Battery peeling hot

[polarbee]

I know it's standard for the Minty Boost to get hot, but I wasn't sure if it should be getting so hot it caused the batteries to peel. I checked the unit out of the tin while charging and the batteries barely got warm while the chip got very hot. This was my first soldering attempt so I'm wondering if perhaps some cold solder joints could test fine on the multimeter but cause this overheating issue?

Editing to clarify: the peeling happened while everything was closed up in the tin and charging my Android phone. The batteries were 2 brand new AA Duracell Ultrapower.

[adafruit_support_bill]

The batteries do get warm in normal operation. Especially when charging a modern smart-phone. But I have never heard of them peeling. Can you post a photo of the peeling batteries?

Is the phone charging OK? If you post photos of the front & back of the MintyBoost board we'll take a look for any assembly problems.

[polarbee]

Here's a link to the gallery since I couldn't get the image insert to work and must flee work:
https://www.dropbox.com/sh/37j2xjkpthlafyj/407pvhY2bR

[adafruit_support_bill]

The assembly looks pretty good. There are a couple of joints with a little too much solder (see here for why this can be a problem sometimes).

But those batteries look seriously overheated. Do all the tests pass and does the phone charge?

[polarbee]

When I tested with the multimeter during assembly, all voltages were spot on and the phone appears to charge at its typical rate.

[adafruit_support_bill]

all voltages were spot on and the phone appears to charge at its typical rate

So there is probably nothing wrong with your assembly.

Was the MintyBoost tin out in the open while charging, or sitting in a backpack or some other enclosed space?

I would also be curious about the charge current from the Minty to the phone. Some phones will try to pull more current than the Minty can deliver. But the boost chip usually shuts down before the batteries get dangerously hot.

[polarbee]

The Minty Boost and phone were both out in the open but the tin was closed. I'll have to check the charge current in a few days.