DC Volt Meters

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DaveK
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DC Volt Meters

#1

Post by DaveK » Sun Nov 22, 2009 3:20 pm

I have been looking for a long time for a digital volt meter to supplement the analog meter in the H2. Two things were necessary, small but readable size and ability to see it at night. I just discovered a huge selection of DC volt meters from Daytel, http://www.datelmeters.com/cgi-bin/webs ... eters.html . Knowing the battery condition, especially when at camp, and using accessories, is important.

While they make a "daylight readable" model, it naturally draws more power. They have a variety of LED models, which I'm told will meet my night time needs. The following is the spec sheet of the model I will be testing.
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Re: DC Volt Meters

#2

Post by Fetus » Sun Nov 22, 2009 8:21 pm

Dave,

Are those going to be mounted in your vehicle?

I'm looking for something similar and have been looking at the Powerwerx line. A bit more expensive though.
http://www.powerwerx.com/emergency-vehi ... meter.html

I am also looking at getting one of those battery disconnects that shuts off the battery at certain voltages.

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Re: DC Volt Meters

#3

Post by cruiserlarry » Sun Nov 22, 2009 8:24 pm

Those are very nice, simple meters, although they are a little deep and use primitive connections - probably adapted from their AC meter line.

The ireason I have not installed a digital voltage gauge is it's hard to determine the affect of the power draw on your battery at that specific instance - you can only see current (no pun intended) voltage; so, you can't tell if an accessory is drawing on the battery at that time, or if that is the actual remaining voltage of the battery in question. The gauge doesn't really indicate what your situation is. It would be nice to find a voltage gauge with a memory, similar to the temp gauges used for freezer-fridges - you can see the current voltage and the recent hi / low state. Or at least an indicator light if you have a current draw on over a certain threshold, which could help you to determine if you have an issue to deal with...

The search, for me, continues... ;)
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Re: DC Volt Meters

#4

Post by cruiserlarry » Sun Nov 22, 2009 8:31 pm

The Powerwerks gauge is closer to what I was talking about, but it is expensive.

They offer another product that gives info about the state of a dedicated circuit, which would work well if you have a secondary battery that you want to monitor the load and it's affects:

http://www.powerwerx.com/tools-meters/d ... nline.html
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Re: DC Volt Meters

#5

Post by DaveK » Sun Nov 22, 2009 10:42 pm

Fetus wrote:Dave,

Are those going to be mounted in your vehicle?

I'm looking for something similar and have been looking at the Powerwerx line. A bit more expensive though.
http://www.powerwerx.com/emergency-vehi ... meter.html

I am also looking at getting one of those battery disconnects that shuts off the battery at certain voltages.

James:

Yes, it will be dash mounted. I think its simplicity will be an asset (along with its small size). Test results to follow.

With a single battery, a disconnect seems to make sense. The only downside that I could foresee is that some of your electronics, that require juice, may lose their memory. I also seem to remember that some vehicle computers require a start-up period after being reconnected to the battery.

The benefits of a battery disconnect may already exist in some of your accessories. I know that my Fridge Freeze and power inverter both have circuitry that will shut them down at predetermined voltage levels. And many newer vehicles have timers on both interior accessories and lights when the keys are removed from the ignition. But in the end, it may be safer to not take a chance.

If you install the powerwerx, please do a write up.
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Re: DC Volt Meters

#6

Post by DaveK » Sun Nov 22, 2009 11:22 pm

cruiserlarry wrote:Those are very nice, simple meters, although they are a little deep and use primitive connections - probably adapted from their AC meter line.

The ireason I have not installed a digital voltage gauge is it's hard to determine the affect of the power draw on your battery at that specific instance - you can only see current (no pun intended) voltage; so, you can't tell if an accessory is drawing on the battery at that time, or if that is the actual remaining voltage of the battery in question. The gauge doesn't really indicate what your situation is. It would be nice to find a voltage gauge with a memory, similar to the temp gauges used for freezer-fridges - you can see the current voltage and the recent hi / low state. Or at least an indicator light if you have a current draw on over a certain threshold, which could help you to determine if you have an issue to deal with...

The search, for me, continues... ;)
Larry:

The claimed voltage draw for this unit is 8mA - a colossal miser compared to virtually every other accessory connected to the battery.

A volt meter will tell you the condition of the battery and the effect that your accessories have had on it's remaining charge. It will also tell you how quickly and by how much the voltage drops once the engine is turned off - an important indicator of battery health. No memory is necessary to know that when the Vs drop below (aprox.)12.0, that it's time to either stop using accessories or start recharging, and it doesn't matter what is drawing the battery down. Therein lies the value of this type of gauge.

Unfortunately, at $50.00, this gauge will not serve as a diagnostic tool to measure the current draw for every (or any) accessory. What it will do is tell you the most important piece of information that you need to know on a trip in the wilderness - the condition of the battery that needs to get you through the rest of the trip.

It's hard to know the full benefit of this type of gauge, but I do seem to remember someone on this site who believes that the more information we have, the better off we will be.

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Re: DC Volt Meters

#7

Post by cruiserlarry » Mon Nov 23, 2009 12:02 pm

DaveK wrote:
The claimed voltage draw for this unit is 8mA - a colossal miser compared to virtually every other accessory connected to the battery.

A volt meter will tell you the condition of the battery and the effect that your accessories have had on it's remaining charge. It will also tell you how quickly and by how much the voltage drops once the engine is turned off - an important indicator of battery health. No memory is necessary to know that when the Vs drop below (aprox.)12.0, that it's time to either stop using accessories or start recharging, and it doesn't matter what is drawing the battery down. Therein lies the value of this type of gauge.
The low draw is very good - it won't affect the battery much on a weekend run or expedition trip.

I disagree with you regarding the info you can derive from the voltmeter alone. You need to monitor the changes in voltage if you really want to see what's up or how much battery life is remaining when you have active, intermittent draws on the battery. For example, when the freezer-fridge is running, the voltmeter might read 11.5-12.2 volts, but that is the line voltage - the battery is not discharged to that point, and when the FF turns off, the voltmeter will again read actual battery voltage of 12.4-12.8 or so. When there is no draw, a 12V auto battery with a reading of 12.0 volts shows the battery to be about 60% discharged (full charge is 12.6-12.8 on a meter).

I do think the voltmeter is useful (and I keep a plug-in model in my FJ all the time). But as a diagnostic tool, the voltmeter alone is limited, and only accurate as a battery check when the system is at rest.

Here's an interesting document I found that gives some additional insight:

http://www.xantrex.com/web/id/329/docserve.asp
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Re: DC Volt Meters

#8

Post by gon2srf » Tue Nov 24, 2009 3:30 pm

cruiserlarry wrote:
DaveK wrote:
The claimed voltage draw for this unit is 8mA - a colossal miser compared to virtually every other accessory connected to the battery.

A volt meter will tell you the condition of the battery and the effect that your accessories have had on it's remaining charge. It will also tell you how quickly and by how much the voltage drops once the engine is turned off - an important indicator of battery health. No memory is necessary to know that when the Vs drop below (aprox.)12.0, that it's time to either stop using accessories or start recharging, and it doesn't matter what is drawing the battery down. Therein lies the value of this type of gauge.
The low draw is very good - it won't affect the battery much on a weekend run or expedition trip.

I disagree with you regarding the info you can derive from the voltmeter alone. You need to monitor the changes in voltage if you really want to see what's up or how much battery life is remaining when you have active, intermittent draws on the battery. For example, when the freezer-fridge is running, the voltmeter might read 11.5-12.2 volts, but that is the line voltage - the battery is not discharged to that point, and when the FF turns off, the voltmeter will again read actual battery voltage of 12.4-12.8 or so. When there is no draw, a 12V auto battery with a reading of 12.0 volts shows the battery to be about 60% discharged (full charge is 12.6-12.8 on a meter).

I do think the voltmeter is useful (and I keep a plug-in model in my FJ all the time). But as a diagnostic tool, the voltmeter alone is limited, and only accurate as a battery check when the system is at rest.

Here's an interesting document I found that gives some additional insight:

http://www.xantrex.com/web/id/329/docserve.asp
Excellent document on voltage. Every year we rent a pop-top camper for Thanksgiving vacation and I always bring along the multi-meter to test the battery when we pick-up the camper. I have had several of the new guys on the lot argue with me when I request a fresh battery. There reply is always predictable "if it reads 12 volts then it's fully charged". :(

I am positive that the marine industry has a meter which measures draw and keeps a memory of pre and post discharge levels and can do so for multiple batteries. I've used them on several cruisers.

Accurate (like fuel gauge) Battery Monitor. Tracks current in and out of battery. Uses Peukert's law to display amp-hours or % charge. Low/High volts and low charge alarms. Calibrated 150 amp shunt provided. NMEA 0183 data output.

$189.00

Close but...
http://www.marinecomp.com/cruzpro_digit ... s_gaga.htm
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Re: DC Volt Meters

#9

Post by OLLIE » Wed Nov 25, 2009 4:17 pm

Damn it Scott. I don't know where to put that gauge in my truck. :lol:
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Re: DC Volt Meters

#10

Post by gon2srf » Wed Nov 25, 2009 11:14 pm

OLLIE wrote:Damn it Scott. I don't know where to put that gauge in my truck. :lol:

Yeah your going to have to build an overhead console soon!
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