Disassembly of 9V LiIon batteries

Disassembly of 9V LiIon batteries

I have reviewed these two batteries and wanted to see how the electronic was made. One is only a protection circuit, the other is a usb charge circuit and a boost converter.


This replaces a normal 9V rechargeable battery.

First step is to get rid of the wrapper, the wrapper is made of multiple pieces.

To open the cell I had to cut the top off, it was glued (or maybe welded) together.

The protection circuit is below a piece of isolation paper.

I could not get the cells or the circuit out, I had to cut the battery open. It is easy to see why the cells would not come out, the gray stuff is keeping them in place.

It was difficult to remove all the gray stuff and when the cell started to inflate I decided to stop (Not really a indoor job).

The two cells are connected in series with the protection circuit between.

The two chips on it are:

3YC9: Dual LiIon protection.

3V451K: Dual mosfet.

Usual protection circuits uses the resistance in the mosfet, but in this case here an external resistor is added (The overload current is fairly low for this type battery).

It do not look like there is any balancing between the two cells.


This is the usb charged battery.

The wrapper is only one piece and there is screws, making it easy to disassemble.

The usb charge circuit and boost converter is placed at the bottom of the battery.

There is two pouch cells in the battery, each rated at 480mAh.

The cells are connected in parallel and has wires to the circuit board. The parallel connection means there is no need for balancing.

There is 3 chips on the circuit board:

2YL6: Independent linear lithium battery charger

5353A: Battery protection IC

UB6FA: Boost converter

The battery is connected at b+ and b- at the bottom, output terminals are at the top.

The two resistors on this side controls the output voltage.


It is interesting to see the two solution. There are many differences in how the cells works and can be used:

  • The iPowerUS has space for slightly larger cells

  • The iPowerUS can deliver most energy, because there is no looses in a boost converter.

  • The iPowerUS will deliver most mAh due to the lower voltage.

  • The iPowerUS has a fairly low output voltage.

  • The iPowerUS can be charged on a normal NiMH charger, the protection circuit will protect the battery (This is not ideal, but will work).

  • The iPowerUS required a special LiIon charge for best performance.

  • The iPowerUS is very good at low power applications, because LiIon can maintain charge for a long time.

  • The iPowerUS may work with a battery gauge.

  • The iPowerUS may die before the cells are worn down due to voltage difference between the two cells.

  • The Znter has highest output voltage (Like a new Alkaline battery).

  • The Znter can be charged correctly with any usb charger.

  • The Znter is not very good at low power applications, due to the boost converter draining the battery.

  • The Znter will prevent any battery gauge from working.

  • The Znter will work until the cells are worn down.


iPowerUS review Zenter Review

It’s interesting to see a usb charge port on a 9V battery. I think it’s strange though, that they put the cells in parallel and used a boost circuit for output. Maybe it’s safer, but it makes the battery not very useful for either high or low drain applications. I think the iPowerUS way of doing it is better over all.

As I list in the conclusion there are god and bad about both ways. What is a high drain application with a 9V battery? At 0.5A the Znter can easily surpass both alkaline and NiMH batteries.

Well, you’re obviously right. There really are no high drain applications for 9 volt batteries because there have never been any high drain 9 volt batteries. I guess I was just caught up in the fact that it was a pair of lithium pouch cells, and should have some great potential, which would be limited by the boost circuit format.

I have not decided that yet, let me test them first.

Thanks for another interesting disassembly.

a couple of questions:

The Znter will work until the cells are worn down. do you mean that it will over discharge the batteries below the recommended minimum voltage, thus reducing their performance and working life?

Could I open my Znter, disassembly and brutally connect 1 or 2 18650 protected cells instead of the 2 lipo cells? So I will have a hell of a runtime.

There is 3 chips on the circuit board:

There is two pouch cells in the battery, each rated at 480mAh

*There are

No, but there is no risk of premature dead due to imbalance (This will often happen with non-balanced cells in series).


You are aware that disassembly requires a knife?

Thanks HKJ. Very interesting and informative. Would a battery like this have any advantage over a non rechargeable battery in a DMM?

Depends on how often you change batteries:
A few years between: Alkaline or lithium
More often: The 2 cells in series type (But it will probably not be economic feasible).
Less than a few months: The boost converter may also be fine.

Thank You for disclosing the innards of these batteries.
I think the lack of a charging balancer in the 2s type(7.4V) is a major drawback. Perhaps they will eventually sneak in, f.i. the BQ29200 charging balancer.

I am glad to see the rear side of the ZNTER PCB with the values of the voltage divider resistors R3/R2 (220k/15k).
If anyone is in need to adjust the rather high battery voltage down to 9.0V they only need to solder a resistor in parallel with R3, the theoretical value being:

for an initial voltage of 9.33V, use 5.6 MOhm for 9.0V out.
for 9.39V, use 4.7 MOhm
for 9.43V, use 4.3 MOhm
for 9.47V, use 3.9 MOhm
for 9.51V, use 3.6 MOhm

Strange that I have received 10 batteries during 4 months and all with English language wrappers and blisters, while yours are with chineese text. Another difference is that (in the one I opened) the 2 LiPo cells are marked 500mAh and yours 480mAh.

I’m not really interested in 9V Li-Ion batteries, but this disassembly-comparison topic is really interesting. Thanks HKJ. :THUMBS-UP:

Another vote for a review and disassembly on Soshine and EBL.
I have a bunch of the iPower. They are vastly superior to NiMh and alkaline for a lot of applications. I’ve got some in ‘test’ smoke alarms that look like they are going to make a year. These are used cells from a place I volunteer from. Some are 4-6 years old with a completely unknown history but since they were in a huge work environment with a lot of people and shifts I assume it’s been not too kind.

Just recently I picked up 2 used EBL from the same source. One was near full the other read 0, but bumped up to 7v with a minor voltage charge, so I guess the low voltage cut-off was engaged. Both seem to have about 450mA @ 0.2A draw. Trying 0.1A draw didn’t really change that much. No idea how well they will hold voltage in the long run.

I used to take the alkaline batteries apart to scrounge AAAA cells for my old Streamlight Stylus. After all what’s more important, that family smoke detector, or my flashlight?

i have some kind of usb-charged 9v li-ion battery as well. i think mine are just connected in series, because IIRC it was 8.4v fully charged.
My DMM don’t do auto off, so after i forgot to turn it off a couple of times i got tired of changing batteries, and not having 9v batteries at home. so i tried one of the li-ion batteries and that seemed to work fine.

I use NiMH 9 volt batteries, composed of 7 internal cells. This gives about 9.6v when fully charged, and about 8.4v when depleted. This works very well as replacements for alkaline.

I can’t imagine the iPower 6.0v - 8.4v range is very useful for applications that require or expect an alkaline battery. My smoke detectors start chirping about around 7.8v, which the iPower would drop to quite quickly.

The boost circuit sounds like a better way to go. The whole point of 9v batteries is that they are needed for devices that require a high voltage.

Generally 9V batteries are first assumed to be empty around 4.8V (Alkaline cells are assumed to be empty around 0.8V). I do not test that low, but stops at 6V. Equipment do not always follow that, as everybody probably has found out.

I can be rather interesting to compare the different 9V chemistries in my comparator: http://lygte-info.dk/review/batteries9V/Common9Vcomparator.php

Yes, that is interesting. The iPower has a lower voltage for most of its run-time than my smoke detectors would allow. Though, it looks good if you don’t really need high voltage.