Favorite way to power Moteinos?

SoLongSidekick · December 16, 2013, 12:13:47 PM

Hey all,

Obviously there are a ton of different options available for powering these bad boys, and I started to realize that there is for sure some really clever ideas out there. So what is your favorite way to power these guys?

Through my research (none applied at the moment) it seems these SparkFun Poly Li-ons would be perfect: https://www.sparkfun.com/products/339. They also have a smaller 400 mAh version.

Felix · December 16, 2013, 12:28:21 PM

Any 3.7-4.2 lipo will work. I have a bunch of those 400mAh from Sparkfun, they are about the size of a Moteino. Once I have the PowerShield ready, it should make for a very compact lipo battery powered Moteino solution, while also allowing for other power options like running from a single AA/AAA cell. Otherwise Straight powering Moteinos works from anything above 3.3V, I particularly like 9V batteries, some people don't though...

SoLongSidekick · December 16, 2013, 01:35:32 PM

Felix you are the man! Thanks!

Quick question (linked so I don't have to retype it): http://www.reddit.com/r/arduino/comments/1t0tf9/momentary_button_power_question/

jbeale · December 16, 2013, 02:17:02 PM

I've standardized on AA batteries for everything that I can, and have several 4xAA battery holders. With 4x AA Eneloop NiMH cells that gives you about 5 V at 2000 mAh. This is of course larger than a 9V battery though.

Felix · December 16, 2013, 06:57:14 PM

SoLongSidekick - In that tutorial the voltage was 5V because it was feeding from the Arduino's 5V regulated output. In the case of Moteino you'd just connect that to Moteino's "3.3" pin, which is equivalent. No level shifting needed. You're merely pulling up that input by means of the momentary button.

jbeale - 4xAA is quite a punch. Should last foreeeever - if you're sleeping them of course

hexibot43 · December 16, 2013, 11:04:41 PM

I would love to see a rechargeable battery with a solar cells shield. For now I'm sticking with 9v (size does matter). Once I get the base station and display node working on my project I'm going to give that a try. I'd really like to see a battery that lasts a good 10 years! Yeah right!

Felix · December 17, 2013, 08:45:54 AM

In all reality I think technology changes too fast for anyone to keep say a Moteino for 10 years somewhere without changing the code or wanting to make some change/upgrade that requires physical operation. That's why I never lost too much sleep over squeezing the last possible nano amp out of Moteino. Others did that and I thought it was interesting and informational but seemed a bit pointless.
If someone can't spend $2 on a battery that will last 1 year, then they are probably in the wrong field. Typically they are the people that want a discount if they buy more than 1 moteino

Now someone will find this post and slam me because the site name is LowPowerLab. I get it, but really Moteino is as low power as you can get without sweating too much, and I'd rather get more things done than spend 6 more months figuring out how to save a few extra nano amps. Besides there are so many cheap power options out there now...

hexibot43 · December 17, 2013, 11:19:47 AM

Felix,
I'm glad you posted your comment on this subject. I've decided you are right. A good year out of a battery should be good enough. I will listen to what you've said and not waste anymore time on battery life. I would just really like to do away with the battery all together. Or just not have to think about it.

Felix · December 17, 2013, 12:35:52 PM

It's a trade off. I think battery life critical projects are outliers that are far less common than other things. I can think of one that I'd like to promote though - the MotionMote. On that one you could use as much battery life as you can get. Even so we're limited by the amount of current drawn by the sensor itself which has to always be ON. In which case a lipo could be used, a more expensive solution, but cheaper in the long term. So yeah ... there's always some kind of quick and cheap solution. You can spend years, and do 100 x PhD theses on saving battery life and coming up with smarter silicon that's more power efficient. I would personally like to rather spend that time building more things...

sketchy · December 17, 2013, 01:08:14 PM

I thought this post on battery power http://jeelabs.org/2010/12/03/what-is-%E2%80%9Cpower%E2%80%9D/

was clear and insightful. I assume a product offering from lowpowerlab.com will be a battery (+ however you need to attach to moteino + arduino library (as needed)).

How would this product offering compare/contrast/be an example of the (cool info for electronic n00bs like myself) pointed out in the above post?

Felix · December 17, 2013, 01:59:17 PM

Umm .. you're probably asking about something that is either being worked on (mentioned here and on the blog as "PowerShield") or does not exist yet

Stay tuned for updates, whenever they become available.

KanyonKris · December 17, 2013, 06:08:35 PM

I was going to use a 9 volt battery, like Felix used for the Mailbox Notifier since I'm building something very similar. But I would like it to be more compact so I'm going to use two CR2032 Lithium (not rechargeable) button cells, 20mm diameter. Each CR2032 is 250mAh @ 3V so I'll have 500mAh at 6V. Since a 9 V battery is also around 500mAh I should get 9+ months out of two small batteries.

I'm tempted to budget more space for batteries and go with 3 AAA Eneloops. 3 X 750mAh each = 2250mAh which is a huge amount of power for a Moteino. And with the insignificant self-discharge rate of <10% per year, I should get 2+ years on one charge.

Rechargeable Lithium Ion batteries also pack a lot of charge in a small package, but watch out for self discharge. I've seen numbers of 2-8% per month. Sparkfun just says <8%. If it's 8% then 80% of the charge is gone in 10 months which is OK but not awesome. If it's 5% then only half the charge is lost. Will the Sparkfun 400mAh Lithium Ion battery last as long as a 9V battery? Maybe.

Lots of good choices for battery power these days.

SoLongSidekick · December 17, 2013, 06:57:37 PM

I've got one more question. I just picked up a few of the SF LiPoly batteries and am wondering how I would power a Moteino and a 5v device at the same time. Help a noob out haha.

Felix · December 17, 2013, 07:22:52 PM

You would need some kind of boost regulator to get that 3.7V up to 5V. PowerShield will do just that.

SoLongSidekick · December 18, 2013, 01:19:26 AM

Ah ok, I placed this on my order (https://www.sparkfun.com/products/12009). Will that work?

Also, do I need to cut the 3v logic level jumper on my FTDI Adapter and solder the 5v one to get it to work with an Arduino Pro Mini 5v (https://www.sparkfun.com/products/11113)?

Thanks for all the help bud.