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PowerBoost 500 Shield Shorted
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PowerBoost 500 Shield Shorted

by matt_dmc on Tue Feb 23, 2021 5:00 pm

I have ordered several of the powerboost 500C arduino shields with a 3.7v 1200mAh lipo battery. At least 3 of them are no longer functional after minimal usage. The charging led is on when connected to usb but the battery never completes charging.

The batteries are all ok (verified independently). However on all boards there is a short between VBAT and ground which explains the lack of functionality. the output side of U5 seems ok.

Its possible that the device downstream of this has caused this problem though I would expect the F1 to trip if too much current was pulled. And as I mentioned this has happened identically on 3 boards.

My issue also sounds very similar to viewtopic.php?f=31&t=174843&p=852912&hilit=powerboost#p852912
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Re: PowerBoost 500 Shield Shorted

by mikeysklar on Wed Feb 24, 2021 6:50 pm

When did you order the shields? Where they all purchased at the same time?

Are the 3.7v LiPo packs from Adafruit or elsewhere?

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Re: PowerBoost 500 Shield Shorted

by matt_dmc on Fri Feb 26, 2021 1:06 pm

lipo packs are from adafruit https://www.adafruit.com/product/258

First shield and battery ordered on December 15, 2020
Second batch ordered on January 12, 2021

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Re: PowerBoost 500 Shield Shorted

by mikeysklar on Fri Feb 26, 2021 1:51 pm

@matt_dmc,

Thanks for the time frame. These are outside of your refund / replacement window.

On the units you have purchased:

1) How many of them are there in total?

2) Is vBAT <--> GND connection showing up as shorted on all units or just the failed ones?

3) Are you able to run this shield without some of the other upstream components to help isolate the failure condition?

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Re: PowerBoost 500 Shield Shorted

by matt_dmc on Fri Feb 26, 2021 2:11 pm

1. There are 4 units in total. 1 is still functional but the rest are not.
2. VBAT <--> GND is shorted on all failed units. Working unit does not have a short.
3. Yes. This issue occurs when the shield is not connected to anything else. Just shield + LiPo battery.

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Re: PowerBoost 500 Shield Shorted

by mikeysklar on Sun Feb 28, 2021 1:43 pm

@matt_dmc,

Thank you for the clear summary.

Where would you like to go with this issue? It sounds like three units originally showed the correct VBAT and GND isolation, but now they are shorted? Is that correct or was that connection always shorted?

My guess is that the remaining unit will fail with your setup if given enough time to run is that assumption correct?

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Re: PowerBoost 500 Shield Shorted

by matt_dmc on Mon Mar 01, 2021 12:27 pm

Correct. These units all initially did not exhibit this short but have now failed. The one working unit seems to be ok as of this moment but I'm guessing it will fail eventually. Not sure I have any other options at this point but to continue using it. I mainly wanted to bring this up given what I read on that other issue. Seems like there may be a manufacturing/design flaw with these boards but given that we have other things downstream of this device, its tough to say that for certain.

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Re: PowerBoost 500 Shield Shorted

by mikeysklar on Mon Mar 01, 2021 5:35 pm

@matt_dmc,

That is good summary of the situation.

I'm wondering what we can learn from this as there does appear to be a situation that can induce board failure. However, it is completely unclear to me how long and under what conditions the board must be used to recreate the failure. Do you feel you understand the time frame or usage scenario to recreate the short?

If you feel up to it reviewing the boards components probably starting with resistance readings from those devices might provide a clue comparing the good board with the three failed.

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Please be positive and constructive with your questions and comments.