MKR 1000 no power at all using batteries

The project I'm working on needs to be powered solely by external power source (e.g. USB power bank and/or batteries) since it will be situated in remote areas. For this occasion, I've bought 3.7V 450mAh Li-ion battery and 3 x AAA battery holder, both with 2-pin JST connector as required by the MKR1000.

The polarity of JST connector on Li-ion battery & battery holder is correct but it doesn't make any difference. Arduino will only work on USB power and appears dead when switched to external power source.

What am I doing wrong? Nevertheless, the inside of the GND pin on the MKR1000 JST pin

seems to be a little rusted, could that be a part of the problem?

Any advice is appreciated, thanks!

If its rusted or corroded that can cause a huge problem. Make sure your connections are clean, if they are test your battery voltage with a voltmeter. If your battery is charged connect the battery to your board and try and test for voltage across where the connecter is exposed a little bit but be carful not to short your battery.

Battery voltage is ok, so is voltage from 3 x AAA holder. How exactly can I clean the corrosion without damaging the pin?

It would be hard but you could use a small piece of sandpaper. Also test for continuity to the battery.

The supported battery for your board is Li-Po single cell, 3.7V, 700mAh minimum. See "Tech Specs" at
You need to meet the 700mAh minimum current requirement.

So if board supports only Li-Po single cell battery I suppose it won't run on 3 x AAA batteries even if the connector is female 2 pin JST PHR2 Type?

@Mimseey Use what is recommended!

Hey y'all, MKR runs fine on 3xAAA batteries after cleaning the inside of JST pin with sandpaper.

I ask moderators to close this topic since it has been solved, thanks for the advice :grinning_face_with_smiling_eyes:

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