MagTag - LiPo battery sizing question

Wearable electronics: boards, conductive materials, and projects from Adafruit!

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
User avatar
mad_robot
 
Posts: 1
Joined: Mon Jun 13, 2011 2:12 pm

MagTag - LiPo battery sizing question

Post by mad_robot »

I am looking to buy a MagTag. The kit has remained 'out of stock' for awhile, so I have decided to buy the individual parts.
The kit comes with 'LiPo 3.7v 420mAh' (which is also 'out of stock').
I am wondering what type of run time I might achieve with the 'LiPo 3.7v 350mAh' (which is sized ~the same).
Or, I would ask what problems might arise if I chose a larger 'LiPo' that physically has larger dimensions.
Will there be problems mounting the larger LiPo within the Acrylic/screw casing?

My goal is to use a minimal case (ie 'Acrylic hardware kit for MagTag' id: 4807) and wear the device as a badge.

User avatar
michaelmeissner
 
Posts: 1819
Joined: Wed Aug 29, 2012 12:40 am

Re: MagTag - LiPo battery sizing question

Post by michaelmeissner »

If you want to mount the battery within the case, you need a battery the same size as listed in the kit (2cm x 3cm). There isn't much additional space

However, you could use double sided tape and/or velcro and mount the battery on the back of the case. If you want to use the magnetic feet, you would want the battery to be 3cm by 5cm. If you aren't using the magnetic feet, you can use a much larger battery (5cm x 7cm). I would suggest using a flat battery rather than one of the round batteries.

If you aren't changing the display, you don't even need to power it, since it has an e-paper display. With mine, I ran a program that displayed various images from flash memory. I put the image I wanted to use in the flash memory, and when the display cycled through the image I wanted to use, I just turned off the magtag and the image is still there after a few weeks.

I think the howtos had examples where you could just have the microprocessor turn on, update the display, and turn off for a period of time to improve the battery usage.

IIRC, I think the Accelerometer used in the Magtag is impossible to get due to the ongoing chip shortages. I recall Lady Ada saying she is trying to find a substitute and redesign the PCB for the Magtag.

Locked
Please be positive and constructive with your questions and comments.

Return to “Wearables”