Lighter Volt Meters

Topic: Lighter Volt Meters (Read 1545 times) previous topic - next topic

Lighter Volt Meters

March 22, 2018, 08:42:58 pm

Replaced cigarette lighters for the house and chassis with volt meters with USB connections. Had to punch the old lighter holes larger in the dash. No damage to lighted dash. All is good. Now to install the Trik-L-Start.

Re: Lighter Volt Meters

Reply #1 – March 22, 2018, 08:46:39 pm

Not sure about those but my limited capacity solar with dirty panels ran down my chassis batteries somewhat with my unknown brand red large led voltage gauges plugged into them. Removed them in storage and the batteries came back up.

Re: Lighter Volt Meters

Reply #2 – March 22, 2018, 08:54:36 pm

Is this what you used and had to countersink?

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Re: Lighter Volt Meters

Reply #3 – March 22, 2018, 09:51:43 pm

No this is what I used. I had to make the hole larger to fit them. Used a punch and die to make the hole larger.

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Re: Lighter Volt Meters

Reply #4 – March 22, 2018, 11:33:38 pm

Quote from: John Morales – March 22, 2018, 08:42:58 pm

Replaced cigarette lighters for the house and chassis with volt meters with USB connections. Had to punch the old lighter holes larger in the dash. No damage to lighted dash. All is good. No to install the Trik-L-Start.

Great idea about the volt meters, I will order them.. Can anyone tell me whether my 2000 U320 should have a lighted dash? If a 1999 has it then it would seem that a 2000 would also, but I don't see it.

Re: Lighter Volt Meters

Reply #5 – March 23, 2018, 01:42:33 pm

If you plan to use the voltage readings to monitor the 12 volt circuits, I have found that two decimal places makes the voltage readings more meaningful, one decimal place is not accurate enough for me.

Re: Lighter Volt Meters

Reply #6 – March 23, 2018, 03:26:01 pm

My question would be would the readings from the accessory outlets on the dash be the same or different then a meter wired directly to the battery banks. If there is, is it enough to matter?

Re: Lighter Volt Meters

Reply #7 – March 24, 2018, 01:45:51 am

I don't know if the readings are the same and I have not compared it. I also don't have a need for 2 place decimal perfection. I'm just happy to have a quick visual of the battery levels. With a little more effort the house batteries can be seen on the Javalina system but I had no quick visual of the chassis batteries. For what I want, the quick visual values are better than nothing and are very useful at a glance, especially on the chassis batteries.

Re: Lighter Volt Meters

Reply #8 – March 24, 2018, 11:30:29 am

Quote from: Peterson143 – March 23, 2018, 03:26:01 pm

My question would be would the readings from the accessory outlets on the dash be the same or different then a meter wired directly to the battery banks. If there is, is it enough to matter?

Randy,

The answers are Different and Yes.

The readings from the accessory outlets can and will be different from a reading taken directly at the battery bank (+) and (-) terminals.

And Yes, the difference can and will be enough to matter, depending upon what is going on in your coach and what you understand about measurements.

[/list]

First, several attributes of voltage measurement need to be understood about instruments and where they are connected:

Accuracy: A location's and an instrument's degree of veracity—how close its measurement comes to the actual voltage being measured.

Resolution: The smallest increment the instrument can detect and display—tenths, hundredths, thousandths, millionths.

Precision: A location's and an instrument's degree of repeatability—how reliably it can reproduce the same voltage measurement over and over.

[/list]

This has been addressed a few times before on the Forum (for example):

Javelina, TriMetric, ARC 50 readings

Consider that the difference between a 100% charged lead acid battery (wet, Gel or AGM) and a 50% charged battery (in an open circuit) is only 0.63 Vdc (12.73 Vdc and 12.10Vdc).

Then consider that the voltage at your dash can and will vary far more than the 0.63Vdc between normal battery minimum load and normal high battery load conditions. That's because loads like headlights, engine and transmission computers, lighting circuits, inverters, motors, ("whatever" draws current) will cause the dash voltage to "sag" appreciably depending upon how many times the wiring from your battery bank to your readout has been interrupted by physical connections (each with their own voltage drop from minute to large, depending upon the condition of the connection and the current being drawn through the connection), what the involved wire gauge(s) and corresponding voltage drops are.

So, if you want to accurately know a battery's SOC (State of Charge), don't use dash pickup points for your "battery voltage" indication. Use only dedicated, direct battery connections.

If you only want to know whether your battery banks are dead or alive, in some undetermined but somewhat familiar condition of health, during an often repeated situation (e.g.- long term parked and plugged into shore power), then the dash pickup locations are fine. They may be telling you a highly inaccurate voltage, but they will tell you if something has changed (emphasis on CHANGED) by a major amount.

If and when voltages at the dash appear wrong, though, break out the accurate DVM (Digital Volt Meter) and start troubleshooting at the battery bank (+) and (-) terminals to understand the reason(s) for the change.

HTH,
Neal

Re: Lighter Volt Meters

Reply #9 – March 25, 2018, 11:56:57 pm

Quote from: P. Wyatt Sabourin – March 23, 2018, 01:42:33 pm

If you plan to use the voltage readings to monitor the 12 volt circuits, I have found that two decimal places makes the voltage readings more meaningful, one decimal place is not accurate enough for me.

Wyatt,

I agree. I want 2 decimal places too. Have you found a voltage meter that reads 2 decimal places? All the ones I've found (with the exception of my TriMetric) only show a single decimal.

see ya
ken

Re: Lighter Volt Meters

Reply #10 – March 26, 2018, 12:55:45 am

INNOVA 3721 Is a two decimal point gauge. Amazon

Re: Lighter Volt Meters

Reply #11 – March 26, 2018, 01:08:04 am

" 2 decimal places" like this one?
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Re: Lighter Volt Meters

Reply #12 – March 26, 2018, 12:51:56 pm

Quote from: kenhat – March 25, 2018, 11:56:57 pm

Wyatt,
I agree. I want 2 decimal places too. Have you found a voltage meter that reads 2 decimal places?
see ya
ken

Howdy Ken, I have used two of these plug-in meters for over 5 years. Our coach has two power plugs, one on chassis and the other on house batteries. I really rely on these meters.
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Good Luck, Dave A

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Re: Lighter Volt Meters

Reply #13 – March 26, 2018, 03:13:50 pm

Quote from: P. Wyatt Sabourin – March 23, 2018, 01:42:33 pm

If you plan to use the voltage readings to monitor the 12 volt circuits, I have found that two decimal places makes the voltage readings more meaningful, one decimal place is not accurate enough for me.

"Two decimal places" refers to the RESOLUTION of a meter: i.e. - being able to read the input voltage to the hundredth's place of one Vdc.

A 3 1/2 digit DVM is necessary to do that. I have never found a "lighter-plug-in" digital voltmeter that has 3 1/2 digits. They are usually 2 1/2 digit DVM's, as Ken has noted.

The "12.1U" example, that Al (propman) asks about, is 2 1/2 digits with a "U" added (which is as close as the Chinese manufacturer has tried to come to a "V", to remind the user that they are looking at "Volts" as opposed to ??

A 3 1/2 digit DVM has three readout elements that are capable of displaying increments from 0 to 9 and one readout element that displays only a 1 or a 0, hence the nomenclature of a "1/2" element. Thus, a "Two decimal places" resolution, 12 Vdc DVM, would need a DVM with a full range of from zero to 19.99 Vdc.

3 1/2 digit Vdc panel meters that are durable and reliable run well over $100 each. There are small, inexpensive, Chinese, panel meters (with questionable durability and reliability) for much less, e.g.-

Lascar Electronics - V 125 - 9 VDC 0.5 in. 3-1/2 Digit LCD Volt Meter Meter...

Inexpensive DVM's are easily damaged if the DVM power supply voltage exceeds the DVM's design parameters. The one above requires a 7.0 to 12.0 Vdc, nominal 9.0, Vdc power supply, so if the coach battery(ies) is/are used to supply the instrument power, an input V(+) circuit, to clamp the DVM power supply voltage to 9 Vdc, must be used (or use a 9 Vdc battery - the drain is on the order of a milliamp).

HTH,
Neal

Re: Lighter Volt Meters

Reply #14 – March 26, 2018, 03:40:45 pm

The only other meter I found was this one on EBAY. I would have had to go directly to the battery battery, install the shunt and run wires for each bank or set it up to read each battery separately.

DC 6.5~100V 20-50-100A LCD Digital Combo Panel Display Volt Amp Power Watt...

Re: Lighter Volt Meters

Reply #15 – March 26, 2018, 03:55:46 pm

Quote from: John Morales – March 26, 2018, 03:40:45 pm

The only other meter I found was this one on EBAY. I would have had to go directly to the battery battery, install the shunt and run wires for each bank or set it up to read each battery separately.

John,
Not a good choice.
I don't imagine that shunt would have stood up well to the (starter) starting current drawn from your battery.
Neal

Re: Lighter Volt Meters

Reply #16 – March 26, 2018, 05:02:35 pm

True that! The max shunt available on the one linked above is only a 100A and then you still have a long run to the dash and the associated voltage drop. I replaced the dash mounted OEM VDO analog volt meter with Victron BMV-702 which is hooked up directly to the negative cable of the chassis battery through a 500A shunt. I wasn't sure that the 500A shunt would stand up to cranking the engine, but so far so good. I realize that if I have to crank the engine extensively to start or for some other purpose, it may go toes up. If that happens, I can easily bypass the shunt and will put in a 1000A Victron shunt (they are available up to 2000A). Not the cheapest way to go, but this way the voltage is read directly at the battery and sent to the monitor digitally, so the length of the wire run won't affect the accuracy of the reading. It also is hooked up to the read just the voltage of the house battery (opposite of the way most use this feature, but I have the Magnum battery monitor for the house batteries (as well as the Midnight Solar Classic 150). The Victron has many functions, including alarms, blue tooth smart phone or USB computer interface.
Don
Edit: to add picture

Quote from: Neal Pillsbury – March 26, 2018, 03:55:46 pm

John,
Not a good choice.
I don't imagine that shunt would have stood up well to the (starter) starting current drawn from your battery.
Neal

Re: Lighter Volt Meters

Reply #17 – March 26, 2018, 11:37:11 pm

I agree with the both of you. Shunts, meters, busbars and cables have to be of a higher quality. I don't have the need for that type of setup. That is a great project for someone that boondocks and lives off of solar 24/7. I don't. That is why I am satisfied with what I have. I'm just looking for a quick reference on the state of my batteries everytime I enter my coach. I always appreciate all of your comments and suggestions.

Thanks, John

Re: Lighter Volt Meters

Reply #18 – March 30, 2018, 05:28:35 pm

The INNOVA 3271 showed up today. Wow. Made my cheap red leds ones embarrassed. They asked to hide in a drawer. So I did what they asked for.

Re: Lighter Volt Meters

Reply #19 – April 02, 2018, 10:13:32 pm

Quote from: P. Wyatt Sabourin – March 23, 2018, 01:42:33 pm

If you plan to use the voltage readings to monitor the 12 volt circuits, I have found that two decimal places makes the voltage readings more meaningful, one decimal place is not accurate enough for me.

Any opinions on this one?
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-Mike-

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