Have you ever shopped for power banks, those lithium battery portable chargers, only to have your brain say “huh?” at the mention of mAh, a.k.a. milliamps per hour? Unless you took shop in junior high school and learned about electricity, you’re like most of us – don’t get into the shower with an electrical appliance; and what’s a milliamp and why should I care about it?
I asked my power bank suppliers to explain milliamps to me. I asked the electrician in my office building. He threw Ohm’s Law at me. I threw it right back. Didn’t understand it in high school, don’t understand it now. But I do have an understanding of mAh and I’ll tell you why you should care.
Power banks were originally introduced to provide “power on the go,” to revive a dead or dying Smartphone. They are handy-dandy, small, compact and easily transportable chargers. If you have one you know how wonderfully convenient they are. No more frantically searching for an available outlet at airports, no more entanglements with long cords.
In order to shop wisely for power banks, whether you’re buying for yourself or your company, you should understand the following:
1) Power banks, and the devices they charge, have electrical capacity that is measured in milliamps per hour (mAh) and the amount of mAh tells us the amount of energy a particular battery can store at one time.
2) To full charge a Smartphone once, the power bank mAh capacity has to exceed that of the device being charged by about 1/3. For example, the iPhone 5 has a 1507 mAh battery. It needs a 2200 mAh power bank to fully charge and it will only be once before the power bank needs re-charging.
3) Power is lost in the form of heat in the charging process. That’s why your phone feels hot.
4) If the phone is in use, even if it’s only the GPS, it won’t fully charge. The GPS is drawing power away from the charging process.
5) To fully re-charge the power bank use the charger that came with your Smartphone or the USB port on a computer. The power bank comes with a short connection cable.
7) A power bank with a low capacity mAh (1200 or 1800) won’t charge a Smartphone with a low battery for very long.
8) Be careful not to drop a power bank – it has internal circuitry that can be damaged.
These are the mAh capacities for the most popular Smartphone batteries.
iPhone 5 – 1507; iPhone 6 – 1810; iPhone 6Plus – 2915
Samsung 3 – 2100; Samsung 4 – 2600; Samsung 5 – 2800
The power bank sweet spot to fully charge a Smartphone ranges from 2200 to 4000 mAh depending on the phone. If you’re not concerned with a full charge, but just need a little juice to keep you going, then 2000 – 2600 mAh should be fine.
And if you ever want to charge your Tesla, there is a 41,600 mAh power bank available.
For more information and details on purchasing power banks contact me at (781)933-4660.