Battery Power Module (with charging circuit) for Gadgeteer

I had this module in my mind for a while now.
Unless it is one of the new 48 modules that Gus mentioned recently I really would like to make that module. Anybody interested to team up on this one? I am pretty good with Eagle now. Having somebody with experience in charging/balancing circuits would help a lot. I think we can do it in a couple of days.

Edit: Wiki page for deliverables

The list is has over 50 modules now! And this one is on the list but if the community/you can help then why not :slight_smile:

Just to clarify. It is on the list, but hasn’t been designed yet, correct?

Yes on the priority list but this is one of the complex modules so it is on the drawing board. There are may variables that play here. Start thinking about it and you will see what I mean.

Keep in mind the battery chemicals and international laws about these chemicals :slight_smile:

Looks like we already have very valuable information on the forum (thanks to Errol and the rest of community)

I am going to do a research on the mentioned ICs.

@ Architect,

I am willing to help ya with the electronics end.

@ jdal Awesome!

I guess the first step would be to answer some questions:

  1. Type of the battery we would like to use (lipo/lion,one cell or multiple cells)?
  2. What is the minimum capacity that would give a good run for main board,display and few more modules?
  3. Output voltage
  4. Anything else?

We can keep it as open conversation here on this thread,so anybody else can jump in.

I prefer the 18650 style batteries with built in protection circuit over the flat Li-Po style.
if you got the Christmas gift, they are the same style batteries that are in there.

If not, they look like this.
I just bought 4 5300mah 18650 from ebay. all 4 for $16.00

You can also get a holder for them which can be mounted to the board.
Single cell:
Dual Cell

What main board are you referring to ?

that’s a good question, I guess it would depend on if its going to be a general purpose or product specific.

Charge input, DC barrel jack or mini usb or both.

@ Architect - I’m down for writing a driver and would certainly like to follow along as you build the circuit.

Check out the circuit SF has on their LiPower shield [url][/url] .

I’m particularly interested in having ‘fuel gauge’ properties available on the driver that let you know what’s left. Maybe even a 3 color LED that indicates good, needs charge, or nothin’ left.

A solar friendly version of this would be sweet, as well, similar to what Adafruit sells.

[quote]I’m particularly interested in having ‘fuel gauge’ properties available on the driver that let you know what’s left. Maybe even a 3 color LED that indicates good, needs charge, or nothin’ left.

Would you want a 3 color led, or an I2c or SPI fuel gauge so you code can know the exact voltage of the batteries.

P.S. that link is bad

@ jdal - by fuel gauge do you mean some sort of button activated 7 segment display? All I’m really gunning for is having the voltage available in software. Anything else is in the bling category (nice to have, but lets keep the cost down).

@ jdal Remove dot at the end.

Depending on the socket we want to use we will have extra pins that we can use to “report” status of the battery or any other statistics and events back to the module driver

A Gadgeteer compatible main board with not many out there right now so Spider/Hydra for sure.

Can we also do 2 pin JST? Or maybe add pads for all three (and include parts) and let the end user solder on whichever they like.

@ ransomhall

We can make it anyway we want. Keep them coming.

@ ransomhall

No, there are quite a few Charger IC’s out there that also have an I2C bus on them so you can read the voltage of the cells, charge current, drain current and few other odds and ends.
The power board would have a type “I” connector to support the I2C, so in your software you can read the battery information. Some IC’s have an IRQ line that you can set via software to trigger when the battery gets to a certain point.

Sure, nothing is etched in stone. The only reason i lean towards the 18650’s is that the protection is built into the battery, so there is never a worry about the customer draining the battery to low.
But you can use whatever you like.

Good idea… I had one build for a previous design where I used an EMX board. As battery charger I used i used the microchip MCP73831 and as buck-boost converter Texas Instrument TPS63001 for 3.3 Volt and TPS63002 for 5 volt. What I had in mind for a new design and might also be interested for a universal board are the following options.

  • an option to switch the power down by the micro-controller.
  • a possibility to power up the device with a tactile switch.
  • possibility to measure the voltage level of the battery, so that almost out of power can be detected by the micro controller.

I have created a Wiki page where we can put our files and use it as a main document for the modules.

I have also put the link in the first post on this thread.

This discussion thread can spread multiple pages and it would be hard to find key points during the discussion. We can update Wiki page for easier reference.

how about this idea…
why not make it expandable… meaning that one can add as many batteries to it as they want…

using external magnets that would stick each extra battery at end, or on Top, or on the side or at the bottom of the module…

where each one would have it’s own electronics to charge it, in a way one would only worry about what each battery requires for charging instead of trying to balance the whole system, where the end result would give you the total amount of amps available from all batteries stuck to each other,.

Similar to B-Square design… in terms to magnets usages.

that would make a sweet product for sure…

in the end if i want to power a Spider board and few LED’s i would require one battery, now i need to add a display i would add two or three batteries to the system and so on.


Interesting idea. Keep them coming.

Added the MAX8934 Dual input Charger IC to the wiki. This is what i used in my design.

The circuit i have designed is as follows, but i never made it or tested it yet.
(not saying, it has to be this, just adding to the pot)