graycole
Posts: 1
Joined: Sat Aug 24, 2019 6:25 pm

won't connect to wifi w/ battery?

Sat Aug 24, 2019 6:31 pm

We are trying to build a raspberry pi bot using the book "building robotics with raspberry pi". We are able to connect to the raspberry pi via the wifi on an ipad, SSH to access for commands when the power is connected via micro USB. However, when we disconnect the USB and connect the power to the battery pack (6 AA through buck converter set to 5.0v), the ipad will not connect to the raspberry pi? The raspberry pi turns on with lights blinking and such, but can't make it connect?

We are new to this and not sure how to proceed? Any thoughts, tips or ideas, would be appreciated!

Thanks in advance,

e and e

wh7qq
Posts: 1328
Joined: Thu Oct 09, 2014 2:50 am

Re: won't connect to wifi w/ battery?

Sun Aug 25, 2019 1:26 am

If the RPi works with the power from an "official" power supply but not with the ~9v battery pack, it points to the the wiring to and from the buck convertor and the buck converter itself. If the converter is set to a 5V output with no load, it may not deliver that voltage level under load. Either the converter is inadequately regulated or the wire gauge to/from the converter is insufficient for the load. Wireless does impose additional current loading on the RPi power bus, possibly dropping voltage through the converter and its associated wiring. Check the delivered voltage to the RPi, in use with the wifi with a digital meter. Take care to avoid at all cost, shorting GPIO pins when checking voltage...suggest female to male dupont wires on pin 2 and to 4 or 6 to the digital meter leads. Also, are the batteries fresh...all of them? Batteries develop internal resistance as they are consumed.

klricks
Posts: 6593
Joined: Sat Jan 12, 2013 3:01 am
Location: Grants Pass, OR, USA
Contact: Website

Re: won't connect to wifi w/ battery?

Sun Aug 25, 2019 3:49 am

graycole wrote:
Sat Aug 24, 2019 6:31 pm
We are trying to build a raspberry pi bot using the book "building robotics with raspberry pi". We are able to connect to the raspberry pi via the wifi on an ipad, SSH to access for commands when the power is connected via micro USB. However, when we disconnect the USB and connect the power to the battery pack (6 AA through buck converter set to 5.0v), the ipad will not connect to the raspberry pi? The raspberry pi turns on with lights blinking and such, but can't make it connect?

We are new to this and not sure how to proceed? Any thoughts, tips or ideas, would be appreciated!

Thanks in advance,

e and e
Which lights are blinking? If the red LED is blinking that means there is insufficient voltage. I would not expect AA batteries to last more than 1 or 2 hours depending on RPi model and connected devices.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

drgeoff
Posts: 9814
Joined: Wed Jan 25, 2012 6:39 pm

Re: won't connect to wifi w/ battery?

Sun Aug 25, 2019 9:10 am

wh7qq wrote:
Sun Aug 25, 2019 1:26 am
If the RPi works with the power from an "official" power supply but not with the ~9v battery pack, it points to the the wiring to and from the buck convertor and the buck converter itself. If the converter is set to a 5V output with no load, it may not deliver that voltage level under load. Either the converter is inadequately regulated or the wire gauge to/from the converter is insufficient for the load. Wireless does impose additional current loading on the RPi power bus, possibly dropping voltage through the converter and its associated wiring. Check the delivered voltage to the RPi, in use with the wifi with a digital meter. Take care to avoid at all cost, shorting GPIO pins when checking voltage...suggest female to male dupont wires on pin 2 and to 4 or 6 to the digital meter leads. Also, are the batteries fresh...all of them? Batteries develop internal resistance as they are consumed.
All good points except that the Wi-Fi is irrelevant. The OP has not said that powering from battery is OK when not using Wi-Fi. Looks like this is a headless RPi and communication with it over Wi-Fi is the only means of ascertaining if the RPi is working.

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