Battery Meter - How to Calculate

[WanderOne]

Hi,

I have a new Cougar 25RES 5w and wanted to ask the seasoned pros her about how to know the % left in my battery.

There are the 4 idiot lights on the control panel, but I don't believe them.

I am looking to know when I am at 50% levels of my battery, for good maintenance.

Is there a calculation by looking at the voltage with multi-meter? Or do I just need to get a better digital gauge?

[chuckster57]

Here is a chart:
https://www.energymatters.com.au/components/battery-voltage-discharge/

[drdarrin]

The idiot lights are aptly named. You can measure the voltage at the batteries when they are not under any load or use a hygrometer to measure specific gravity.

Or, if you really want an accurate measure, get and install a TM-2030.


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[JRTJH]

The "four idiot lights" for the battery condition is probably the most accurate measurement on that panel. That said, what does 2 lights really mean??? Hard to tell objectively, so I installed a voltmeter panel above the stereo in our Cougar so I can get an accurate voltage reading by turning on a switch. The switch is just to the right of the panel and when turned on, powers all three devices. There is a "cigarette lighter socket", a USB plug and the volt meter. The switch must be turned on to power any of the devices and during use, I can monitor the battery voltage. For my purposes, this allows us to power the TV (with a plug in inverter) and monitor how much battery power is remaining during the entire time we're watching TV. Same with recharging devices using the USB connections. The switch also gives us the ability to remove the volt meter drain (even though it is a very small drain smaller than the propane monitor, stereo backlight, etc).

If I were you, rather than dig out a multimeter, walk out to the tongue (or battery box) to measure remaining voltage, I'd suggest considering installation of a device similar to this.

[Hodgy]

I like that install John.

[WanderOne]

The "four idiot lights" for the battery condition is probably the most accurate measurement on that panel. That said, what does 2 lights really mean??? Hard to tell objectively, so I installed a voltmeter panel above the stereo in our Cougar so I can get an accurate voltage reading by turning on a switch. The switch is just to the right of the panel and when turned on, powers all three devices. There is a "cigarette lighter socket", a USB plug and the volt meter. The switch must be turned on to power any of the devices and during use, I can monitor the battery voltage. For my purposes, this allows us to power the TV (with a plug in inverter) and monitor how much battery power is remaining during the entire time we're watching TV. Same with recharging devices using the USB connections. The switch also gives us the ability to remove the volt meter drain (even though it is a very small drain smaller than the propane monitor, stereo backlight, etc).

If I were you, rather than dig out a multimeter, walk out to the tongue (or battery box) to measure remaining voltage, I'd suggest considering installation of a device similar to this.

I really like this too. Simple install gives you the same control over the main worries.

Simple and smart. :facepalm:

[dcg9381]

Voltage is OK. There are "more advanced" power control systems (hundreds of dollars) that actually monitor the charge/discharge of the battery in terms of amp hours and you setup specifically for your battery type.... If you want a true %, you have to do it this way.

John's way is next best and WAAAY cheaper. Not to mention much easier to install.

[fourfourto]

I bought 2 of these use 1 in truck and 1 in camper ,mounted it over inverter,
pics of inverter before I put in meter

cheap buy 2 easy install
https://www.ebay.com/itm/12V-Digital-LED-Panel-Digital-Display-Car-Motorbike-Meters-Voltage-Gauge-Meter/202031586960?epid=2199505554&hash=item2f0a055e90:g:l3UAAOSwEFNZnPe9

added small rocker switch from radio shack a buck or two

[Steveo57]

I bought 2 of these use 1 in truck and 1 in camper ,mounted it over inverter,
pics of inverter before I put in meter

cheap buy 2 easy install
https://www.ebay.com/itm/12V-Digital-LED-Panel-Digital-Display-Car-Motorbike-Meters-Voltage-Gauge-Meter/202031586960?epid=2199505554&hash=item2f0a055e90:g:l3UAAOSwEFNZnPe9

added small rocker switch from radio shack a buck or twoI installed one of those little meters on my control panel. Going to add an inverter similar to what you did by the power panel. Easy access to the battery supply there to hook up the inverter.15578

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[fourfourto]

nice set up mines just a 300 watt portable one I installed, good enough for 19 inch tv and dvd.
I use a flat plugged 3 foot extension cord with a 3 plug end to reach up where outlet is .

I don't dry camp much , usually for overnight at casino or rest area

[JRTJH]

If you're looking for something that's about as easy to use as it could possibly get, you can always just get one of these, plug it into the 12 volt socket on your TV antenna booster. I used one similar to this in my boat before I bought a GPS/sonar system with a "real" voltmeter built in. It's somewhere in the bottom of a tackle box, I think....

https://www.amazon.com/Zeltauto-Cigarette-Lighter-Digital-Voltmeter/dp/B00VL9JZ0K/ref=sr_1_76?ie=UTF8&qid=1520561552&sr=8-76&keywords=lighter+socket+voltmeter

[flybouy]

I used this voltmeter https://www.amazon.com/gp/product/B01FH9NJ7O/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
15584
It's waterproof so I installed it into the front of the battery box, and a battery disconnect on the lid. When I go to hitch up in storage the battery state is easily seen and when setting up I can see when the ems kicks in and the converter is charging.

[BrentB]

Or install one of these and it will do the calculations for you, and function as a true "fuel gauge" for your battery:
https://smile.amazon.com/gp/product/B01M5CWR2P/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1