Photos 2015

External Power Bank Packs

Today’s “photos of the day” are for an Octagon Technology blog about smartphone and tablet battery life.

My external power bank packs – 25Ah unit – iPod Touch (to show the sizes) – 50Ah unit

For a while now I have used a series of large external power bank packs when I am camping and backpacking to charge my various devices. These large batteries are a great way to supply power to power hungry gadgets when there is no mains power available. My current model is rated at 25Ah, has two USB outputs one is 5v at 1A the other is 5v at 2.1A and is slim and lightweight, ideal for backpacking.

Charging in the MX-5

When I am car camping I regularly charge my gadgets from the car lighter socket, including using a power inverter and a mains plug for my iPad, even when parked and the engine is off. Parked charging is not an issue (although I always take advantage of charging whilst driving) when I am using my diesel car with a large battery.

But when I am using my Mazda MX-5 things are different! Charging whilst driving in the MX-5 is not a problem – I have a USB charge point on the car radio and I have a twin USB socket in the lighter socket.

However the car battery in the MX-5 is small and I do not want to risk using it to charge gadgets, so I have bought a 50Ah external power bank pack for charging at the campsite.

When is 50Ah not 50Ah?

The other day I decided to full cycle my 25Ah external power bank pack, getting it ready for a camping trip later this month. The first thing I did was charge the iPad Mini, which had closed down because the battery was drained – the power pack was showing a three quarters charge (3 LEDs showing out of 4). However when the iPad was fully charged I was disappointed to see that the power pack was more discharged than I was expecting.

Was the pack faulty? Had the eBay seller description not been accurate? Were there excessive power losses through heat and inefficiencies?

A check of the spec on the 50Ah pack showed it was 50Ah at 3.7v but I needed the vales at 5v.

3.7/5*50=37Ah and 3.7/5*25=18.5Ah

About 25% less capacity than advertised and then add to this power loss through heat and inefficiencies.

The iPad battery capacity is 4.4Ah so it looks like the power pack is OK, I was just a little misled when buying the packs! I am not disappointed by my findings, they will still meet my needs and were great value, I paid £9 for the 25Ah unit and about £11 for the 50Ah one.

If you are planning to buy one if these devices be aware of the actual capacities, check with the supplier if you want clarification.

Charging requirements – car camping

iPhone5 1.44Ah
iPod Touch 1.03Ah
iPad Mini 4.44Ah
Bluetooth speaker 0.4Ah

Maximising battery life in iOS devices.