Adding a Voltmeter to check Battery Status

[CoventryKid]

Hi guys:

I would like to install this voltmeter and a push-button switch onto my 12v batteries so I can push the button and have the current battery status displayed.

I purchased the v/m from a reputable electronics shop in Vancouver but there were no instructions included. I'm okay with wiring, just not great with electronics, so I'm not sure what to connect to what - there are multiple Ins, Outs, and Grounds. Click on the picture for a larger image.

I'm hoping someone can tell me or direct me to a diagram as to how to connect it. Or point me to something that I can order that will work.

Thanks in advance for any and all help!

[AnthonyH]

Hi guys:

I would like to install this voltmeter and a push-button switch onto my 12v batteries so I can push the button and have the current battery status displayed.

I purchased the v/m from a reputable electronics shop in Vancouver but there were no instructions included. I'm okay with wiring, just not great with electronics, so I'm not sure what to connect to what - there are multiple Ins, Outs, and Grounds. Click on the picture for a larger image.

I'm hoping someone can tell me or direct me to a diagram as to how to connect it. Or point me to something that I can order that will work.

Thanks in advance for any and all help!

Pictures were blurry, but basically run a hot wire to momentary switch then to positive input on meter. Then run wire to negative on battery and connect to negative on meter. Looks like there is a diagram of sorts on the meter that would let you know the + and - on the meter.

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[IndyTom]

It looks like the meter requires a 5 volt power supply to power the meter itself. The four pin connector on the back looks like it needs, from left to right, 5v, gnd, positive from your battery, and then minus from your battery.

[Graniterich]

I have used a few of similar type meters. The meter required power to work, so the red and yellow on mine went to + 12v and black to-12v. Of course with a switch inline

[dancam]

Google or look on ebay for that voltmeter or ones that are very similar and they should have wiring diagrams with the listing

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[GuitarPhotog]

Regardless of what you use for a voltmeter, be aware that to get a valid reading of the battery state of charge, it must be unloaded (i.e., completely off) for more than 30 minutes before taking the reading to allow the chemistry to stabilize. Temperature is important also, most SOC charts are for use at 70F/20C.

But that said, any indication is better than none.

<Chas>

[CoventryKid]

Thanks to all for the help/suggestions!

I think I might try and find a "simpler" display that doesn't require power to operate. Or in other words, where do I get 5v from in a 12v system to power the meter? I'm really out of my depth here.

Thanks again!

[John61CT]

Even an accurate voltmeter is a very rough guide to state of charge, much less state of health as batteries decline with age.

A proper smart gauge is hundreds though.

Are you deep cycling batteries bought at retail big box?

If so never mind. . .

[low277]

Maybe a battery gauge for a boat would work? There are simple round analog ones for single or multiple batteries.

[onehoser]

this is what i went with, bought it on ebay for $1.90 usd free delivery

[HotRod1]

Your 12v will work for the 5v supply. It just needs to be at least 5v. That is what feeds the display. The meter will only work with both hot wires on. A momentary switch (push button or rocker) in the hot lead will interrupt the power feed and keep the meter from draining the battery. Push button, read meter easy.


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[Graniterich]

Your 12v will work for the 5v supply. It just needs to be at least 5v. That is what feeds the display. The meter will only work with both hot wires on. A momentary switch (push button or rocker) in the hot lead will interrupt the power feed and keep the meter from draining the battery. Push button, read meter easy.


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That was my experience as well

[flboy]

I'd be careful with that meter being it needs a 5V input. Putting 12VDC on the supply line may just damage it. Usually the supply allows for a few volts variance, but not 7 volts.. The IC's on that are likely +5VDC supply and they are not regulating on board.

In case you have never thought about it... the following is a great way to monitor your batteries and it gives a Red/Yellow/Green indication on charge as well as a read out. So simple and no hookup or extra switches. Also, you can back it out of the socket a bit to turn it off if you don't want it on. You can pick one up for <$20.00 . Saw this on sale on AdventureRV.Net for $14.99. Can get one on Amazon also that is nice for $12.00 https://www.amazon.com/INNOVA-3721-Batt ... WD6ZSC00V5

Digital-Voltage-meter.jpg (17.44 KiB) Viewed 2681 times

The following chart will help you if you just have a Voltmeter without the Red/Yellow/Green indication and it also accounts for the different types of batteries.

BatteryVoltage.JPG (23.01 KiB) Viewed 2678 times

[John61CT]

Useful rough guide. Note the correspondences change from one batt to another, as well as every month, as every battery's gap between actual vs rated capacity widens.

Accurate SoC can ONLY be determined by a hydrometer (why FLA is great vs AGM) or expensive equipment.

[CoventryKid]

Thanks, guys, for all the info and suggestions.