Join for quick access. Enter your email below and we'll send confirmation plus sign you up to our newsletter.
By submitting your information, you confirm you are aged 16 or over,
have read our
Privacy Policy
and agree to the
Terms & Conditions. Geographical rules apply.
Stay On the Cutting Edge: Get the Tom's Hardware Newsletter
Get Tom's Hardware's best news and in-depth reviews, straight to your inbox.
You are now subscribed
Your newsletter sign-up was successful
An account already exists for this email address, please log in.
External Battery Roundup: Stay Away From The Wall Socket
Battery life is always such a big deal in our mobile coverage (often because gaming systems fall so short). But don't feel limited by the built-in power source. Today we round up 15 external batteries that can keep you running longer away from a socket.
We are listing the total capacity of the batteries here, but we want to point out this isn't always an apples-to-apples comparison. mAh is the SI abbreviation for milliampere-hour. This is a quick and dirty way to compare the relative energy stored in one battery to that of another. However, these comparisons are only useful if you are looking at same battery chemistry.
If you want to think of capacity as how much fuel the battery holds, like a tank of gas, then chemistry is the type of fuel. If you are comparing lithium-ion polymer to nickel-metal hydride batteries, you might as well be talking about diesel and gas-powered cars. Also, think of the huge energy difference between one pound of coal and one pound of uranium. So, the only real metric of a battery's utility is to measure how long it actually runs. In lieu of automobiles and miles per gallon, our benchmark lab tests notebooks and battery life.
Excellent article. I had an idea that this stuff was out there but never really bothered to look. If the 4-5 hours I get from my Asus 1215t begins to not cut it, I now know where to look. Thanks!
I did not understood any of the technical reading especially the part about the desktop PSU.
At one point, it is stated that AC adapters have higher voltage than the battery on a notebook so that it can be charged. Then, how can a external battery damage a notebook's electronics with a higher voltage (only if it's too high)?
It is not stated how to set the external battery voltage correctly. What then is the correct voltage? Correct me but I believe the voltage has to be equal that of notebook battery.
It's pretty remarkable that after page 2 I could guess who the author of this article was (without looking of course) due to the thoroughness and good grammar/lack of typos. Hats off to you yet again, Mr. Ku. Job well done as always.
zodiacfmlI did not understood any of the technical reading especially the part about the desktop PSU.At one point, it is stated that AC adapters have higher voltage than the battery on a notebook so that it can be charged. Then, how can a external battery damage a notebook's electronics with a higher voltage (only if it's too high)? It is not stated how to set the external battery voltage correctly. What then is the correct voltage? Correct me but I believe the voltage has to be equal that of notebook battery.Your guess is actually right. The battery with its voltage set too high can damage the notebook.
If you need to know the voltage required, you just check on your laptop AC adapter or power brick. It is not always the same as the battery.
For instance, a Compaq R3000 has an 18.5 volt AC->DC(120w) power supply and its battery is only 14.5 volts. The voltage regulators in the laptop(in the charging system) it self cut it down to the needed 14.5-15volts to charge the battery.
Also note that the AC adapter does NOT spit out AC it in fact spits out DC(it has a rectifier to convert AC to DC).
As you can see by this picture(you have to click the link), The adapter takes in AC 120V and spits out DC 18.5V. AC is shown with a ~ and DC with a --_---_-- cant make it on here, but you get the point.
http://img269.imageshack.us/img269/1950/powerw.jpg
Quite a different experience on my end testing the Energizer XP8000 and XP18000.
For my smartphone and MiFi, the XP8000 just can't be beat. 5x runtime guarantees me 20+ hours of 3G broadband and week-long phone use. Being barely bigger than a Blackberry, I can effortlessly stash the XP8000 on my belt, and charge my smartphone while I walk.
The XP18000, on the other hand, was a huge disappointment. Using a Toshiba NB305 netbook, it was incapable of recharging the factory 6-cell battery while powered on, and could not provide 2 full charges while powered off. For my usage scenario, that's a failure, as I plug in the external battery when my netbook hits 3% critical, right before Windows does a force shutdown, allowing me to continue working.
Using this deplete-charge-deplete approach SHOULD allow me 14+ hours of continuous power-on time, except that even the beefy XP18000 couldn't get through 1 netbook charge. Had it been capable of providing one full charge powered on, or two full charges powered off, I would have recommended the XP18000 as well.
Nice article. I wonder if these units can be used as a mini-ups for equipment like a NAS, routers and modems. It would be great if you could wire these with the NAS, and be sure that a power outage wouldn't damage the NAS. Considering that the NAS units typically consume much less power than a notebook, these should be able to cover 4-5 hrs of power outage (?) Any thoughts?
shineon2010Very good info , alot of products that im having second thoughts about.
Just buy an automatic inverter that works for hours with a car battery
