretty much the same voltage.

Still if the battery is bad the converter may hold 13.2 to 13.6 volts and you don't know the difference. Need to unplug now and then to get independent battery voltage.

mabynack wrote:
It's a pretty good run from the panel to the battery, so I was hoping to just run it to the sensor.

My sensor still had all the lights illuminated when the battery voltage was only 7 volts.

Thanks for your inputs. I'll try hooking it up to the panel and see what happens.

If you are talking about the sensor panel that has the lights for the holding tank levels, and the battery condition, it will always say full battery and light up all the lights anytime the trailer is plugged into the shore power. That battery indicator is only good when the trailer is on battery power.
Barney

mabynack wrote:
I had problems with my 12 volt system on my FW and when I pulled the battery I found that it was only putting out 7 volts. The rig stays plugged in all the time.

A few weeks ago someone posted a thread about installing a permanently mounted voltmeter to monitor the battery. I purchased one and now I'm looking at installing it.

The question is - can I wire the positive terminal of the voltmeter to the battery monitor in the panel or should it go directly to the positive terminal of the battery?

I have four individually monitored batteries on my Class A rig. I installed battery disconnects for each of the battery so I can check the voltage of each battery without getting a feedback when checking a particular battery. If you only have one battery, you wouldn't have to have multiple voltage monitors.
I can charge each of my battery through my solar panel or through my alternator if needed. I installed the voltage monitor(s) close to each battery. You did mention that you keep your rig plugged-in which means your charging system is capable of switching (you wish) to trickle mode whenever the charge is complete. This is where most of the problem occurs where the battery gets overcharged if left plugged-in indefinitely. I've had this problem which prompted me to install voltage monitors. In your case, you have a 7 volt reading despite being plugged-in which tells me that the battery is probably sulphated--rendering it unchargeable.
The charge voltage from your coach converter puts out 18 to 20 volts which is hard on your battery plates if it fails to switch to trickle mode. It's a good idea to have a voltage monitor but keep in mind that even small gadget will draw power from your battery. To solve this problem I installed a momentary switch so it's not on all the time. A properly charged battery should read anywhere between 12.3 volts to 12.7 volts. If you decide to hook it up directly to the battery, it's a good idea to install a 5 amp fuse just in case there is a short.

From sunny California
V.A Vasquez
Retired Electrical Engineer, Computer Data Network Engineer, Electrical Contractor.
1986 Bounder Class A, 24-year Good Sam Lifetime Member.

It can be placed anywhere within the DC circuits supplying your rig. If you require millivolt accuracy measure at the source, although that kind of precision isn't needed in RV power distribution management. I use the plug in types for both AC and DC voltage monitoring that provide results to the tenth of a volt.

Our rig came with several interior 12 volt power ports and I installed 12 volt power ports in the AC/DC distribution box, one directly to the battery, and one in our basement passthough storage. No matter where I measure with the plug in meters, results are nearly the same. A few tenths of a volt if even that much disparity.

You can hook it to the present monitor. There is no current draw all the time, the new meter draws so little current the voltage will read the same as when connected directly connected to the battery. :)

It's a pretty good run from the panel to the battery, so I was hoping to just run it to the sensor.

My sensor still had all the lights illuminated when the battery voltage was only 7 volts.

Thanks for your inputs. I'll try hooking it up to the panel and see what happens.

Try both. If you get nearly identical readings at both locations then either one will work. If you find there is a substantial difference you should wire it directly to the battery bank.

You can wire it to the panel but you will get a more accurate reading if you wire it to the battery.