Low Current Lithium Ion Battery Pack Broken

Components & Accessories Power
1

My Low Current Lithium Ion Battery Pack ([TOL-15204) is borked, and I’m trying to figure out why before deciding to buy a new one or get something else.

Brief description of symptoms:

During the first charge right out of the box at 5 V, I noticed the battery pack was drawing 2 A. After a small popping noise, the charge LED went out, and now the output is reading 0.0 V.

Longer story for context:

Right out of the box I checked the input and output voltages with a multimeter: 4.7 V for the output; 0.0 V for the input. So far so good. I was also interested in testing out a [wireless charging module, so I hooked that up. I measured that it was supplying the battery pack with 4.9 V and 0.75 A. So far so good.

I then hooked up the battery pack input to a regulated power supply at 5.0 V. Fairly quickly (within a few seconds) I noticed that it was drawing over 2.0 A. Something popped, the charge LED went out, and I disconnected the supply immediately. Testing the output of the battery pack with a multimeter gave 0.0 V. Supposing that perhaps the battery pack only supplies power when the load is greater than 20 mA (as advertised), I also hooked up the battery pack output to a test LED circuit known to work and known to draw more than 40 mA, which didn’t show any signs of life.

Committed now to having lost the battery pack, I took it apart to investigate. There were no obvious signs of damage. The battery cell itself read 3.6 V, and I suspect it’s perfectly fine. Connecting my power supply to where the battery used to be, and setting the regulated voltage to 3.7, I see that the circuit is drawing about 300 mA from my “battery” with nothing else hooked up. I can only assume that’s not normal behaviour, or the battery would drain very quickly.

Technical details:

Since this isn’t a Sparkfun designed product, I’ll share some details that I learned by my dissection that might be useful to know. The backbone of the circuit is the [IP5305 chip. The circuit, by visual inspection, appears to largely conform to Figure 6 in the IP5305 datasheet, with the addition of the [FH8208 battery protection IC on the BAT line.

My questions:

I’m particularly interested to know:

  • - Does this battery pack expect a current-regulated input? That feels to me like a strange requirement for a battery pack of this sort.
  • - Is it likely that I happened to get one with a bad chip or something, and another pack would suit my needs? Or is it more likely that the circuit design is fundamentally flawed?
  • - *Not related to the above over-current problem, but important for my application*: The [[IP5305 chip's datasheet](http://aitendo3.sakura.ne.jp/aitendo_data/product_img/ic/charger/IP5305/IP5305-Injoinic.pdf) (bottom of page 5) states that the load removal detect timer will put the system in standby mode whenever the load current is continuously less than 45 mA, whereas the [[Sparkfun page](https://www.sparkfun.com/products/15204) claims that this cutoff is 20 mA. Has Sparkfun tested this? Which spec is accurate? I had planned to test it, but ended up frying mine first :/
    • [/list]](https://www.sparkfun.com/products/15204)](http://aitendo3.sakura.ne.jp/aitendo_data/product_img/ic/charger/IP5305/IP5305-Injoinic.pdf)](http://www.xfhong.com/PIC/PIC/202041142930.pdf)](http://aitendo3.sakura.ne.jp/aitendo_data/product_img/ic/charger/IP5305/IP5305-Injoinic.pdf)](https://media.digikey.com/pdf/Data%20Sheets/Seeed%20Technology/106990017_Web.pdf)](https://www.sparkfun.com/products/15204)
    2

    Hmm, that is strange. The battery should not be drawing any current while charging. I would imagine the pop was perhaps a component on the charge circuit failing.

    1: It should have a protection circuit in place that should only allow for 5v 1A input. I am guessing that if you used a power supply that could provide more than that and if the input circuit was faulty that is perhaps why a component “popped”. It may have taken as much current as the supply could provide which would cause issues. I don’t think it would have mattered if you used a 5v 1A supply, the component probably would have failed anyways.

    2:I think you got a battery pack with a compromised circuit.

    3: I have not tested this personally, however, I am sure one of our purchasers had an engineer verify the 20mA load discharge rate. Some customers left reviews stating that they can power a couple LEDs with the battery pack.

    If you wanted to fill out a return ticket we can send you a replacement unit if you wish.

    https://www.sparkfun.com/returns

    3

    Thanks, that’s what I was beginning to suspect. Everything else about this battery pack is exactly what I need, so I’ll definitely look into replacing it.

    Thanks again for your help :slight_smile:

    Cheers