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I want available backup power for my laptop (ASUS ux51vz, 19V/4.74A), I've got a pile of 10-20k mAh power banks, and I'd like a solution to marry the two somehow.

I know that I can get an external battery with a selectable DC output & appropriate power plugs (e.g. Anker Astro Pro2) for about $100, but that also only recharges from its wall plug instead of micro-usb like "regular" power banks (and so do all of its peers that I could find: poweradd, ravpower, qi-infinity, maxoak).

From a safety perspective, I suspect I'm better off getting a "laptop" power bank and using my regular power banks to charge that instead of directly charging the laptop (that way when I inevitable mess up, I only burn up a $100 battery instead of the slightly more valuable laptop).

It looks to me like one of these (DROK LTC1781 100W DC/DC Step Up Converter) will let me boost the 5V/1A or 5V/2A output of my power banks up to 19V, but is this a valid solution to the problem at all, and will it produce enough current to charge another battery? Should I connect two input batteries in series to get more current?

I would be open to commercial solutions, but it would be nice if I can do this with a minimum of new hardware.

Similar questions, all asking if a power bank can charge a laptop directly:

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    "Is there a commercial solution to this" makes it off topic here ... maybe you can rephrase it? – bummi Jan 5 '16 at 15:22
  • Possible duplicate of Need to charge my laptop from my powerback? – Canadian Luke Jan 5 '16 at 15:44
  • My question is much more specific about using 5V power banks to produce 19V for charging (and that question was closed without a useful answer <grin>) – Otto Blorstead Jan 6 '16 at 3:02
  • bummi, my concern is that I just don't know the terminology and there might be an existing solution (though I'd prefer to tinker my way to some knowledge) – Otto Blorstead Jan 6 '16 at 3:11
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The DROK LTC1781 100W DC/DC Step Up Converter would work to use your 5 volt power banks to power your laptop - you would set the input voltage to 5 volts, and output voltage to 19 volts, although it seems to me this is quite big to lug arround with you - and you still need a solution to charge your batteries as this won't do it for you.

As it can output up to 100 watts, you should be able to output the amount of power to charge the laptop battery, provided your input batteries can handle it. 100 watts is more then the 90 watts your current power bank provides.

Using this is probably also going to put a lot of stress on your batteries, so they will probably not last as long as you might hope.

The problem you will have is charging your battery back up. You would presumably need to either connect this to a wall jack or use the USB port on your laptop - which will be glacially slow. The maximum a USB port can output is 10 watts - 5 volts at 2 amps - which means you are going to be looking at VERY long recharge times relative to use.

  • No lugging around - this is for backup power at home. At any given time I've got 80-100k mAh in power banks which would get me about 2 extra days of normal use, hopefully long enough to get power working again. For battery recharge, I have small 14W solar panel that does a decent job of filling 10-15k mAh in a day, so you are right that recharge is the bottleneck for long-term. – Otto Blorstead Jan 6 '16 at 3:12

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