View Full Version : External DC Voltage Range?
01-14-2009, 03:55 AM
I need to power my m1300 from an external battery to give it a longer run time - 6 hours. The standard DC input voltage from the power supply is 19 volts. This isn't a very common battery voltage and I'd prefer to run it from a 14.4 volt power tool battery, for example.
DC to DC voltage converters, like the auto 12 volt power supply, aren't efficient and not recommended when on a limited power budget.
Has anyone run their tablet from a lower DC input voltage?
01-14-2009, 01:17 PM
Voltage input can have profound affect on laptop performance/reliability and tablet PC's are particularly sensitive to voltage variances affecting digitizer function.
External power supplies with 19v output are very expensive. Cheapest alternative is to use 12v AC converter and plug AC power brick into that. There are automotive-based 12v to AC self-contained battery units worth checking out.
01-14-2009, 01:39 PM
thanks for the reply. I've read about someone using an auto based unit to power a camera but they found that it didn't last long because of the in-built inefficiencies of the inverter. Also, lead acid batteries have a lower power density than those of laptop or camera batteries.
The performance/reliability issues you mention sound a bit worrying...
01-14-2009, 10:37 PM
I would do what I do, buy a bunch of 1300 batteries on eBay and Motion dual charger (found mine for $10 on eBay) and carry 4 extra batteries in pouch case, far lighter and smaller than any external source and just hot-swap out as needed. Even at 2 hours per battery, 4 would exceed 6-8 hours running time.
01-15-2009, 06:58 AM
sadly, here on treasure island (UK), ebay batteries are $50 and ship from Hong Kong. I've always been wary of such batteries in case they are either fakes or worn out used ones.
It's an interesting point, though. I'll be using the tablet to record HD video coming in on the firewire port and won't have time to check if the battery needs changing, I just want it to keep going. That said, I would be able to check it every 2 hours or so but, with the tablet also powering a portable usb drive, a battery might expire before I get an opportunity to change it.
02-07-2009, 07:48 AM
Here's the answer, sort of. I used the supplied car adapter power supply and measured the current of my Motion 1300.
Motion idle: 1.3 Amps
Motion idle, powering an attached USB drive, both drives idle: 1.5 Amps
Motion with active internal disk: 1.9 Amps
Motion with external drive active: 1.9 Amps
Motion with both internal and external drives active: 2.1 Amps
Of course, the car adapter is consuming power too as it converts the 12 volts to 19 volts.
To get a guaranteed run time of 6 hours, I'll need a battery with 13 AmpHours capacity. I'll actually get away with a little less, as the internal battery will keep it going for a while, when the external battery has dies.
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02-13-2009, 09:22 AM
Ian: Is there some specific reason why you're wedded to the idea of an automotive or tool battery? External batteries made specifically to power electronics aren't numerous, but there is a reasonable selection out there... Eletrovaya (PowerPad 95 & 130), BatteryGeek (Power Station) and Tekkeon (my PowerALL) all offer new product with outputs compatible to your Motion. APC just left the market, but there are still new APC batteries (UPB70 and 90) available.
Have you considered these alternatives...?
02-16-2009, 11:25 PM
I'm seeing quite a number of 19VDC power adapters on eBay right now.
06-09-2009, 01:51 PM
can anyone suggest a good brand/external battery to get?
i have a few devices now, and would like to get one..($100-$300)..
also, how do they work? do you suggest getting one that plugs
in directly to the ac adapter slot?
or are there ones that can supply power through USB..
i've done some research, but am not sure which type to get,
or try out..
something that gives 4 hours-8 hours is the range i'm looking
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