I just saw this while I'm looking for a battery pack.

On a german page I found this interesting:
w w w.intecro.de/XTPower-MP-16000-Powerbank-mobiler-Akku-mit-16000mAh-fuer-Laptop-Handy-iPhone-iPod-iPad-PDA-MP3-Player-mit-20-Adaptern
(can'f find an english page for this product)

Could I use this one by using an adapter?

I just got an Anker Astro3 10000mAh battery pack. I plan to use it while camping this summer, mainly to charge a phone, but occasionally to charge my tablet.
It is intended to charge 5V USB devices, and has two USB ports. It also has a 12 volt port. The adapters for the 12 volt port, of course, do not work with USB or the Transformer. So I made an adapter, and I am good to go now for charging the tablet.
The battery pack charges from a 12 volt wall charger. I have also made an adapter to charge it from the 12 volts on my motorcycle. So I will be charging it from the motorcycle during the day when riding, then using it to charge my devices in the evening at the camp. I've already tried it a couple of times, and it worked well.
I tried to charge the battery pack using a solar panel, but the solar panel was far too wimpy. It was like trying to run a house air conditioner from a penlight battery. It may make you feel good to try it, but it isn't going to do much.
So far so good. This is very close to what I need.
The issues I have had to work around are:
1) I want to also charge an in helmet bluetooth intercom from the USB port. But the charge current is so low, the battery pack auto powers off, thinking nothing is plugged in. Not a big deal because I can plug in my phone at the same time. That keeps it turned on until everything is charged, then it auto shuts down.
2) When I charge the Asus Tablet, it doesn't appear to auto shut down. Just the opposite of #1, it looks like the load stays high enough to never shut down when charging the tablet. This may not really be true, as I have only tried it a couple of times. Also, it isn't good for much more then one and a half charges of the tablet, as expected.
3) You need to figure out your own harness to get the 12 volts to the tablet.
4) No charge cable for a car. I mean this is rated for an input of like 10 to 15 volts, or some such. This thing is GREAT for charging portable devices. Charging it from a car is as simple as a cable, but there isn't one.

Over all this charger is a winner. At right around $55 US, I recommend it, if you can fabricate a plug for charging the Transformer.

Try a 12V UPS type battery along with a 2A fuse and adapters. It only costs about $20 or so. Plan on using only 50% of its capacity and recharge often to get the most life out of it.

Someone posted this product on another post
http://www.sobuying.com/products/Sol...-11200mAh.html
May suit your needs

Originally Posted by NiHaoMike

Try a 12V UPS type battery along with a 2A fuse and adapters. It only costs about $20 or so. Plan on using only 50% of its capacity and recharge often to get the most life out of it.

For me, this is actually what I use now. But it has issues.
One is simply that it is large. I carry it in the trailer that I tow behind the motorcycle, so it is OK, but a bit too large and heavy. It is a gel cell that has about a 48 WattHr capacity. LiIon has a a lot less and weight. In this case, it has about the same capacity, in a very small light weight package.
The other problem is charging the lead acid battery is an issue. I need to carry a AC charger and find AC when camping. I put a diode/resistor combo in the trailer and tapped off of the taillights. but by the time the weak motorcycle voltage gets to the taillights, add in the diode and other losses, and I'm lucky to see 13 volts at the battery. Not enough to charge it very well. The LiIon pack I use has the supply built in to charge properly from +12.
So I've tossed the lead brick battery (literally) and upgraded to a portable LiIon pack. So far so good.

This is what I use "Portable 12V DC USB 5V Rechargeable Lithium Li-ion Battery Pack for CCTV Camera" search on ebay, you can get one up to 13AH

I got a 3.8AH version for $16 , Dimension: 9.2cm X 6.0cm X 3.0cm
Outout rated 5V (5.8AH) and 12.8V (3.8AH)

small modification because the charger is NON-US wall plug, I just pull the plug pin out and add in a regular power cord cut off from an old appliance


Keep the USB plug for 5V use, cut the 12V DC cable and connect it to a female USB cable (pin 1 and pin 4) , then you can plug in the Asus usb/charge cable directly and charge or power the Asus


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