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USB Battery pack for Raspberry Pi

by jmorris on Thu Jan 03, 2013 7:31 pm

Running to issues with the Raspberry Pi (Digipower) batter pack (http://www.adafruit.com/products/962). The battery just appears to shutoff after ~5 minutes for no apparent reason. Here is what I was doing.

[list=]- charged it up with a 5.2 USB power supply (http://www.adafruit.com/products/501),
- plugged the Raspberry into the "Output 1 Fast Charge port"
- the Raspberry is running headless, no keyboard or mouse, and has a USB WiFi dongle ( http://www.adafruit.com/products/814)
- Turn on the battery, Raspberry boots up, establishes WiFi connection
- I can connect remotely to the Raspberry via SSH over WiFi.
- and then after 5 minutes, the battery turns off and the Raspberry turns off with it (all LEDs go black).
- During operation, I am able to measure just over 4.8v consistently across the T1 and T2 test points on the Raspberry.
- Battery still reads 4 solid blue bars of power when I turn it back on.
[/list]

Am I doing something wrong here or is my battery pack a dud?
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Re: USB Battery pack for Raspberry Pi

by jmorris on Thu Jan 03, 2013 7:33 pm

Forgot to mention, I get the same shutdown occurence even when the WiFi dongle is not attached.
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Re: USB Battery pack for Raspberry Pi

by jmorris on Fri Jan 04, 2013 4:04 pm

Okay, I may have figured out the battery issue, but it still has me scratching my head.

On the Adafruit webpage for the battery (http://www.adafruit.com/products/962), the description clearly covers the fact that the battery has two USB ports, a 500 ma port and a 1A port. The description also clearly states that the 1A port is the one that should be used, because the the Raspberry Pi model B needs at least 700ma to run, and probably even more if you are using a WiFi stick like I am ... On the battery, the USB ports are labelled "Output 1, Fast charge" and "Output 2, Standard charge", with output 1 being the one closest to the power switch and LEDs. The label on the back also states that Output 1 is 1A and Output 2 is 500ma.

During my initial testing I was using "Output 1" (the 1A port) as suggested in the Adafruit documentation. When that consistently failed for me, I looked at the pictures provided on the product page and note that both of the pictures showing a Pi plugged into the battery, had the Pi plugged in the location of where "Output 2" (the supposedly 500ma port) is on my battery - the USB port farthest from the power switch and LEDs. When I tried booting using Output 2, the system appeared to boot fine (even with the WiFi stick in place). The system has been up and running now for over an hour without issue, whist when I was using the "Output 1" port, it failed to remain up for 5 minutes.

I was wondering if someone else with access to this battery can verify my finding. I am wondering if my battery ports are mislabeled, the documentation on the Adafruit site is wrong, or the Adafruit pictures of the battery are wrong.
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Re: USB Battery pack for Raspberry Pi

by adafruit_support_bill on Mon Jan 07, 2013 4:32 pm

Checking with the manufacturer's docs, it is designed to shut down when it "senses that the device is fully charged". I suspect that the high-current port has a higher threshold than the regular port and when the current demand of the Raspberry Pi falls below that, it is shutting down.
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Re: USB Battery pack for Raspberry Pi

by jmorris on Tue Jan 08, 2013 3:01 pm

One would have thought that a Raspberry Pi alone, given that it draws on the order of 700ma, would have been drawing more then a cell-phone battery is once it is fully charged. I tried adding an extra peripheral to the Raspberry Pi (a webcam known to work with the PI) to draw a bit more juice, but the battery port still turns off after 30 seconds.

Do you have one of these batteries handy to test out? The Adafruit documentation for the battery says that the " 1 Amp output is key for when you want to power the Pi", yet both pictures on the Adafruit site showing the PI connected to the battery show it connected to the 500 mA port ... My battery just does not want to run a PI on that 1A port and I am just trying to make sense of this disconnect between the documented functionality and reality ...
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Re: USB Battery pack for Raspberry Pi

by adafruit_support_bill on Tue Jan 08, 2013 3:04 pm

I have one charging up now to test.
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Re: USB Battery pack for Raspberry Pi

by adafruit_support_bill on Tue Jan 08, 2013 5:01 pm

I see similar behavior. Not every time, but sometimes after a few minutes on the high-current port, the pack shuts down.

I hooked the Pi up to my bench supply to see what the actual draw was. With no peripherals attached, it bounces around between 300 & 400 mA, then settles down to just over 300 mA. I suspect that the 700mA rating assumes that the Pi is driving some peripherals as well. What do you have connected to yours besides the WiFi?
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Re: USB Battery pack for Raspberry Pi

by jmorris on Tue Jan 08, 2013 9:59 pm

I've tried running the Pi by itself, with the WiFi, and with the WiFi and WebCam - in each case the power drops in the 30 to 60 seconds time frame when using the 1A port.
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