Cheap Li-Ion Replacement Batteries – “Lies, damned lies …”

Most people may have a phone – maybe an older one where the battery is just no longer holding enough useful charge. Or maybe it’s a camcorder, where you need some more record time, or a Bluetooth GPS unit. Whatever it may be, you are thankful that it has a removable replaceable battery, and so you dutifully go online and look up a replacement.

As usual, you’ll find a genuine replacement often costs $40 – $80 and you think that’s a bit rich, when your eBay specials can get you something like a Nokia BP-5L lithium-ion cell for AU$3.49 delivered.

Of course, maybe you’re not expecting much – your phone might be due for an upgrade soon and you just need a quick fix to tie you over or add a little additional run time. It’s not good value to invest money into it anymore.

So you buy that cheap battery, and what do you get? Well, I’ve covered this once before in my legacy pages, you get less than what is advertised. Surprised? Maybe not, but lets dig a little further.

Today, we’re looking at the DB-L80 compatible battery which I purchased merely two years ago for my crappy Sanyo Xacti camera. It was barely used – only two cycles or so, but yet, it fails to operate the camera for more than 30 seconds at a time! It does charge successfully, and the terminal voltage is okay – so it sounds like the internal resistance has gone too high.

It is known that Lithium-Ion batteries have a limited shelf life, so don’t buy them and store them if you don’t need them because the capacity will permanently reduce, used or not. But I have five of these, and all have failed within two years under almost no use. Hmm. I expect a bit more from it.

The rear of it is somewhat nondescript, but there is a classic “Made in China” sticker. The overwrap is a self adhesive tape of some sort, as is normal for prismatic cells like these.

It’s a regular three terminal design – similar to most older Nokia mobile phone batteries.

Lets just remind ourselves that the overwrap states it’s a 740mAh battery. Unwrapping the overwrap, we find (after I’ve mirrored the image to make the battery code readable) …

It’s an ICP553034ART62 cell. Again, this turns out to be a YikLik cell, although not presently produced, several distributors websites give the following specs:

Hmm. It’s only a 620mAh cell, not a 740mAh!!! The labelled capacity overestimates the true capacity by 19.35%, and that is quite optimistic as it is as it’s been done at a 5-hour discharge rate, whereas the camera it’s being used in will easily chew it up in under an hour. The effective capacity is even less.

I suppose the lesson is – if you’re buying cheap cells, chances are that paying more for higher labelled capacities might just be throwing money into the seller’s hands! And don’t expect the cells to last – one year is probably about the service life you can expect from these cheap cells, and so don’t rely on just one of them.

The rear side of the cell where people would pry the cell out of battery compartments is protected with a plastic strip glued on. As this prismatic cell has both terminals on one side, there is no “terminal strip” between the bottom to the top PCB.

One place where cheap batteries can really be a problem is a lack of proper protection of the Li-Ion cell. Short Circuit, Overcharge, overdischarge and over temperature are very serious conditions with Li-Ion cells which can lead to fires and explosions – so cell protection is very important. Luckily this cell seems to have some level of protection – unfurling the PCB reveals a fuse in line with one of the tabs. The fuse is a JK-D175 from Shenzhen Xinwanzer Technology with a hold current of 1.75A and a trip current of 3.8A. It can sustain 8.75A for 5 seconds, with a 12V maximum working voltage and 100A maximum interruption current. It doesn’t seem this is a good choice – the maximum continuous discharge is only 650mA with 1.86A for 2 seconds being the maximum pulse current, so the fuse tolerance could be a bit closer to these values to improve the protection.

The other side of the PCB reveals the other part of the protection.

It’s a bit sparse. Strangely, it doesn’t seem to have a thermistor in it – just a single IC marked 6002D 803M3. I don’t recognize the logo, and I can’t find any information about this chip, but I suppose it could provide over and under voltage protection, but it’s a bit of a mystery.

Would that stop me from buying these batteries? Of course not. I probably would be a little more careful about relying on them, and factor in the need to carry a few spares and replace them more frequently – while expecting a little less run-time from them.