Meter on aux battery question

[thatbaldwinlife]

Bear with me here...

I have the house battery running the Dometic, LED lights and radio. I would like to install a meter that will tell me based on the current load, how long I can run the accessories before the battery is flat. Is that possible? If so, with what? Also the current voltage, etc.

I thought an amp/hour meter but the one I bought did not do what I wanted.


Thanks for the help!
nate

[MidwestDrifter]

You are looking for a battery monitor that has a shunt. Something similar to the xantrex linklite or the Victron BMV-700. These monitors will show you SOC, remaining amp-hours, and amp draw. From there it is easy to determine how many hours it will take to deplete your battery.

http://amzn.to/29aBEAl
http://amzn.to/29cjZd0


These monitors are quite accurate. The SOC % number is really the simplest way to determine bank charge at a glance.

For many applications this level of monitoring is overkill, but it does what you asked for.
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[thatbaldwinlife]

Thanks for the reply! Those are way more expensive than I thought but I guess if that is what I want, I have to spend the money.

nate

[MidwestDrifter]

Yeah, not cheap. Are you trying to run the original dometic 3 way fridge from your battery? It pulls something like 6 amps, and is not feasible to run this way. Running it on propane is the way to go.

The only other option is a cheap amp/volt meter. (less than 30$). These units will not track SOC or total battery amps, they will just show current amp draw and voltage. You could use this to make a guess at your batteries SOC, but its a guess at best.
_________________
2004 Dodge/Mercedes Sprinter (Custom Camper)
2000 Jetta TDI
1982 Diesel Westy W/ ABA I4 hybrid (Sold)
Epic Road Tripping since 08/05/12 | http://VagariesAbound.blogspot.com/
My Current Build | http://sprinter-source.com/forum/showthread.php?t=41215

[thatbaldwinlife]

I am only running the Dometic on battery while driving and for short stops like stores, quick 10-15 min breaks. During camping it is on propane.

[davevickery]

I just have a plug in voltmeter that I stick in the cigarette plug. I added a 12 V socket running off the house battery and I usually leave the voltmeter in there when I am camping to keep an eye on the battery. I can plug it in to the front plug to see the starting battery too.

It works well enough. After a while you get good at estimating how much charge is left in your battery and how long it will go based on the things you usually run. I have a furnace but also sometimes use a DC fridge. And the stereo uses a fair amount of power too especially over many hours of use. I have run the Dometic off the battery for several hours at a time so the voltmeter is helpful.

When something is running the voltage reads lower than it really is, but you get pretty good at estimating what it really is. For example, the Dometic fridge pulls a lot of current so with a full battery, the voltmeter will show more like 12.3 volts. When it shows 11.6 volts, I am getting down to around 12 volts and that is as far as I usually like to drain it.

So for $10 it works good enough. Mine also has a USB charge port in it so I can see the voltage and still be charging my tablet. The tablet uses less power to charge so the voltage only drops by .1 volts when I plug it in.

[dobryan]

Here is some good reading.

https://www.batterystuff.com/kb/articles/battery-articles/battery-basics.html

You can use a voltmeter to get a good idea of the state of charge of a battery for pretty cheap. Not as fancy as those meters.......
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[Ahwahnee]

[thatbaldwinlife]

I have tried driving with the fridge on propane and it usually goes out. Ours works well on 12V while driving and it is nice to have it run while out for a quick hike or food stop.

With solar in the future, maybe I will wait a bit and get a unit that will work with the entire set up versus maybe buying something twice.

thanks for the replies.

nate

[PDXWesty]

There are much much cheaper options available.

This one was like $20. http://www.thesamba.com/vw/forum/viewtopic.php?t=649232

https://www.amazon.com/bayite-6-5-100V-Display-Mul...k129040-20
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[joetiger]

Cheap and effective. I mounted it down by the house battery that lives under the seat:

https://www.amazon.com/gp/product/B011010HXW/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
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