[space_traveler]

Anyone tried one of these BB Playbook battery back up power units?
Amazon.com: System-S Battery Extender Portable Charger for BlackBerry PlayBook: MP3 Players & Accessories
I am just curious how good or not it may be and how much added time (hours?) it could give me with my Playbook. I understand this could vary a lot depending on what I was doing. Just trying to get a general idea on how much added time it would give me if I plugged it in when my battery was getting low.

Thanks for any info.

[peter9477]

Notice that no useful specs are provided: I'd stay well away from it without credible reports from others how well it works. (Let others waste their money before you do...)

It says it uses four AA batteries. Per random web pages I checked, it appears an AA battery gives you about 2.4Wh at an average voltage of 1.2V. Four of them simply increases the voltage to a useful level for charging the PlayBook, but you'd still have 2.4Wh from the set.

Per my notes at PlayBook: Power Consumption that would give you roughly one hour of run time at 50% brightness, and doesn't account for whatever inefficiencies there would be in the system.

I'd expect no more than one hour from it, and probably less, though of course you might be able to stretch it out a bit past one hour if you ran with minimum brightness and didn't do much, as you might if you were forced to use it.

[space_traveler]

Thanks for the info!

[bbvj]

I found the EVOPower Black 2-Port Ultra High-capacity Portable External Rechargable Backup Battey Pack -10000mAh on Amazon and wondered if it's worth buying for the 64gb playbook. Anyone have any experience with this one? Or found anything else that works to fully charge the pb?

[peter9477]

See bbvj's quote (below) of the original content of this post, where I reversed my math and gave completely wrong advice as a result...

The correct version, as fazluke pointed out later, is that 10000mAh would be close to 38Wh, which is roughly twice the capacity of the PlayBook, or 200%, rather than the 14% or so I had originally calculated.

Contrary to my original conclusion ("can't imagine that's worth it"), this makes it appear the device could be quite effective.

Apologies for the mistake...

[bbvj]

10000mAh would be, at an average voltage of 3.8V, about 2.6Wh. The PlayBook's battery is nominally 19.98Wh, and practically about 18Wh in most cases.

Dividing the two, that means this device would, in the theoretical best case, recharge approximately 14% of your PlayBook's battery.

In reality, since power transfers of this nature are never 100% efficient, you can probably count on only about 10%.

I haven't looked at the device or the price or anything, but I can't imagine that's worth it to almost anyone.

Thanks so much for your quick and helpful response. I won't bother to waste my money on it. Any suggestions as alternatives?

[peter9477]

I know of none, but this isn't my area. My suspicion is that such devices are impractical for something like the PlayBook and you'd be much better off travelling with a car adapter and a spare charger, and just recharging from available sources when required. I'm sure there are battery packs out there suited for the job, but they'd be big and heavy and cost a bundle... (I'm guessing.)

[fazluke]

10000mAh would be, at an average voltage of 3.8V, about 2.6Wh. The PlayBook's battery is nominally 19.98Wh, and practically about 18Wh in most cases.

Dividing the two, that means this device would, in the theoretical best case, recharge approximately 14% of your PlayBook's battery.

In reality, since power transfers of this nature are never 100% efficient, you can probably count on only about 10%.

I haven't looked at the device or the price or anything, but I can't imagine that's worth it to almost anyone.

If I remember right from my college days; 10 Ah x 3.8 V gives 38 WH not 2.6 WH which would be more than enough for the playbook, what I am missing?

[majorusa]

I purchased the Mili Powershine 3.7V/4000 mAh battery. I used it on the Playbook while down to 50% and recharged it full but the Mili was completely depleted. It has 2 normal USB outlets one that is 5V 1A and the other one 5V 2.1A(max). I want to retest from 20%. With Batttery Guru open it took close to 3 hours to recharge the PB and it was recognized on the 5V 1A as USD wall charger.

The Mili is very light, Iphone 4 size and 20 grams lighter than the before said phone. It is expensive, 97 USD but as a back-up is well worth the money.

MiLi Power Shine Review | GadgetReview

[majorusa]

I redid the test last night from 20% battery charge and ended with the PB charged to 77% this morning. Here are the battery guru pictures.

So the battery can give a +57% additional time while you are in the plane by example. Overall I am very pleased with the acquisition. One distinctive feature is that it has two usb ports being able to charge both the PB and the BB phone if you need the bridge.

[peter9477]

If I remember right from my college days; 10 Ah x 3.8 V gives 38 WH not 2.6 WH which would be more than enough for the playbook, what I am missing?

You're not missing anything... that's totally correct. I clearly had a mental block that day and mixed up whether I was supposed to be dividing or multiplying... I'll try editing the post.

[bbvj]

You're not missing anything... that's totally correct. I clearly had a mental block that day and mixed up whether I was supposed to be dividing or multiplying... I'll try editing the post.

Peter, fazluke, and anyone else I missed, Thank You for your input/responses....and a thanks to you, Peter, for taking the time to edit your post and notify me!