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How long does a 200Ah battery last – what can it power?
As a general rule, the run time of a 200Ah battery depends on the battery chemistry and the size of the load connected to it. Battery temperature and discharge rate also impacts how long a battery will last, but it’s the load that drives it all.
The two major types of batteries in this size range are lead acid and lithium phosphate. Each type has different characteristics, advantages and disadvantages.
A 200Ah lead-acid deep-cycle battery running a 400 watt DC load with 50% recommended Depth of Discharge will last for approximately 3 hours. A 200Ah deep-cycle lead-acid battery will power a 400W rated refrigerator for about 25 hours at a rate of 40 watts per hour.
Page Contents
- Are 200Ah lithium batteries better than lead-acid?
- How long will a 200 Ah battery run an appliance that requires 400w?
- What can a 200ah battery run?
- How long can a 200Ah battery run a fridge
- How long will a 200ah battery run an appliance that requires 200w?
- How long will a 200ah battery last taking 20A continuous current?
- How many solar panels does it take to charge a 200 Ah battery?
- How many amps does a 200 watt solar panel produce?
- How many watts is a 200Ah battery?
- How long will a 48V 200Ah battery last?
- How long does it take to charge 200Ah lithium battery?
- How many solar panels do I need to charge a 200Ah battery in 5 hours?
- How to calculate battery capacity for a solar system
Are 200Ah lithium batteries better than lead-acid?
Lithium phosphate batteries are more expensive, but they have several advantages, the biggest being that they are intrinsically deep-cycle.
They can be discharged to a much greater depth than lead-acid deep-cycle. This means that you can get more power out of it for the same rated capacity.
Most LiFeP04 batteries can be discharged 95%, but 80% is recommended to maximize battery life.
A 200Ah lithium phosphate (LiFeP04) batteryconnected to a 400 watt DC load with 80% Depth of Discharge will last for almost 5 hours. A 200Ah lithium phosphate (LiFeP04) will run a 400W rated fridge for about 55 hours at a rate of 40 watts per hour.
Video – 200 Ah Battery Power – How long does a solar battery last?
How long will a 200 Ah battery run an appliance that requires 400w?
There are two basic types of loads:
DC, such as supplied by solar panels and batteries
AC, such as the power supplied by utility companies
In general, a 200Ah battery will run an AC load for less time than a DC load, simply because an inverter is needed to convert DC to AC.
The best quality inverters are about 95% efficient, so you lose 5% running time as extra power is needed to power the inverter electronics.
A 200Ah lead-acid deep-cycle battery should only be discharged 50% in order to maximize battery life, so only 100Ah is available for use. (80% can be used now and again.)
100Ah converts to 1200 watt-hours. Dividing this by 400 watts load gives us the answer:
A 200Ah lead-acid deep-cycle battery with 50% Depth of Discharge will run a 400W AC appliance for about 3 hours.
What can a 200ah battery run?
Unless using the battery for marine or RV purposes, 200Ah battery run questions normally have AC home appliances in mind.
Such a battery will run a variety of home appliances with different power ratings but the run time will decrease as the wattage increases.
This is fairly linear, unless dealing with large motors that cycle on and off, such as found in fridge compressors. (Read about running compressors here.)
The table below shows approximate run times for home appliances running from a 200Ah lead-acid deep-cycle battery with 50% discharge, compensated for inverter losses:
Table – 200Ah battery backup time – home appliances run-times
200Ah 12V deep-cycle lead-acid battery (50% discharge) with inverter fed AC loads. | ||
Home Appliance | Rated Load (watts) | Estimated Running time (hours) |
Air purifier | 25 watts | 48 hours |
Portable Air Conditioner | 500 watt rated load (70 watts average per hour) | 16 |
Ceiling Fan | 60 | 20 |
Coffee Maker | 800 | 1.5 |
Deep Freezer | 25 | 48 |
Electric Shaver | 15 | 80 |
Fluorescent Lamp | 30 | 40 |
Fridge | 120 | 10 |
Freezer | 40 | 30 |
Laptop Computer | 100 | 12 |
Pedestal Fan | 60 | 20 |
Tablet Charger | 10 | 120 |
Vacuum Cleaner | 500 | 2.4 |
WiFi Router | 10 | 120 |
Water Filter and Cooler | 80 | 15 |
Treadmill | 300 | 4 |
How long can a 200Ah battery run a fridge
A typical fridge power rating as read on the name-plate might be about 400 watts. However, this doesn’t represent the power taken at any instant in time.
This is because the compressor motor starts and stops, so it’s difficult to assess instantaneous load at any instant in time.
The fridge draws almost no current when it’s cold enough i.e. the motor doesn’t run, it draws a lot when the motor starts (inrush current) and a smaller amount for continuous running.
This why the amount of energy used over time is more important when considering battery run-time. A 400 watt fridge will pull about 40 watts per hour.
A 200Ah lead-acid deep-cycle battery will run a 400W rated fridge for about 25 hours at a rate of 40 watts per hour.
200Ah battery run-time calculator
Use the calculator below to find a realistic run-time for any AC home appliance running from a 200Ah battery through an inverter.
This calculator assumes an inverter efficiency of 85%, which is a bit low, but ensures that the run-time will be of practical use and not just theory.
How long will a 200ah battery run an appliance that requires 200w?
If the load is DC, such as might be found on boats or RVs, then the calculation is pretty straight-forward:
200Ah = 200 x 12 volt = 2400 watt-hours
However, only 1200 watt-hours is available at the recommended 50% discharge so:
Run time for 200Ah battery running 200 watts DC = 1200 watt-hours/200 = 6 hours
For an AC load, it’s a little bit different. Let’s assume it’s a constant load and not a fridge, heat pump or air conditioner with compressor motors on board.
AC appliances use inverters which also need power to run i.e. they have losses. If running at full rated capacity, an inverter may have an efficiency of 95%, if it’s high quality.
The calculation becomes:
Run time for AC load = 1200 watt-hours/200 x 0.95 = 5.7 hours
How long will a 200ah battery last taking 20A continuous current?
Logic tells us that it should be 10 hours, by dividing 200 amp-hours by 20 amps.
This is not the case. You can see from the specification for a 200Ah AGM lead-acid battery below that if 18 amps is drawn from the battery, it’s capacity is only 180Ah. That’s the first thing.
Also, batteries should only be discharged to 50% of their rated capacity in order to maximize battery life, so the real available capacity is nearer 100Ah.
All of the above means that you should only draw 20 amps from a 200Ah battery for 5 hours, if you don’t want to have a very short battery life.
Renogy 200Ah Battery Specification Sheet PDF
How many solar panels does it take to charge a 200 Ah battery?
Assuming that the battery is a deep-cycle lead-acid depleted 50%, then it needs 100Ah or 1200 watt-hours to recharge it.
100 watts of solar panel rating generates about 400 watt-hours per day on average, so a 300 watt panel should charge the battery during a day.
A 400 watt solar panel using an MPPT solar charge controller will charge a 50% depleted 200Ah battery in about 5 hours with irradiance of 4 peak-sun-hours.
How many amps does a 200 watt solar panel produce?
A typical 200 watt solar panel can have different numbers of cells, which changes the voltage delivered by the panel.
The Renogy compact 200W solar panel has 40 cells, giving Open Circuit Voltage (Voc) of 27 volts and maximum working current of 8.85 amps.
The Sunpower SPR-200-BLK-U 200 watt panel has 72 solar cells – Voc is 47.8 volts and current is 5 amps.
Amso Solar AS200M-36 200 watt solar panels have 36 cells – Voc is 24.1 and current is 10.1 amps.
How many watts is a 200Ah battery?
You need to think in terms of watt-hours (energy), not watts. Watts can change at any time.
For example, if a battery delivers 10 amps at 12 volts, then power in watts is found by:
10 amps x 12 volts = 120 watts (instantaneous load)
In general, if you double the amps then the power in watts doubles.
On the other hand, the energy capacity of a battery takes into account time, just like amp-hours. It’s measured in watt-hours.
200Ah x 12 volts = 2400 watt-hours
I often find it convenient to use watt-hours for battery capacity for sizing batteries to loads, and also to solar panels for solar charging purposes.
How long will a 48V 200Ah battery last?
On the face of it it seems that theoretically the absolute capacity of a 200Ah battery is 200Ah, but this is not the case. If a 200 Ah battery has a discharge rating of 0.2C, for example, then it its rating will be 200Ah if discharged at 200 x 0.2 = 200Ah.
However, as more current is drawn from a battery temperature rise and the increased chemical activity internally has the effect of reducing the capacity. The table below shows how increased current draw reduces the capacity of a Renogy 100Ah battery:
Capacity in Amp-hours | Current Draw in Amps | Actual Capacity |
10 Hour Rate (20.0A to 10.8V) | 200.0Ah | |
3 Hour Rate (52.0A to 10.8V) | 156.0Ah | |
1 Hour Rate (122.0A to 9.6V) | 122.0Ah |
From the table above you can see that if the current draw was 20 amps (960 watts load), the battery would last 10 hours before the terminal voltage falls to the level specified by the manufacturer.
- At 52 amps (2496 watts load) the battery would last 3 hours.
- At 122 amps (5856 watts load) the battery would last 1 hour.
How long does it take to charge 200Ah lithium battery?
Lithium Phosphate Batteries (LiFeP04) are extremely robust, both physically and electrically. Some models can be discharged completely 100%, while most specify maximum 80% discharge to maintain long life.
The image below shows that the maximum charge current for this battery is 100 amps, so a fully depleted Renogy 200Ah battery can be fully recharged in 2 hours.
Download 200Ah Lithium Battery Spec. Sheet PDF
How many solar panels do I need to charge a 200Ah battery in 5 hours?
- 200 Ah to watt-hours = 200 x 12 volts = 2400Wh
- 80% discharged = 1920Wh
- 100 watts solar panel output at 4 peak sun hours = 400 watt-hours
- Number of 100 watt solar needed to recharge = 1920/400 = 4.8 (5) solar panels
5 solar panels of 100 watts each would be needed to recharge an 80% discharged 200Ah battery in 5 or 6 hours with average irradiance and no clouds.
How to calculate battery capacity for a solar system
Once you know how many kilowatt-hours (kWh) your home consumes each day, and how big the solar system you need to meet your needs, it’s easy to work out how much battery energy storage you need.
It’s best to work it out per day. For example, in the table below I assume an energy demand/supply of 30kWh per day. It shows how to work out how many batteries tyou would need for one day’s autonomy. Just multiply the result by the number of days autonomy you need.
Note that the battery Ah needed is reduced by a factor of 60% for deep-cycle lead acid and 80% for lithium phosphate technology. These are the recommended Depth of Discharge for each type of battery.
Solar battery capacity calculation step-by-step:
- Take home energy consumption in kWh/day (US average is 30kWh)
- Divide kWh by battery voltage (48 volts in this case) – answer is in amp-hours (625Ah)
- For lead acid divide by 60% (max discharge advised) – 1041Ah
- Divide by individual lead-acid battery capacity (assumes 250Ah) – 4 batteries required
- For Lithium Phosphate batteries divide by 80% (max discharge advised) – 781Ah
- Divide by individual Lithium Phosphate battery capacity (assumes 250Ah) – 3 batteries required
Table – Calculate battery backup for a 30kWh/day home solar system
Backup For 24 Hours | Rating | Measurement Units |
Total load for 24 hours backup | Say 30kWh (average O.S. home enrgy consumption) | kiloWatt-hours (Wh) |
Battery bank voltage | 48 | volts |
Total amp-hours | 30000 watts-hours/48 volts=625 Ah | amp-hours (Ah) |
Required Ah Batteries (60% Depth of Discharge) Lead-Acid Deep Cycle | 625/0.6 = 1041Ah required | Ah |
How many lead-acid batteries - 250Ah each | 4 | |
Amp-hours Lithium Iron Phosphate Batteries? (80% DOD) | 625/0.8 = 781Ah required | Ah |
Number of Lithium batteries batteries @250Ah each | 3 |