supplierdeeply

NB-4L clone teardown.

  • 5 Replies
  • 2112 Views
*

Offline ahull

  • *****
  • 634
NB-4L clone teardown.
« on: 04 / July / 2013, 11:06:20 »
Advertisements
...just because taking things apart is fun...



See the full gory details here... Warning, batteries were harmed in the making of this album.


Re: NB-4L clone teardown.
« Reply #1 on: 04 / July / 2013, 11:13:38 »
Nice!

Did you try and actually open the cell?  Or fully remove the electronics strip?
Ported :   A1200    SD940   G10    Powershot N    G16

*

Offline ahull

  • *****
  • 634
Re: NB-4L clone teardown.
« Reply #2 on: 04 / July / 2013, 12:42:39 »
Nice!

Did you try and actually open the cell?  Or fully remove the electronics strip?

Well, I didn't crack open the LiPo cell, but I did unsolder the electronic strip from the cell, (reverse side pictured below).



 I may attempt to charge up the unprotected cell with a dangerous amount of voltage later  :haha

EDIT: Although I suspect that requires a spouse and dog free zone.. :P

The electronic strip contains one of these and one of these in a configuration that looks similar to the DW01 ref. design.

I may re-use the strip to charge some recovered laptop cells.
EDIT: 8205A link updated.
« Last Edit: 07 / June / 2014, 11:37:40 by ahull »

*

Offline ahull

  • *****
  • 634
Re: NB-4L clone teardown.
« Reply #3 on: 04 / July / 2013, 15:40:27 »
One (unconfirmed) observation, there are three resistors there (marked 101 (100 Ohm), 102(1K Ohm) and 103(10K Ohm)), and a capacitor but nothing that looks like a thermistor.

In other words, I doubt that the temperature that this battery claims to be at, ever varies...  :blink:

Time to grab the multimeter and find out if I am correct.


*

Offline ahull

  • *****
  • 634
Re: NB-4L clone teardown.
« Reply #4 on: 04 / July / 2013, 16:00:43 »
I was correct.

Furthermore I can identify the Genuine Canon NB-4L batteries in my collection blind. They all read >11K Ohms at room temp. All of the clones read 10K Ohms exactly.



Note: The component marked "103" is a 10K Ohm resistor, not a thermistor.

Finally I grabbed the circuit board out of the clone and strapped it the side of the kettle, and waited for it to boil, while watching the reading of the multimeter with the probes across the "thermistor", the reading didn't budge from 10K .... The kettle boiled and the board was way too hot to touch.

Moral of the story is, if you buy cheap batteries, the chances are they don't have any thermal runaway protection, or to be strictly accurate, they don't tell the camera if they start to overheat, which I guess is not quite the same thing, since all the camera can do is shut down, it can't put out the fire :P.

The battery protection circuit and the mosfets will however protect the cell from over charge and deep discharge, so in that sense things are relatively safe.


One more observation, the board is very well constructed, and there are a couple gold plated test points across the "thermistor", so perhaps there is a version which does include a real thermistor.

Why would they do this you ask? Money of course, thermistors are much more expensive than resistors.
« Last Edit: 05 / July / 2013, 17:44:16 by ahull »

*

Offline ahull

  • *****
  • 634
Re: NB-4L clone teardown.
« Reply #5 on: 06 / July / 2013, 09:12:25 »
The final word (maybe) on this subject, what happens if you remove the charge protection circuitry on a small lipo battery...
Sadly I haven't had time to try "this at home", but I was sure someone would have... so here goes..

Lipo Battery Fire

Enjoy... Now you know what the thermistor and charge regulator is for..  :P


 

Related Topics