index
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RV Maintenance
Current draw of things
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I hate raw camping, I really do. I love campfires and friends,
but there are bad elements to camping that can be eliminated by a modernized RV.
You need a bathroom, refrigerator, automatic heat, and possibly air conditioning.
You can have it all by addressing consumption concerns. Then camping is fun.
solar cells or generator
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current
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batteries, q storage
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current
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consumer things
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"Well... He should have armed himself."
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Off the Grid
Poochy, and my wife, and me like to go to state parks where there are no hookups.
In such situations, it is important to know the power
consumption of things.
The Power Budget...
Power from the solar cells leaves the solar cells in the form of current i.
This current changes all the time, from day to day and from minute to minute.
This current is subject to fog and clouds, and temperature, and the suns elevation.
During the day, the charge q is stored in the batteries, and is usually stated in the nomenclature of "Amp-Hours".
A few amps for many hours is the same as a huge amount of amps for a few minutes.
The batteries accept this energy at any rate and at any time.
The solar energy becomes stored energy.
Not long after that, the younger son got together all he had,
set off for a distant country
and there squandered his wealth in wild living.
Luke 15:13
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Many devices such as refrigerators, lights, and TVs, pull the charge q back out of the batteries, each at their own rate.
The devices use up and "consume" the energy.
The energy is available from the batteries for consumption, day or night.
When you are far from home, the electricity can not be squandered.
The object with any RV, that is "off the grid", is to have more production of electricity than what electricity is used.
RV On-Demand Water Pump
The on-demand water pump starts out below 5 amps when the pressure is 25 lbs.
Then as the pressure builds in the accumulator, the load builds.
The pump labores more and more, and slows in the number of pulses per second.
And finally, at "cut off" the pressure is about 50lbs, and the current is 6.45 Amps (as shown).
The pump pulls slightly more current as the time increases between pulses which is the time that the solenoid is
actually working.
At night, with the pump turned off, I can use the commode several times without the noise of the pump coming on
and awaking my wife, or even the dog. I built my own accumulator, which prevents blown water hoses, (which has happened to me) and reduces current draw.
I will have to show it in another section.
I should point out, that after this picture was taken, the pressure was reduced to 30 lbs.
The original hoses were bursting seals at 50 lbs. And to make matters worse, the
water pump is not adjustable, and under low battery conditions can no longer pump up to 50 lbs .
I had to go buy an external pressure switch, which was easy to do and install.
Otherwise, the pump would just hammer away at 49 lbs all day. Gaining nothing!
This would continue indefinitely untill the battery would be dead.
I never thought the RV industry would have overlooked this problem:
Two simultaneous conditions of Low voltage and too high of pressure.
There is no solution for ordinary RV life if the pump is not adjustable in pressure; You are screwed!
Eventually it WILL happen. You will have a dead battery for no apparent reason.
Also, for power consumption, a 30 lb setting consumes less current than a 50 lb setting.
5 amps verses 6.5 amps
RV Radio
I never listen to the radio. But here is the current with the audio turned down: about 400mA.
The current comes up slightly as you turn up the sound volume, maybe .5 amp.
This radio is a particularly bad one. It is complicated, and can not be figured out.
And it will turn on the alarm for no apparent reason. I hate this thing.
The alarm always comes on at midnight, and defaults to the outside speakers. And every time that it has
happened, it has defaulted to "loud" - really loud. After the damn thing woke all the peacefully sleeping neighbors
at midnight one night, I cut the wires to the outside speakers with a pair of dykes - twice. Both wires!
...Why? Because it felt good. The park's deer were running for cover, and every ones lights were coming on.
That will NEVER EVER happen again.
And why it is legal to sell a RV with outside speakers is beyond me!
It should be a criminal act to sell an RV, with outside speakers, in conjunction with a damn demon possessed radio.
All cubards have Strip Lighting, with magnetic switches.
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RV Lights
These are the first and easiest things to change in an RV.
10HiCluster .... 6HiCluster .... 14DescreteCluster .... Incandescent .... Single
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Five kinds of lights:
Single LED
Incandescent C921 1400mA 260 to 100 Lumens $ 2.00
14-Cluster- Discrete LEDs- 40mA 25 to 35 Lumens SkyBlue $ 8.95
06-Cluster- HyBright LEDs- 145mA- 120 Lumens PureWhite - $11.98
10-Cluster- HyBright LEDs- 230mA- 200 Lumens NaturalWhite- $12.98
These look like two single bulbs, but they actually are two 14-led clusters under the covers.
Almost 100mA for two. Luminosity depends on voltage: 13.99 volts is brighter than 12.60volts.
(This changing of Coach voltage later became a huge problem for LED bulbs.
It took two years for the problem to become painfully evident.
The LEDs were becoming dimmer do to overdrive. I later found and built the perfect solution...)
G-4 Bi-Pin LED Lamp
40mA 10000mCd
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The cheapest way to go. If you can get the small flashlights for about $2 a piece...
Got these at Harbor Fright for two for $3.00.
Here are two flashlight assemblies installed in my 12 volt stove hood.
Go here to see how to wire these LEDs up...
LEDs have made this little RV Trailer the brightest thing in the RV park.
And it is not even connected to the Grid!
LapTop DC-DC Charger
The Laptop is pugged into the 12v DC Cigarette Socket.
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Here is a charger just sitting on a table, plugged in to a cigaret lighter receptacle.
The DC laptop charger uses 12 volts to obtain 18volts. And just sitting idle pulls about 100mA.
The digital meter reads 0.12 Amps for the DC charger.
That is not too much overhead, and 20mA of that is for the two LED indicators!
Quiescent Laptop under DC power.
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Quiescent Laptop under AC power.
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Now the Laptop is onn, and Charging. It is pulling about 1.5 amps DC input to the 12v to 19v Boost Converter.
This is comparable to the 1.6 amp current into the inverter, which supplies 120 AC charging to the 19v Down Converter.
So, I do not see any notable difference between Direct 12v DC vs the 120v AC under a light load.
LapTop AC Charger
AC Laptop charger.
Nothing is plugged into DC Socket.
The AC charger pulls 14mA idle, 0.15 watts. This is to be compared to the DC charger of 120mA idle.
But the AC charger can not exist without the Inverter, about 400mA idle, and to be fair,
needs to be added to it if the Laptop is all that it is running.
However, if the inverter is already onn and used for other things, then the AC charger is clearly the winner.
And also, the AC charger combo will be at least as good as the load increases and efficiency increases of the Inverter.
And also, 120v AC runs around the RV with less wiring loss as the DC.
RV AC-Inverter
The inverter pulls about 400mA quiescent, no load, just sitting there.
If the load is too much, this inverter,
as well as all other inverters, will beep and shut down.
The ones that I have seen will shut down from two reasons: thermal heat, and instantaneous current.
For several years this inverter has been running even my power tools with no problems.
It is a 600 watt Pure Sine Wave. The inverter has a small internal fan that kicks on and off, as the scene changes on the TV.
The fan is audible, and slightly irritating.
Hair Dryer
Behold, he put no trust in his servants; and his angels he charged with folly:
Job 4:18
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I do not know why I tried this, there is no rational reason...
Only a genuine nut would try this...
Insanely nuts!
The hair dryer is a 1600 Watt unit. That is over a 100 Amps. And that is way more than 15 Amps.
Lucky that I did not burn up my meter!
Curling Iron
Wife's curling iron is fine at about 7.4 Amps.
She does not know anything about amps.
Funny thing is that she does not even want to know anything about amps.
RV Air Heater
Central Air, runs under the floor in ductwork using return vents.
I was lucky to find a 21 foot RV with Central Heat.
I had an earlier RV without it.
It was loud and noisy, and was hot and cold.
Air Heater on the left.
Here is the heater blower in the still-running-cycle, but with the gas cycled off.
The air heating unit uses about 700mA for its solenoid, which is for the gas, and about 6.7 Amps for the blower,
as shown on the meter. The meter 6.7 amps shows the cool down cycle: blower with no solenoid.
With both the solenoid valve and the squirrel cage blower on, the heating unit pulls a little over 7.5 Amps.
There is also an igniter that consumes 100mA, but is only on for a few seconds.
RV Refrigerator
Solenoid and Relay, Curtesy G4 Halogen 10W Lamp, and circuit board
Climate Control (Turned off, Heater that evaporates condensation. Use sparingly.)
RV Water Heater
6 gal
Hot Water Heater on the right, and is incased in styrofoam.
Solenoid that turns on the gas pulls almost one amp.
The resistance is about the same as the Air Heater, at about 16 ohms.
3/8 Drill
Drill 3/8
This variable speed drill starts out at about 2 amps climbs to 10 amps with no load.
With load; 12 amps or more. Shown here is 12 amps drilling through wood.
If you look at the rating label, you will see 3 amps at 110vac.
So, under heavy load this thing can go 3 amps at 110 volts,
or aprox 30 amps at battery voltage.
30 amps is over 300 watts.
My 600 watt Inverter is very OK with the drill. Out of convinience the corded electric drill is falling out of favor.
I find myself using the battery drill more often.
USB
USB Power Supply
At only 14mA, You can leave this thing plugged in all the time. It makes yet another "night light".
Saber Saw
SaberSaw
variable speed SaberSaw: 8 amps, no load. I can bog it down, but still no problem.
Weller Soldering Station
Weller Station
Max current 3.4Amps, (has not reached temperature). After it reaches temperature, the ONN light "flutters".
The inverter handles fast ONN and OFF current changes just fine. So, the current never goes above 3.4 amps.
Absolutely no problem.
Weller Soldering Gun
Before tip replacement
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Weller Soldering Gun
8.6 Amps
After tip replacement
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Weller soldering Gun
New tip! And using the pure sine wave inverter, instead of the modified sine wave inverter.
Inverter fan comes on full force, instantly.
With new tip, 11 Amps (including the fan)
I have had this Weller Jr for almost 30 years, and I use it all the time. I use it as much as the Station.
Got it out of High School. It has a miner crack in the case.
Never a problem.
Range Hood Fan
Range Hood Fan
1.5 Amps for the Hood Fan.
This is one device that is not even close to what is printed: 3 amps.
I later put in a speed control that saved power and greatly reduced the loud noise.
Electric Blanket
Electric Blanket
7.2 Amps
For that kind of current, you might as well run the Furnace and heat the whole place!
An electric blanket is not a viable option for being Off-The-Grid.
I might also note that electric blankets DO NOT like square wave inverters!
The electric blanket control box began to smoke. Actually, I could not see any smoke,
but could smell it. The blanket was on for only a couple of minutes. It is the only device
that I have ever seen that did not like 120 volt AC power from square wave inverters.
I quickly replaced that Square Wave long ago with a Pure SineWave inverter.
This blanket is a Queen size, and is not practical in an RV unless you fold it to cover only your body.
You can also buy a small 12v DC blanket that does not fill the intire bed.
Probably the most efficient placement is under you. If above, place an extra blanket on top of it.
Tire Pump
Picked up this nice pump at Harbor Freight. Set all my tires to 42 lbs.
I have sense changed to 50lbs, which is the tire rating, because I have a lot of junk inside.
The current varies according to the air pressure:
At zero lbs the current is about 5 Amps.
At 42 lbs about 10Amps.
The literature warns to not turn on the pump "loaded", or the fuse will blow.
So I guess that you have to start it at zero lbs. Otherwise; Works fine.
Full load is already 10Amps, normal running at 42 lbs. Would not take to much more
to be at the max rated 15Amps - like in a starting "stall".
I have to feed out a window on both sides of the trailer to get to all four tires.
The window screens slide independently from the glass. Fortunately, I had previously wired
12 volt cigarette lighter receptacles on all four sides.
There is a law somewhere that states that you will always need more 12volt receptacles
and more 120 volt receptacles in any well planned installations.
LCD TV
LCD TV
4.5 Amps to 9.0 Amps
And according to the manufacturer can go to 10 Amps, or 120 Watts!
An LCD is NOT a good choice for an RV. Instead, inside an RV use a LED tv.
The LCD uses a mercury lamp for the back light; and more importantly, is lit
ALL the time. It waists energy ALL the time.
I use this monitor for my computer room in my house. And I carry it out to the RV
when we go on a trip.
The current consumption for an LCD is totally dependent upon the "blacklight"
adjustment. With backlight adjusted to minimum, the current for my tv is 4.5 Amps, no matter the
screen content. With the backlight adjusted to maximum, the current is more than 9 Amps.
At night, I have found that there is only marginal detrimental effect from the backlight being
all the way down. Four hours of viewing at 4.9 Amps results in a battery voltage of 12.450 volts.
That is 4.9 Amps times 4 hours. Or 19.6 Amp-Hours of TV viewing.
According to a chart for flooded batteries, 12.45 volts is approximately 84% of full capacity.
Therefore, full capacity (=19.6/(1-.84))of my two batteries seems to be about 123 Amp Hours.
Rather disappointing. I was hoping for more.
But getting back to the TV.
You get what you pay for. Don't ever buy a cheap LCD for a RV. This one has a sticker on the
back that warns the set can pull 120watts. That is about 10amps with the black level turned up.
I can not afford that kind of waist! And it gets warm at the top.
On the other hand, an LED of the same size may only pull 2 amps, and it is lighter too. Now that is sweet!
But LEDs do not come cheap; I can not afford one at this time.
Also, don't ever buy a computer monitor: they can not be viewed from all angles.
Laptop screens can not be viewed from all angles either!
Therefore, DO buy a TV, and make it a LED TV.
A friend GAVE this nice LED TV to me.
LED TV
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Great friend! His name is Dan...
Don't mount flush with the wall. Leave space in the back for cables.
This thing is so cool!
LED TV
It uses 2.6 amps. This is in contrast to the old LCD which uses 5 amps for the same brightness.
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With a setting in the menu for BackLight at "5".
Uses 2.4A Current
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With a setting in the menu for BackLight at "93".
Uses 4.8A Current
The conclusion is that LCD TVs and/or monitors are not RV fiendly.
Only LED TVs and monitors should be used in a RV.
LCDs will work OK in a house or mobile home with full hookups.
Plasmas are not even a consideration; Much worse.
The screen of the LED TV/MonDisplay can be "shared" with a laptop in several configurations:
Laptop uses 3A with its LCD screen brightly lit, 2.5A in black. (6A when charging)
Published listing is 3.42A at 19 volts. (BackLighting is not specified, and is probably higher than my setting.)
2.5A: LaptopBody and its LCDscreen lit black
3.0A: LaptopBody and its LCDscreen lit white
5.5A: LaptopBody and its LCDscreen, and TV/MonDisplay both on with both screens lit.
Therefor, 3A LaptopBodDisp + 2.5A TV/MonDisplay = 5.5A
4.7A: No Laptop screen. Therefor, Laptop LCDscreen is 5.5A-4.7A=0.8A, during one test.
4.5A: No Laptop screen. Therefor, Laptop LCDscreen is 5.5A-4.5A=1.0A, during another test.
2.5A: TV screen on
5.2A: Laptop LCD screen on black (2.5A), LED TV/MonDisplay on Programing.
Therefor, TV/MonDisplay is about 5.5A-2.5A=3A (in programing).
Therefor, the individual pieces can be deduced...
Laptop Body 1.5A, Laptop Screen 1.0A (in black)
TV Body 0.3A, TV Screen 2.2A (in black)
In the prefered configuration of the laptop (without screen), driving the LED TV/Monitor Display:
is from 4.5A to 5.5A, depending on picture content. This is a bright picture.
However, 3.7A is still a very good picture with BackLevel down to 20%.
Most young people simply use a laptop in an RV, and are adept and comfortable.
But I can not use a laptop; with the complaints being the keyboard and mouse, and also the screen size.
Perhaps I am spoiled; I like the big DeskTop! In fact, I am resigned to it.
If you can not get beyond it, have you ever wondered which is better: an RV 12 volt desktop PC, or a Laptop?
First of all, I have never seen an RV 12 volt computer.
They have all been ordinary computers with converting power supplies, most with 12v to 19v boost converters.
I could haul out my big honking Desk Computer to the RV, and run it on the 120 volt inverter. No problem!
And call it an RV computer!
I could say that it even runs off of 12 volts, if you do not look where each of the power conversions are taking place.
It is all symantics.
Anyway, getting back to my point...
My Laptop only uses 1.5A for its motherboard, which is everything except the display.
A 12 volt "RV Desktop" will pull 2 or 3 times that! A laptop is the way to go!
After all, a laptop was designed with efficiency in mind because of the internal battery. A main selling point is how long will a battery last.
And therefor, great for an RV.
And mine can be improved even more... It uses a mechanical hard drive; not the best thing to be bouncing around.
Mine is getting kicked by my feet and bumped around. After all, it is always in a tight space.
My son has the solution: an SSD Laptop.
When I can afford it, I will have a Solid State Drive SSD Laptop driving an efficient external TV/Monitor.
In the old days, you could not use a Computer type Monitor in an RV with multiple viewers; Not all will be able to see it.
Monitors, that are conventionally used with computers, have severe limitations on viewing angles, both horizontal and vertical.
If you had a partner or pet, TV/Monitors were the only way to go. Now days there have been improvements in viewing angles,
so that computer monitors can successfully be used with their higher resolutions. But I have NOT heard of any RVers doing so.
The rate of solar charging can be from 9 amps down to 1 amp, depending on fog and rain.
Over the period of six good hours from 09:00 to 15:00, an average of 5 amps might be typical.
That constitutes a budget of 5 times 6, or 30 amp-hours.
What ever amp-hours I use, those same amp-hours must be replaced, and then some.
Coincidently, my computer work uses 5 amps too, as outlined above.
I can not use more than the "30 amp-hour" budget.
Therefor, I can not work more than 6 hours on the computer per day,
and still hope for any type of permanent sustainability.
Update...
Here is a "house" computer monitor. LED 32 inch Horiz.
120vAC 16mA asleep, 500mA Surge, 231mA up& video.
Therefor should pull 2.31 Amps at 12 volt sources.
Here is the "gift" LED TV Mon.
14mA Sleep, 170mA Up&video.
Can watch TV, or run as a monitor, for less than 2 amps.
Inverter takes about 0.5 amps. So total would be about 2.5 amps. Unfortunatly, I never watch TV.
This thing is already out in the RV, as my wife likes it and loves to watch tv.
This monitor is RV friendly, and if I want to keep my wife friendly, guess I better leave it.
Also, it was a gift from her son, who passed away.
Here is a laptop, internal battery not charging, but including Wall-Pack pwr sup.
16mA Sleep, 400mA Surge, 292mA Running&video.
As discussed earlier, a laptop can not be beat for power consumption.
And this is both the body and the monitor; the whole thing, for under 3 Amps at 12 volts in the RV.
Here is a Dell computer Win7.
47mA Sleep, 860mA Running
At times over one Amp at 120volts.
That is a huge 10 amps out in the RV at 12 volts. That is a "no go" for the RV!
That is 120 watts, and although not beyond my 600 watt pure sine wave inverter, just too scary inefficient.
Old House LCD TV and Monitor. If this was out in the RV, It would pull 4 amps at 12 volts.
383mA Up&Video
The two LED monitors pull have as much. An LCD Monitor is therefor a "no go" for an RV.
HP House computer
41mA Sleep, 286mA to 322mA Working
Wow! The other computer runs three times this amount.
Wow, at about 3 amps, this thing has real possibilities in the RV.
I want to explore the possibility a bit more. I will take this "house" computer to the RV.
When a house computer and monitor are initially turned on, almost 10 amps are drawn.
If the set stayed at 10 amps, this would be a no-go. The current jumps around wildly, but begins to come down
... During boot up the current begins to come down.
While the computer is booting up, I will look at all the solar panels. Here is a vertical array of six meters, five of which are about 100 watts each.
This is my "Solar Collector and Combiner".
And, wow, there is plenty of solar current available: As an example, here is the current from just one set of panels.
It is the "30 and 50" watt panels in parallel with schottkys.
It reads 1.2 amps, under its pretty blue light.
I can press its button switch, and see the maximum current available.
And here is the same set at a dead short, which represents the maximum capabilities of this set.
It reads 2.8 amps, as indicator light goes out under Short Circuit Current.
Actually, this over estimates the maximum, as this is at zero volts, not the Max Power Point.
I guess it is correct to say it "represents" the maximum, and may not be the actual maximum.
As I press the button for any panel, all other panels go up a little. This is in response to the loss of that panel.
After the computer and monitor are up for 10 minutes the current is compared for a dark picture and for a light picture.
A dark picture pulls 5.5 amps and a light picture pulls 5.6 amps. I never expected this; there is no difference.
Current draw depends more on what the computer is doing, rather than what the monitor is doing.
Battery A is not affected much, as its Post Regulator is not engaging much. Batt-A is absorbing about an amp.
and its voltage is unchanged at 13.40 volts.
The bottom meter is the Reject voltage at 13.6 volts, and it is pulling about 1.8 amps.
However Battery B has a Post Regulator that is engaged,
and is evidently responsible for running the Computer and Monitor.
Batt=B is absorbing about 5 amps, and it is to replenish what is being pulled out downstream by its Post Regulator.
There is a problem! The voltage of Batt-B has dropped to 12.6 volts. It should have not dropped at all!
It has to be a ground current problem. It is not likely a ground current over at the inverter.
More likely ground current at this Regulator. It has a dedicated remote sense wire, it should not be going down. I will look at it later.
Dometic DM2652
Power Module Electronics Board 0.4 amps
Pizo Electric starter 0.05 amps, drops out after start
Solenoid for gas 0.25 amps, 49 ohms
(Total for normal running is 0.65 amps)
Inside Courtesy light, old: 0.8 amps, New LED:
(Total for running and door open is 1.45 amps)
Climate control 0.5 amp, 24 Ohms
Installing Chimney Fan 0.16 amps
Stated on label 1.3 Amps, total 12v DC Amps.
Shut off is 9.6 volts, Service Voltage, Coach Voltage, Coach LowLevel DC Utility Voltage.
The Tail Lights are not part of the RV current draw. The draw is from the towing vehicle.
The Stop/Turn Filaments as well as the Tail/Running Filaments derive their power DIRECTLY from the tow vehicle.
The smaller and finer, or "lesser", filament is on for the Running lights. With the LED, the lesser intensity setting is on, characteristic of the Running lights.
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The original Bulb on the RV is a 2057, and is not as bright as the Tow Vehicle's 1157.
The voltage is way down to 9.4 volts by the time wiring reaches the end of the RV.
This was measured with the engine off, and all side and tail lights on.
The voltage would be even less, if RVs used the customary automotive 1157 bulb.
Wow! I never ever expected this!
Also, theoretically, there could be a legal problem:
When you step on the brake,
the extra wiring losses would prevent the brake filament from fully lighting as designed.
The result is that there is little difference between running lights and brake lights.
This may be an issue with DOT, where brake/turn must be much brighter.
I am eliminating ALL those problems; I am going LED!
The 1157 is a 26.9 watt bulb (at 12.8 volts). Amp draw is 2.1 amps
1157 is 3 cp candle power for running lights. And 32 cp for brake/turn.
1157 is rated at 1200 Hours.
The 2057 stop/turn is the same as 1157 stop/turn,
but the RV 2057 Running lights are dimmer.
2057 is 2 cp candle power and 32 cp for brake/turn.
Used in the left Tail Light.
A white wedge directed down towards the licence plate.
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Before buying LED, you should consider one more thing.
Do not be forced into buying a White LED
because you have to simultaneously light your licence plate on the left side with a single bulb.
You will have an efficiency problem of pushing white light through a red lense.
Just as with the incandescent bulbs; You are going to lose light.
When I took the cover off, this was indeed my case.
I simply installed a second dedicated LED bulb for the license plate,
and I was able to keep my RED LEDs. You can only use white on the plate, as police need the true
color to help identify the state.
Also, some Red LEDs have a label saying for "off road only".
Meaning the color has not been formally approved, but in practice is accepted on road.
Others dispense with the label.
Many styles and intensities to choose from.
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from SUPERBRIGHT...
Stop/Turn intensity: 270 lm = 270/(4*pi) = 21.4 candle
1157 LED Bulb - Dual Function 18 SMD LED Tower - BAY15D Retrofit
1157-x18-T-RVB
That is not all the lights; there are side lights.
These are C194 wedges.
7 reds, and 4 yellows.
That is a total 2.7 amps of normal incandesents for side lights.
This waist is not necessary!
And the original incandescents are 25 lumens each.
The 25 lm is only produced at 14v which is not noted at the rear of the RV.
Therefor the lumens is less than 25 lm.
The incandescent pulls 243mA.
The LED pulls 50mA.
The lumens is claimed to be 100 lm, but looks about the same to me. Maybe a little brighter.
And I went with red to get a little richer red color through the lens, which is what I got.
Also, I have found after 20 years or so, the lenses weaken in color purity and are more white.
An Oscilloscope is one of my engineering instruments. It gives me pretty pictures of electrical voltages anywhere in the RV.
The Oscilloscope pulls 3.7 amps. I thought it would pull more because it is an old CRT (Cathode Ray Tube) scope.
With this low current, I can even work at night in the RV with little concern.
In the day there is no concern at all, and can run as long as I want, as the solar panels more than make up for it.
RV CrockPot
Actually, that is a brand name. This is really a 3 quart "SlowCooker" with pretty flowers on it.
I love a "SlowCooker" by any name. Because even I can cook with it without screwing up.
I just throw in some little red potatoes whole, and throw in some, otherwise noneatable, chunks of meat.
Perhaps, a little wild onions, gathered on the way to a pond.
And four hours latter... All done!
There is another reason that I love this thing:
My inverter is only 600w, and I do not have the power to run my Microwave Oven which is about a thousand watts.
Nor do I have the power to run a Pressure SlowCooker, which also is a thousand watts.
Both these would be nice to have for Boondocking.
But a thousand watt inverter would be too inefficient at normal low wattage levels.
A work around solution would be to have, say, three inverters.
But selection would have to be applied at both the low DC side as well as the output AC side.
The nightmare solution is getting me off the subject: CrockPots.
Here is our RV CrockPot:
A small CrockPot better designed for an RV.
Selectable: 75 Watts, and a 150 Watts...
The only thing it lacks, for a true RV classification, is a thermostat for energy savings and efficient cooking.
The CrockPot nob setting is on low, or 75 watts.
First Meter: High AC Side: Reads 0.633 Amps (at about 120volts),
Therefor Low DC Side should theoretically be about 6.33 Amps (at about 12 volts)
Second meter is the same meter with a setting of Watts. The wattage reads 74.44 watts, in agreement with the label.
This first two meters are the 120 volt "output, or AC" side. This is the Inverter Output.
The next meter is the current, voltage and power going into the Inverter from the Lithium Battery.
This is the "Low Side, or DC Input Side"
The Inverter reads 13.20v, 6.3 Amps are going from the battery into the Inverter, and the meter reads 83.16 Watts inverter usage.
The efficiency of the inverter is, input watts to Output watts, 74.44w/83.16w = 89.5%
The next meter, in red, shows how much Replacement Current, or Charging current is going into the Lithium Battery.
It is desireable to have the same current going into the battery, as is leaving.
It reads a little over 6 amps. That be about perfect.
Now this is on the High setting of the CrockPot nob: about 150 watts.
High AC Side: Reads 1.254 Amps (at about 120volts),
Therefor Low DC Side should be about 12.5 Amps (at about 12 volts)
The same AC meter reads 146.56 Watts
The next meter feeds the inverter:
The inverter DC Input reads 13.09v, 12.4 DC Amps, 162.3 DC watts
The efficiency of the inverter is, input watts to Output watts, 146.56w/162.3w = 90.3%
The next meter in red:
The Battery Replacement Current, or Charging Current, going into the battery is a little over 10 Amps.
This meter itself has withstood a little overrange for several hours before. It is OK.
I suspect it is not quite 12 amps because there is a choke that is a little hot in the Controller.
I really should replace it.
This next crockpot belonged to my wife's mom, Joyce. She passed away at 99 years.
And I have carried the crockpot out to the RV...
It is 4 quarts and too big for the RV, but I want to see how it functions in an RV setting.
I will carry it back before my wife notices it is gone.
Two settings: 178 Watts, 240 Watts.
The AC Output side shows 170.25 watts.
But the DC Input Side shows 185.5 watts.
Efficiency is 91.77%
The CrockPot nob on the high setting of 240 watts...
The AC Output side shows 226.44 watts
DC Input Side shows 242.7 watts
Efficiency is 93.3%
Playing with the Crockpots has also yielded a study of inverter efficiency.
75w 89.5%
150w 90.3%
178w 91.77%
240w 93.3%
So, my 600w sinewave becomes more efficient as wattage increases...
Before I leave the subject of CrockPots...
If the sky is dreary, you really should not use the CrockPot. You will have to take your chances with the skillet.
The large AmpHour demands should not be taken out of your poor batteries. Your batteries will not be drained during the day.
Use the sun totally. I take a walk during the day while the sun runs the CrockPot.
It also recharges my batteries, and heats water, all while I am gone. Batteries are for night time.
However, at Black Butte while there was one and a half days of solid rain, I would break my own rule and use the crockpot without sun replenishment.
It is here that I discovered something else about crockpots. They are 99.99% inefficient.
I am putting in 150 watts to cook my split pea soup. The contents are at 143F degrees.
And that is as hot as they are going to get with an ambient air temperature of 75F degrees.
I have been putting in 150 watts for two hours, and the temperature of the split pea soup will not go past 143F degrees
That tells me that the crock pot is sending 150 watts into the air.
It is waisted energy. 100% of the energy is waisted in a normal crockpot.
Very little energy is going into changing the molecular bonds in the actual cooking process.
So, now I try a little insulation:
I rap one layer of reflectix around the crockpot, completely down to the counter. Crude, but this is an experiment...
I can wave my hand over the top, and still feel a lot of heat rising from the lid.
So, then I make a top hat of reflectix and styrofoam that just slips over the the bottom jacket, down to the handles.
Top and sides are all insulated.
Now with new readings, the temperature quickly sours to 176F degrees for the lid, and 175F degrees for contents.
And after 40 minutes it was up around 180F degrees for both lid and contents.
Without insulation, that crockpot would not get above 143F degrees, no matter what.
My split pea soup was edible in three hours, instead of 4 or 5.
The insulated crockpot is still 100% inefficient,
in that 150 watts is still going to the enviroment, but cooking times are reduced.
One more thing is necessary to make an ordinary crockpot RV friendly: a thermostat.
Cooking times will increase again, to those of an ordinary crockpot,
but the overall wattage will decrease dramatically, because the crockpot is not on all the time.
Also, a thermostat would be nice for safety concerns, as well as safety concerns with the contents.
After a long walk, there could be a terrible surprise waiting:
the contents will boil over, and spill all over the counter. Or dry up, smoke, or even start a fire.
Update:
By accident, I put the setting on high and forgot about it.
I ment to return it to LOW. After about an hour came back to the RV to find a burnt smell.
Contents had boiled, and there was a burnt ring inside the pot. To modify an ordinary crockpot to RV use, you must to BOTH:
Insulate AND
Thermostat
When I first bought the RV, I was NOT comfortable. It was like "camping", and not
fun. I HATE camping, I really do. I love campfires and friends,
but it is camping without bathrooms and refrigerators.
With modifications my RV has become very comfortable.
It is now without compromise and a modern pleasure.
On this page I have shown gobs of consumption stuff.
Your RV will be different, but you
get the idea. With planning, you can have-it-all too.
STANDARDS
One more thing; Standards.
I have been an Engineer all my life.
Before I was in kindergarten I was an engineer, and I rode a tricycle.
I had a coffee can on the back step of the tricycle. Not an ordinary coffee can; It was a gas tank.
I remember that the stupid can would not stay on the tricycle. ...And I could not tie a string.
I always had to run into the house and have Mom resecure the coffee can with a string.
As a result Today, I have overcome the string problem of when I was a four year old engineer.
I wear velcro shoes. Something only an Engineer with a problem would understand.
Anyway, I digress...
I punched a small hole in the side of the can, down near the bottom.
This was my gas tank, and I filled it with water. Before I could go anywhere I had to have gas (water).
When I was ready to hit the road (dusty path), I would pull the nail out of the hole in the side of the can (gas tank).
The high octane of what was in the can would shoot the tricycle out ahead, and down the path.
As a child, I knew that I had limited range before my fuel ran out.
I loved to peddle the dusty paths, and watch my little trail of water,
as it marked everywhere that I had been. You would not recognize it, but the gas station was the spigot of the well,
located on a dusty worn path marked by the narrow marks of tricycle wheels.
This familiar path had no gas signs, and went a long way to the west of the house.
My sisters knew to always make it to the gas station. Never be caught out of gas. A hard rule.
They were girls, and operated by different rules. Rules that were kind and soft:
A girl would fetch a cup of water and give to the stranded motorist, and pour into their coffee can.
I stood in wonder of a parallel universe, but continued with my engineering.
Regaining focus, I added a second hole in the can that I left plugged with a nail until I needed more power.
But all this extra power came with a price. There was a tradeoff: my gas consumption would increase.
Every once in a while, I would need more power. So, I would remove the second nail, and let'r rip.
I have been an Engineer all my life, and just naturally know all about RVs and Tricycles.
I digress again. So, allow me to get back to standards...
Solar Panels and Batteries are much like gas cans of two different colors.
Solar Panels and batteries are measured in different units. They need not be.
Solar Panels are measured in Watts, and batteries are measured in Amp Hours.
This is how you buy them, one in Watts, and one in Amp-Hours.
But both are containers of Energy, and this is the common ground.
First; for batteries:
Amp Hours are very convenient, and refect indirectly the real measurement of energy, if volts are assumed.
The real measurement of energy is Volts x Amps x Time.
I will continue to use Hours for time, as it is convenient.
And if so, the Units are Watthours.
A 100 Amp-Hour battery, at 12 volts, is equivalent to 1200 Watthours.
(12.0 volts is a mean point between 12.6 and 11.0. Lithiums have flatter decay slopes and voltages.)
For Solar Panels:
The energy of a solar panel is its Watts x time. Again we will use Hours.
But there is a problem: We must assume a standard length of time in a day.
For example: What is an appropriate average, considering cloudiness and latitude?
Of course, there is no standard, so you must create one for your own unique situation.
For me: "Five hours".
If so, then a 100 Watt solar panel is equivalent to 500 Watthours.
(For RV life, a day is a convenient unit of lifestyle.)
One more consideration if you are comparing solar panels to batteries.
Lead Acids, unlike Lithiums, are not designed to be taken down below 12.0 volts.
Therefor, the useful, or available, energy is only half of the above calculations.
Therefor, for 100 AmpHour Lead Acids, half of 1200 Watthours is 600 Watthours.
And that is numerically similar to a 100W Solar Panel of 500 Watthours.
Numerically, a common 100AH battery and a common 100W panel, yeld similar 600Wh and 500Wh values.
So now, batteries and panels can be compared, side by side, as energy producers.
If you want to ride our tricycles together, I can show you more...
