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There are a growing number of solar power users who prefer 24 volt batteries because they contain twice the energy of a 12V of the same capacity. But how long will a 24V 200ah battery last? Is it better than a 12V battery and worth the price? Before you buy one, you should know how much load it can carry and for how long.

**A 24V 200ah battery contains 4800 watts, so the duration will depend on how many watts are drawn per hour. If the system is connected to a 350 watt hour load, the battery will last about 12 hours before it is drained.**

### Calculate How Many Hours a 24V 200ah Will Last

Calculating the runtime for a 24V 200ah battery is similar to a 12V battery. The runtime is determined by the watts or amps per hours drawn from the battery and its depth discharge.

To determine the battery runtime, use the following formula:

**200 ah (amp hours) x 24V = 4800 watts**

**4800 watts / watts used per hour = battery life**

Suppose you want to run a 50 inch TV, a 12V fridge, a few lights and a small fan. The total load is 500 watts per hour. Divide battery watts by watt hour:

4800 / 500 = 9.6

A 24V 200ah battery like the ExpertPower AGM can run a 500W load for 9.6 hours before it runs out. If you connect this system to a 24V solar panel the runtime will be even longer. Why? Because the solar panel can keep the battery fully charged even as you run appliances off it.

As you probably noticed this runtime assumes the battery will be drained completely. You can do that with a lithium system, but for lead acid batteries the depth of discharge should be 50%.

If you recharge at 50% the usable battery capacity is reduced to half. Instead of 4800 watts there is 2400 watts available for load. You can still run the 500W load we mentioned, but it will be for 4 to 5 hours only. If you recharge at 70%, 30% etc., adjust the numbers accordingly.

These numbers are not exact because of the way batteries work. When more watts or amps are consumed per hour, the faster the battery gets discharged. The fewer amps or watts used, the slower the discharge rate.

### Amps Drawn and Battery Capacity Explained

Another way to find out how long a battery lasts is to calculate the amps drawn per hour. A 200ah battery literally means 200 amp hours, or the battery will last one hour if you pull 200 amps.

However, Peukert’s Law states that **the higher the discharge rate, the faster usable capacity goes down**. In other words, the more amps are drawn the faster the battery gets depleted. There is no exact formula to determine the rate, only estimates.

So if the load is 100 amps an hour, the battery can theoretically last for two hours, but due to Peukert’s Law it will be less than that. The lower the amps drawn the longer the battery life. Drawing 50 amps an hour means the battery could last around 4 hours or near to it.

Your battery documentation includes details on its specific runtime so you should check it. Also keep in mind that these estimates assume the battery will be fully drained. Reduce the run times if only half the battery capacity will be used.

If you have the Ampere Time 12V Lithium you can do a 90% or 100% discharge, but otherwise you should not let the percentage drop below 50. If you need the full 200ah capacity, get a lithium 200ah or a 400ah lead battery.

Whether you compute the power load in watts or amps, one thing is certain. You should never overestimate how long the battery will last. It is always better to underestimate the runtime and have more capacity available.

### What Can a 24V 200ah Battery Run?

A 24V 200ah battery can run TVs, coffee machines, blenders, laptops, fans, lights, power tools, a mini fridge, microwave and other appliances. With literally thousands of watts at your disposal, the battery can run a wide range of electronics.

If the battery will be used to full capacity, it can:

- Run a 60 inch TV for 25-30 hours
- Run a ceiling fan for 72 hours
- Power a clothes dryer for 2 to 3 hours
- Use a corded drill for 1 and half hours
- Power a deep freezer for 45-50 hours
- Run an espresso machine for 2 hours

A lot of these tools and appliances are not run continuously. A blender uses 400 watts an hour, but you only use it for a few minutes at a time. Same thing with a drill and other power tools, so a 200ah battery can last for days on end.

The appliances and tools above are just examples. You can combine various items and run them on the battery for hours or days.. The duration will depend not only on the load but also how much of the capacity will be used.

A 200ah battery is large enough to take during camping. If you have an RV you can use it to charge other appliances. If you have a solar powered jeep you can connect it to a solar panel and run even more devices for longer stretches.

No matter what battery type or size, avoid using it to the maximum capacity. Calculate the amp or watt load and if the total is at 4800 watts / 200ah or near it, reduce the load or get a larger battery. Inverters, charge controllers and solar panels should never be used at their maximum capacity. The same applies for the batteries.

### How Many Solar Panels to Charge a 24V 200ah Battery?

By hooking up a battery to solar panels, you can run an appliance on both and conserve battery life. Instead of using it all day, let the solar panels charge the system so you have full power available when the sun sets.

**It takes 4 x 300 watt or 3 x 350 watt solar panels to recharge a 200ah battery.** If you are using a 24V battery, the panels must also be at least 24V. A 12V system cannot charge a 24V battery because the PV voltage has to be higher.

If the solar panel and battery voltage are both 24V you can use a PWM charge controller. If the solar panel is 48V, use an MPPT charge controller. A PMW controller will just drop the panel voltage down to the battery and waste its power. With an MPPT, it will run the panel at 48V and adjust the current going into the battery. for the best results.

#### Sample Calculations

A 300 watt solar panel is good for up to 1500 watts a day with 5 sun hours in perfect condition. With three of these the power output can reach 4500 watts, which is not enough to fully charge the battery. If the battery is only 50% discharged then it is enough.

200ah = 4800 watts

4800 watts / 2 = 2400 watts

**To fill up a fully discharged battery however you need 4 x 300W or 3 x 350W solar panels**. With three 350 watt panels you have 5250 watts in 5 sun hours. Even assuming for energy losses, imperfect weather etc. there should be enough power here to produce the 4800 watts needed by the battery.

We chose 5 hours in this example, but yours might be different. During summer your area might receive up to 7 hours of sunlight. With that much sun you can use 3 x 300W solar panels (300 watts x 6 hours = 1800 watts x 3 = 5400 watts).

the reverse is also true. You might need more solar panels if the sky is overcast. In this case you should charge the battery at home before leaving or use more solar panels. If you plan ahead a lot of these potential issues will be resolved.

### Conclusion

A lot of the calculations involving batteries and solar panels are not exact because of how solar power works. But using the tips given above you can get a pretty good estimate of how long you can use a 24V 200ah battery.

I am an advocate of solar power. Through portablesolarexpert.com I want to share with all of you what I have learned and cotinue to learn about renewable energy.