Watt Hours to Milliamp Hours (Wh to mAh) Conversion Calculator

Updated:

May 23, 2023

Watt Hours to Milliamp Hours conversion calculator

Milliamp-Hours Results:

Wh × 1,000 / V =

0.00 mAh

Conversion formula: mAh = Wh × 1,000 / V

What Is Watt-Hours?

Watt-hours (Wh) is a unit that measures the amount of electrical energy consumed or produced by electrical appliances over time. To be more descriptive, it is the amount of electrical energy generated or used when a certain amount of power is used over one time.

What Is Milliamp-Hours?

Milliamp-hours (mAh) is a unit that measures battery capacity. It is equivalent to the amount of electric charge a power source will discharge over time.

While milliamp-hours (mAh) is more commonly used to represent battery capacity, watt-hours (Wh) may also be used for the same purpose.

Why Convert Watt-Hours to Milliamp-Hours?

To Calculate Battery Runtime When mA Load Is Known

Converting watt-hours (Wh) to milliamp-hours (mAh) may come in handy when trying to determine your battery’s runtime when connected to a given current (electric charge).

Ordinarily, if you know the wattage on your battery, you can calculate the battery’s runtime from the battery’s watt-hours. However, if you only know the electric charge in milliamps (mA), you’d have to do a Wh to mAh conversion then calculate the battery’s runtime from the milliamp-hours (mAh).

For instance, if 50 W is connected to a 250 Wh, 20 v battery, the battery’s runtime would be 250/50 = 5 hours. However, if we did not know the wattage, we will not be able to calculate the runtime.

So, what if we only know that the electric charge on the battery is 1000 mA. What would be the runtime?

To answer this, we’ll do a watt-hours (Wh) to milliamp-hours (mAh) conversion = 250/20 x 1000 = 12,500 mAh

Then, we’ll get the runtime by dividing mAh by mA = 12,500/1000 = 12.5 hours

To Figure Out the Best Charging System for Our Battery

When trying to figure out the best electric charge current of your battery’s charger, you’ll need to know the recommended C-rate for the battery type and the battery capacity in Ah or mAh.

C-rate is the ratio of a battery’s charge current to its battery capacity. So, with its value and the value of the battery’s capacity, we can calculate charge current.

For instance, if your battery’s C-rate is 2C, and your battery capacity is 6000 mAh, the ideal maximum electric charge rate of the charger would be:

2 x 6000 = 12,000 mA

How to Convert Watt Hours to Milliamp Hours (Wh to mAh)

Watt-Hours (Wh) to Milliamp-Hours (mAh) Conversion Formula

The formula for calculating watt hours to milliamp hours (Wh to mAh) is mAh = Wh x 1000/v.

To derive the formula, we started out with the formula of power in watts and electrical energy in watt-hours:

electrical energy e (Wh) = power (W) x time (h) (1)

power (W) = voltage (v) x current (A) (2)

Then we replaced power with voltage x current in (1):

electrical energy e (Wh) = voltage (v) x current (A) x time (h) (3)

Using just units, we rewrote (3) as:

Wh = v x Ah (4)

Then we converted Ah to mAh in (4) using Ah = mAh/1000:

Wh = v x mAh/1000 (5)

Finally, we made mAh the subject of the formula:

mAh = Wh/v x 1000 (6)

Basically, to convert watt-hours to milliamp-hours (Wh to mAh), divide watt-hours by voltage then multiply by 1000. This is pretty much what Wh to mAh electrical calculators do.

To do a milliamp-hours (mAh) – watt-hours (Wh) conversion, we’ll multiply voltage and mAh then divide by 1000. Doing a milliamp-hours (mAh) – watt-hours (Wh) conversion is as simple as that.

Of course, with our watt-hours to milliamp-hours (Wh to mAh) calculator, the process is simplified. Just enter energy in watt hours (Wh), enter voltage in volts (v), then click on the calculate button on the Wh to mAh calculator & Wh becomes mAh.

Conversion Examples

Example 1:

We have a solar generator that can give off 30 W from its DC compartment for up to 8 hours before running out of juice. If said DC compartment has a voltage of 20 v, what is the milliamp-hours (mAh) rating of the solar generator?

To convert Wh to mAh for this solar generator, we will calculate the energy in watt-hours (Wh) first. Then we’ll divide the value of energy in watt-hours (Wh) by the voltage in volts, then multiply by 1000.

energy in watt-hours (Wh) = 30 x 8 = 240 Wh

Now that we know the energy in watt-hours (Wh), let’s calculate the battery’s milliamp-hours (mAh):

milliamp-hours (mAh) = 240/20 x 1000 = 12,000 mAh

Example 2:

We have a 24 v battery that powers a 300 W solar refrigerator for up to 5 hours when fully charged. What’s the milliamp-hours (mAh) rating of the battery?

As with the previous example, to convert Wh to mAh, we’ll start by calculating the total energy in watt-hours (Wh) stored by the battery.

energy in watt-hours (Wh) = 300 x 5 = 1500 Wh

Next, we’ll divide the value of energy in watt-hours by voltage then multiply by 1000 to get milliamp-hours:

battery in milliamp-hours = 1500/24 x 1000 = 62,500 mAh

How to Convert Kilowatt-Hours to Milliamp-Hours (kWh to mAh)

The formula used to convert kWh to mAh is not too different from that used to convert Wh to mAh. In fact, the only difference is that we’ll multiply by 1,000,000 in the kWh to mAh formula instead of 1000 like the Wh to mAh conversion formula.

To derive the formula for converting kWh to mAh, we’ll start with the Wh to mAh conversion formula:

mAh = Wh/v x 1000

Next, we’ll define the kWh to Wh formula:

Wh = kWh x 1000

Now, we’ll substitute Wh for kWh x 1000 into the Wh to mAh conversion formula:

mAh = kWh/v x 1000 x 1000 = kWh/v x 1,000,000

Simply put, to convert kWh to mAh, divide kWh by voltage then multiply by 1,000,000. This is what kWh to mAh electrical calculators do.

Example

How many milliamp-hours (mAh) is a 48 v battery bank rated 6 kWh?

milliamp-hours rating of the battery bank = 6/48 x 1,000,000 = 125,000 mAh

Quick Watt-Hours to Amp-Hours (Wh to mAh) Conversion Chart

As mentioned earlier, to convert Wh to mAh with our calculator, enter energy in watt hours (Wh), enter voltage in volts (v), then click on the calculate button on the Wh to mAh calculator & Wh becomes mAh. But whenever you have no access to a calculator, you may use these charts:

For a 12v battery:

Wh	mAh
1	83.33
2	166.67
5	416.67
10	833.33
20	1666.67
50	4166.67
100	8333.33

For a 20v battery:

Wh	mAh
1	50
2	100
5	250
10	500
20	1000
50	2500
100	5000

For a 24v battery:

Wh	mAh
1	41.67
2	83.33
5	208.33
10	416.67
20	833.33
50	2083.33
100	4166.67

Charles Noble

Here at Spheral Solar, I’m a hands-on solar power enthusiast, constantly exploring and experimenting with DIY solutions. I’m dedicated to sharing my discoveries, insights, and even the bumps I hit along the way, all in the pursuit of a more sustainable future.