# How to estimate battery recharge time

Electric skateboard manufacturers don’t always state the time needed to recharge their board from empty to full, but this is something you can easily calculate on your own. Here’s how.

#### Find out battery amp hours

Find out the board’s battery capacity in amp hours (Ah). This is written like 6Ah, 8Ah, 14Ah, etc.

#### Find out charger output amps

Each charger has a label that tells you its input and output specs. Look at the number for output. It’s normally written as something like 2A, 3A, 4A, etc.

#### Divide Ah by A

Suppose the battery is 8Ah and the charger is 2A. Just divide the 8 by 2 and you get the number of hours needed to recharge the battery.

`8 ÷ 2 = 4`

Under ideal conditions with those specs, this 8Ah battery with a 2A charger should take 4 hours to recharge from empty to full. In reality though it can take anywhere from 10% to 25% longer. To keep the math simple, just add 30 to 60 minutes to the calculated time and you should be pretty close.

#### Can’t find the amp hours?

Sometimes the manufacturer only shows Watt hours (Wh). In that case, you need to find out the battery voltage, or how many cells it uses in series (usually 10S or 12S). If the battery is 10S (examples: 10S2P, 10S3P), then it’s 36V. If the battery is 12S (examples: 12S2P, 12S3P), then it’s 43.2V.

Now divide the Watt hours by the voltage to get the amp hours.

`Wh ÷ V = Ah`

Let’s use the Exway Flex as an example. We know that it uses a 259Wh battery, and also that it is a 12S2P battery. 12S means it is 43.2V.

`259 ÷ 43.2 = 6`

This battery is 6Ah.