How long amp hours last

How many amps does a watt inverter draw? It is the actual load watts, not the inverter rating that counts. So a W inverter with a Watt load would be 50 25 Amps, not 75 Amps. The same inverter with a Watt load would draw 60 Amps. How long will my battery last with an inverter load of Watts? How long will a leisure battery last? How many batteries do I need for a watt inverter? How long will ah battery last? The AH battery can feed Amps for 1 hour, or Amps for 2 hours, or 10 amp for 20 hours.

How long will a deep cycle battery run a fridge? A decent fridge around that size under 30 degrees ambient temperature shouldn't use more than around 30 - 40 amp hours a day. How many batteries are needed to power a house? Number of Batteries A battery bank designed to power an average American household for three days would need to supply 90 kilowatt-hours of energy. The battery from the previous example can supply 2. Using a battery below these levels will also severely reduce the number of recharge cycles you get from your battery.

Battery chargers like the SETEC there are others control the current draw from the battery as well as charging the batteries.

These will prevent you drawing current from the batteries once the voltage drops below the ideal minimum level. Yes, you may need to replace your battery a year earlier, but you have made savings along the way. If the battery has just been charged or heavily discharged, it must be given time to equalise before taking a reading. Using a water example, imagine 6 tanks of water like 6 cells in a battery each joined together with a straw. If you fill one end tank using a garden hose or drain the other end using a garden hose it will take some time for all tanks or cells to be at equal levels.

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. A low load that is drawing power no faster than the battery can equalise will give a reasonable value for the Charge remaining , by reading the voltage. Be aware also, that a battery under no load at all may still show 12V, but have little or no amp hours left.

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. 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.

While the volts is indicative of how much power is left, it is not like a fuel gauge. Petrol left in a fuel tank would show up as a straight line from 13 to zero in the chart above. They accept charge easier and faster than wet cell batteries. They are able to recover better from a lower discharge. Yes, they cost more than Wet Cell batteries, but with correct usage can last twice as long.

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.

If you leave V for only one or two days at a time, and you use only LED lights and say a water pump, you should manage quite well with a cheaper Wet Cell battery. Caravans Plus does not sell Wet Cell batteries as these are harder to ship and are readily available in most locations. Wet Cell batteries need to be upright and located in a ventilated area that is not in the living area.

AGM batteries are completely sealed and can be used at any angle. They can be placed under your bed without risk. Batteries say ah battery have been tested at a given discharge rate of 20 hours. The specifications should indicate this. The bad news is that if you exceed that discharge rate quoted you will see a significant drop in capacity. If you need more than 5 amps per hour you should consider having two or even more batteries.

The good news is if you use less than the 5 amps per hour, you can get more than the quoted ah. Figure 2: Battery capacity decreases as the rate of discharge increases.

Also if you are charging your battery from your solar panels, you need to ensure your solar regulator is up to the job. Voltage drop is one of the biggest problems in getting the battery in your Caravan or Camper trailer fully charged from your vehicle alternator.

You can never charge the battery more than the voltage that reaches it through the copper cables. The longer the cable, the more the voltage drops. This can be compensated to some extent by increasing the cable x-section but even this has limits. With your trusty voltmeter you can check what voltage your alternator is producing by starting your vehicle and connecting your voltmeter to the battery terminals. Ensure electrical accessories are NOT switched on.

This should read from Figure 3: Less charge due to voltage drop Next test your voltage at the rear of the vehicle with the engine still running. This may be at an Anderson plug or the auxiliary wire in the trailer connector. Record this voltage and note any voltage drop. My vehicle has heavy duty cables and only dropped 0.

Next take a reading where the auxiliary cable goes to the RV battery or battery charger. My caravan has lighter wiring and the voltage loss was another 0. The total voltage drop was 0. When you look back at Figure 1, you will see that a reduction 0. There are two solutions to this problem. First you can increase the size of your copper wires so that the voltage drop is less.

Second you can add a voltage booster that will step up the voltage to compensate for the loss. This must be placed between the alternator or vehicle battery and your RV battery so that current coming in will reach the battery at a higher voltage and thus increase the speed of charging and get more amp hours into that battery. This rule of thumb allows for greater discharge on occasions, e. Calculating Your Amp Hours Examine the following chart to calculate the number and size of batteries you will need.

You can download a blank calculation form and enter your battery size to determine how long it will last. Notes explained: 1 The water pump has a rating of 5.

Three fridge options are provided, select one. It uses too much power. They do use more than you think. Switch off when not required. 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.

This gives me ample capacity. It is only the inverter extravagances that have taken me over the limit, so for many people a single AGM to ah battery will be enough unless you have an upright 12V fridge, or need your TV when away from power.

Nothing forgotten. A single-stage charger is much more blunt. Whether your battery is lead acid or lithium it has a finite number of cycles that it can be depleted and recharged. This is the cycle life of the battery. Generally, lead-acid batteries if maintained properly can be good for a few hundred cycles. Lithium batteries on the other hand can last thousands of cycles. But the number of times and how deeply a battery has been depleted and then recharged affects how much capacity it can hold.

The more times it has been cycled, the less able it is to hold its maximum capacity. As you can see, there is no one-size-fits-all answer to this question, because there is no one-size-fits-all way that we each use our RV battery on a day to day basis. But hopefully, this helps you understand how the battery works and just what that amp hour rating means in the real world. I think the thing to stress is you need to have a reliable battery monitor installed and you need to actively manage you usage.

Good article guys keep up the good work. Hey guys! We had 4 panels squeezed onto the roof of our GDRV RL with a multiplus inverter to charge our 4 battle born batteries. Good article Jason! I have a battery question for you: We are FullTimers in a Newmar diesel pusher for the last 4 years and for the next years, if our health allows.

We currently have lead acid batteries in the original set up. His advice was that the total cost to upgrade to a full solar system with Battle Born batteries was not something we would recoup in years. Do you agree with this advice? Any thoughts would be appreciated.

You might benefit from a single lithium battery because of the weight and being able to use the entire battery capacity AH but for your needs, it does not sound like you need a large solar array. Honestly, for most people, a generator to recharge your batteries will be enough. I also built a suitcase solar panel set using two w panels. Great job Jason. I learned a lot. I have a question.