DFRobot MP2636 question / issues with Pi Zero


#1

So, as a cheap solution to battery powered pi, I recently picked up one of the DFRobot MP2636 PowerBoost & Charger modules and a 6600mAh Li-ion battery.

Struggling to find any documentation for it anywhere (i can find the datasheet for the chip, but not the board). Does a flashing “CHG” LED mean the battery is fully charged?

The other problem in having is when using it with a Pi Zero W (+ micro dot PHAT + pico hat hacker + 3 GPiO LEDs + 2 tactile switches). When I disconnect the mains power from the DFRobot board, the Pi freezes and reboots. If i do the same with a Pi 3b+, I get a warning about power fluctuations, but it keeps running. Anyone had similar, or have any idea if there’s anything I can do to keep the Pi Zero running? I need to turn off a bunch of stuff (like bluetooth and wireless) to try and conserve power, and might even try to underclock it (since it’s only being used as a simple timer for a CTF game we’re running). Any other advice / help will be gratefully received, thanks…


#2

I’d leave it charging and see if the LED stops flashing or goes out. It will take a while to charge that battery first time. I have 2 of the Adafruit 6600 MAH LIPO’s. They took a good long time to charge via my PowerBoost 1000c.
On my power banks the charge LED flashes until the battery is fully charged, then it stays a steady on.
On my Power Boost its yellow while charging then turns green when fully charged.
I don’t have an MP2636, not yet anyway. Its on my wish list though.

The Pi Zero has an issue where it will reboot if you plug something into its OTG USB port. If I have a USB hub plugged in its not an issue. I can plug devices into the hub and its fine. It only glitches when connecting directly to its USB port. I’m not sure if that related to your problem though? Maybe your battery isn’t fully charged, or not charged enough to give a full 5V?


#3

Thanks for the reply! :-)

The light was solid originally, and only started flashing after an afternoon of charging. Unfortunately, I’m colour blind, so I have real problems with red/green/yellow colour changing LEDs. I’ll get someone with better eyes to look at it and see what colour it is. I’ve got it running on a test loop on my software now, so I’m hoping it’s still going when I get out of bed in the morning. ;-)

I’ve currently got a keyboard plugged in via OTG USB, and monitor on the hdmi port, both of which won’t be needed once the software is finished (the micro dot phat / gpio switches are the only output / input that it’ll need). I’m hoping getting rid of those will help drop the power consumption a bit. I should have a USB power measuring device turning up from Amazon tomorrow, so I can do a bit more testing to see how much power the thing is actually drawing. I do wonder how much power that phat is taking (and whether I can do anything to reduce it, like dimming the leds)…

I did realise one stupid mistake I made. Last night I spent about 4 hours working on writing code on the box. I thought i had it plugged the charger in, but I realised I hadn’t, so that is probably why the battery started dropping out after a couple of hours use today. That’s irrelevant to the problem with it rebooting when I disconnect the mains power from the DFRobot board though. That seems to happen regardless of how well charged the battery is.

Whilst the MP2636 is ok, I think next time I’m going to look for something that I can more easily monitor / control from the Pi itself. It would be nice to be able to track charge and stuff in software…


#4

One thing I like about the PowerBoost is its well documented what the LEDs mean, and what the various extra contacts are for. It has a low battery contact you could use to turn your Pi off before the battery dies for example. I haven’t used it, but I know its there from reading the documentation. My only complaint would be the 1A out limit. I’ve been hoping Adafruit would do a PowerBoost 2000c or 2500c based on the chip in the MP2636.

I’ve been tempted to buy the MP2636 but have resisted. No Enable Pin is the decider for me. I use that on the PowerBoost to turn the upconverter (boost) part off when all I want to do is charge the battery. I’m also not all that impressed by the one loan mounting hole. That would be one thing I don’t want moving around in my project.


#5

I’ve just made my life considerably easier. I realised I had a 16750mAh RavPowerUSB battery pack sat in one of my drawers - so I’ve scrapped the MP2636 and 6600mAh battery, and am just going to run the larger capacity battery pack instead. It’s physically a bit bigger, but size really isn’t an issue for this project, and it’ll save me a load of time trying to optimise the power usage on the pi… #lazywin ;-)


#6

Those battery packs can be very useful. I nabbed a couple of small ones on sale the other day. 2200 MAH or so. Enough to run a Pi Zero for a long long time. One draw back to some of them is they can’t charge the battery and power the device at the same time. For mine its one or the other but not both at the same time. The up converter turns off when in charge mode. Mine are on the inexpensive side though
The powerboost on the other hand can do this though. Assuming the power supply feeding it can supply enough current to do both. ;)


#7

With a 6600mAh Li-ion battery, I was only getting 5.75 hours of life out of a Pi Zero W before the battery got to the point that it wouldn’t run the Pi any more. The little USB measuring device I got showed that it was using ~0.75A when running my software (or ~0.50A when it was idle). To be honest, I thought it would run a lot longer / use less power…


#8

According to this, https://www.raspberrypi.org/help/faqs/#topPower the Pi zero W only draws ~150ma when idle. Not sure what the Mico dot pHat draws.


#9

I’ve just set it up so I can manage it via wireless, rather than a keyboard / monitor. Killed bluetooth and disconnected hdmi and otg usb. Now, when idle, it’s sitting at ~0.13A, or about ~0.40A when running my code and the micro dot phat…


#10

0.13A IS 130ma and 0.40A is 400ma, just in case you didn’t know.


#11

Well, pedantically, it’s mA, since MA is Mega Amp - but, yeah, that’s more like the published figures… ;-)


#12

Yeah, I’m on my laptop and I keep hitting caps lock instead of shift, lol. I went back and edited it but missed some. =(

EDIT: Just went back and fixed it. ;)