How to calculate if my battery will be allowed in hand luggage? (Voltage in mAh to Wh conversion)

12/17/2015 11:32:50 AM

The maximum nominal voltage of a Lithium battery cell is 3.7V (according to Wikpedia). Thus, in order to get an upper bound on the energy stored in the battery in Wh, you need to take the mAh rating and multiply it with 3.7/1000. External battery packs that provide USB power (at 5V) use additional circuity to step up the voltage.

Having said that, there are batteries that consist of multiple cells. In such a case, the battery normally either has a Wh rating printed on it (e.g., for laptops) or a voltage rating printed on it.

They may of course be exceptions to the rule that it’s either at most 3.7V or something else is printed on the device. However, this would make the battery look unnecessarily bad, so for marketing reasons, there should be few exceptions.

12/17/2015 11:02:06 AM

Broadly speaking you have the problem that if you can take it on or not is at the discretion of airport security. If you can’t clearly show that it is within their rules, then good luck convincing them to beleive your calculations. On the other hand, they may not be aware that there are any restrictions, or choose not to inspect the battery too closely.

The current-time rating of a battery normally refers to the voltage of the actual battery itself. However it isn’t entirely clear here what that is – in fact it is possible that changing to voltage output rewires how the cells are connected in the battery. Equally, there is a marketing reason to give bigger numbers throughout the product range, even though the smaller devices only provide 5V through USB.

This amazon page however does provide some useful hints. It says that a full charge takes 5-6 hours at 18.5V/2 Amps. So that’s a maximum of:

6 * 2 * 18.5 = 222 WH

We know that there will be inefficencies there, so it will definitley be less than that.

As several other items in the range are USB only, and it’s the only value from the 4 that fits under our calculated maximum, I’d guess that they are referring to the battery capactity at 5V, meaning 130WH.

But as we’re making assumptions here based on limited information I’d suggest two things:

  1. Contact the manufactorer asking for the capacity in power-time units as opposed to current-time.
  2. Don’t try to take it unless you are prepared to leave it behind in the event of an unusally thorough security check.

Credit:stackoverflow.com‘

About me

Hello,My name is Aparna Patel,I’m a Travel Blogger and Photographer who travel the world full-time with my hubby.I like to share my travel experience.

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