Detachable battery

wminarik

I've soldered the battery on using a JST-PH connecter (from SparkFun: https://www.sparkfun.com/products/9914) and some heat shrink insulation.

It adds a bit of bulk (the wires can be shorter).This makes it possible to power down MetaWear without waiting for the battery to discharge, and to monitor the current drawn.

wminarik

Here's a link to the image (the MetaWear Community site doesn't have image hosting turned on):

http://tinypic.com/r/20tpkyt/8

I apologize for the ads.

andrew

And if you're unsure about your soldering skills you can do what I've done and buy one of these JST battery connectors: http://proto-pic.co.uk/jst-right-angle-connector-through-hole-2-pin/

If you wiggle it you can just about get the pins to go through the correct holes on the MetaWear board and they seem to make good contact. Then you can solder the matching plug onto the supplied battery leads as above or buy a compatible battery ready soldered such as this one: http://www.adafruit.com/products/1317

Seems to work well - it's been going for three days now:

Andrew

Laura

This looks really amazing, nice hack guys!

sublime9co

I was thinking of using this breakout w/switch but I'm not sure which ones to solder to the Metawear board. I have the extra jst-ph connector for the battery end just don't understand why there are two grounds and what the SW means next to the +. It would make it perfect because I can charge the battery fine but also be able to switch Metawear off whenever I want.  Any advice?  

https://www.adafruit.com/product/1863

Laura

Looks like there are two grounds:

There's two ground pins, one 'switched' power pin, and one pin that is always on.

You can connect the ground of the MetaWear to the switched ground of the jst-ph connector.

sublime9co

so the positive of MetaWear to the + on the breakout and the ground on MetaWear to the SW on the breakout board?  skip the ground off and ground on all together? Am I understanding that right? Thanks for all your support!

wminarik

@sublime9co: As I read the product description, I'd suggest a different wiring:

The two ground connections (pins) are connected and hence are interchangeable. Either one could be attached to the Vgnd (pin #3) of the Metawear. The (+) connection on the breakout is not switched; if you connect that to the Metawear Vbat (pin #2), it would be the same as soldering in a standard JST-PH connector. If you connect (SW) of the breakout to the MetaWear Vbat (pin #2), it will work as you intend with a functional battery switch.

You'll still have to solder wires to bridge the connections; I've not found an elegant way to connect the 2mm pin spacing of the JST-PH directly to the 0.05" (50 mil, 1.27mm) pin spacing of the MetaWear. The AdaFruit breakout has a 0.100" (100 mil, 2.54mm) pin spacing.

*The AdaFruit breakout is useful: it allows two separate connections to the same battery: one always on (using one Gnd and the (+) pin) and one switched.

sublime9co

I think I understand what you're saying. I'm new to electronics so I'm definitely just trying to get it to have an off an on switch. Am I understanding it correctly that the MetaWear board itself doesn't have it's own switch to turn off and on?  So because I already soldered the battery directly to the board as indicated in the getting started guide, I was going to just cut the wires, solder a male jst-ph connector onto the battery and then solder the red pin2 to SW and black pin3 to one of the grounds.  Or would it be better to carefully try to desolder the wires from the board instead and start from scratch? Now that I think about it if just the positive wire was still connected wouldn't that cause issues? 

sublime9co

sorry I just remembered the advice when hooking up the battery in the first place to start with the ground wire so I would assume I should cut the positive wire first and ground second then hook them up to the breakout board.

JpEncausse

Would be great to have this on default board !