External Battery Pack for the Gateway


#1

Hi All,

I’m working on a project that uses the Gateway primarily and need it to be portable as it needs to work anywhere.

At the moment it is powered via USB + plugged into my PC.

Could I use something like this to power it?
http://www.harveynorman.com.au/verbatim-aa-power-pack.html

Or will I have issues with power supply / flow / voltage regulation etc?

Do you guys have any other recommendation? I want to fit it into a small enclosure so the smaller the better.

Thanks very much,
Mark


#2

The biggest power draw on the gateway is the P1 module, which is basically a Photon. There are numerous articles on the Particle forums about powering the gateway shield with AA batteries: https://community.particle.io/search?q=Photon%20AA%20battery

It is certainly all possible. The regulator in the gateway is a bit different than the one on a Photon: https://github.com/bluzDK/gateway-shield/blob/master/v1/Datasheets/22056b.pdf

We didn’t really design the gateway with that purpose in mind as we always expected it to be plugged in to the wall. Chances are your battery life won’t be so great and you will go through a lot of batteries.

LiPo batteries may be a better solution, they are rechargeable and higher capacity. Many solutions exist for portable phone chargers that will output a regulated 5V, like this one: https://www.amazon.com/Portable-RAVPower-22000mAh-High-density-Li-polymer/dp/B01G1XH46M/ref=sr_1_18?ie=UTF8&qid=1475081802&sr=8-18-spons

May be more expensive, but my guess is you would burn through AA batteries so fast that this will be cheaper in the long run.


#3

Is it possible to use a 3.7V LiPo instead of a 5V one?


#4

Sure. I would recommend a shield that has a fuel gauge such as this one: https://www.sparkfun.com/products/13626

That will work great, the only downside is that you can’t charge the LiPo since it utilizes the USB connected on the Photon, and bluz doesn’t have one. SO you would need to rig up a different way to charge it, but it is certainly possible (and hopefully not required often as long battery life is the point of bluz!).


#5

Unfortunately I need this to be the smaller possible. Can’t I directly connect the battery to the board? (I’ve never used that, so I have no idea)

EDIT: I’ve just realized this post refers to the gateway and not to the Bluz DK, I feel so stupid.


#6

No worries, I didn’t even notice that either!

You theoretically can hook the battery direct, but there is no connector for it on bluz. There is also no way to recharge it, so you would have to connect the battery somehow where you could easily disconnect it and charge it when you need to.

If you wanted to go this approach, make sure you use the VIN pin and not the 3V3 pin.


#7

can’t I charge it while it is still connected to bluz?


#8

You could, but then you would somehow have to build in the charging circuit around bluz. It would basically be replicating what is already in the SparkFun battery shield.

That is certainly a route if you are trying to miniaturize, but it would require some customization and extra work.


#9

Can’t I use this https://www.adafruit.com/products/1904? I would do something like


(using a Bluz instead of the Photon, I did’t find the Bluz file for Fritzing)


#10

You certainly can do that, but there is a risk of damaging the LiPo. If the voltage drops too low, they can get damaged and won’t work as well. The further the drop, the more damage can be caused.

Generally, people use a fuel gauge to judge how much battery is left and then will cut-off the battery when the voltage drops too low to prevent damage. That doesn’t exist here, so it could cause issues. You can potentially mitigate some risk by measuring the voltage through the ADC on-board bluz, but that would come after the regulator so it wouldn’t give you an accurate reading of the battery itself.


#11

What type of damage are we talking about? I’d like the battery not to explode while I’m wearing it. However, what’s the smallest solution you can suggest me?


#12

I don’t know of something small off the top of my head. You may want to start with the SparkFun battery shield I sent earlier, look at the components they use and then search around for a smaller breakout board that uses the same things.


#13

And what are the risks if the voltage drops too low?


#14

I’m not an expert on LiPo batteries, but it would be more about the battery not being able to take a charge again. I don’t think there is a risk of fire/explosion in those case, that seems to be more likely from bad charging/overloading.


#15

I’ve found out that Particle sells a Power Shield that is perfect. Is it compatible?


#16

I haven’t specifically tried this shield, but yes, it should be. Power requirements from bluz to a Photon are the same and the only pin conflicts we do have should not change anything with respect to the power shield.

Does anyone out there with bluz have this shield or have tried to two together?


#17

I’ll give that a try this week. I know it uses I2C to read the voltage (should you choose to do so programmatically) on D0 and D1


#18

Oh… what if I’m already using D0 and D1?

It’s not really a big problem, I use them for a not necessary feature, so I can remove it without problems but I’d like to have it


#19

All depends if you want to gauge the battery or not. For my project, I had plenty of open pins so I moved what I planned D0 and D1 to be so I could read the battery state. I assume if you don’t use the gauge, whatever I2C chip that’s on there will interpret whatever you’re doing on D0 D1 as nonsense and ignore it.


#20

Great news! You can absolutely use Particle’s battery shield.
I didn’t test any further than watching it boot up and connect to the cloud, but I assume that’s enough to prove it works