Inexpensive Battery Monitor -entry Level

[Mustang65]

You do not need SOLAR for this product.

A lot of the members are interested in monitoring their battery performance (or lack of), but do not want to invest a lot of money and time into an expensive system. So enter a product that I just found on AMAZON (of course) and it will meet your basic battery monitoring needs for only $17.98.

The order comes with an EASY TO READ DISPLAY (yes you can turn it on/off) and a 100Amp shunt resistor. All you add is the wire (telephone quad wire, or Cat5) between the display/battery/shunt. You will also need to install the shunt resistor between the battery and the frame connections.

I did a temporary install just to test it out and believe it or not it is very accurate. My unit was 0.01 volts off from my volt/ohm meter and the MPPT SOLAR charge controller output. I was impressed. I may mount it on my SOLAR Charge Controller board, for a quick glance at the system. Maybe not, it is easier to pull out my smart phone and check the system.. I will figure out a use for it. Attached a picture of it wired into the TT.

Yes it can be reset. The display is a solid blue color, but the reflection of light distorted the camera shot.

Don

[dalebra]

Sweet!

I just added it to my Amazon Cart.

Thanks

[oldmanAZ]

Awesome! Thank you.

[Crabman]

That`s in my price range!

[oldmanAZ]

Don:
I have no solar... yet or generator... yet, but I'd like to monitor the batteries and the current when charging...(connected to shore power) and discharging (boondocking). I've been monitoring the system/battery voltage using a voltmeter plugged into the TT 12v outlet.

(Edit: Never Mind. It DOES MATTER... Does it look to you that the shunt will measure current while charging and discharging without changing the wiring? If the shunt is determining current by actually measuring voltage drop, it seems to me it would be OK whether current is flowing into or out of the batteries.Please disregard.)

Yes, I'm in the a 'little knowledge is dangerous' group and have learned that
'for every problem, there is an answer that is quick, simple, and wrong.'

[Mustang65]

Originally Posted by oldmanAZ

(Edit: Never Mind. It DOES MATTER... Does it look to you that the shunt will measure current while charging and discharging without changing the wiring? If the shunt is determining current by actually measuring voltage drop, it seems to me it would be OK whether current is flowing into or out of the batteries.Please disregard.)

Yes it does matter. I was looking at it from the "LOAD" side of the circuit, to measure how much the battery(s) have been discharged. You can monitor the voltage level on the display for charging voltages by reversing the shunt leads from the Digital Display.

If you are interested in looking at the battery status in both charging or discharging modes, there is an easy fix. Wire the load/battery display connections that connect to the shunt to a DPDT (Double Throw-Double Pole) switch and manually switch it when you are charging or discharging. This will change the display from one mode to the other. You could mount the DPDT switch right next to where you mount the Digital Display.

I can give you a circuit that will automatically switch between charge/load by using a relay, but it involves activating the relay with 110VAC shore power. If there is 110VAC from shore-power the display will show charging, no 110VAC will show discharging. I would not recommend this option unless you have a background working with 110VAC.

Attached is the DPDT wiring diagram... that is the easy one.

Don

[Yamerhammer]

Thanks Mustang65. I just ordered it from Amazon.

[oldmanAZ]

Thanks, Don.

When I get my trailer home (it's at the dealer now for warranty & other stuff) and the weather warms up a tad, I'll be in touch regarding this mod. This meter seems to be a good place to start.

[hoppers4]

Wow, what a great price! Been eyeballing these things for years but they've been way too expensive. Just ordered one. Thanks Mustang!!

[Seann45]

Don did you ask Amazon for a commission yet? <grin>

[norty1]

Do you have a source for the switch? I'm going to order one also.

I have a small mod that I have used for years that indicates when my water heater is actually heating water. Small green LED indicator. If I can find the circuit and components I will post it.

[hoppers4]

Deleted by me.

[RodgerS]

Just for information purposes:
This meter has a reported accuracy of within 1%. Meters typically are within about 1/2 % for digital DC measurements.
For what it is worth, without going deeper.
Made in China, about $12 lowest price I saw.

[Mustang65]

Originally Posted by norty1

Do you have a source for the switch? I'm going to order one also.

I have a small mod that I have used for years that indicates when my water heater is actually heating water. Small green LED indicator. If I can find the circuit and components I will post it.

It doesn't matter about the voltage or amps, as this circuit is only mA. Just make sure that it is not a momentary DPDT (it will specify if it is in the description). You can get a good looking DPDT rocker switch at Radio Shack (if their is still one around you), automotive parts stores have them, usually in the electrical section or stereo section.

I usually use Jameco, Digi-Key or Amazon electronic parts.

Don

[norty1]

Follow up question?

Where are you going to mount it? Do you have a source for a small surface box? That's what I am thinking, right near the monitor panel.

[Mustang65]

Originally Posted by norty1

Follow up question?

Where are you going to mount it? Do you have a source for a small surface box? That's what I am thinking, right near the monitor panel.

Funny you should ask. DW was going to throw out a decorative piece of wood that she received some dried fruit on. So, I decided to keep it and think about what I could use it for. Well here it is. The hard part is done, now I just need to get the wires to it.... PHASE 2. DW approved (the main interior decorator) so I guess it is OK... Still thinking of painting the bottom display trim a different color..

Now where to hang it?

Project Box Link
I order mine from Amazon

Don

[Cdash]

Mine showed up yesterday. Smaller than I expected.

Was kind of surprised that the wiring connects at the end of the unit, especially when it snaps into a box or opening. Not much room for the wire. I'm thinking that I should use furnace wire, that way I can put 90 degree bends in the write it to keep things tight to the box/opening.

Is there any reason, outside of not cutting a big hole in the (interior) wall, to cut a hole in an interior wall and snap it in?

Keep in mind I don't have my trailer yet, so it's all planning at this point.

[Mustang65]

Originally Posted by Cdash

Mine showed up yesterday. Smaller than I expected.

Was kind of surprised that the wiring connects at the end of the unit, especially when it snaps into a box or opening. Not much room for the wire. I'm thinking that I should use furnace wire, that way I can put 90 degree bends in the write it to keep things tight to the box/opening.

Is there any reason, outside of not cutting a big hole in the (interior) wall, to cut a hole in an interior wall and snap it in?

Keep in mind I don't have my trailer yet, so it's all planning at this point.

I used cat5 wire as I had a spool of it (need to order more), the old 4 conductor gray telephone wire will work fine as it is only carrying mV. Furnace wire will also work fine. I am not a fan of putting holes on the interior of the TT (DW would not be a happy camper) so I used a decorative board we received at Christmas with cheese on it for a mounting (picture in earlier post). I will hang it with a couple of those tape strip picture hangers by the thermostat and run it down the inside of that wall.

Don

[Cdash]

Originally Posted by Mustang65

I used cat5 wire as I had a spool of it (need to order more), the old 4 conductor gray telephone wire will work fine as it is only carrying mV. Furnace wire will also work fine. I am not a fan of putting holes on the interior of the TT (DW would not be a happy camper) so I used a decorative board we received at Christmas with cheese on it for a mounting (picture in earlier post). I will hang it with a couple of those tape strip picture hangers by the thermostat and run it down the inside of that wall.

Don

We used those tape strips in the old camper. When we went to remove one, took part of the wall with it. Just a warning.

[norty1]

I am going to use a small box for electronic equipment.

Problem is, since Radio Shack closed I can't find one to look at and have found some online but am still looking for one in person to get it right the first time.