12 Volt Cooler Amp Draw
how long volition my 12 volt refrigerator last
when camping ground?
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| suitable size solar panel & bombardment setup for long stays when bush camping |
How long will a 12 volt compressor fridge run on a 12 volt battery when camping is a very mutual question, withal it does not have a simple answer. Information technology is a fleck more involved than buying a refrigerator & plugging information technology into a battery. This article is non meant to be too technical, but a fiddling theory is needed to explain how things work & how to select the right bombardment size to suit your needs without bravado your budget.
a little theory
A function from Lithium Iron Phosphate batteries (LiFePO4) & the new Pb Crystal batteries that are at present on the market, an AGM (Absorbed Glass Matt) deep cycle 12 volt battery is the best battery type suited for camping, as it can be discharged more deeply & accepts a charge more than readily than a cranking battery which is used to start your vehicle. The chapters of an AGM deep bicycle battery is stated in amp-hours (Ah).
On each 12 volt accessory there will be a characterization with electrical terms & figures. From this y'all can summate the ability an accessory will consume from an AGM battery? Listed on the label will exist amperage, (A or amps) at 12 volt. There may besides be 24 volt or 240 volt if the accessory has dual voltage input. If the label but shows watts & volts you can easily piece of work out amps by dividing the watts by volts ie 100 watts divided by 12 volts = viii amps.
Amp 60 minutes is the amount of current that flows in 1 hour. To work out the amp hours that will be consumed by an accessory from an AGM bombardment, you simply multiply the amp draw by the number of hours the accessory is running. As an example the accessory has 8 amps draw x 4 hours running time = 32 amp hours used.
You run a LED light under the awning of your camper trailer & it draws 2 amps.
* over ane 60 minutes the light volition draw ii AMP HOURS from your AGM battery,
* 1 AMP HOURS in HALF AN 60 minutes
* 0.5 AMP HOURS in a QUARTER OF AN 60 minutes
* if the calorie-free ran for 4 HOURS it would consume 8 AMP HOURS, that is 2 amps x 4 hours = viii amp hours.
Permit's say you run a 12 volt electric blanket for two hours before you lot spring into bed on a cold winters night so the sheets are nice & warm. The blanket draws 4 amps, therefore information technology will utilize viii amp hours. That is 4 amps x 2 hours = 8 amp hours.
You set up a 12 volt water pump for showering which has a draw of 8 amps. When bush showering to relieve your limited water supply, you utilise the shower to moisture down, plough it off & then back on to wash the lather off. All up the pump will be running for around 2 minutes per shower. In these circumstances the pump would employ 0.25 amp hours per shower. If there were four people showering, the pump would use ane amp hour.
12 volt compressor fridge
A compressor fridge/freezing may take a depict of 2.5 amps at 12 volt on the label as an example, however it does non run continually, but cycles or turns on & off to maintain the internal temperature you take set. There are a number of factors that will govern how ofttimes the refrigerator will run to keep the preset internal temperature. These include -
* size of the fridge
* internal preset temperature
* ambient temperature
* how total the refrigerator is
* the number of times the refrigerator is opened
* the number of items at ambience temperature that are placed in the fridge
* the fridges position such as inside a hot vehicle.
So how do y'all work out what amp hours the fridge really draws over a 20-iv hr menses. There are a number of meters around which you tin plug into the power pb between the fridge & battery. The meter not only shows instant readouts, just also counts the amp hours used, which is a very handy tool to exit connected over twenty-iv hours to give you the daily amp hours a fridge has used.
I have a Watts Up Meter http://world wide web.campertrailers.org/watts_up_meter.htm which I have built onto a jiffy box so it can plug into different 12 volt accessories with cigarette lighter fittings. Information technology can also be used between the solar panel & battery which uses Anderson connectors, so I can run across what the panel produces over a mean solar day.
If the fridge drew ii.5 amps & did run continuously, it would consume threescore amp hours over a mean solar day. Hither are the actual amp hour figures of our 40 litre Engel run as a fridge in the back of our vehicle when camping ground over a twenty-four period in three dissimilar ambient temperature ranges. Every bit you can meet the hotter the day, the more than the refrigerator runs or cycles to keep the same preset internal temperature.
| 40 litre Engel bodily power depict when camping ground | |||||||
| refrigerator punch | refrigerator internal temp | ambience min temp | ambient max temp | amp depict | amp hours over 24 hours | boilerplate amp describe | run fourth dimension |
| i.3 | 2.5 celcius | x celcius | 20 celcius | 2.v | x | 0.four | one-sixth |
| 1.iii | 2.5 celcius | 20 celcius | 30 celcius | ii.5 | xx | 0.83 | one-third |
| 1.iii | two.5 celcius | 30 celcius | 40 celcius | 2.5 | 40 | 1.vi | ii-thirds |
This is a examination I did in the garage at home running the 40 litre Engel as a fridge & then on another twenty-four hour period as a freezer later letting it settle at the freezer temperature http://www.campertrailers.org/fridge_draw.htm
getting the best out of your fridge
By sticking to a few guidelines your fridge should piece of work at the optimum operation when out camping.
* A cover protects the fridge & gives some insulation, helping to keep your fridge absurd & reducing the ability consumption.
* Absurd the refrigerator & its contents before leaving home.
* When packing your vehicle make certain the fridge motor vents are given space to allow ventilation for best operation.
* Use the correct cable size from the 12volt battery for the amp describe of the refrigerator & cable length.
* Keep your fridge cool by taking it out of the vehicle on a hot mean solar day & placing it in the shade under the camper trailer awning.
* Limit the number of times the refrigerator is opened. This can be difficult with kids.
* Water ice bricks or Techi Ice sheets placed inside the fridge will add to thermal insulation & reduce the power consumption.
* Keeping the fridge full rather than role empty will reduce the power consumption.
* Vacuum seal your meat & run as a fridge rather than a freezer will reduce the power consumption.
* Clean the inside afterward a trip with hot soapy h2o. We so wipe the inside with diluted vanilla essence.
* It is recommended that you run the fridge at regular intervals if its being stored for a period of time.
* Leaving the lid slightly open will reduce mould if not using the refrigerator.
a lilliputian battery theory
An AGM or absorbed glass matt deep bicycle battery is the best 12 volt battery type suited for camping as it can exist discharged more deeply & accepts a charge more than readily than a starter battery. A good dominion of pollex to follow for all-time battery life is not to discharge a deep wheel bombardment below 50% capacity or 12.2volts. As you can see on the graph beneath, continually discharging only ten% of the battery capacity may requite y'all 5000 cycles, compared to continually discharging it to ninety% which may give yous only 400 cycles. It is better to take a large deep cycle bombardment discharged by a pocket-size percentage than a minor battery discharging deeply.
Checking the land of charge of a deep wheel battery while information technology is charging using a voltmeter will but show the surface charge. When discharging a deep cycle battery the voltage will be below its true country of accuse. You need to allow the battery to 'residual' for at least a couple of hours, preferably eight, for the surface charge to dissipate. It is like filling a drinking glass with Coke & looking as if it is full, when in fact the elevation is froth. You need to let the fizz settle to see how much is really in the glass. The state of charge does not measure the storage capacity, operation level or the health of a battery. The best time to bank check your battery with a voltmeter is commencement affair in the morning before you open the fridge & before you lot place the solar console in the dominicus.
A battery monitor measures the amp hours in & out of a full bombardment via a shunt & is the well-nigh accurate fashion to proceeds the truthful state of charge. There are a number of different brands & types of battery monitors on the market place. I installed an Everdrive Elite battery monitor on our camper trailer's AGM batteries http://world wide web.campertrailers.org/enerdrive_elite.htm
battery size
A bones 12 volt battery system can exist as simple as a portable AGM battery in a plastic bombardment box to cover your 12 volt compressor fridge's ability needs over a weekend & a multi-stage 240 volt battery charger around 10% to 15% of the battery capacity to maintain the bombardment at dwelling betwixt trips. From there yous tin can add a portable solar console to top up the bombardment during the twenty-four hour period when camping ground & later perhaps a DC to DC charger to fully charge the battery from the vehicles alternator when driving between campsites on a touring holiday.
When setting up a 12 volt system to suit your needs ever wait at the bigger motion picture as a whole or what your ultimate bombardment setup will be. This will relieve you money in the long run every bit you tin buy the right size chargers & cablevision right from the start.
Lets say if your compressor fridge is run as a fridge & uses 20 amp hours over a 24 hour menstruum. Over a 2 twenty-four hours weekend the fridge would employ twoscore amp hours. Therefore a 100 amp 60 minutes AGM battery would be suitable, keeping in heed not to belch your deep wheel battery below 50% capacity.
If yous are camping ground over four days, the fridge would consume lxxx amp hours, so you need 160 amp hours of battery in total. One 150 amp hr battery is heavy & takes upward a lot of space, so two 100 amp hour batteries would be a suitable choice installed in the camper trailer also spreading the weight. Even if you exercise have a solar panel, you cannot rely on the sun beingness out & you are more than likely to be running other accessories.
solar panel size
What size solar panel do you need to fully accuse your bombardment? This depends on the season, your location & the available Acme Solar Lord's day Hours. Again it is not simply a simple process of maxim A+B=C.
Peak Solar Sun Hours is the number of hours when solar irradiance averages thousand watts per square meter, however with a portable solar panel you can option up more than solar by pointing the panel to face the sun during the twenty-four hours. It is a skilful idea to choose your solar panel size then the bombardment is fully charged by after lunch.
You also need to take into account the output loss caused past temperature of the solar console & cable voltage drop which tin can effect in the console only producing seventy% of its rated output. Printed on the rear of a solar console there will be two output figures, one at 25 degrees celcius & the other at say 47 degrees celcius. These are the actual temperatures of the panel itself & not air or ambient temperature. Typically there is 5% output loss for every 10 degrees celcius the panel is above 25 degrees celcius.
putting information technology all together
Richard'due south Solar Spreadsheet is an easy way to work out the battery & solar panel size y'all require past computing the ability usage of various 12 volt accessories http://www.campertrailers.org/solar_spreadsheet.htm
On the info page y'all will find a table for Superlative Solar Sun Hours showing selected locations & months. In Sydney for case around the bound & autumn equinoxes when there is twelve hours daylight & twelve hours dark, there are only 5.6 Peak Solar Sunday Hours, if you take a fixed solar panel facing north.
In your calculations you tin can throw into the spreadsheet an overcast day with piddling or no solar input & see how the bombardment recovers via the solar console. This tin can be of import if you are setting up a remote campsite for a catamenia of time & relying only on solar to maintain your bombardment that is running everything.
solar regulators
A solar panel produces around xviii volts or more and so this needs to be reduced as not to overcharge & damage the bombardment. This is done by connecting a solar regulator betwixt the panel & the battery. A solar regulator tin be mounted on the back of the panel or adjacent to the bombardment that is being charged. At that place are two different types of solar regulators, PWM & MPPT.
PWM or Pulse Width Modulation slowly lowers the corporeality of power applied to the bombardment as the battery gets closer to fully charged. This allows the battery to be more than fully charged with less stress, extending the bombardment life.
MPPT or Maximum Power Point Tracking regulators are able to catechumen backlog voltage into amperage past calculating the output from solar panels to provide the maximum current possible at the required voltage at whatsoever given point. During depression light level situations the MPPT will compensate for the low light level & find the new point at which the solar cell delivers its maximum power output.
chargers
After running the fridge from a suitably sized deep cycle battery over the weekend & keeping the battery chapters above 50%, you will need to accuse the battery at domicile to maintain it in a state of good health. A rule of pollex for sizing a 240 volt multistage charger is around 10% to 15% of the bombardment capacity, that is a x amp to 15 amp charger is suitable to charge a 100 amp hr deep cycle battery. If you are looking at calculation another battery sometime in the future, yous will save money past buying a charger to arrange your intended battery chapters from the start.
There could also be times when y'all are on a touring holiday & encounter some bad weather needing to drop into a caravan park to connect the 240 volt charger to your camper trailer batteries. A smaller charger will do the job, but the recommended 10% to 15% capacity will accuse the bombardment overnight so you can continue your vacation with a fully charged battery.
What does multistage mean? The charger will go through three or more than stages to fully charge the 12volt AGM bombardment. The most common multistage charger has three stages to give the battery a more consummate charge.
Phase i is also know as boost mode & charges the battery at a constant amperage until the battery voltage reaches around three quarters capacity.
Stage ii is also known as absorption. This way maintains the elevated voltage from the bulk phase, merely adjusts the amperage accordingly. As the battery accuse level approaches capacity, the current approaches cypher. Assimilation voltage output depends on the bombardment type, for instance an AGM/Gel is 14.5 volts, standard lead acrid xiv.9 volts & a calcium bombardment 15.three volts.
Phase three is also known equally float. After the bombardment is fully charged the voltage is reduced to a lower level to reduce gassing and prolong battery life. This is sometimes referred to as a maintenance or trickle accuse. Bladder voltage for an AGM/Gel, standard pb acid & calcium battery are nevertheless at 13.3 volts, the chief purpose of which is to keep an already charged battery from discharging.
The same 10% to 15% rule of thumb applies when selecting a DC to DC charger which are too a multistage battery charger & charges the 12volt AGM battery in the camper trailer from the vehicles alternator when driving. Some DC to DC chargers also incorporate an inbuilt MTTP solar regulator. This ways non-regulated output from the solar panel is connected directly to the charger which is installed next to the bombardment it is charging. About commercial folding portable solar panels will already have a solar regulator on the back, however this can be kept on the panel & hands bypassed. The regulator on the back of the panel may come in handy one day to accuse your vehicles battery or perhaps someone else's bombardment.
cable size
Cable size is an important attribute of any 12 volt system. Undersize wiring is the most common trouble equally to why a refrigerator or any other accessory for that matter, does not work equally information technology should. Undersize wiring causes heat & therefore voltage drop, which in turn is similar running the refrigerator on a flat battery in extreme cases. Collyn Rivers recommends a 3% voltage drib is the acceptable maximum for runs from the battery to a 12 volt accessory.
12 volt wire size tin can be very confusing as in that location are several wiring codes being used in the industry such every bit AWG, ISO, auto cablevision, B&Due south & square mm. To make it more confusing, auto wire measures the outer bore of the insulation itself, having no reference to the actual copper conductor size.
The Solar Wind online figurer is an easy way to piece of work out what size cable to employ by placing the amp describe of the accessory & cable length in the windows http://www.solar-wind.co.uk/cable-sizing-DC-cables.html Solar Current of air has given campertrailers.org permission to reproduce the cablevision size estimator establish on their website.
The foursquare mm result can be converted to the nearest B&S or auto cable size past using the table beneath. Campertrailers.org has permission from Collyn Rivers to reproduce his cable conversion tabular array which gives a handy reference converting between the various cablevision sizes. Cable suited for 12volt work effectually the camper trailer under vi square mm is usually referred to in machine cable size, while over 6 square mm is B&S. Twin core sheathed cable is used where the cable could exist exposed to chaffing, giving it more protection. If the cablevision is exposed to the harsh surround on the outside of the vehicle or camper trailers it tin can be encased in plastic corrugated dissever tubing.
cable conversion table
| Sq.mm - ISO | 0.75 | 1.0 | ane.v | 2.5 | 4.0 | 6.0 | ten | 16 | 25 | 35 | fifty | 70 | 95 | 120 | 150 |
| Auto Cablevision | 2.five | 3.0 | 4.0 | 5.0 | half-dozen.0 | viii.0 | 5/0 | ||||||||
| AWG | 18 | 17 | fifteen | 14 | 12 | 10 | 8 | 6 | four | 2 | one | 2/0 | three/0 | 4/0 | v/0 |
| B&S | 18 | 17 | 15 | xiv | 12 | 10 | 8 | 6 | three | 2 | 0 | 2/0 | three/0 | four/0 |
Note: this table is copyright �Solar That Actually Works' tertiary edition, 2012
Ca r avan and Motorhome Books by Collyn Rivers
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| our 12 volt battery wiring diagram |
our setup
On our camping trips we tend to roam, exploring every bit we travel from one bush camp to the next, mostly staying only a twenty-four hours or 3 at each location http://world wide web.campertrailers.org/newcastle_to_brisbane_backroads.htm The longest menses we camp in the 1 spot is half dozen days over Easter & ten days during the Australian CamperTrailers Group national meets, while the longest duration wandering has been over 4 months. We have no trouble keeping the batteries fully charged thanks to the Redarc BCDC1225 DC to DC charger. At that place is no need to visit a powered site at a caravan park.
The two 120 amp hr Ritar AGM deep cycle batteries are housed in a box each side of the camper trailer & wired in parallel, that is positive to positive & negative to negative, making them one big battery of 240 amp hours at 12 volt.
The positive of the chargers are wired to the positive terminal on ane battery while the negative of the chargers are wired to the negative terminal on the contrary bombardment. The same method is used with wires from the both battery terminals going to the fuse block. Connecting, charging & discharging batteries in this manner has proved very successful for battery longtivity as the batteries are now eight years old & bear witness 12.8 volts at rest.
While at domicile the batteries are maintained using a 25 amp 240 volt multistage battery charger which is portable as there is no room in the battery boxes. The battery chargers charging outlet has an Anderson connector then it can be easily connected to the 2 camper trailer batteries when needed. I tin likewise use the charger on the vehicles starter or auxiliary bombardment.
Between campsites the 25 amp output of the Redarc BCDC1225 3-stage charger sees the batteries fully charged in almost circumstances from the vehicles alternator while we drive during the day. When camped the batteries are charged via the MPPT solar regulator inbuilt into the Redarc BCDC1225 from the unregulated output of two 65 watt Kyocera folding panels. This is the Redarc install http://www.campertrailers.org/bcdc1225_install.htm
The Plasmatronics PL1210 solar regulator was left in place on the dorsum of the solar panels & bypassed to allow unregulated output to the Redarc BCDC1225 MPPT solar regulator. The solar panels tin can be used to charge our vehicles starter battery if needed via the Plasmatronics regulator. The 2 Anderson connectors on the solar panel are simple to apply, unregulated output is cerise, while the grey Anderson has regulated output. Different coloured Anderson connectors cannot be joined together, however to proceed information technology uncomplicated I have doctored the crimson Anderson. Alternately y'all could paint the unregulated Anderson with cerise smash smoothen or label it.
At that place is very little voltage drop from a x metre length of 6mm twin core sheathed auto cable running from the solar panel to the MPPT regulator in the Redarc BCDC1225 next to the batteries. We have institute information technology is a skillful length to chase the sun around the shadows of trees during the twenty-four hour period.
An Enerdrive bombardment monitor is used to give us a accurate indication of the batteries state of accuse. It does crave periodical synchronizing so the monitor displays the correct figures http://www.campertrailers.org/enerdrive_elite.htm
We take an average daily power consumption of around forty amp hours over a twenty-4 hr menses depending on the season for the fridge ability draw. On most days in camp the batteries are fully charged by after tiffin cheers to the Redarc BCDC1225 MPPT solar regulator. The boilerplate battery draw broken down is.....
* 20 amp hours boilerplate for the forty litre Engel fridge running as a fridge
* ten amp hours for the 12 volt Cpap auto running for eight hours
* perhaps 10 amp hours average depending on what we are charging including.....
* laptop via the laptop 12 volt power supply http://www.campertrailers.org/laptop_power_supply.htm
* Canon camera batteries via a 12volt battery charger
* iphone & ipad via a USB port cigarette socket adaptor
* 12 volt charger for rechargeable AAA batteries used in hand held torches & caput torches
We take 12 volt chargers for all accessories as nosotros did non desire to go down the 240 volt inverter road. That may have been different if the Cpap was a 240 volt model. It can become complicated with the different 12 volt chargers & leads, only everything is labelled to avoid confusion. Bar clamps are useful to stop leads from tangling too.
further reading
Bill Darden battery facts http://www.batteryfaq.org
Collyn Rivers manufactures https://caravanandmotorhomebooks.com
Smart Guess http://www.smartgauge.co.united kingdom of great britain and northern ireland/technical1.html
wiring diagrams http://www.campertrailers.org/jamies_12volt_wiring_diagrams.htm
voltage drop figurer http://www.solar-wind.co.uk/cablevision-sizing-DC-cables.html
Collyn Rivers folio http://world wide web.campertrailers.org/collyns_page.htm
Redarc BCDC1225 install http://www.campertrailers.org/bcdc1225_install.htm
Redarc BCDC1225 feedback http://world wide web.campertrailers.org/bcdc1225_feedback.htm
Enerdrive bombardment monitor install http://www.campertrailers.org/enerdrive_elite.htm
Watts Upwardly meter http://www.campertrailers.org/watts_up_meter.htm
35 litre Engel refrigerator describe http://www.campertrailers.org/fridge_power_consumption.htm
info past Rob
january 2018
grantjurnerridich.blogspot.com
Source: http://www.campertrailers.org/12volt_compressor_fridge_draw.htm
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