External Battery Roundup: Stay Away From The Wall Socket

Benchmark Results: Netbook Battery Life

We expected Amstron's MedXP 300 to lead the pack. Its sheer size suggests lots of battery life. But notice just how far ahead it scores.

Besides the obvious, we have a couple of surprises. Notice that Brunton's Sustain has an output rating of 60 Wh, but comes out ahead of the three ~100 Wh batteries: XP18000, PowerGorilla, and PPU916. This just goes to show that the manufacturer's stated capacity isn't the final word. Voltage and current levels the company uses to test also matter.

Our updated benchmark generates a platform average design power of 11.5 W for the Dell Inspiron Mini 10. We used this value to normalize the capacity of all the batteries tested.

Even though we normalized battery capacity, that doesn't take weight into account. We weighed all of the batteries and graphed capacity and minutes per pound. Similar to normalized battery capacity and battery life, our per-pound metric presents the same data using different units.

While our calculations include the weight of a battery's physical shell, the graph takes us by surprise. Pound for pound, Energizer's XP18000 and XP8000 deliver the most battery life. Meanwhile, many of the solutions geared toward industrial use (and consequently employ more durable enclosures) fall to the bottom, including the PowerPad 95 and MedXP 140. Obviously, making a robust battery means using thick armour to protect the battery cells from damage.

The Energizer batteries are the stand-outs here. Compare them to Tekkeon's batteries, which do worse in battery life and have a poorer weight efficiency.

Create a new thread in the UK Article comments forum about this subject
This thread is closed for comments
Comment from the forums
    Your comment
  • sylvain
    Interesting read. Would it be possible to do a similar test for pure USB external batteries. Used for adding that extra bit of juice to an iPad, iPhone or similar devices?
  • Anonymous

    I am interested in using the battery for a DSLR video rig, i want to use the 12v to power the camera, then split the 5v to power both an asus wicast and a SDI to HDMI down convertor. both these last two devices take a 5v feed. would this be possible do you think?
  • Spanamana
    I purchased one of these batteries from a UK supplier and have to say I have never encountered such poor customer service in a long time. They claim that they supply one free tip a year. Rubbish! When you try to get one for a iPad 3 or later, they charge you $10 because they changed the name of it from "tip".

    After 8 months the battery started not keeping its charge. I tried to use the 2 year warranty to get it replaced and found out that although the unit is guaranteed for two years, the battery is only guaranteed for 6 months. Then I was told that it would cost too much to get it repaired as there is no UK repair centre and therefore there is a charge of $30 for a replacement.

    Having delivered the replacement battery, I have not received a VAT order for £21 for import duty from TNT. So a battery that cost me £50 has now cost me £95.

    Shonky product, useless service. Don't waste your money.