Power consumption of various 12 volt items

[guy99]

When I installed my Trimetric 2020 which allows one to measure how many amps are being withdrawn from the batteries I used it to measure the power consumption of most of the 12 volt items in our 1984 310 Limited MH.

I thought this information might be useful for others so I'm posting it here.

Amps ...... Item
0.5 ........ Everything off - I assume this is the draw from the detectors (LP and CO) and the logic boards in the appliances
0.2 ........ 400 Watt inverter with no loads on it
12.0 ....... Main cabin lights on high consisting of (12) 1141 incandescent bulbs
6.5 ........ Main Cabin lights on low consisting of (12) little bulbs - don't know the number of the bulb
1.0 ........ Individual 'eyeball' lights in main cabin - there are a total of 4 of these with individual switches
6.8 ........ Kitchen lights on high
3.2 ........ Kitchen lights on low
2.6 ........ Kitchen exhaust fan
2.1 ........ Fantastic fan on high
1.6 ........ Fantastic fan on medium
1.1 ........ Fantastic fan on low
1.7 ........ Shower fan
1.5 ........ Bathroom fan
0.1 ........ Water pump Idle
2.7 ........ Bathroom ceiling light
1.4 ........ Shower light
1.4 ........ Medicine cabinet low - fluorescent light
4.7 ........ Medicine cabinet track lights
3.9 ........ Bedroom dual fluorescent
1.4 ........ Bedroom Individual reading light
0.2 ........ 15 inch LCD TV plugged in to 12 volts but turned off
2.8 ........ 15 inch LCD TV powered directly from 12 volts turned on
3.8 ........ 15 inch LCD TV powered by the 'brick' that came with it plugged into 400 watt inverter
2.6 ........ Satellite PVR plugged in to converter
0.5 ........ Toshiba laptop plugged in to inverter but with computer off
2.5 ........ Toshiba laptop plugged in to inverter but with computer on

[pmclemore]

That's interesting stuff, Guy. Thanks for the post

Pat

[guy99]

5.0 amps - furnace and blower

[doorgunner]

Thanks Guy!
how about the oven light?
See you in April

[Fyrzowt]

Good post, good info.

[guy99]

Originally Posted by doorgunner

Thanks Guy!
how about the oven light?
See you in April

Oven light? What's that? Maybe I don't have one.

[SilverCabin]

Originally Posted by guy99

5.0 amps - furnace and blower

That's what I suspected. On our way to the Can Opener, we overnighted at a truck stop. It went down into the 20s that night and we ran the furnace (set at 50 degrees) and the tank heaters all night to keep us warm and thawed out. By morning we had an amber warning on the battery monitor, and after we cleaned up it was in the red and flashing if we turned anything on. In the three hours we drove from there to the Can Opener, the truck had charged it up to full again.

Randy

[CanoeStream]

Originally Posted by SilverCabin

It went down into the 20s that night and we ran the furnace (set at 50 degrees) and the tank heaters all night to keep us warm and thawed out.

Tank heaters? Aren't those supposed to be 120V? Do you have an inverter? I've boondocked nights down into the mid-teens with just furnace alone and had plenty of battery. I do think conditions that cold are too much for the furnace to keep up with while underway -- so I drain all 3 tanks if I have to pull in the cold and set the furnace at about 50. I set it at 65 once and used 25# of LP in 300 miles!

Excellent report Guy!

[byamcaravanner]

Originally Posted by CanoeStream

Tank heaters? Aren't those supposed to be 120V?

The tank heaters I plan to use are 12v (actually 13.5v). They are also available in 120v.

The model 1200 which is good for up to 40gal tanks is rated at 9.9amps.

Bob... you are braver than me. We don't plan to do much winter camping and if we do it won't be boondocking. I am installing the heaters as a precaution... just in case we get some of that unpredictable upper-Midwestern weather.

[CanoeStream]

Steve -- winter? It was mid-October 2006 while driving to Madison for a wedding! Guess I should have said 350 miles...

To the sunny-staters -- we have seen subfreezing temps even in September. August 30, 1974, dawned to about 16 degree temps and was the worst in my memory.

Guy, I don't know if your fridge is a 2-way or 3-way. Do you know what current is used when running on LP? Thanks again -- karma your way!

[byamcaravanner]

Originally Posted by CanoeStream

Steve -- winter? It was mid-October 2006 while driving to Madison for a wedding!

Exactly! This is why we need the heaters. LOL! BTW they are thermostatically controlled so they only heat when the heat is needed.

Guy,
Thanks for the interesting info. Your post will serve as a great reference.

[guy99]

Originally Posted by CanoeStream

Steve -- winter? It was mid-October 2006 while driving to Madison for a wedding! Guess I should have said 350 miles...

To the sunny-staters -- we have seen subfreezing temps even in September. August 30, 1974, dawned to about 16 degree temps and was the worst in my memory.

Guy, I don't know if your fridge is a 2-way or 3-way. Do you know what current is used when running on LP? Thanks again -- karma your way!

Mine is two way. I think the power it uses while on LP is included in the .5 amp base load. Sometime that base load will go up to .7 or .8 for no reason I can detect. Maybe the fridge is up to something?

I wonder how much those 12 volt tank heaters actually run. They would sure would consume battery capacity if they were on much. Might be handy for when you are underway and have power from the tow vehicle?

[2airishuman]

Originally Posted by SilverCabin

... In the three hours we drove from there to the Can Opener, the truck had charged it up to full again...

sorry but this is not likely.

IF the coach battery/s is depleted much, 3 hours of driving isn't gonna recharge them.

depending an alternator and wire size (output) 30-50 hours of driving without usage is needed to bring them up to 80% or more...

the confusing thing is your monitor 'shows' fully recharged which IS confusing...

that's is only a surface reading of voltage; once the electrolyte as homogenized charge across the plates/gel/fluid a lower reading will appear.

this is sort of like judging the temperature of a full body of water by touching the surface...

seems warm (fully charged) but go deeper or stir it up and the true temp is much different.

after the 3 hours of driving and the apparent 'full charge' had you boondocked, the voltage would have dropped way down really fast...

again this is confusing but that sudden drop is a reflection of how little juice had actually been replaced.

cheers
2air'

good list guy'! thanks.

with the various models of lights, fridges, and appliances in use it's important to keep differences in mind while using this reference.

[CanoeStream]

Originally Posted by 2airishuman

sorry but this is not likely.

IF the coach battery/s is depleted much, 3 hours of driving isn't gonna recharge them.

depending an alternator and wire size (output) 30-50 hours of driving without usage is needed to bring them up to 80% or more......

.....after the 3 hours of driving and the apparent 'full charge' had you boondocked, the voltage would have dropped way down really fast...

again this is confusing but that sudden drop is a reflection of how little juice had actually been replaced....

I noticed this issue earlier but didn't have time to post. I'm in full agreement here. Most TV's alternators have little reserve output beyond what it takes to run the TV's systems, air conditioner, etc. Less of that small margin of amperage makes it to your converter and battery due to the length of the wiring run. What about amps to run a resistance tank heater? Ulp!

I've read (and sadly repeated ) figures here at AIR about a minimum of 200 miles to recharge the coach batteries. I've since heard from better sources that this isn't close to enough. 30-50 hours? Ya picks yer poison. But at Topsail you probably had a 30A power pillar to plug into, right? Let me hear ya say, "Ahhhh!"

My truck has an optional snowplow package with an extra output HD alternator and 2 batteries -- I'm won't even bank on that recharging much while I drive. The lightweight Honda genset comes with me everywhere I don't have a hookup.

[SilverCabin]

Okay, stop beating up the new guy

I only reported what my monitor panel showed (full charge) but what 2air says makes sense. That probably was the condition of the batteries, but we plugged into a power post at Topsail and didn't worry about it anymore.

I have read that deep cycling your batteries periodically is better than leaving them on a trickle charge all the time. So I guess that counts for a deep cycle.

Tank Heaters. On the side of my bathroom wall are two switches that turn on the tank heaters. One for Black and one for Gray/Fresh. I was shown these at delivery and the tech explained that these should be on when the temps are freezing (driving or parked). They light up when not plugged in, so I assumed they ran off the 12v system. Is this not correct?

Randy

[CanoeStream]

Originally Posted by SilverCabin

I have read that deep cycling your batteries periodically is better than leaving them on a trickle charge all the time. So I guess that counts for a deep cycle.

You shouldn't discharge a lead-acid below 50% -- that will affect it's life & capacity.

OEM tank heaters? I thought they were 110V -- maybe got that from NeatAirstream in a post? For sure they won't do much off of batteries if they are 12V! Talk to your dealer?

[SilverCabin]

Originally Posted by CanoeStream

You shouldn't discharge a lead-acid below 50% -- that will affect it's life & capacity.

OEM tank heaters? I thought they were 110V -- maybe got that from NeatAirstream in a post? For sure they won't do much off of batteries if they are 12V! Talk to your dealer?

I was recalling an Article I read in Airstream Life (Fall/Winter 2006). I looked it up, and stand corrected. Here's what it says:

If a new deep cycle battery is routinely discharged to 10% or less remaining and then properly recharged (i.e. initially a high current bulk charge, followed by lower topping-off-current-charge), it will have an average life of about 300 - 350 cycles. This amounts to a few years of typical useage in most Airstreams.

On the other hand, if that same battery is routinely discharged to around 40% to 50% remaining and then recharged, that battery will have a life span of around 3,000 cycles.

My question now is: If the monitor was showing red in steady state and flashing red when something was on, what was the battery level? Especially since we now know that an indication of full charge may not be necessarily so.

I'll have to see if I can find anything about those suspicious heaters.

Randy

[tslanier]

I realize that it depends on how much usage, but my wife and I want to do some dry camping this spring. Could I expect the batteries to last 4 days with just basic lights at night, water pump and flushing the commode, radio etc?

[azflycaster]

Originally Posted by tslanier

I realize that it depends on how much usage, but my wife and I want to do some dry camping this spring. Could I expect the batteries to last 4 days with just basic lights at night, water pump and flushing the commode, radio etc?

We have only one battery in our trailer and can get four days out of it if we do not use the furnace.

[boondockdad]

good thread... just installed the 2020... used the 100A shunt... also ordered the 25' connector cable... not sure if I got the right black wires connected to G1 and G2... no markings at either end (whole length sleeved), and i didn't have my tone generator... but here's what i'm getting:

kill switch 'off' .05
kill switch 'on' everything off .05 (so far so good)
backlight on thermostat .14
systems monitor 'on' .12 (jumped to .15 when checking status for LP only)
front sofa fluorescent .67
front sofa direction spot (high) .47
sony stereo receiver .52
disc changer at rest .65
disc changer cycling .93
front fantastic fan (high/3) .92
water pump 1.60
(1)bedroom sconce 1.81
all fluorescent fixtures 4.57
all lights inc. fluorescent 11.70