MKR1310 and Battery, doesn't Power up

Hardware MKR Family MKRWAN1310
1

If I connect just the LiPo the µC it doesn't Power Up. Only the power Led lights up slightly.

If I connect the micro usb to the board and its starts normally. Then I connect the Battery, it starts charging. Then I can unplug the usb and the Ardunio runs flawless on battery, for multiple hours.

The Battery is fully charged in this scenario. Is there a way to be able to start up the board only with the Battery?

I tested four different fully charged LiPos and three different MKR1310 Boards. All have the Same Behavior.

Cheers

2

Do you have
while (!Serial);
in your sketch ?

3

That's a good point, but in this case sadly not the issue.

But I recognized something different after uploading the Blink example and testing again. The µC actually starts Blinking the led, even though it doesn't light up the power Led.

The Power led (labled ON) only lights up if you connect the usb and strangely enough it stays on after disconnecting the powersource, thats why I thought the µC only runs when the power led is on. Such weird behaviour.

4

Does that mean it was going but you didn't know that (owing to the LED)?
For some applications an LED would be a "current-sucking deal-breaker".
I'm not a MKR maven.

5

exactly! Its especially weird that the led is light up slightly, you can only see in the dark. Which also seemed like a buggy state of the µC. And I interpreted the blinking of the the charge LED, which the mkr does on every boot if you connect a usb cable, with the startup process of the µC. Which it also doesn't do if you startup on battery.

6

Screenshot_20231231-133151-189
Screenshot_20231231-133151-1892076×1022 227 KB

When you say "power led" is that green?

And the charging led is orange?

Looking at the above, I wouldn't expect the green LED to light when running on battery power.

7

yep! To minimise confusion I made three videos, sadly youtube publishes it as short and a vertical video because of the length, sorry about that.

I would thought so, too. But it does, look for yourself.

ChargeLED: Top Left
PowerLED: Top Right
Arduino onboard LED: Bottom Right

Startup with Usb: https://youtube.com/shorts/OlLyP9QFxn0?feature=share

Startup with Battery: https://youtube.com/shorts/7DeUaRlzuYU?feature=share

undefined situation with the Power Led being lit on battery: https://youtube.com/shorts/PDri3RWD_48?feature=share

Seems like the BQ24195LRGET chip is in a state of boosting the Voltage to 5V on VBUS, also.

8

Barely lit, almost like a tiny current leaking somehow to the led.

That is odd.

I did think I noticed a change in the brightness of the green LED when you plugged/unplugged USB power. Maybe that's because the led is lit by ~3.7V without USB and 5V with USB. But why it's so much brighter than the preceding video, I have no idea.

9

Its really weird, but thanks for your input nonetheless.

The MKR 1310 seems to be really strange how it handles the Battery overall. I have three mkr boards and four Lipos to test with. Yet I did not get a grasp how to get the mkr board to charge the battery consitently. Like I connect the battery first, then the usb. Or first the usb and then the battery. Or do i have to plugin the battery a specific timing. Doing random pluggin like that, at somepoint the mkr boards starts charging (the CHG led lights up and the usb-meter (connected inbetween) measures about 1,4 W). The Lipos are at 3.1 - 4 V.

10

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