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-   -   How to power Mini-PC on robot? (http://www.chiefdelphi.com/forums/showthread.php?t=154152)

rich2202 24-01-2017 12:56

Re: How to power Mini-PC on robot?
 
I initially saw the rule (COTS device with Battery) as a power limiting concession, but can also appreciate how it is a safety issue (did the team design the power circuit correctly).

A COTS device that includes a battery is an easy bright line to enforce. If you allow teams to install any battery, then what are the rules on what can get a battery? If a fire starts because a custom battery circuit shorted out, how do you turn it off?

I'm surprised that Samsung 7's weren't banned.

marshall 24-01-2017 12:58

Re: How to power Mini-PC on robot?
 
Quote:

Originally Posted by rich2202 (Post 1635630)
I'm surprised that Samsung 7's weren't banned.

Shh! Don't ruin it for us.

Chris is me 24-01-2017 13:03

Re: How to power Mini-PC on robot?
 
Quote:

Originally Posted by rich2202 (Post 1635630)
A COTS device that includes a battery is an easy bright line to enforce. If you allow teams to install any battery, then what are the rules on what can get a battery? If a fire starts because a custom battery circuit shorted out, how do you turn it off?

How do you turn off a laptop battery that's shorted out and started a fire? It's certainly happened before.

People aren't asking for "any battery" to be legal, just USB batteries of some shape or form. These are common devices, with a known output plug, voltage, and current. A restriction saying "COTS batteries that output 5V power over USB at 2 amps or less and 10,000mAh or less" for example would be reasonably narrow, wouldn't result in these strange nightmare slippery-slope kids-wired-a-battery-at-home-using-bare-copper scenarios people keep jumping to, and would fix this and many other problems.

Jon Stratis 24-01-2017 13:13

Re: How to power Mini-PC on robot?
 
Quote:

Originally Posted by Chris is me (Post 1635636)
How do you turn off a laptop battery that's shorted out and started a fire? It's certainly happened before.

People aren't asking for "any battery" to be legal, just USB batteries of some shape or form. These are common devices, with a known output plug, voltage, and current. A restriction saying "COTS batteries that output 5V power over USB at 2 amps or less and 10,000mAh or less" for example would be reasonably narrow, wouldn't result in these strange nightmare slippery-slope kids-wired-a-battery-at-home-using-bare-copper scenarios people keep jumping to, and would fix this and many other problems.

Chris, your interpretation of what's been posted here is very different from mine.

Quote:

Originally Posted by marshall (Post 1635594)
I'd like to see one of two things:
A) Say that teams can use batteries for computing devices provided it is done safely and doesn't interface with the control or motors for the robot. This can be demonstrated by having the team turn off the robot and see what is still running.

or

B) Make the only legal source of power on the robot to be the ROBOT battery.

There certainly is room for the rule to be expanded by the GDC without getting too crazy (such as allowing USB battery packs design to work with an arduino), but that's not what people have been pushing for in this thread.

marshall 24-01-2017 13:17

Re: How to power Mini-PC on robot?
 
Quote:

Originally Posted by Jon Stratis (Post 1635640)
There certainly is room for the rule to be expanded by the GDC without getting too crazy (such as allowing USB battery packs design to work with an arduino), but that's not what people have been pushing for in this thread.

https://www.cnet.com/how-to/three-th...ut-usb-type-c/

Quote:

USB 3.1 Type-C cables offer a transfer rate of 10Gbps, which is double the transfer speed of USB 3.0 (5 Gbps). Additionally, these cables will offer 20 volts and 5 amps of power, compared with the 5 volts and 1.8 amps of its predecessor. This means less waiting around for devices to transfer data or for their batteries to charge.
WOPR wins again... darn it!

Kevin Sevcik 24-01-2017 17:35

Re: How to power Mini-PC on robot?
 
Wow, 3 pages of replies to the poor guy that needed to source a weird power supply for his mini PC. He must be getting lots of help, I probably don't even need to... Oh.

So team-4480, have you gotten any more info on the stock power supply? I'd love to help you figure out an off the shelf solution for powering that.

team-4480 24-01-2017 19:55

Re: How to power Mini-PC on robot?
 
Quote:

Originally Posted by Kevin Sevcik (Post 1635803)
Wow, 3 pages of replies to the poor guy that needed to source a weird power supply for his mini PC. He must be getting lots of help, I probably don't even need to... Oh.

So team-4480, have you gotten any more info on the stock power supply? I'd love to help you figure out an off the shelf solution for powering that.

So here is the picture of the back of the power brick.

I did some searching on bypassing the "smart power plug" and there are some people suggesting that it has been done just to wire in a 2K resistor to the positive side and a capacitor to the negative and feed that into the white wire. Apparently, that white wire wants something like 12-13V.

Kevin Sevcik 24-01-2017 20:17

Re: How to power Mini-PC on robot?
 
Quote:

Originally Posted by team-4480 (Post 1635861)
So here is the picture of the back of the power brick.

I do some searching on bypassing the "smart power plug" and there are some people suggesting that it has been done just to wire in a 2K resistor to the positive side and a capacitor to the negative and feed that into the white wire. Apparently, that white wire wants something like 12-13V.

This is not always the case. Some of those smart power supplies have a one wire communication chip that sends an actual digital code the laptop/PC is looking for.

At any rate, this car charger will probably work. It's listed as compatible with the same laptops that your stock charger is compatible with.

It has to be a boost charger of some sort, though there isn't a guarantee of how low an input voltage it'll work with. Still $20 for a potential off the shelf solution seems reasonable to me.

team-4480 27-01-2017 21:38

Re: How to power Mini-PC on robot?
 
Quote:

Originally Posted by Kevin Sevcik (Post 1635875)
This is not always the case. Some of those smart power supplies have a one wire communication chip that sends an actual digital code the laptop/PC is looking for.

At any rate, this car charger will probably work. It's listed as compatible with the same laptops that your stock charger is compatible with.

It has to be a boost charger of some sort, though there isn't a guarantee of how low an input voltage it'll work with. Still $20 for a potential off the shelf solution seems reasonable to me.

We bought the charger and.....it worked! Thanks for the help! I don't know how long it would've took me before I realized there was a smart pin.

Also, the charger states it can go from 11.5V to 15V so it should work no problem as long as we have a full battery. Or maybe it may be worth to get booster to 14V just to be sure....we will see after actually testing it on the robot. Thanks!

Kevin Sevcik 27-01-2017 22:54

Re: How to power Mini-PC on robot?
 
Quote:

Originally Posted by team-4480 (Post 1637301)
We bought the charger and.....it worked! Thanks for the help! I don't know how long it would've took me before I realized there was a smart pin.

Also, the charger states it can go from 11.5V to 15V so it should work no problem as long as we have a full battery. Or maybe it may be worth to get booster to 14V just to be sure....we will see after actually testing it on the robot. Thanks!

11.5V? Eeeehhh.... You're going to want to test that on an actual robot. Battery voltage can dip shockingly low in a match. There's a reason the roboRIO has brownout provisions to kill speed controllers and shed load when battery voltage dips below 6.8V. This means the roboRIO will be perfectly happy with a voltage of just 7V out of the battery. Dips below 9V are pretty common towards the end of a match.

The charger might be specifying 11.5V just because that's an expected auto electrical voltage. Maybe buy one of those giant 6V lantern batteries and hook it up to that and see if it still puts out 19.5V? If not you might need a separate DC-DC that can boost 6V up to 12-14V. Which is starting to sound complicated, but I'm not the one who chose a PC that needs a smart pin power supply...


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