Battery usage meter?

[joandthe3boys]

I thought I would take the easy way out and ask the pros before I started my web search.
I have a 2006 Fleetwood EV2 and I am looking for a meter to install so my lovely bride can tell what battery reserve remains after 2 or 3 days of dry camping.

Any recommendations? :confused:

Thanks in advance,
Greg

[JimS]

There are a few routes you can go.  An RV shop like Camping World and others have meters that you can hook up to the battery and check reserve left, or there are meters that can be permanently mounted inside the PUP - more involved in wiring them up and mounting - or you can get a simple volt meter and wire it into a 12V source in the PUP and keep tabs on the voltage.  By reading the voltage, you can see how much capacity is left.  Trojan batteries has a chart listing batery voltage and corresponding battery charge.  For example: with everything off, a reading of 12.37 volts would indicate about 70% of full charge, or 30% discharge.  For your standard dual purpose marine/RV/automotive type of deep cycle battery, (the most common type supplied to PUP's) 70% is about as low as you want to go without battery damage and maintain longevity.  True deep cycles can be drawn down to less than 50% and in many cases as much as 80% without damage.

Hope this helps,
Jim

[mike4947]

Measuring voltage is a losing battle. Here's links to two brands of amperage measuring devices. A little pricey but they get the job done in measuring amperage both in and out of the battery as well as telling you the state/percentage of battery charge.
 
Trimetic
 
Link

[wavery]

I wouldn't waste my $ on one of those meters with color coded faces for the state of charge. They're all junk.

I would recommend getting a digital volt meter and using the chart suggested. Digital volt meters are far more accurate than those needle things.

It's best to hook it up directly to the battery if possible. If you read the voltage in 5 different places in your camper, you'll get 5 different readings for various reasons. If you read the voltage right at the battery, You'll get the correct reading every time.

[austinado16]

I wouldn't waste my $ on one of those meters with color coded faces for the state of charge. They're all junk.

I like my little colored meter.  It's very eighties!  And......when it's green, we camp.  When it's red, we pack up and come home.

So there.

[JimS]

Oh boy!!!!

Here we go again

[joandthe3boys]

I like Jim's and Wavery answer the best so far.  Mostly because of the low $$$.:#  

But where do I find the chart to determine the Voltage vs remaining capacities?  

I have a Interstate Mega-Tron, SRM24 , with 690 Marine Crank AMPs.  Okay I admit I have no idea what a 'Crank AMP is?  :eyecrazy:

Thanks again for the assist.  You saved me from a long internet search and hours of reading stuff I didn't understand anyway.

Greg

[JimS]

BATTERY SPECIFICATIONS

Percentage of Charge / Open

[austinado16]

I have this one printed out and stuck to the top of my battery box (under the dinette seat).

[joandthe3boys]

You guys are the best!


Thank you!

[coach]

The above chart is for use while actually using the battery.

This link has that chart and another for testing after the battery has not been used several hours.

This link SoC is state of charge, is an .xls with temp / voltage / specific gravity. All you care about is voltage and temp. The specific gravity is for use with a hydrometer.

This hydrometer has floating colored balls.
This one has a pointer/scale!

[mike4947]

The orblem with those voltage charts is they list resting voltage. Just watch the volt meter when you turn on a light, the furnace is sunning, or anything electrical is drawing juice. You get a lower reading than what the battery actually is.
That's why the amperage meters are far more accurate and TANSTAAFL.

[coach]

The orblem with those voltage charts is they list resting voltage. Just watch the volt meter when you turn on a light, the furnace is sunning, or anything electrical is drawing juice. You get a lower reading than what the battery actually is.
That's why the amperage meters are far more accurate and TANSTAAFL.

So you under estimate the battery charge, so what!
Mickie, if that is a problem then use the other chart.  One chart ( from 12 volt side of life) is for "in use" and one is rested. Why is this hard to understand. It's a lot cheaper than the meters you suggest. In fact, lots of PUs are cheaper than the meters you linked. It's camping by golly, it's not rocket science.
You might take readings a few times "in use" and then let 'em rest, remeasure. In the future you can just measure i'n use' and make an adjustment.
Expensive meters are not the answer, expecially when they cost more than the PU.
No one is asking for a free lunch, getting closer than a red hair ain't the goal!