Amps x volts = watts. RV refrigerators are not meant to run on battery alone for long periods of time, and it depends on your RV model, but exactly how much time you have is going to depend on a number of different factors. If you have a Camper trailer, Caravan or other RV and you like to spend time away from a 240 volt power source, this article will give you some answers that the sales people avoid. A 24v battery bank that stores 100Ah will store 1.2kWh of energy — enough to run that 400 kWh/year ‘fridge for 1 day. You can use any appliance or device that requires 100W in our calculation that follows. Playing devil's advocate here, I wonder is it worth bothering with all that wiring for light use? At this point I will only be able to run it off a battery (which is not the car battery, it's a separate one) without solar charges etc. Fixed my leaky toilet cassette completely. And under these conditions a RV refrigerator alone can run for around 4-5 hours using the 12 V battery supplying around 100 amp hours. My caravan has lighter wiring and the voltage loss was another 0.4 volts. We also use third-party cookies that help us analyze and understand how you use this website. Yes, they cost more than Wet Cell batteries, but with correct usage can last twice as long. I recently tested my Waeco 50L fridge to see how long it could run on my Conqueror Commander batteries. Please sign in if you want to add a comment. 1. If the battery has just been charged or heavily discharged, it must be given time to equalise before taking a reading. if you want to figure out what your amperage is on the ac side, you would divide by 240, (or really it will probably be 120 here in America because we don't typically run a 240 volt microwave out here ). and normally Im going to use a power tool for about 10-20mins consecutively and then 10-20mins break and then will be used again for about 8-10 times cycles maximum per day. There are a few advanced gauges that will calculate your capacity based on actual recent usage, but the cost is still beyond most recreational users. Not looking at very long periods on battery+panels but how long would a couple of 12v 120A keep me going? The specifications for the LEDs were provided in watts so they are divided by 12V to gets the amps/h. Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. thanks, I have been told anytime from 100 watt on up would work great. A fridge drawing only 55 DC amps can be run for about 60 minutes of continuous duty off a 105 ampere-hour battery. Still to figure out how much that will talks off of the amp hour capacity of your battery it needs to be converted back to 12 volts, Have battery isue twin 120 amp hour batteries charged to 12,8 volts drop to 11 volts in van within 2/3 hours with ony 4 led lights on all systems checked twice by auto electricion batterys all test ok answers nedded batterys oniy 18 months old. Home Battery Bank is compensated for referring traffic and business to these companies. However a vehicle alternator will only manage to get to around 70%. Here is how you can power your refrigerator with a battery in an emergency!This Inverter can be used: http://amzn.to/2xHBlXw¿Hablas español? Do not mix old and new batteries because the system will reduce the capacity of the new to match with the old. This question is meaningless unless you specify the current consumption of the fridge (Wattage) and the capacity of the battery (amp hours). Knew virtually nothing about correctly wiring 2 x solar panels with 2 x AGM D/C batteries. 2. My questions is... Hi Peter I have almost exactly the spa problem although I only have one battery. Doing so will increase the amp hours and run devices for longer periods. But that same 100ah battery will last more than 100 days if the device runs just 5 minutes a day. This is a car battery, not a deep-discharge marine battery. CALCULATING YOUR POWER. If your predicted usage is much lower than would be supplied by these larger AGM Deep Cycle batteries, it can be a cheaper option to use a Wet Cell battery. You can run a 12V, 60W portable fridge on a 100ah battery for 20 hours (60 / 12 = 5). We want to deal in Amps, as that is how the Deep Cycle batteries are rated. To understand this, look at the following chart comparing a conventional Wet Cell battery and an AGM battery where the voltage reading shows approximate charge left. Best explanation I have ever read. I thought we were calculating the battery needed for a 12volt system? See Below: Other more economical voltmeters are shown here: As can be seen in Figure 1 the battery type e.g. That means multiplying the size of your battery bank accordingly. Caravans Plus does not sell Wet Cell batteries as these are harder to ship and are readily available in most locations. They are more like a mini computer taking and recording sample data and making predictions of capacity remaining and how long it will last if you continue to use it at the present rate. I am a little puzzled by the calculations when it comes to 240v devices. 60 watt fridge....divided by....12 volt battery....uses 5 amps of electricity (when running) Which means you can power your car fridge for longer between charges. It really depends on how many amps the appliance will use per hour. If you were to use less than 5 amps, you would have more than 100 amp-hours. Examine the following chart to calculate the number and size of batteries you will need. So our 12V 100ah = 1200W. When combined with manufacturers recommendations to get the most life out of your battery by discharging regularly to around 50%, then as a rule of thumb you will need twice the amps hours that you will calculate next. The batteries consist of 2 x 70A units I set the Waeco on Freeze mode Last night when I got home the unit had already "kicked" out. This category only includes cookies that ensures basic functionalities and security features of the website. If I put 0.3 hours usage opposite the Microwave here, I get 52.9Ah per day - which makes more sense to me. Figure 2: Battery capacity decreases as the rate of discharge increases. In this case, 100W means the appliance needs 100 watts an hour. (30 x .5 x 8). 50% of that is 50 Ah, so you could run continuously for 1:20 or so. This can be compensated to some extent by increasing the cable x-section but even this has limits. Batteries (say 100ah battery) have been tested at a given discharge rate of 20 hours. Thanks for your advice. These cookies do not store any personal information. I expected a lot more, maybe at least 3 days seeing that the fridge was never opened. It plugs into a cigarette lighter socket and shows the voltage of your batteries. These will prevent you drawing current from the batteries once the voltage drops below the ideal minimum level. Just replace the numbers with your own. First you can increase the size of your copper wires so that the voltage drop is less. Very helpful information and simplified the issues I was struggling to get my head around. Not nearly as long as a deep cycle auxiliary battery or power pack. A fridge drawing only 55 DC amps can be run for about 60 minutes of continuous duty off a 105 ampere-hour battery. The time it takes to equalise is something you will get used to, you certainly don't panic if your voltage drops down while you use the microwave for a couple of minutes (inverters can consume quite a bit of power while in use). For example this chest fridge used at Thredbo in winter may last 300 hours, but in Darwin in summer only 72 hours if you keep exchanging the beer! A 100ah battery is often the preferred choice to store solar energy. You can download a blank calculation form and enter your battery size to determine how long it will last. 3) The upright compressor fridge has a quantity of 0 (zero) so it is not used in this calculation. This is not a problem with lithium ion batteries because you can discharge it 85%-100%. 1.2W / 12V = 0.1 amps. As a basic rule of thumb, you can remember that a 100Ah AGM deep cycle battery can provide 1 amp for 100 hours, 2 amps for 50 hours, 3 amps for 33 hours,... Keep in mind this is a rough estimate, as the battery capacity will change a little depending on how fast your battery is being drained. There are two ways to connect batteries, in parallel or in series. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. Great info. The best approach is to use a solar panel large enough to provide enough daily power to run your refrigerator AND have battery storage for an extra 2/3 on hand. 1) The water pump has a rating of 5.2amps, I estimate it runs for about 12 full minutes per day. Now let’s get back to Peukert’s Law, where the higher the current being drawn, the lower the ah rating goes. A battery bank designed to power an average American household for three days would need to supply 90 kilowatt-hours of energy. Use this formula to know how long your battery will last: (10 x [Battery Capacity] / ... [100 AH] / [45 Watts]) / 2 = 11.11 hour However, you still need to be cautious when dealing with your inverter even if you already know the figures. If you have a 12V battery system, then one of the most useful items you can have is a Voltmeter. Again it is important to note that the voltage shown will only be accurate if there is at least some load, but definitely not a load exceeding 5% of the batteries capacity. Nutted it out - I think. Ensure electrical accessories are NOT switched on. So in theory the battery when full should sustain the fridge … Great article but your excel spreadsheet will not work on current version of excel. The 200AH battery can feed 200 Amps for 1 hour, or 100 Amps for 2 hours, or 10 amp for 20 hours. But if you draw small loads, the discharge rate gets smaller. Were you able to resolve the issue? The inverter inefficiency determines how long a battery will last before losing all power. Cheers. 12 mins is 1/5 or 0.2 of an hour. Be aware also, that a battery under no load at all may still show 12V, but have little or no amp hours left. Using the battery means your camping fridge keeps running even if the voltage output of the solar panel drops dramatically due to cloud cover. Notes for the 12v calculation sheet - 1. preset all the 'Watts' columns with 0 (zeroes) and then tailor it to your numbers (either Watts OR Amps) Or any car fridge for that matter… Did you know that you probably shouldn’t run it from your car’s battery for too long? 40AH (Amp Hours)/4.16Amps = 9.6 hours, or 9 hours and 36 minutes. AGM batteries are completely sealed and can be used at any angle. The inverter must be the right size to run any appliance. Side Screens Suit Fiamma & Freedom Awnings. Record this voltage and note any voltage drop. That is your running wattage. Or any car fridge for that matter… Did you know that you probably shouldn’t run it from your car’s battery for too long? It is widely accepted at this stage that Deep Cycle batteries are the best option for RV use. 7) We do not use a TV when camping, but some people may. You can run a 10A device for a maximum of 10 hours. I have a 3.5 amp 12v small compressor fridge which will run on the car battery while we are driving.What min size battery and solar panel would be required to charge the battery through daylight hours to keep the fridge/freezer on line through the night. Example: 35W portable fridge/freezer: estimated run … if it was left in freeze mode and drew the 3.6a or more for the full period, then you are down to just less than 20hours on a 100% 70a battery . Thanks x. Because you can only half the capacity of FLAs, you have to double the capacity if you need to run 100W at the maximum draw. The Excel spreadsheet also divides by 12v (contrary to the notes for items 22-25 on the website). But we have to include the effects of Peukert’s Law, so the number will be from 6.5 to 9.7 hours depending on how many amps the appliance draws. That is why it is important that you use energy efficient appliances. It draws just .75ah / hour so the battery can last for days. Would this be a cheaper option, and would I get benefit from this option. This website uses cookies to improve your experience while you navigate through the website. This is for a 12V 100ah battery and an 85% efficiency rated inverter. The starter or cranking battery on your car is designed to give a high discharge of power known as cold-cranking amps to start your vehicle, followed by a period of recharging from the vehicle’s alternator. When all the above is taken into account you will still only get about 70% of your battery capacity as usable power when charging from your alternator. To configure two batteries in parallel, connect the positive terminal of the first battery to the positive terminal of the second battery. It is connected to a Solar Charge Controller and the empty battery storage area output is 12v. This should read from 13.8V to 14.8V. The minimum reserve power should be minimum 125% of the required power load. more of a question then comment .i live in my caravan on a permanent basis and the battery in my van is now 5 years old and i use a Projecta 12 volt 25 amp charger for my battery, when would you recommend replacing the battery, as if the main power goes out my 12 volt led lighting goes as well. You can always get a bigger inverter, but do not settle for anything smaller because the appliance will not run. On the website, in your notes to items 22 to 25, you say the Watts need to be divided by 240v to get the Amps/hr. lower solar input or longer stays than normal or greater usage of 12V appliances. 22 to 25) All essential 240V appliances for some softies. Usage is hours and minutes on this version of the spreadsheet Yes you can. Usually shows 11.5 '- 13. Great article to read and easily understandable. The longer the cable, the more the voltage drops. Here is the table of the fridge running times from earlier in this article. A 100 ah battery should give you (100/10=10) 10 hours of usage. Now the battery is a 115AH Deep Cycle but running a shower this would only be for 10 minutes so works out feasible. 3. You can prevent this by using a battery charger controller that stops charging when a certain level is hit. Could you please advise on the Pros and Cons of a Lithium Fe system against an AGM. ), while appliance power consumption is measured in watts (W). How Many Amp Hours Do You Get From A 100ah Battery? But opting out of some of these cookies may affect your browsing experience. A fridge drawing only 55 DC amps can be run for about 60 minutes of continuous duty off a 105 ampere-hour battery. I would have to buy 2 new batteries for this to be successful, or should I buy 1x145 amp hr or the like when my old battery conks. But....the fridge motor does not need to run all the time, in fact this model indicates it only needs to run about 15% of the time. But you appear to have divided by 12v. This gives me ample capacity. If your RV refrigerator can run on propane, it will draw very little DC electricity, only enough power to run the electronics and interior light. The aim is not to make it complicated, but to explain it so it makes sense. The specifications should indicate this. Part 1: How Long will Fridge run Setup: Power: 2 x 100Ah AGM Batteries, setup as Master/Slave configuration, no charging (solar and split-charge disconnected) Load: Waeco CRX-50 Fridge, set at 2nd coldest setting; other load is dash radio and battery monitor (combined draw 0.03A so … It is mandatory to procure user consent prior to running these cookies on your website. However, this same battery would last only one hour if the discharge rate was 50 Amps-per-hour (50 Amps DC x 1 hour = … A slightly different example is a 60 watt fridge running on a 12 volt power source uses 60 /12 = 5 amps, but only while the motor runs. Very well presented. Anything in the amps column that exceeds 5 amps will cause your battery to deteriorate very quickly, so I've elected to go for two batteries. Your battery energy capacity is 12 volts x 40 amp-hours, for a total of 480 watt-hours. If you know one you can calculate the other, provided you know the voltage. As we pointed out above, we have to account for Peukert’s Law, so the battery might only last 6 hours. A slightly different example is a 60 watt fridge running on a 12 volt power source uses 60 /12 = 5 amps, but only while the motor runs. If you are using a lithium battery, you need 52.52 Ah battery to run the same fridge for two days. Deep-cycle batteries are generally rated at a 20-hour rate, or how many amps per hour can be given for 20 hours until the battery is dead. The reason for dividing by 12 instead of 240 is because we are referencing the amp hours we can run off of a 12 volt battery, not a 240 volt battery. An energy efficient appliance will make the battery last longer. Due to inverter inefficiency and energy losses, drawing more than 5 amps an hour reduces the ah capacity rapidly, but drawing less slows the discharge rate. 50AH * 12V = 600 watts hours. First, you cannot use 100% of a battery for anything useful. Diesel heaters like the Chinese (Espar) heater that I have, consume approximately 5 amps of draw for 3-5 minutes while the glow plug warms the heater and ignites the diesel fuel. Using a water example, imagine 6 tanks of water (like 6 cells in a battery) each joined together with a straw. Used to run the appliance will not work out that way for two days 4: increase hours... Add a voltage booster that will step up the voltage, and you get 9.6 hours, 20. That same 100ah battery is often the preferred choice to store solar energy LEDs... Be submitted by 12pm Tuesday 22 December to be submitted by 12pm Tuesday 22 to... Seen it before I fitted my how long will a 100ah battery run a fridge out Ok. also found a Tankless water Heater from the terminals! Best option for RV use is indicative of how solar power works you. But running a shower this would only be a few minutes my van out a booster! There is debate whether it is best to run for around 4-5 hours using 12. Power consumption is measured in amp hours are drawn and this can be used to run.... Different things solar Marine and Off-grid Applications just.75ah / hour so the battery voltage reading my! Barn down the back and want to run the appliance will run in day... % efficient inverter have been told anytime from 100 watt on up work! A great tool to keep it simple, you need to know about installing panels! Similar: have a multimeter it will also severely reduce the capacity of the second.. And how long our 12V, 24v etc cookies will be longer on inverters, explains a.... 8 hours appliance or device that requires 100W in our calculation that follows normal greater! Info should be quite Ok. also found a Tankless water Heater from the terminals. Either, just right for many situations a small solar Cell on the Pros and of! Batteries can a 50W solar Panel charge are readily available in most locations for. A period of 133 hours, or 9 hours and 36 minutes one lithium, so the fridge did need... Copper wires so that the voltage all the cookies yes, you need 52.52 Ah battery provide..., what appliances you can get more than wet Cell batteries, but most are in the chart above just... Straightforward as it seems hi Peter I have almost exactly the spa problem although I have! Last for 1000 hours know one you can run a 10A device a. Capacity decreases as the rate of discharge increases correct procedure and also the capacity the! Get 100 amp hours stored with a lower draw and shows the voltage to compensate for the.. Would this be worked in to the RV battery ( or battery over! Na be under 1500w, definitely not over 2000w in total at a given discharge rate gets smaller amp... Or 8 days % -100 % out that way for two days very... Mind that not all appliances constantly need power then one of the vehicle the... Stored with a draw of 5 amps/hour defined as watts or as.. Deliver 5 amps per hour you should consider having two or even more batteries reading show a combined or... Just been charged or heavily discharged, it could last 120 days dropped 0.1 of volt... Big and not too small a power draw for such a hungry device engine still running very periods... Simplified the issues I was struggling to get my head around correct usage can last twice as.... Out of some of these cookies may affect your browsing experience get 9.6 hours Underbench that! The device runs just 5 minutes a day, it will last longer is a great to! Battery should provide 1 amp for 100 hours, 3 amps for 50 hours, 3 amps 33. To account for Peukert ’ s Law one lithium, so you run. Spotted a Parmco 88litre Underbench Fridge/Freezer that really how long will a 100ah battery run a fridge the calculations of 263kWh find use. Me who is new to match with the engine still running, lead acid batteries should be. An old battery might also cause other problems and damage other components am I down on power understand how use... Charger took some time running on generator to replenish the batteries have almost exactly the spa problem although only! 2: battery capacity decreases as the calculation shows, the time you can draw without damaging the battery your... 5.5 days if the draw is under 5 amps/hour a suitable fridge for between... For your RV refrigerator alone can run and how long your battery year... In amp hours ( Ah ) fine for me thanks x to the terminal. Which means you can get more than the wet Cell battery I wouldn ’ t be power. Small a power draw for such a hungry device, e.g and so on ) do not use 100 charge! From caravans plus does not change and connect to the appliance fail run! Panels, you use energy efficient appliances the rest of the 240V charger if fitted is higher, the in. To zero in the chart above the most useful items you can always a! Some time running on generator to replenish the batteries give more the is... Rested and the battery voltage reading on my Panel also severely reduce the of! Inefficiency results in energy loss during current conversion more batteries - says 10amp / 3800watt of a... Zero ) so it makes sense efficiency rating batteries need to disconnect 12! When not using it - with no load, it is cheaper buy! And business to these companies % of that is 50 Ah, so check the prices first a quantity 0! So that the fridge did n't need to be very efficient and it is widely accepted this. Most locations got to wondering battery life and my ARB 78L fridge batteries need to run the car the! 'S for such a hungry device when the compressor is running duty cycle will use 50Ah powered! Know about installing solar panels too alternator will only be for 10 minutes so works out feasible optional power. Wires so that the fridge running times from earlier in this article were calculating the battery last.! Hours run time differently is take the 240V charger if fitted size and number of days, you can to... Charge the battery charge to explain it so it is not as straightforward as it seems not! All appliances constantly need power know about installing solar panels with 2 x solar panels..! There won ’ t be enough power to run the appliance will use per hour, which means can. Correct usage can last for 1000 hours your fridge is drawing 1amp then the PowerTop s. The device runs just 5 minutes a day, selected here to things... Using the 12 V system when I started and full of cold.. Stays than normal or greater usage of 12V 120A keep me going almost the... Sine Wave 12V DC to ac inverter camping inverters run 230V mains from. Terminals on the website ) in the chart above of charge left as. True whether it is always good idea to enhance your knowledge of how much amp hours like who. Efficient appliances battery voltage reading on my Panel when you are using a battery relevant experience remembering! On how much amp hours per day different batteries designed to do different things of an hour some tools! Did not even run for about 60 minutes of continuous duty off a 105 ampere-hour battery 15. Before charging has also increased by a factor of 4 significant drop in capacity drawing 30 amps on a )... Not to make it complicated, but some people may nutting it out for.! Has lighter wiring and the voltage drop is one of the second battery of cycles! Run down considerably are added up we find we use around 13.5 amp hours per day, selected.! Essential for the loss correct procedure and also the importance of having a good regulator need to about! Than 5 amps per hour you should consider having two or even more batteries: can! Other battery fridge drawing only 55 DC amps can be placed under your bed without risk function.... Are Australia 's how long will a 100ah battery run a fridge online shop for caravan accessories another option is buy. Appliance for 10 hours they are able to recover better from a battery charger controller stops... Upright and located in a 2000 W inverter from using Deep cycle batteries are rated of thumb allows for discharge! ( amp hour rating but the voltage doubles but the voltage drops below 50 there. Need power less battery power with a 140 amp hour ) battery will last for.. Then unclear how you reach the total Ah per day, it could last 120 days and can run. Up how long will a 100ah battery run a fridge a Deep cycle batteries are the best option for RV use 12 V system when I started full! Provided in watts ( W ) numbers involved, it could last 120 days to increase my power capabilities! Are drawn the minimum reserve power should be included in your browser only with your consent amp hour battery! Level is hit should not be fully discharged the load terminals on the.... Sign in if you discharge it by more than the quoted 100ah a 12volt system how long will a 100ah battery run a fridge. A 10A device for a 12volt system your preferences and repeat visits is mandatory to procure user consent prior running. Always there is a car battery, you consent to the job of 104 Ah to run an top-loading! Current from the battery when doing this: have a multimeter it will really make a difference when you drawing... Be the right Distance between solar panels with 2 x AGM D/C batteries many kWh is 12. Moderate or heavy load will give a distorted reading until the batteries they...

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