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Topic: MKR NB 1500 not charging (Read 299 times) previous topic - next topic


I am having problems with the charger on the MKR NB 1500.

When powered ON with battery and then connect usb power to the unit it goes to 100mA current limit.

When I can press and hold RESET for 1 second and release, it goes to full 350mA charging and current limit goes to normal.

Way is that?


Hi Kimlorentz,

Please look at my post here.

Scenario 1 seems pretty similar as the beaviour you have.

So far I didn't get any real explanation, except maybe this one as a result of observations.

PMIC (charging chip) is configured by the bootloader before running your sketch.

So, in theory, it is done ones, and whatever you do after shouldn't influence PMIC config.

However, I have noticed that anything blocking, like the begin function, has an influence, somehow...

I have sorted this issue out by having non-blocking code wherever I can, and I didn't see this issue anymore.

Not sure how the complete charging mechanism works, and if there is maybe in-memory code which continues to deal with that while your sketch is running (pure speculation).


I tryed using a blink without delay code and nothing else.
Still the input current goes to 100mA limit. Only goes to normal if I press reset again.

Are in contact with support but no solution.

DO you have a code I can test?


Hi Kimlorentz,

I wanted to come back with some code, but realized between yesterday and today that charging is still behaving erratically...

I did run my MKRNB on a full 2400mAh LiPo until it drains to check how much time it can sustain.

I did reach this state, so I plugged a 2A charger on the USB port, but charging LED didn't light on. However the board was connecting to my MQTT broker.
I was monitoring the battery voltage I was noticing a small increase in voltage, so it was charging in a way, probably thr 100mA you mention.

I unplugged the power source, and charging LED did light up for some seconds (?!?!?).

I then plugged it again, nothing changed, then pressed the reset and charging LED went on...

No way to understand on my side exactly what is going on here...

On my end, it seems that charging current is quite high (don't have proper tools to measure), PMIC is getting pretty warm to the touch and LiPo is full very rapidely, much less than the time it take for the MKRGSM to charge the same LiPo, which doesn't get warm to the touch...

Next step for me is to order a SWD programmer, upload the original bootloader, and eventually modify it to suite my needs.



I got an official answer from Arduino support that the problem we are encountering is a known issue.
They are working on it and will keep me posted.
I asked if the issue is SW or HW related, but they seem to be quite on the subject.
I'll post on here once I have news.




Aug 13, 2019, 10:02 am Last Edit: Aug 13, 2019, 10:03 am by sfletc
Just bought 2 of these and have the same problem; they'll neither charge the battery for more than a few minutes, and won't run off a charged battery.  Finding lots of problems with stability when running on USB too, so making a lot of use of watchdog, which is annoying.  Both are exactly the same, so suspect there's some intrinsic issues that really shouldn't have been missed prior to launch.



Well, I have three of these boards, on the first one the SAMD lost communication with the ublox, so it became unusable. However I'm not experiencing such similar bad behavior on the charging aspect. It is working as expected.

Second board I got I noticed this charging issue. I made a lot of noise and sent a third one which also suffurs from this problem.

As I said they informed this is a know issue, but they didn't say yet if this is a software or hardware problem. I tried flashing different bootloaders through the SWD pad at the bottom, but that didn't change anything.

In any case, I will post on there as soon as I get some info from them.




have you got some information in the past months?

Btw, i was reading this post and looked into the datasheet of the BQ24195L from TI.


The 100 mA limit could come from the input detection, at page 17.
Maybe this helps a little bit.

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