Testing the battery board

There is a bootstrapping problem with the gas gauge.  There are a few ways around it, but the easiest is to manually turn on the charger, which will bring the gas gauge out of reset.  Run:

ch> chg 1000 12600 3000

Then give it a second or two, and turn the charger off:

ch> chg -

You should see life when you run "stats".

Once you get it running, you'll need to program the gas gauge with charge voltage and settings for a three-cell battery.  The numbers are still a bit off, and it abuses the battery a bit, so be warned the battery will degrade quicker than normal.  It's a thing we're still working on, and part of why the laptop version is coming out later.  Anyway, program the capacity and the cell count:

ch> gg capacity 3 3000
ch> gg cells 3

The code will eventually flip the charger on momentarily when it boots, in order to kick the gas gauge into action.  But that'll come after we completely, 100% refactor the code.  We've got a branch going where we're moving to ChibiOS 3.0.

Oh, fun side fact: We have Senoko driving WS2812s.

It didn't work, I think that for some reason the charger isn't turning on...

Which firmware do I have to use? I used your repository in https://github.com/xobs/senoko-chibios the code is from 5 months ago. The commands "capacity" and "cells" for the gg are not implemented in the code I have, instead there is a command "setup" that sets-up both things.

Anyway I think that the firmware is not the problem, I suppose that when I run "chg 1000 12600 3000", the charger should turn on and I should get 12.6V in the "BAT_PROTECTED" trace, is that right? well... that's not happening

If that's the case, I have to check for a problem in the charger circuit, maybe it's the U200 itself or any of the circuitry around it... I have checked the U200 several times and I don't have short circuits, but it could be any other thing.

I have to say that I ordered the wrong shunt resistors, so instead of 4 terminal resistors I have normal 1206 resistors of the same value and tolerance... that may cause a reading on the current a bit off, but it shouldn't prevent it to work...

Edit: I made some progress!

I have been studying the schematic a bit more (I should have done that from the beginning) and I didn't understand why I didn't get any output in the +12V pins of the SATA connector, it turns out that I had a bad solder at the source of Q202 and that prevented Q205 to turn ON...

So, I'm still unable to talk to the gas gauge, but at least I have solved one problem

My main problem now is that I don't have an oscilloscope at home and probably I won't have spare time at work to use one there until September or so...

Anyway, with the multimeter I'm able to see the charger turning on during a brief period of time, then turning off. The multimeter has a max-hold feature and I was able to measure the BAT_PROTECTED voltage and it seems to work well, I tried several output voltages and it seems to reach the specified voltage and then it turns off.

These are good news, because it means that the charging IC is working, but it has a lot of protections and conditions which if they aren't meet they cause to turn itself off, so probably I will have to check for every one of them during the turn-on process

Also, today I changed the shunt resistors I had (which were the wrong type) for the correct ones, mainly to ensure the current reading is accurate enough for when I get the circuit to work, but of course, that wasn't the problem.

Finally, today I was able to run my Raspberry Pi from the senoko board with a 3S LiPo battery!! In fact, I'm writing this post from the rPi right now:

As you will see from the picture I'm getting the 5V from a linear regulator which is really a bad thing to do with such a great voltage drop. I will replace it with a switching regulator as soon as possible. In fact, I'm running the rPI from batteries because that implies "only" a 7 volt voltage drop in the regulator, but with the AC power is much worse, (12V drop) and the LM317 gets hot really fast...

Apart from powering the rPI, I also have the serial connection working, next, I will use some GPIOs to control the board as the novena does.

Wow very good work.
So I hope you're in for a assembly workshop at 31c3 as our "dark lord"

"one board to controll them all, one board to connect them,
one board to power up them all, and with novena to light them.
In the land of 31c3, where the creativity lie"

Thanks everyone!

Today I was able to change the LM317 I was using for a buck converter, I used a MC33063A. This way I can use the rPI while the charger is connected. The IC warms up a little but nothing compared with the linear regulator.

Next I would like to test some 18650 batteries I have in a 3S 2P configuration, which should give me a lot of capacity. I haven't measured the exact capacity of the cells I have but should be something between 2000 and 3000 mAh, so that would mean a battery pack of 4000 ~ 6000 mAh.

I'm trying to come up with a battery holder that fits in the novena case, but the vertical space is very limited! The cells are about 18.5mm in diameter and the holder should be 21mm or less, so not much room to put the cables below the batteries... I will have to route them on the sides.

Have you made any progress with this? I've got a bunch of 18650's I'd like to use in my Novena and it'd be great not to have to reinvent the wheel...

I made the horrible discovery this evening that 18650's are *just* too big to fit by themselves, without any battery box. My micrometer pegs them at 18.25mm diameter.

Augh! For the sake of 0.5mm, all is lost.

On further investigation, part of the problem is that the LCD bracket tends to bow out a bit in the centre, which removes a couple of mm of clearance. I'm not sure there's much I can do about that.