# Recommend me an external battery backup/charger



## fatboyslimerr (Dec 28, 2012)

I'm looking for an external battery backup/charger and have read up about them extensively.
My conclusion is that my HP touchpad running CM10 probably needs one of the more chunky and expensive 2amp output external batteries to charge properly and that a 12000mAh one will probably offer 2 complete charges for the touchpad. Whilst that is great, size and weight is more of a factor to me.

The nice small external batteries are all 1amp output and so could someone please tell me if I could charge or at least sustain my TP with one of those of whether I need a chunky expensive 2A one?


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## nevertells (Oct 29, 2011)

HP did a number on us by making the charging system on the TouchPad proprietary. In other words, the only way a TP charges at the rated two amps is if one us using the charger made by HP for the TouchPad. All other after market chargers will provide a charge, but only at around 500mA.


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## noseph (Feb 19, 2012)

nevertells said:


> HP did a number on us by making the charging system on the TouchPad proprietary. In other words, the only way a TP charges at the rated two amps is if one us using the charger made by HP for the TouchPad. All other after market chargers will provide a charge, but only at around 500mA.


The problem is not that HP made the TouchPad usb proprietary, it follows the USB specification, the industry problem is that Apple made their iPhone/iPad usb proprietary and everyone builds to that.


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## nevertells (Oct 29, 2011)

noseph said:


> The problem is not that HP made the TouchPad usb proprietary, it follows the USB specification, the industry problem is that Apple made their iPhone/iPad usb proprietary and everyone builds to that.


I'll drink to that too. Regardless, fatboys idea is still toast unless he can somehow verify that the device he wants to purchase conforms to the USB spec, not Apples.


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## fatboyslimerr (Dec 28, 2012)

But what is it specifically I need to look out for? Does the TP need a dedicated charging port (DCP)? All external batteries say they do not support DCP such as Samsung galaxy tablets.

If someone could find an example of a battery that would actually charge the touchpad properly I'd really appreciate that. I've found a tecknet one that provides 2.1A. iEP392.

Thanks

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## Gradular (Feb 1, 2012)

fatboyslimerr said:


> But what is it specifically I need to look out for? Does the TP need a dedicated charging port (DCP)? All external batteries say they do not support DCP such as Samsung galaxy tablets.
> 
> If someone could find an example of a battery that would actually charge the touchpad properly I'd really appreciate that. I've found a tecknet one that provides 2.1A. iEP392.
> 
> ...


This works well with cm10 20121216 build. Still not as fast as the hp charger and has to sleeping to get a positive charge rate. Jcsullins charge app says the current limit is 900mah.

http://www.bestbuy.com/site/Lenmar+...97307007&skuId=3386191&st=powerport&cp=1&lp=1

Sent from my GT-P3110 using RootzWiki


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## Colchiro (Aug 26, 2011)

I have no experience with that battery, but most places online will have it for about half that price. http://www.amazon.com/gp/product/B005DTJI7Y?linkCode=xm2&tag=invihand-20


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## fatboyslimerr (Dec 28, 2012)

Thanks for suggestions. Based on a number of reasons I opted for an external battery that takes x3 AA batteries.

http://www.amazon.co.uk/PortaPow-Pr...4?s=electronics&ie=UTF8&qid=1361112454&sr=1-4

I plan on putting 2900 mAh rechargeables in this and I'm not particularly bothered about not charging at 2A. Even 500mA would make the battery last a lot longer.

Thanks again for saving me the money of buying an expensive external. I'll let you know how that pack is when it gets delivery.

Sent from my cm_tenderloin using Tapatalk HD


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## nevertells (Oct 29, 2011)

fatboyslimerr said:


> Thanks for suggestions. Based on a number of reasons I opted for an external battery that takes x3 AA batteries.
> 
> http://www.amazon.co.uk/PortaPow-Pr...4?s=electronics&ie=UTF8&qid=1361112454&sr=1-4
> 
> ...


Make sure you run Battery Monitor Widget to give you real time monitoring as well as usage history tracking.


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## Razor512 (Aug 22, 2011)

The HP touchpad can charge at 2 amps using any charger, the problem is that to put it in a full charging mode, you either need to short the data pins, or have some resistance on them that is not inifnity.

I currently use one of these 12000mah chargers from ebay http://www.ebay.com/...=item56531dcbef

they are cheap but work well and why they do not actually give 12000 mAh, and with it it charges at around 1.1 to 1.2 amps

(and can do about 1.6 to 1.7 full recharges)

I have also done another test using a 2.5 amp boost converter and wiring it up to a USB header, then shorting the data pins, and was able to get a full 2.1 amps charge rate out of it.

Another issue with the HP touchpad is that you cannot use a long USB cable. The cable it comes with a little stiff because it uses thicker than normal copper cable. and anything less than 4.95v automatically disables the charging process (it will list that it is still charging but if you monitor the charge using an application like system tuner, you will see that it will drop from a charge rate of 2.1 amps, to around 100-300ma (meaning that the device will use more power than is coming in even with wifi off and the screen at the lowest level (you can test this by using a USB extension cable with the HP charger, and if you want to monitor voltage, connect a USB hub to the charger (at the end of the extension cable and then using a old device that you do not mine taking apart, talvage the USb header and connect it to the hub then connect your multipmeter to it, you will see that across the extension cable, you will get an at load voltage drop to around 4.8 volts and it will pretty much stop the charge process.

I plan to eventually take apart my ebay battery charger and replace the boost converter while keeping it's charging circutry in tact, so that I will have one that can do a full 2.1 amps (only issue is that they not only screw the case shut, they also glue it)


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## fatboyslimerr (Dec 28, 2012)

How do you go about shorting the data pins? Is it a simple job or quite fiddly?


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## Razor512 (Aug 22, 2011)

For my setup, I did it in an extremely simplified manner (I used a tiny screw )










I will later on build a simplified DC to DC converter that can use smaller more efficient components that can be installed on a perforated PCB and just have a simplified design of 1 power inputs, and 2 outputs targeted at just 5.05V (to counter the line voltage drop)

But at the moment, I am using other components designed for a wide voltage range and are not very efficient and do not use the full life of the battery due to their min voltage being too high.


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## Gradular (Feb 1, 2012)

Colchiro said:


> I have no experience with that battery, but most places online will have it for about half that price. http://www.amazon.com/gp/product/B005DTJI7Y?linkCode=xm2&tag=invihand-20


 only reason I bought it because I worked there at the time I bought it. But it does work now with the current cm10 rom.

Sent from my cm_tenderloin using RootzWiki


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## nevertells (Oct 29, 2011)

fatboyslimerr said:


> How do you go about shorting the data pins? Is it a simple job or quite fiddly?


Have a look at this: http://forums.webosnation.com/webos-accessories/314741-how-get-full-power-charge-mobile-battery-car-hp-touchpad.html

You can use your hotmail login to view the skydrive links.


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## Gradular (Feb 1, 2012)

fatboyslimerr said:


> Thanks for suggestions. Based on a number of reasons I opted for an external battery that takes x3 AA batteries.
> 
> http://www.amazon.co.uk/PortaPow-Pr...4?s=electronics&ie=UTF8&qid=1361112454&sr=1-4
> 
> ...


 It will not charge any tablet, let alone the touchpad. That charger is only made for phones. Its output is only 600mah.

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## Razor512 (Aug 22, 2011)

not sure how the PortaPow Premium compared to the chinese/ ebay versions that sell for, but the ebay ones that sell for about $1.50 to $2, can output around 800ma which can slowly charge the touchpad (but not by much since you are using AA batteries) (though I do not recommend it, I tried it a few times with my 2700mAh AA rechargables and it killed permanantly (che charger refuses to charge them) (left it connected to my tablet to test it out and the batteries were too hot to touch when I came back 10 minutes later)

if you need a charger, check out their $17 USD 12000 mah batteries, (the actual capacity is closer to about 9500mAh, but they work well (I have had mine for about 3 months now and it has been working great).


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## fatboyslimerr (Dec 28, 2012)

So the PortaPow Premium is a huge success! Not entirely sure how but using jcsullins' charge app the portapow gives 2000mA!
Actual charge rates are around 1A to 800mA and around 500-600mA with the screen on. Extremely happy with this purchase although initially I tried it using what turned out to be flat disposable batteries and it bricked my TP. Only use rechargeables that have some juice in them. I'm using 2900mAh rechargeables 
See pictures below.


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## Gradular (Feb 1, 2012)

Damn..... Well someone messed up on there describion. Did that cable come with it?

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## fatboyslimerr (Dec 28, 2012)

Gradular said:


> Damn..... Well someone messed up on there describion. Did that cable come with it?
> 
> Sent from my cm_tenderloin using RootzWiki


Yes cable came with it. Going to buy more rechargeables so my TP can be run away from the charger for weeks muahaha!


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## Mpgrimm2 (Dec 6, 2012)

fatboyslimerr said:


> For my setup, I did it in an extremely simplified manner (I used a tiny screw )
> I will later on build a simplified DC to DC converter that can use smaller more efficient components that can be installed on a perforated PCB and just have a simplified design of 1 power inputs, and 2 outputs targeted at just 5.05V (to counter the line voltage drop)
> 
> But at the moment, I am using other components designed for a wide voltage range and are not very efficient and do not use the full life of the battery due to their min voltage being too high.


Have u ha a look at www.Adafruit.com and their "Minty Boost" related items & charge controllers?

Sent from my "Up all night, sleep all day" HP CM9 Touchpad


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## fatboyslimerr (Dec 28, 2012)

Ok it turns out the fact it charges at 2A is really bad. It can only charge about 30% of the battery before the rechargeables are out of juice.
I'm assuming this is because the AA batteries are 1.2V which are then uprated to 5V at the expense of reduced capacity?

Does anyone know the exact equation? No idea of the resistance of the external battery pack.

Can anyone think of a way to actually limit the charge input to 500mA as this would allow a slower but longer charge? 
Going to try with another cable. Bah!


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## Colchiro (Aug 26, 2011)

I wouldn't be surprised if it gets hot too.

First of all, your battery is recommended for phones, not tablets (which use a lot more power for that big screen).

Secondly it's intended to supplement your fully charged battery, not recharge a nearly-expired battery.

I think you're wasting your time. You need to work near a power source or rethink you choice of a tablet.


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## fatboyslimerr (Dec 28, 2012)

I love my touchpad and I actually think, with CM10, the battery life is very good.
I get about 6-7 hours of life with almost constant browsing or writing using office suite and this includes using a bluetooth keyboard.

Only problem is I have 8 hours of lectures a day..... I'd be willing to try another battery pack with a 5v 2A rating because I really need that extra bit of juice. 
I just wonder if these large external batteries would actually charge the TP at 2A or at least provide the same current as my little AA one.

Weirdly my little AA battery pack says on the back of it output is 600mA but I have seen it give 1.2A??? How bizarre?


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## Gradular (Feb 1, 2012)

Colchiro said:


> I wouldn't be surprised if it gets hot too.
> 
> First of all, your battery is recommended for phones, not tablets (which use a lot more power for that big screen).
> 
> ...


 Even though it costs morem the one I suggested charges a lil faster. At some point ill have to see how much it actually charges up the tp. It has a 2.0 output as well as a 1.2. I've charged my phone and sgt2 at the same time. Less power requirements though.

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