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Old 07-25-2011, 10:36 AM   #1
N1VWD
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Default Monitor for battery bank status

I have two size 27 deep cycle batteries wired in parallel for my TT. My TT has the basic combo tank and battery column of lights level monitor. I would really prefer a number read out and not an idiot light set up like I have now. I wish to monitor my batteries and prevent them from being discharged bellow 50% to maximize their usable life. Who makes a decent monitor that can be wall mounted in my TT. What do you recommend??

Thank you all in advance for your replies.
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Old 07-25-2011, 05:16 PM   #2
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Who makes a decent digital monitor.. Well, since this forum is dedicated to hams, I'm going to assume you have basic electronic skills.

you go to the RV forums like RV.new and look up the phrase "The 12 volt side of life" then click on that and print out the battery charge level charge (Voltage to state of charge)

Now, many companies sell small digital voltmeters or kits. I have a Vector plug in automotive volt meter (plugs into a 12 volt accessory socket) that could be easily turned into a wall mount.. VERY Easily in fact. Or you can buy any decent digital panel meter and wall mount it.

hook it to the switched side of your levels sensor switch (For positive) and any handy ground.

Now, the problem.... This wno't give you an accurate reading unless the rig has been unplugged (no 120v) for at least 30 minutes and EVERYTHING 12 volt is off.

To get an accurate reading you really need to measure AT THE BATTERY.

Same thing, only conect to the battery via a fractional amp fuse (most any fraction is good, 1/8, 1/4 1/2) and a push button swith.
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Old 07-26-2011, 06:27 AM   #3
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For an inexpensive panel meter check out ,
http://www.allelectronics.com/make-a...s-Panel/1.html

To do an actual "STATE OF CHARGE" test you need to use a hydrometer (SP?) , or in other words , take a specific gravity reading on each cell relative to ambient tempture and do the math.
As far as I know there is no-one that makes an "affordable" panel meter to do this.
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Old 07-26-2011, 07:09 PM   #4
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Lightbulb

Quote:
Originally Posted by N1VWD View Post
I have two size 27 deep cycle batteries wired in parallel for my TT. My TT has the basic combo tank and battery column of lights level monitor. I would really prefer a number read out and not an idiot light set up like I have now. I wish to monitor my batteries and prevent them from being discharged bellow 50% to maximize their usable life. Who makes a decent monitor that can be wall mounted in my TT. What do you recommend??

Thank you all in advance for your replies.
I keep a $3.00 digital multimeter found at Harbor Freight
http://http://www.harborfreight.com/...ter-90899.html
permanently attached to my start battery bank.
When I want to know that all is well I simply look at the voltage reading on the meter.

My batteries will hold 12.6v for several months of parking. If I don't like the voltage I turn on the charger until I do.

There is a model "Guest" charger that will automatically charge and taper off to float charge. Can't think of the model but will look it up if you ask.
It will automatically hold the battery in peak condition.

If and when my manual charger fails I will get the "Guest".


JIM
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Old 07-31-2011, 10:37 AM   #5
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We have an accessory (used to be called cig. lighter ) plug-in, and as I recall, the general rule of thumb is to not allow a voltage below 11.5 or damage occures.

Our house-batteries are skronked because we let them run dry last year. Before you flame me for it; I am disabled and trying to talk the wife into checking them takes up to 17 months. Our next set of batteries need to be maintenance free!
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Old 07-31-2011, 12:30 PM   #6
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The problem with those accessory sockets is they are not located at the battery, The voltage you find there may be higher (during charging) or lower (When using batteries) than the battery voltage, often (IN RV's) by as much as a volt or more. Yes, that is excessive voltage drop, but when running a 2KW inverter.. .... ...
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Old 07-31-2011, 01:51 PM   #7
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Steve:
Sounds like to me that you'd better grab the neighborhood 10 year old and teach him how to read a volt meter .
I say use a 10 year old because they are trainable with-out too many hit's of the "SHOCK COLLAR" and not quite into the pre-teen "KNOW-IT-ALL" stage yet, they might even remember something useful when they do hit the teen years !
73, John
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Old 08-01-2011, 12:33 PM   #8
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Careful with those $3.00 multimeters....I've had two go out on me in the last couple of months. Went to check a battery and almost welded the leads to the post (and yes I had it set right). Wound up chucking both of them.
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Old 08-02-2011, 08:52 AM   #9
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Hey with the 3.00 meters (Heck I've found analog multi-meters for a buck in a dollar store, not good for battery monotoring but good for a lot of non-critical stuff)

The nice thing about 'em is you can buy 'em in bulk and if they go bad just chuck them because it would cost you more than 3 bucks to return it to the store!!! (Gas prices beign what they are)
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Old 08-06-2011, 10:11 PM   #10
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Here is one solution for a charge meter.

http://www.bogartengineering.com/products/TriMetric
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