Power pack batteries cause cut off

Other Hardware General Electronics
1

Hi all,

I have an 'Energizer' power pack that failed to supply power for more than a few minutes. I presumed the two parallel 18650 cells had exceeded their liftime.

I replaced these two cells with new ones i had and soldered via the cell's tags, i.e. not to the end caps.

When I use the power pack and draw about one amp after a short while, say ten to fifteen minutes the power pack shuts down, i.e. no output. If I measure the cell's terminal voltage they have dipped to ~2.4V. After the shutdown the cell's terminal voltage rises to ~3.7V, which I understand to be a normal voltage for such a cell.

The power pack uses an IP5209.

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My questions are:

  • Have I suspect 18650 cells?
  • Would I expect cell voltage to drop as low as 2.4V?
  • If I do not have faulty cells, how did the original cells work so well?
  • Am I missing something?

Thanks for input and thoughts. Steve

2

Google for: forum.arduino.cc power bank auto shutdown

3

Thanks :slight_smile:
The first ten links or so that google gives refer to shutdown due to the load drawing too low a current. I do not think that applies in the case I am referring to above, as I am drawing about 1 A.

4

OK. That is a different case to the usual problem reported here where power banks cut out due to under current. The mAh rating of power banks is usually at their internal voltage of 3.7v. What claim is made for your power bank? Anyway, 1 amp for 15 minutes seems low.

5

The original pair of batteries, as supplied by the manufacturer; Energizer would provide the 1A current until the cells were depleted.

I wonder if I have a bad pair and should try another new pair of cells?

Hmm, nothng much to lose, just some time and effort. Perhaps I've answered most of my own question. :wink:

6

I'm sorry that I misunderstood your original question.

If you have changed the cells and the problem, that is apparent low capacity, persists, then the likely conclusion is that there's something else wrong, maybe the controller circuit.

An example capacity of a powerbank is 10,000 mAh (at 3.7 volts). That should be able to supply 1 amp at 5 volts for a period of about 7.5 hours.

I personally would regard a power bank as non-repairable, especially if it is factory sealed, and throw it away. The main risk is that it could cause a fire, depending on the nature of the problem.

7

Very likely, I'll give it one last chance :wink: It is my desire to refurbish and repair that makes me want to return its use.

That is broadly my expectation. :slight_smile:

This one unclipped.

8

Hi 6v6gt

I connected two new, unused cells this morning to the power pack. I used thick wire (16AWG) between the pre-welded tags on the cells. This ensured that I did not apply any heat to the cell's ends. The cells were not fitted into the power pack's case.

I did a quick ten minute test to determine if the cells worked and put the pack on charge while I went out.

This arrangement has been supplying ~1 amp to my mobile 'phone for around 90 minutes without issue.

I can only presume that I previously used damaged or faulty cells; unlikely or that I caused damage, probably during soldering. :frowning:

I will carefully re-assemble the cells into the case sometime soon. :slight_smile:

Thanks for your support 6v6gt :slight_smile:
Stephen

9

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