A good quality, fully-charged 200 Ah battery can last between 2.5 – 10 hours (estimated) depending on the power consumption of the connected appliances.
This assumes that the battery is discharged to only 50% of its capacity to maximize battery life.
- with a 120W appliance connected, the 200Ah battery lasts for an estimated 10 hours. Find out how to calculate how long a battery lasts
- whereas with a 425W appliance the battery only lasts for an estimated 2.5 hours
Note: The above estimates assume that the battery is discharged to 50% of its capacity only.
In general, connecting appliances with high current draws lowers the overall available battery capacity and can shorten battery life. Learn how to estimate battery capacity.
With a 425W appliance connected to the battery, for example, the estimated battery capacity reduced to about 177Ah (a 10% reduction in available capacity from 200Ah).
In my design applications, I aim for a battery discharge rate of no less than 8hr to get as much cycle life from the batteries – for a 200Ah battery, this will equivalent to not drawing more than 200/8 = 25A from the battery.
You can use the calculator below to get an estimate of how long a battery lasts when connected to appliances with different power ratings (watts).
Note: This assumes that the appliance is connected to the battery through a DC-AC inverter with an efficiency of 80%.
Note: The battery runtime information provided by the calculator is a guide.
Actual times will likely vary because of the factors described above.
Frequently asked questions
# 1. How long will a 100Ah battery run an appliance that requires 400W?
Assuming the appliance is connected to an AGM deep-cycle battery, it will run the appliance for about 1 hour.
A 100Ah battery has about 100 x 12 = 1,200Wh of energy. If you are to limit the depth of DOD to 50% (recommended for AGM), only 50% x 1,200 = 600 Wh is available. In theory, it would for about 600/400 = 1.5 hours.
In reality, it will be less because, at that much current draw (400W/12V = 33.3A), battery capacity can reduce to as low as 77Ah!
# 2. How long will a 100Ah battery power a TV?
100Ah battery can power a 60W TV for about 10hrs.
For an estimate of how long different appliances can run when connected to a 100 Ah battery (assumes AGM, 50% DOD), refer to the table below.
Table showing estimates of how long an appliance lasts with a 100Ah battery
|Appliance (W)||Amps||Estimated runtime (hours)|
Appliances rated 400W, 500W will run for about 45 min when connected to a 100Ah battery while that rated 700W, 800W, 900W will last for about 20min.
Note: All of these times are estimates.
# 2. How long will a 200Ah battery run an appliance that requires 400W?
A 200Ah battery will power a 400W appliance for about 2 hours.
A 200Ah battery has about 200 x 12 = 2,400Wh of energy.
If you are to limit the depth of DOD to 50% (recommended for AGM), only 50% x 2,400 = 1,200 Wh is available.
In theory, it would for about 1200/400=3 hr. In reality, it will be less because at that much current draw (400/12=), battery capacity can reduce to as low as 177Ah!
|Appliance rating (W)||Amps drawn||Estimated Run-time|
# 3. How many 200Ah batteries can power a home?
To work out how many batteries of a certain size (200Ah) to power a home, you need the combined power consumption of your appliances and how long you need to power them.
For example, a single 200 Ah AGM battery can provide a combined power consumption of 400W (2 laptops each consuming 40W, 6 lights each 10W, a fridge drawing 200W) for about 60 min only.
Should your power consumption be higher i.e. you have more appliances or you want to run them for longer then you need more batteries.
# 4. How many amps does a 200ah battery have?
The number of amps you can draw from a 200Ah battery depends on the power consumption of the connected appliance.
This in turn determines its discharge rate.
The table shows the estimated number of amps available when different appliance ratings are connected to a 200Ah battery.