How long will a 200ah battery last

May. 13, 2024

How long will a 200ah battery last

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How long a 200ah battery will last depends on a number of factors, including, the efficiency of your inverter, depth of discharge, and how much load you are running. A new 200ah deep cycle battery connected to a 12v inverter, will last 10 hours if discharged with a load of 150 watts at 80% efficiency and depth discharge. If your load is 300 watts, however, the battery will only last for about half that time.

How to calculate Inverter battery backup time

To find how long will a 200ah battery last, first, you'll need add up the total wattage of the devices you want to power with your 200ah battery bank. Let's say you want to power six 9-watt LED light bulbs, a 45 watt TV and a 90 watt fan for 10 hours.

You will not only need an inverter capable of carrying the load, but also a battery bank capable of powering the load for the required backup period.

After you have determined your load's power consumption, the efficiency of the inverter, size and voltage of the battery bank, you can use this formula to determine how long will a 200ah battery will last:

12v (Battery Bank Voltage) x 200ah (Battery Capacity) x 0.8 (Depth of Discharge) x 0.8 (Efficiency) / 189 watts = 8 Hours

The above result shows that a single 200ah battery cannot power a load of 189 watts continually for 10 hours (at 80% depth of discharge and efficiency) to get the desired result (without damaging the battery) you would need to add an additional battery.

12v (Battery Bank Voltage) x 400ah (Battery Capacity) x 0.8 (Depth of Discharge) x 0.8 (Efficiency) / 189 watts = 16 Hours

Examples

Inverter SizeBattery BankLoadBackup Time Mercury 1KVA Inverter 12v 1x 200AH 150 Watts 10 Hours at 80 % depth of discharge Mercury 1KVA Inverter 12v 1x 200AH 300 Watts 5 Hours at 80 % depth of discharge Mercury 2.4KVA Inverter 24v 2x 200AH 150 Watts 20 Hours at 80 % depth of discharge Mercury 2.4KVA Inverter 24v 2x 200AH 300 Watts 10 Hours at 80 % depth of discharge Mercury 3.5KVA Inverter 48v 4x 200AH 500 Watts 12 Hours at 80 % depth of discharge Mercury 3.5KVA Inverter 48v 4x 200AH 1000 Watts 6 Hours at 80 % depth of discharge Mercury 5KVA Inverter 48v 4x 200AH 500 Watts 12 Hours at 80 % depth of discharge Mercury 5KVA Inverter 48v 4x 200AH 1000 Watts 6 Hours at 80 % depth of discharge Mercury 7.5KVA Inverter 120v 10x 200AH 1500 Watts 10 Hours at 80 % depth of discharge Mercury 7.5KVA Inverter 120v 10x 200AH 3000 Watts 5 Hours at 80 % depth of discharge Mercury 10KVA Inverter 120v 10x 200AH 1500 Watts 10 Hours at 80 % depth of discharge Mercury 10KVA Inverter 120v 10x 200AH 3000 Watts 5 Hours at 80 % depth of discharge Mercury 30KVA Inverter 384v 32x 200AH 2500 Watts 19 Hours at 80 % depth of discharge Mercury 30KVA Inverter 384v 32x 200AH 5000 Watts 9 Hours at 80 % depth of discharge Mercury 30KVA Inverter 384v 32x 200AH 10000 Watts 4 Hours at 80 % depth of discharge

How To Calculate Battery Run Time - DNK Power

How To Calculate Battery Run Time

There are just too many questions you will wonder when designing your device with a battery inside it.

The boss just want a cheap and small battery with it, but with no further information on how long does the end customer wants, how small can it be.

in this article, we will show you:

1 How to Calculate the Run Time of a Specific Battery?
2 How to Calculate Battery Capacity ?
3 Battery Capacity Calculator (Instant Calculation Tool)
4 Battery Run Time Calculator
5 How to convert Watts to Amps or Amps to Watts or Volts to Watts

Ready for your battery design?

Let’s go.

In the ideal/theoretical case, the time would be Time(H) = Capacity(Ah)/Current(A).

If the capacity is given in amp-hours and current in amps, time will be in hours (charging or discharging).

Feel Confused ?

So how to calculate how long a battery will last?

Throw away how long will a battery last calculator, and let’s see an actual case, 12V 10 Ah lithium battery delivering 1A, would last 10 hours. Or if delivering 10A, it would last for only 1 hour, or if delivering 5A, it would last only for 2 hours.

In other words, you can have “any time” as long as when you multiply it by the current, you get 10Ah (the battery capacity).

It is that simple.

so no more confusion on how to calculate battery life.

For a 18650 2500mAh(2.5Ah) battery with a device that draws 500mA(0.5A) you have:

2.5Ah/0.5A=5 Hours

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For a 36V Li-ion Battery with capacity of 24Ah battery delivering 2A current, then you can constantly use your battery for:

24Ah/2A=12 Hours

Please take note that most batteries, especially those with circuits, will not work down to 0 Volts as a power supply (if it goes to zero, it will have shorter battery life, or even become dead battery if not charged in time), that’s to say,your circuit will stop working at a set voltage before the battery is fully drained.

see below dischaging chart

it will not go to zero(totally empty)

We, therefore, will need to times 0.8-0.9 for the calculation:

that’s 2.5Ah/0.5A*0.9=4.5 Hours

What if you know Watts only, you will notice that every device use watt to determine it’s main specifications.

5 Watt bulb,

20W Laptop,

100W Motor,

200W Solar Street Light

Just name a few.

In Theory, that’s:

Discharging Time=Battery Capacity*Battery Volt/Device Watt.

Say, 5AH*3.7V/10 Watts = 1.85 hrs

With 90% Power efficiency for Li-ion/LiPo batteries. Then

Discharging Time=Battery Capacity * Battery Volt*0.9 / Device Watt

5Ah*3.7V*0.9/10W = 1.66 hours

Let’s explain with more examples:

for a 1800mAh 3.7v 18650 battery to power a 3.7V 10W digital device, how to calculate the running time?

for 3.7V 10W device，working current would be 10÷3.7 = 2.7027A = 2702.7 mA

In theory that’s: 1800mAh ÷ 2702.7 mA = 0.666 h = 40 min

In reality that’s: 1800mAh ÷ 2702.7 mA*0.9 = 0.599h = 36 min

Quick Notes: 1A=1000mA (mA is current, mAh is Capacity)

Or you can use 3.7V*1.8Ah(1800mAh)*0.9/10W=0.599h=36min

Another example: 12V 60Ah li-ion battery pack to power 220V 100W light

Working time: 12V*60Ah*0.9/100W=6.48 H

If you want to learn more, please visit our website Home Solar Lithium 48v 200ah LiFePO4 Battery.