Desktop PC battery? Does such a thing exist?

[SpeedEnforcedByAircraft]

Hello fellow readers! Today I need your help on a rather ridiculous proposition in order to make something nice.
The deal is that I want to make a headless Mini ITX computer that can control our robot when wearing it like a backpack. I have a Mini ITX computer ready, and it only uses about 70w when working. How can I power this with a battery?
Here is the build on PCPartPicker:
http://pcpartpicker.com/b/sz8KHx
I noticed it has a barrel connector going to the power brick that actually provides the power. How could I replace that with a battery?
I appreciate the help! In addition, I notice that this computer has a memory and CPU leak problem, but maybe that's for a different thread.

 

[CorsairSSC]

You'll just need a ridiculously large power bank.

 

[SpeedEnforcedByAircraft]

Does such a thing exist? I need it to supply the following, the specs of the brick are in the manual: https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.antec.com/pdf/manuals/ISK110_manual_EN.pdf&ved=0ahUKEwi03ITAheDQAhVRkRQKHboRBmYQFggaMAA&usg=AFQjCNEHOg7nVvgOQBNBzRexXERX7Ud9-w&sig2=Pm5nPmIbIMPccfdy_Z6fcQ

 

[Paperdoc]

Unfortunately the manual specs do NOT include an important item. Is the power output from the "brick" into the computer AC or DC? You can only provide DC power from a battery.

Now, IF the power into the computer is DC, its rating is 19 VDC at 5 amp max. Getting a battery for 19 VDC will be tricky. But you MIGHT approximate that by using two batteries for small vehicles or boats or something. I'm thinking one "12 V" battery in series with one "6 V" battery, but they'd have to be somewhat matched for other characteristics. Maybe better, three identical "6 V" batteries in series. Now an automobile lead-acid "6v" battery actually supplies about 12.6 to 13.2 VDC under moderate load, so maybe three "6V" batteries in series can deliver about 19 V. You probably also should look for something that will not leak acid, like a sealed gel electrolyte type.

Now, next you need to consider current draw and lifetime and weight. Your batteries ought to be able to handle a 4 to 5 amp load continuously for some time without dropping their output voltage by much. Many auto batteries can do that for perhaps 12 hours, but I'm not sure about the smaller 6V ones used in smaller vehicles. Maybe look at the "deep discharge" types used for things like electric boat trolling motors. But you will find out pretty quickly that three of these with enough storage capacity for your needs will weigh a LOT - quite possibly between 10 and 25 pounds.

 

[SpeedEnforcedByAircraft]

Unfortunately the manual specs do NOT include an important item. Is the power output from the "brick" into the computer AC or DC? You can only provide DC power from a battery.

Now, IF the power into the computer is DC, its rating is 19 VDC at 5 amp max. Getting a battery for 19 VDC will be tricky. But you MIGHT approximate that by using two batteries for small vehicles or boats or something. I'm thinking one "12 V" battery in series with one "6 V" battery, but they'd have to be somewhat matched for other characteristics. Maybe better, three identical "6 V" batteries in series. Now an automobile lead-acid "6v" battery actually supplies about 12.6 to 13.2 VDC under moderate load, so maybe three "6V" batteries in series can deliver about 19 V. You probably also should look for something that will not leak acid, like a sealed gel electrolyte type.

Now, next you need to consider current draw and lifetime and weight. Your batteries ought to be able to handle a 4 to 5 amp load continuously for some time without dropping their output voltage by much. Many auto batteries can do that for perhaps 12 hours, but I'm not sure about the smaller 6V ones used in smaller vehicles. Maybe look at the "deep discharge" types used for things like electric boat trolling motors. But you will find out pretty quickly that three of these with enough storage capacity for your needs will weigh a LOT - quite possibly between 10 and 25 pounds.

I just got home so I could find the specifics. According to the adapter, it outputs 120V AC to 19V DC, at 4.74 amps. DO you think an external laptop battery would do?

 

[Paperdoc]

I don't know. The key thing to recognize is that a laptop machine is designed in part to minimize power consumption, thus allowing a smaller battery. You machine design does not have that as a major criterion. So while the battery might do the job, the length of time it will perform is in question.