Aftermarket laptop batteries: is this any good?

This is about laptop rather than flashlight batteries, but since many of you have experiences with Lithium Ion batteries which are also used to power some flashlights, I decided to post it anyway...

Today I got a shipment of another battery for my Lenovo Thinkpad T61 laptop. I ordered the battery through Amazon and decided to take my chances on an aftermarket battery this time. There are some more differences between it and the batteries I had so far:

- The batteries I had so far were 6-cell batteries, the new one has 12 cells (I don't think Lenovo even manufacturers 12-cell batteries in this shape, but they do sell 9-cell packs)
- It obviously uses different cells since the cells of the Lenovo packs were rated at 2.6 Ah, but this one is rated at 2.2 Ah (for a total of 8.8 Ah)
- I noticed that it charges slower... the genuine Lenovo packs top out at 3.5 Amps (so each cell gets 1.75 Amps) but go down near the end of the charge, however, this aftermarket battery only takes in a maximum of 1.8 Amps, that's only 0.45 Amps per cell.
- Even though the number of cells is higher, the internal resistance of the whole pack still seems to be higher than the original one when it was new (140-170 mOhm vs. 100-120)
- The pack was much cheaper at only € 23,75 vs. € 70-80 for an original Lenovo pack with 6 or 9 cells... this amounts to only 25 cents per Wh which actually is ridiculously cheap

The pack says the cells are manufactured by Sanyo. They obviously used different cells than Lenovo. Do the 2200 mAh cells have any advantage over the 2600 mAh cells despite being cheap, maybe more cycles? (Like Eneloops have less capacity, but endure more cycles than higher-capacity cells) Or is this pack crap in your eyes?

Right now the pack is calibrating, we'll see how the real capacity turns out...

Aftermarket batteries haven't been very good for me. I've gone through two 12-cell packs for my now-defunct HP Pavilion DV6, and neither of them were very good at all.

The first one initially had better than rated capacity (9 Ah versus the rated 8.8) but steadily and quickly degraded until after about 100 cycles. At that point, the battery couldn't run the laptop for more than 10 seconds; the fuel gauge on that reported 800 mAh capacity. The second had a bad fuel gauge, so I had to transplant one from the first pack. The first one (and likely most aftermarket batteries) used a bq3060 fuel gauge from Texas Instruments. I had to replace and reprogram the chip since the original was locked down (and the maker actually bothered to change the password), and ended up with a battery that had 7.6 Ah out of the box (so ~86% capacity). It wasn't even worth shipping it back to get it replaced, and now it sits on my shelf gathering dust.

The only relatively good aftermarket battery I had was from BTI for an old Gateway laptop, and that used nine 2200mAh Panasonic CGR18650CGs. Even that one eventually encountered a balancing issue and the fuel gauge on that had no ability to balance the cells (granted, most laptop batteries can't either).

Here's a couple blog posts (not mine) that talked about some aftermarket batteries and their failures:
http://goughlui.com/2013/07/22/teardown-anatomy-of-a-failed-aftermarket-laptop-battery/
http://goughlui.com/2015/04/12/teardown-another-dead-compatible-laptop-camera-battery/

See if your laptop supports a battery health checker utility (the ones you usually find online don't provide too much info, but my HP had one that could read out individual cell voltages and even the Smart Battery System status codes).

All in all, good luck (you might need it)!

Kurt_Woloch said:

The pack says the cells are manufactured by Sanyo. They obviously used different cells than Lenovo. Do the 2200 mAh cells have any advantage over the 2600 mAh cells despite being cheap, maybe more cycles? (Like Eneloops have less capacity, but endure more cycles than higher-capacity cells) Or is this pack crap in your eyes?

Click to expand...

Generally all the after market packs I've opened up have crappy cells. Some unknown but mostly Chinese bulk 18650 cells. Some are made to look like a genuine replacement but are not. I don't even bother to harvest the cells from those packs any more

Well, the calibration results are in... sadly, the battery only delivers about 59% of its claimed capacity, which puts it next to the 6-celler when it was new (actually, the 6-celler was better because it came in a few percent above the 100% mark when it was new). But the logic in the battery doesn't admit it... it still claims it has the rated capacity, the gauge only jumps from 59% to 100% (with the Watt-hours jumping accordingly) at the end of the charge. The discharge was different, however... it seemed like every time I looked away, the battery cheated and subtracted a few additional Watt-hours so it hit the 0% at the end of the discharge. However, it took 66 minutes from 100% to 85%, but only 21 minutes from 17% to 1%. The battery is still cheap for what it delivers, but unneccessary bulky. I even doubt that all moulds are really filled with cells because the battery didn't seem to heat up at all although it claimed a temperature of 37°C.

Another thing I noticed during the discharge was that the battery, on calibration, stopped the discharge surprisingly early when it still had 10.69 V (the Lenovo batteries went down to 10.13 to 10.36 Volts before starting the recharge. Actually, at 10.69 the voltage wasn't dropping very fast yet, but I think it was still in the middle of the "knee" where the voltage drops very slowly before it starts dropping faster, which means it still had about 14 Wh in it when it started the recharge, so if that was factored in, the capacity would be 73% of the claimed capacity (still not 100%, but better). However, 10.73 Volts is a very low voltage for a "knee", the original Lenovo replacement battery had the knee at about 11.1 Volts when it was new (slowly sinking with cycles, but at 300 cycles it still was at about 11.07 Volts). It almost seems to me that they used USED cells which came in at 2.2 Ah when the pack was "manufactured" (about 6 months ago according to what it says), but have degraded somewhat since. Do you think the battery will improve if I calibrate it once more?

Sounds like the battery fuel gauge is having some qualms about the cells it's hooked up to. Another calibration cycle or two might make for a more accurate estimation of capacity, but I doubt it'll provide much improvement in terms of runtime.

Frankly, I'm not surprised at the results... you really get what you pay after all. Really though, I rather take some usability from a crappy battery than none at all from a dead one.
When a laptop battery dies, the laptop is probably a few years old anyway. So the big question is, is it worth spending the money on a genuine battery, or just a cheap aftermarket?

Of course, you can always refurbish one yourself by sourcing good quality cells yourself. But, I never had the bravery to try to disassemble a battery pack. Seems a little complicated to me.


Anyhow, I'm curious of any further results on this

Well, just to clarify... the laptop actually is from 2008 or 2009. I bought it used from the company I work for back in 2012 when it was retired there. It came with a battery that was pretty much shot... though the battery hadn't been used much (only 4 cycles on it when I got it), it had spent most of the time being fully charged at 100% with the laptop in operation, that is, at high temperatures. When I got it, the battery had about half of its capacity left and quickly degraded further to 20-25% in a matter of two months. I can't tell exactly because the old battery had the same display errors I have now with the aftermarket battery... on the last attempt to calibrate it, it went from 100% to 85%, then jumped down to 4%, discharged to 0%, charged back up to 33% and then jumped back to 100% (100% actually being 49% of the rated capacity which still was three times as much as really was left).

So I bought the first replacement battery quickly after the actual laptop, in April 2012. This was a genuine Lenovo battery. Actually it has held up well until now, it's lost about 15-20% of its rated capacity (actually it was at 105% at the beginning) at 404 cycles. I had some swimming sessions with my father this summer playing music on the laptop, and the battery usually died before the session was over, that's when my father said I should get a spare battery. I don't consider the life of the old battery being over yet...

Actually one of my colleagues already back in 2012 said it wouldn't be worth buying a new battery for this old laptop, but without it the laptop would have become nearly useless for me even though I had just bought it. Is that what you meant, or did you mean it would be worth it to buy an aftermarket battery, but not a genuine one?

If it wouldn't be worth to even buy an aftermarket battery, the only solution would be to buy a new laptop... but that would bring along a new set of difficulties. My current laptop still runs on Windows XP, but I realize this OS is outdated, so I'd probably install a new laptop with whatever OS comes with it. But that would cause some of my software not to run anymore, aside from the fact I'd have to reinstall everything. I'm currently running the music with a program I've written myself in VB5 accessing an Access 97 database, which are both very old pieces of software. I've had a training on .NET programming last fall, but it seems like nowadays programmers are supposed to program for pay, not as a hobby for themselves. So this would mean that this music program should be dropped entirely along with its databases because I'm not supposed to have a database running on a private PC anymore. So if I buy a new laptop, that music program I had running probably would degrade into listening to the radio.

I know this is a long shot, but it's what I always have in mind if questions come up if I should upgrade this and that.

Kouryu said:

Frankly, I'm not surprised at the results... you really get what you pay after all. Really though, I rather take some usability from a crappy battery than none at all from a dead one.
When a laptop battery dies, the laptop is probably a few years old anyway. So the big question is, is it worth spending the money on a genuine battery, or just a cheap aftermarket?

Of course, you can always refurbish one yourself by sourcing good quality cells yourself. But, I never had the bravery to try to disassemble a battery pack. Seems a little complicated to me.


Anyhow, I'm curious of any further results on this

Click to expand...

OK, another update... I did a second calibration cycle yesterday, and the battery didn't improve... in fact, it only seemed to get slightly worse. I've now followed the gauge more closely, and it behaves like this:

It took about three hours and 14 minutes to go down from 100% to 50% relatively steadily. Then it jumped down suddenly from 50% to 40% (the Wh jumped accordingly) and then the meter dropped more quickly, along with the Wh which now went away at 5-6 times the rate that would correspond to the actual current flow. This basically went on until the meter hit 0% (after 29 more minutes), then recharging began. The last voltage I read was 10.7 volts, and it was again during the "knee" before voltage actually starts to drop sharply. The recharge this time only took in 54.45 Wh before jumping up to 95.04 (again without readjusting)... on the first recalibration it took in 55.53 Wh, at least that was the last reading I got. During the recharge, the meter rose from 0% to 58% with the slowdown of the charge starting at 46%, then it jumped up to 100%.

I don't think the battery will improve with further calibration cycles, but it may deliver more energy if it's actually used and doesn't switch off at the point where recharging starts in calibration mode.

The total time I got during calibration is 3:43 vs. 3:16 on my old 6-cell battery on its last calibration cycle (after which it showed 90,78% of rated capacity). This would correspond to an actual capacity of 54.9 Wh or 5.08 Ah, 57.8% of rated capacity.

These batteries might be said to have 6-9-12 etc cell, but often there will be only 3, others will be duds or just extra sand and stones .

Even the real ones, usually have 2000 mah max per cell, and heavily degrade after 20-30 cycles.

Well, it must be at least 6 cells in there, a smaller number of cells wouldn't be able to deliver the capacity they're doing. In fact 6 cells is still a bit low considering the way they do the "knee". I do think they have at least a total capacity of 70 Wh, only that it's hidden by the battery management system and by their relatively high internal resistance, or whatever it is that causes their plateau being that low. I'd guess that there are really 12 cells in there, but that they were used ones.

CuriousOne said:

These batteries might be said to have 6-9-12 etc cell, but often there will be only 3, others will be duds or just extra sand and stones .

Even the real ones, usually have 2000 mah max per cell, and heavily degrade after 20-30 cycles.

Click to expand...

Another update here... I contated the seller of the battery since they say in the invoice you should contact them before posting a negative review on Amazon. I said that their delivery was fine, but the battery itself leaves a lot to be desired, stating the facts I posted here, and also that, as I found out now, the battery indeed reaches the "critical level" at the level where the recharge begins on calibrating, which means that the laptop can't turned on at this level anymore, and you don't know where the level is that causes the laptop to shut off. It may be an hour away or only a few minutes... I didn't reach it yet. Anyway, the seller mailed back and said the battery is possibly defect and they would mail me another one. They said I don't have to ship back the possibly defect battery, but I should keep it until I get the new one. Meanwhile I've still used it a few times, and the rubber feet have fallen off while the Laptop's rubber feet still stay on after over 3 years of use.

I have opened a lot of after market laptop battery packs and analyzed the cells.

All aftermarket batteries I encountered uses ti bq series of chips. Cells used are either cj lishan or few other vendors.

Individual cells extracted from these battery packs which are used for a year or so are showing high resistance in range of 150_200 very few cells show below this. Using opus bt-c3100 charger they are unable to deliver current at 1am. They heat up and opus stops discharging them. At 0.5amps draw they do get heated up but opus doesn't stops discharging them. capacity is what is stated in cell.

The interconnection between series and parallel cells packs is using normal thin wires instead of metal stripes. Instead of using some good quality insulating tape used in genuine they use something slightly better the masking tape. It's very gunky inside.
Spot wielding is very poor. Some spots don't make any connection between the metal plate placed at battery terminals to which interconnecting wires are soldered.
Very poor soldering.
Some times positive terminal is like a time bomb for short circuit.