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Feature Checklist

External Battery Roundup: Stay Away From The Wall Socket
By
Feature Checklist Dual Charging Separate Charger Charges Dell Charges Mac with MikeGyver MagSafe
Amstron MedXP 140YYNY
Amstron MedXP 300YYNY
Brunton ImpelNYYY
Brunton SustainNYYY
Digipower Universal Notebook BatteryN/AYN/AN/A
Electrovaya PowerPad 130YYYY
Electrovaya PowerPad 95YYYY
Energizer XP18000YYNY
Energizer XP8000YYNY
Lenmar PPU916NNNY
PowerTraveller MiniGorillaNYNY
PowerTraveller PowerGorillaNOptionalNY
Tekkeon MP3450YYNY
Tekkeon MP3450iYNNY
Tekkeon MP3750YYNY
Feature ChecklistAccepts MikeGyver ChargerUse Dissimilar Input/Output Tip CombinationOff stateLinear Battery Gauge
Amstron MedXP 140NN/ANY
Amstron MedXP 300NN/AYN
Brunton ImpelNN/AYY
Brunton SustainNN/AYY
Digipower Universal Notebook BatteryN/AN/AN/AN/A
Electrovaya PowerPad 130YNYY
Electrovaya PowerPad 95YNYY
Energizer XP18000N/AN/ANY
Energizer XP8000N/AN/ANY
Lenmar PPU916YN/ANY
PowerTraveller MiniGorillaN/ANYN
PowerTraveller PowerGorillaNN/AYN
Tekkeon MP3450N/AN/AYN
Tekkeon MP3450iNNYN
Tekkeon MP3750N/AN/AYN


Dual Charging: If your external battery and notebook are both short of a full charge, you need to charge both batteries. If they are connected, the external battery always takes priority. Some batteries will charge both systems at the same time by demanding a higher current from the wall socket. Notice that only a handful of the batteries in this roundup are capable of this.

In the case of Brunton and PowerTraveller, you need to physically disconnect the AC charging cable before using the external battery to power the notebook. The battery refuses to output power otherwise. In the case of Lenmar, you don’t need to disconnect, but everything is done on a priority-based system. Say your notebook is at 50% and the PPU916 is at 90%. First, the PPU916 finishes charging, then it stops charging and charges your notebook. After the PPU916 goes to 0% or your notebook hits 100% (whichever occurs first), it repeats the process. Obviously, Lenmar's implementation is very inefficient. It doesn't properly shunt power.

Separate Charger: Not all of these batteries allow you to make dual use of your notebook’s charger. Some require you to use the one included in the box. Only the PowerGorilla provides an option to choose. Remember that this benefit is a double-edged sword. With a separate charger, you are guaranteed a way to charge your battery. An input tip system has no guarantee unless the company explicitly states that your notebook is compatible.

Charges Dell Notebooks: The majority of Dell notebooks (excluding the Minis) have a power circuit that requires a proprietary identification signal before charging initiates. If this signal is absent, you can only power the notebook. That is why third-party chargers often do not work with Dell notebooks. Some vendors have figured out Dell’s charging scheme and others haven’t. The only batteries in our roundup that can actually charge a Dell notebook are from Electrovaya and Brunton. Every other battery could not charge our Vostro 3300.

Dell's Power WarningDell's Power Warning

Charges Mac with MikeGyver MagSafe: All of these batteries will output to the old 16 V ThinkPad tip. Every battery in our roundup will power and charge a Mac notebook provided you have a modified MagSafe cable.

Accepts MikeGyver’s Charger: MikeGyver’s modified MagSafe charger uses the old 16 V IBM ThinkPad tip. This setup only works with the Electrovaya’s PowerPads and Lenmar’s PPU916. Why? Well, technically Apple’s power brick sends out three voltages. The default is 12 V, which is enough to keeps your Mac powered. That is why the MagSafe’s LED turns green when you first plug it in. When the notebook needs to charge, it demands 16 V (or 19 V if you have a 15.6” or 17.3” MacBook). This demand initiates a voltage switch in the adapter. Electrovaya’s tip system is based on sense resistors, so it demands 16 V from the beginning. The PowerGorilla and MP3750 also use sense resistors, but because the resistor is set up on the input side within the battery, both only detect the default voltage (12 V). This is insufficient to charge either battery. Lenmar doesn’t use sense resistors, but it does have a manual switch that forces the battery into a 16 or 19 V mode. This allows the PPU916 to demand a voltage higher than 12 V from the power brick. The solution is to move to a third-party power brick like Targus' Premium Laptop Charger (APM69US).

Use Dissimilar Input/Output Tip Combination: This is a safety issue. In order to prevent overload (or underload), the entire circuit must maintain the same voltage. This only applies to Electrovaya’s PowerPads, because they allow you to use a notebook’s charger for dual charging. Simply put, you cannot use a 16 V IBM adapter to charge and power a 19 V Dell notebook. If you force this, the PowerPad will refuse to output power until you disconnect the input power source.

Off State: Using a multimeter, I found that only some of these batteries have what would be considered an off state. Even if it has an on/off power state, there is no guarantee that the battery is completely powered down. The lowest state for some of these batteries is similar to the ACPI S3 state. Simply put, the circuit is nearly always live in a kind of sleep state. The difference is minor, but having an off state is important if you want to put these batteries into storage. If we don’t consider chemistry, the ones with a S1-like power state would exhibit the slowest rate of energy leak.

Linear Battery Gauge: Electrovaya no longer uses a digital battery counter. So, all battery gauges are incremental, using bars in an LCD display or multiple LEDs. I have read the manuals to confirm, but several of these batteries have an odd number of indicators or a number that isn't a factor of 10. This means the first LED may indicate a 0-5% charge while the second indicates 5-20%. This is a feature to keep in mind if you need to keep track of how much charge you have left.

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  • 0 Hide
    lashabane , March 9, 2011 5:18 AM
    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!
  • 0 Hide
    zodiacfml , March 9, 2011 6:41 AM
    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.
  • 0 Hide
    burnley14 , March 9, 2011 1:22 PM
    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.
  • 0 Hide
    Anonymous , March 9, 2011 1:43 PM
    @zodiacfml

    it's simple really, AC adapter spit out AC, Batteries spit out DC
  • 0 Hide
    nukemaster , March 9, 2011 2:16 PM
    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
  • 0 Hide
    Onus , March 9, 2011 2:55 PM
    Thanks for the comments on Digipower. I've placed them on my personal "Do Not Buy" list.
  • 0 Hide
    Luscious , March 10, 2011 6:29 AM
    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.

    http://lgponthemove.blogspot.com/2010/07/accessory-corner-3-energizer-xp18000.html
  • 0 Hide
    a_fortiori , March 11, 2011 3:05 AM
    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?
  • 0 Hide
    shineon2010 , March 15, 2011 6:12 PM
    Very good info , alot of products that im having second thoughts about.
  • -1 Hide
    junixophobia , March 15, 2011 8:24 PM
    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
  • -1 Hide
    junixophobia , March 15, 2011 8:25 PM
    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
  • 0 Hide
    Anonymous , March 15, 2011 8:33 PM
    Im missing the portable powerstation, especially the spps-200.
    i wonder how that scores against the others.
    i think they are from novuscell
  • 0 Hide
    junixophobia , March 15, 2011 8:35 PM
    sorry guys, just gettin the hang of this...
  • 0 Hide
    Onus , March 15, 2011 9:39 PM
    If you deep-cycle a car battery, you'll kill it in a matter of weeks, as its thin plates deteriorate. For deep-cycle applications, you want to get an AGM battery, containing much thicket plates; and even then you don't want to drop the SOC too much between charges, perhaps 60% is the lowest you should go.
  • 0 Hide
    Anonymous , April 13, 2011 10:54 PM
    Carrying an extra battery adds a lot of weight. And once the battery is depleted, you are dead in the water if the power socket is out of reach.

    If I am going off grid, I would rather bring a solar panel and charge the battery I already have in my device.

    http://leicadig.blogspot.com/2011/04/digital-camera-off-grid.html
  • 0 Hide
    acku , April 13, 2011 10:56 PM
    Which sonar panels are you looking at? I use Brunton myself.

    Cheers,
    Andrew Ku
    TomsHardware.com
  • 0 Hide
    agnius , April 13, 2011 11:13 PM
    I am debating between Brunton, Powerfilm and Voltaic.
  • 0 Hide
    acku , April 13, 2011 11:14 PM
    I have all three. What's holding up your decision?
  • 0 Hide
    agnius , April 13, 2011 11:34 PM
    Andrew,

    According to my calculations I would need about 25-30W to power/charge a netbook directly and charge my camera battery.

    In theory Solaris 26 could do the job, but I am not sure - I have not read any reports about it. I was planning running Targus DC adapter from Solaris 26 straight into a netbook (I had HP Mini but it broke so now I am looking at Lenovo X120e as a replacement).

    Also, I read that CIGS panels after being stored in the dark take days to reach their peak output. Solaris is CIGS, PowerFilm 30W is silicon which does not have that problem.

    But PowerFilm 30W is also considerably larger which makes it less feasible to deploy while riding. Hence I am looking at Voltaic panels which are much smaller, but I am not sure how to route power without an intermediate battery from them (because they are 20V).

    I am stuck in this decision loop while looking for more information.
  • 0 Hide
    acku , April 13, 2011 11:38 PM
    Are you only trying to charge the camera and netbook at the same time? I assume the camera charger requires an AC outlet?
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