Genuine Lenovo Batteries vs. Generic Replacement?

[bill bolton]

They have ALL failed just past the one year mark.

That in itself is prima facie evidence that you are doing something to your batteries that causes them to fail.

I have a whole bunch of personal ThinkPads, plus ride shotgun on a large number of T and X series ThinkPads in our consulting group, and have never had battery become unusable in less than 2 years (and those with very high cycle counts), with most lasting over three years.

Cheers,

Bill B.

[pgoelz]

They have ALL failed just past the one year mark.
That in itself is prima facie evidence that you are doing something to your batteries that causes them to fail.

I have a whole bunch of personal ThinkPads, plus ride shotgun on a large number of T and X series ThinkPads in our consulting group, and have never had battery become unusable in less than 2 years (and those with very high cycle counts), with most lasting over three years.

Cheers,

Bill B.

I figured someone would go there... blame the user

The fact is that aside from NOT cycling the battery very often, there isn't anything I CAN do to shorten the battery life. My batteries do what just about every other battery does... they sit in my laptop which spends most of its life connected to AC. These days I have battery manager set to charge when below 90% and stop at 95% which hopefully helps a bit. But that of course gives away some run time.

So tell me what I am doing that is killing my batteries when no one else has problems? ??

The sad truth is that lithium batteries are not the panacea that many think they are. They degrade with every charge / discharge cycle and they degrade from the moment they are born, regardless of whether you use them or not. Higher temperature and higher voltage accelerates this degradation. In a laptop, they are often hotter than room temperature and fully charged.

In addition to laptop use, I also fly electric model airplanes. Until last year I only bought name brand batteries and had the same issues with them (although airplane use is more strenuous than laptop use). The name brand suppliers will usually replace packs that fail after a year or two, but I finally got tired of it and started using off brand packs with a good street rep that cost about 1/4 the price of the name brands. So far they are lasting at least as long as the name brand packs. And if they ultimately don't last, they didn't cost much.

I have that same choice with laptop batteries.

So what's the bottom line? For starters, the laptop manufacturers need to re-think their pricing and warranty strategy. If their batteries cost less, I wouldn't be so angry when they only last a year and a half. And even better if they get replaced at no or reduced cost if they don't produce a reasonable number of charge cycles. Also, there is a difference between a battery slowly degrading until you decide it is time to replace it..... and a battery like mine that suddenly and precipitously goes from acceptable run time to near zero.

If keeping them fully charged is responsible for premature failure, re-think the charge algorithm.... like add a CHARGE button so the charge - discharge points could be set more conservatively but still make it easy to fully charge when needed.

So again..... if this is all my fault, please tell me what I am doing wrong. I don't see it.

Paul

[bill bolton]

Until last year I only bought name brand batteries and had the same issues with them....

Model aircraft lithium battery packs are quite a different thing from processor monitored laptop lithium battery packs, so there's no way I can see that you had the same issues with them!

It seems to me that you are comparing dis-simlilar battey applications and drawing a flawed conclusion from that comparision.

Cheers,

Bill B.

[pgoelz]

Model aircraft lithium battery packs are quite a different thing from processor monitored laptop lithium battery packs, so there's no way I can see that you had the same issues with them!

It seems to me that you are comparing dis-simlilar battey applications and drawing a flawed conclusion from that comparision.

Cheers,

Bill B.

Not sure I follow your logic but I understand where you are coming from (if that makes sense).

I have researched this issue through both my hobby contacts and some professional contacts. Obtaining detailed engineering information on lithium cells and associated failure mechanisms is not easy but as far as I know, LiPoly (model airplane) and LiIon (laptop) cells are similar except for packaging. Their internal chemistry is very similar and they have similar degradation issues with age, temperature, voltage and use. In fact, my model airplane packs are also "processor monitored". When I charge them I use an intelligent charger that monitors and controls individual cell voltage and current and monitors cell impedance. Between sessions, they are stored at between 40% and 80% charge and at reduced temperature. They are charged to 100% immediately prior to use and never discharged below about 20%. In other words, they are treated much better than laptop batteries. Since I started storing them at reduced temperature and reduced charge, they seem to be lasting longer but I still have one name brand pack that is showing early signs of failure (rising internal impedance) at less than a year old. The two "cheapie" packs are still going strong at a year old.

I am not doing anything to my laptop batteries other than using them like everyone else. The last failure I had was the battery I have been talking about most recently, in my X61s. I believe it has a bad cell but without opening it I cannot be sure. By contrast, we have an old Dell from about 1998 with the original lithium battery in it. It has been on AC and fully charged (to 100%) for YEARS and it still holds a decent charge. I don't know who made the cells, but I want more of them

Bottom line for me is that I am using my laptop as intended (although I admit it is possibly on AC more than "normal"). My IBM/Lenovo batteries don't last two years, EVER. Non-OEM batteris sometimes do. I don't consider that acceptable for >$100 OEM batteries and I am open to suggestions re: how to improve it.

If I really am the only one that isn't happy about Lenovo battery life, I'll shut up and go away. I was under the impression that the issue was bigger than just me.

Paul

EDIT: It just occurred to me that I bought all three of my Thinkpads used. It is entirely possible that the previous owner "abused" the batteries although the cycle count when they died was (I think) less than 100. However, other than being exposed to high temperature I'm not sure that is possible to abuse them since as you say, they are "processor monitored". They certainly can't be overcharged or over discharged, which would definitely shortent heir life. And it doesn't explain the "Genuine" replacement TP600 battery I bought from IBM, which lasted about a year and a half and then died suddenly.

[bill bolton]

I am not doing anything to my laptop batteries other than using them like everyone else.

Cleary NOT everyone else, but I'll leave to your strongly held beliefs then.

Cheers,

Bill B.

[pgoelz]

I will say to you what I have said to the several battery vendors I have dealt with...... if you think I am responsible for the failures, TELL ME WHAT I AM DOING. So far, nada.

How about we just agree to disagree. I value this forum too much to argue about this with you and I'm weary of feeling like the bad guy for reporting a problem. My complaint is with Lenovo, not you.

Paul

[dr_st]

It's possible that you've just been tremendously unlucky with bad batches of Lenovo batteries.

I've a few Thinkpads pass through my hands over the years, and not a single battery failed. The worst one is now 4.5 years old and holds 40% of its design capacity. All others are 80%+, many after 2-3 years and 200+ cycles.

Your problems are certainly not unheard of, in general. For instance, with Lenovo's value laptops, I've heard quite a few stories, and even have a couple friends who experienced the battery sudden death syndrome.

My experience with Thinkpads is much more positive. It seems that generally people on this forum will have more bad experiences to share about generic batteries than about original IBM/Lenovo. Speaking of which, it is sometimes possible to get them for reasonable prices, you just have to look.

I am not trying to suggest you are doing anything wrong with the batteries. But I do believe in things like karma (not being cynical). You really may have bad luck with Lenovo. If non-OEM batteries have served you much better - by all means, continue using them, and save some cash in the process.

[pgoelz]

It's possible that you've just been tremendously unlucky with bad batches of Lenovo batteries.

Thanks for that Indeed I have.

I've a few Thinkpads pass through my hands over the years, and not a single battery failed. The worst one is now 4.5 years old and holds 40% of its design capacity. All others are 80%+, many after 2-3 years and 200+ cycles.

Please tell me your secret. I'm not kidding. What is the normal use of those laptops? Do you charge them and then disconnect them right away? Or are they on AC for most of their lives?

My normal use is on AC, on my lap, in the family room. I take it portable once in a while but not often. From what I know of lithiums, that is potentially a problem. What I HAVE been able to glean from manufacturers is that the degradation increases very non-linearly with increasing voltage. At 4.205V the degradation is much greater than at 4.200V (100% charge). I have not been able to find data on degradation below 4.200V but I have to assume it decreases in the same manner. For that reason it makes sense to limit the full charge to something less than 100% if you can accept the reduction in capacity.

My experience with Thinkpads is much more positive. It seems that generally people on this forum will have more bad experiences to share about generic batteries than about original IBM/Lenovo. Speaking of which, it is sometimes possible to get them for reasonable prices, you just have to look.

Well, I have had no WORSE luck with aftermarket batteries. Generally it has been better. When they have failed, it is because the capacity degrades gracefully. I have never had an aftermarket battery do the sudden death thing. And as I have implied before, even if an aftermarket battery fails, the investment is so small that I could buy four of them and have them fail in a year and still be considerably ahead.

I would be perfectly comfortable using aftermarket batteries except that I know how dangerous lithiums can be when provoked or when defective. Since I have no easy way to determine whether the cells in any given aftermarket battery are from a reputable manufacturer, I would prefer to stick with Lenovo. I just can't stomach the cost when they don't last even as long as the average aftermarket battery in my experience. And as I have said before, you have no way of knowing prior to purchase if they have been on the shelf for several years, slowly degrading.

Paul

[dr_st]

Please tell me your secret. I'm not kidding. What is the normal use of those laptops? Do you charge them and then disconnect them right away? Or are they on AC for most of their lives?

Hard to say. Right now my main laptops are a pair of T60s, with 4 batteries between them. This has been the case during the past year or so. So 2 of the 4 batteries are generally stored at about 50% charge, as recommended. The batteries that are being used (I change them once in a while, depending on whether I want the lower weight of the 6-cell or the large capacities of the 9-cell), are generally on AC maybe about 30% of the time, and the rest they either travel with me or just sit there unplugged. Even when unplugged, battery level is at 100% or close to that, minus normal leakage.

I guess that the old T42 with the degraded battery has spent more time being plugged in. Is it possible that it affected it? Maybe. However my experience shows that it's just the nature of Sanyo batteries to start losing their capacity rapidly after 1.5-2 years. The better preserved batteries I have are Panasonic. They do lose charge over time and cycles, but tend to do it linearly. My wife's old X32 had a Panasonic, which also held close to 80% capacity after 3+ years.

I don't normally run on battery a lot. My main 9-cell has reached 184 cycles after 27 months of use. I've seen people that get to 300 cycles in a year. The worn out Sanyo in my T42 barely has 100 cycles.

What I HAVE been able to glean from manufacturers is that the degradation increases very non-linearly with increasing voltage. At 4.205V the degradation is much greater than at 4.200V (100% charge). I have not been able to find data on degradation below 4.200V but I have to assume it decreases in the same manner. For that reason it makes sense to limit the full charge to something less than 100% if you can accept the reduction in capacity.

It does make sense, however here we are talking about the normal capacity loss, and how to minimize it. But it does not explain the sudden death phenomenon, where a battery either loses almost all of its capacity overnight or just quits working. These phenomena are likely caused by defects in the battery itself.

[pgoelz]

I guess that the old T42 with the degraded battery has spent more time being plugged in. Is it possible that it affected it? Maybe. However my experience shows that it's just the nature of Sanyo batteries to start losing their capacity rapidly after 1.5-2 years. The better preserved batteries I have are Panasonic. They do lose charge over time and cycles, but tend to do it linearly. My wife's old X32 had a Panasonic, which also held close to 80% capacity after 3+ years.

I don't normally run on battery a lot. My main 9-cell has reached 184 cycles after 27 months of use. I've seen people that get to 300 cycles in a year. The worn out Sanyo in my T42 barely has 100 cycles.

OK, so it looks like you are the inverse of me. You put more cycles on your batteries (in general) than I do (mine have died with less than 100 cycles on them) and yours are held at 100% charge less than mine. That would tend to make the case for cycle to cycle degradation being less damaging than being held at 100% charge. That is information I have yet to be able to obtain from the manufacturers. They are very difficult to reach. More easy to talk to are the distributers but they don't tend to have good data on cell degradation. That, or they are unwilling to share it because it is not good for their business.

It (non-linear cell degradation with terminal voltage) does make sense, however here we are talking about the normal capacity loss, and how to minimize it. But it does not explain the sudden death phenomenon, where a battery either loses almost all of its capacity overnight or just quits working. These phenomena are likely caused by defects in the battery itself.

It depends on the failure mechanism that causes the machine to suddenly shut down or hibernate with >50% capacity remaining as reported by battery manager and WITHOUT a low battery warning. I am assuming that if the pack detects a cell at or below 3V it simply triggers an emergency shutdown. If so, that would indicate it was one cell that was seriously out of balance. It would be very interesting to see if that is because the cell is in fact lower in capacity or whether the battery manager in the pack is not adequately balancing the cells during charge. I REALLY need to open up my X61 pack and see which it is.

And note that if the issue with the sudden death packs IS a bad cell, this is a defect and not caused by anything a user could do to the pack. In my case, the emergency shutdown occurs at between 70% and 80% capacity remaining, so at least SOME of the cells are at a normal capacity.

It also just occurred to me that I reset the battery meter in an attempt to fix the pack. It ran for a decent amount of time before it shut down. So perhaps the reset process either ignores a low cell or..... something else is going on? Like a defect in the battery monitor circuit or firmware in the pack itself.

But this is all moot, right? Lenovo thinks everything is okie-dokey so whatever we or I discover is responsible for sudden death failures won't result in a resolution of the problem. Because there isn't a problem. Sigh. THAT is why I was hoping Lenovo would replace my battery and get the failed one back for examination.

Paul

[mfbernstein]

My general impression is that battery quality over the last few years has gone down (and not just for Lenovo).

I've had 3 batteries for my X61. The first was a 4-cell that came with the computer. It was basically dead within 14 months. The second was an 8-cell generic bought on eBay. It failed in 5 months (going from 70% to shutdown in a matter of seconds).

My current battery's a Lenovo 8-cell, but bought from their refurbished store at ~40% of the new price. So far so good, but it's only been 6 months so far.

I'd suggest giving the refurb. store a try. The equipment is genuine, but the prices are almost as good as the generics, and I believe you get a reasonable warranty too.

[pgoelz]

Never thought of looking in the refurb store for batteries. I wonder what Lenovo calls a refurbed battery.

Paul

[mfbernstein]

Never thought of looking in the refurb store for batteries. I wonder what Lenovo calls a refurbed battery.

Not sure either. Unfortunately they seem to be out of batteries at the moment: http://outlet.lenovo.com/

[tamasrepus]

My X61 tablet battery died last week, going from 2/3 of it's original charge down to zero (w/ a blinking battery light). I really don't think I was doing anything abnormal, and apparently there was a Lenovo battery recall for certain Sanyo batteries a month or two ago (Sanyo batteries like the one mine uses), but my FRU was not included in the recall. After this, I really don't feel like forking over more cash to Lenovo when their battery quality (as well as, honestly, all other manufacturer's batteries) has gone so much downhill.

Good call on the Lenovo Outlet Store batteries! Unfortunately, the warranty is only 90 days, and I really wonder what the word "refurbished" means wrt a battery...

[jwthinkpad]

Just ordered a tablet x60 8-cell battery from outlet, with tax it's about $60. I'll post some feedback later when I use it.

still some available:
http://outlet.lenovo.com/accessories/ba ... y9130.html

[gp2stroker]

has anyone tried the 12cell 7200mah on ebay.... thinking of getting replacement for my 8-cell. haven't seen any reviews yet for the 12-cell, if their capacity is good as promised... would really like the 12 hrs capacity on my X61s

[pkiff]

I obtained two X60 Tablet 8-cell batteries from the U.S. Lenovo outlet store, and both seem to work great. The manufacture dates are January 2009 and Dec 2008. They both claimed to have 0 cycles, and were at maximum designed capacity, though one of them initially only reported that it was at 99% designed capacity.

No problems with either battery yet.

Phil.

[jwthinkpad]

I obtained two X60 Tablet 8-cell batteries from the U.S. Lenovo outlet store, and both seem to work great. The manufacture dates are January 2009 and Dec 2008. They both claimed to have 0 cycles, and were at maximum designed capacity, though one of them initially only reported that it was at 99% designed capacity.

My friend thinks that for those refurbs from outlet, Lenovo puts in new cells and reset count to 0. Idk if he's sure though.

I ordered one but is taking a while for order to process.

[m509272]

Any update on these Lenovo refurbs, I just got the 75% to zero on my OEM X60 8 cell. Literally worked one day and not the next. I switched to my 4 cell and it turns on so the battery is totally toast I presume. Did not make two years. Also a laptop that is plugged in 99% of the time and on all the time.

Where can I get the recall info to see if my battery is covered?

[Cunha]

Take your battery out if you leave the computer on constantly and plugged in. It gets the battery warmer than necessary, it also keeps the battery full charged which for whatever reason seems to be a bad way to store a battery.

Your batteries last as long as they are guaranteed to, but leaving a computer on and plugged in with the battery for extended periods and seldom cycling it seems to be the worst thing you can do for a battery.

I do believe that there could be some more clever ways of dealing with batteries. Are you battery slayers using the battery mode where the computer will automatically select its charge threshold to maximize battery life?

Just curious.

[dr_st]

Take your battery out if you leave the computer on constantly and plugged in.

If you do this on a recent Lenovo Thinkpad (I think everything from the 60 series onward), and you happen to have a 65W PSU, you will be unpleasantly surprised by the fact that your CPU clock will be limited to the lowest possible setting, which will hinder performance in CPU-intensive tasks.

It gets the battery warmer than necessary, it also keeps the battery full charged which for whatever reason seems to be a bad way to store a battery.

Through the use of power manager, it is possible to set charging thresholds to the battery. So if you always leave it plugged in, you can tell it to only charge it to 50-60% of the max, which is commonly believed to prolong battery lifetime.

[John H]

I guess everybodys experience is different.

I've been using Thinkpads exclusively for about 13 years, and I always treat them the same: usually plugged in, occasionally on the battery, and very occasionally running the battery all the way down. I have NO dead batteries, and the worst I've seen is that the new chinese copy 4-cell I bought a month ago for my X60s now only charges to 40%. The 8-cell i got a month ago is OK. The T60 and T40 that I use daily have big batteries (that I bought a year or two ago), are occasionally used unplugged, and are OK.

The old 600, 560 and 570 computer batteries are OK as far as i remember, though I seldom use them anymore.

[pgoelz]

Take your battery out if you leave the computer on constantly and plugged in. It gets the battery warmer than necessary, it also keeps the battery full charged which for whatever reason seems to be a bad way to store a battery.

Lithium cells degrade chemically from the moment they are manufactured. The degradation is directly proportional to the cell voltage and is therefore greatest when the cell is fully charged. The degradation is slowest when the cell is fully discharged (3V) but that is not an ideal place to store a cell because the cell degradation also increases below 3V. Any self discharge will therefore reduce the cell voltage below 3V and cause accelerated degradation and outgassing.

Your batteries last as long as they are guaranteed to, but leaving a computer on and plugged in with the battery for extended periods and seldom cycling it seems to be the worst thing you can do for a battery.

Fully charged is not good. "Seldom cycling" is in fact good. Lithium cells degrade during each cycle and do not require periodic charge/discharge to remain "conditioned" like some Ni based cells.

Paul

[pgoelz]

Take your battery out if you leave the computer on constantly and plugged in.

If you do this on a recent Lenovo Thinkpad (I think everything from the 60 series onward), and you happen to have a 65W PSU, you will be unpleasantly surprised by the fact that your CPU clock will be limited to the lowest possible setting, which will hinder performance in CPU-intensive tasks.

Whoa.... do you know if the X6* series actually draws power from the battery if the 65W adapter cannot supply 100% of the power it requires while on AC? Perhaps that explains my somewhat higher than expected "self discharge". I'll check but I think my AC adapter is a 65W. I assumed on AC, the battery was disconnected and never powered the machine.

Paul

[dr_st]

Whoa.... do you know if the X6* series actually draws power from the battery if the 65W adapter cannot supply 100% of the power it requires while on AC?

It shouldn't normally do it. I think it is just a precaution.

[Hauskaz]

I have an X60 Tablet with the 65W adapter and remove the battery all the time. SpeedStep still works just fine for me. I have it set to full CPU speed and it stays there regardless of whether or not a battery is installed.

As for the aftermarket battery thing, I have had this 8-cell battery off eBay for about a month now. So far it's functioned just fine, but one thing that really bothers me are these two bumps on the bottom of the battery that cause the tablet to wobble around on flat surfaces. It's incredibly annoying, even on my lap. There are two spots where it looks like rubber feet would go to make it sit stably but they are not present. Examine the following:

http://imgur.com/7ATAn.jpg

It annoys me enough that I wouldn't mind purchasing another battery. Are there any aftermarket ones that don't have these bulges on the bottom?

[dmatko]

well, im back to my power woes. i recently ran the "reset" procedure and ended up ??fixing?? my previous problem with my battery. by fixing, im referring to the Power manager>Battery Information>Battery details info resetting to "true" battery Full Charge Capacity readout. it looks like it was just a temp fix ((1 month)) and now its degrading again.

Previous Stats::
8 Cell
Manufacturer=Sony
First use date=2007-04 >>>> Manufacture Date=2007-3-26
Design Cap.=74.88Wh
Cycle Count=151
Full Charge Cap.=52.42Wh

ive never abused the battery, set it to do its own thing. the system is 2 years, 8 months old and im on the last leg of the batteries life. as i type this, im now getting the dreaded 38% charge to sudden 4% charge remaining dropoff. i fear its only a matter of time before this battery eats the big one. i will once again reset the battery to see what my new REAL full charge capacity is and report back with the new stats.

[John H]

I just received a new $25 Chinese copy 4-cell for my X60s, and they included a little "Instruction Booklet", which I actually read (for a change), and I found these interesting comments:

Calibrate your battery to optimize performance

Batteries must be calibrated from time to time to ensure correctness of time and percentage displayed on screen. You must implement a complete cycle of charging/discharging at the beginning of using the computer and repeat this cycle every two or three months.

[then they say to set power to allow rundown to zero and operate computer until it shuts off]

3. connect AC adapter and charge to 100%. before initial use of computer battery must be charged full and discharged for 3-4 times to optimize performance. The charging process takes more than 5 hours.

You must discharge battery to let computer power off, then charge battery to 100% to calibrate it. Then you can connect or disconnect AC supply anytime regardless of battery volume.

......................

3. Question : do I have to remove the battery when I use the AC supply?

Answer: ... we recommend you not to remove battery because this prevents data loss in case of interruption of the AC supply....perform a complete charging/recharging cycle every month to prevent the battery from losing activity.

4. Question: is the battery life reduced if the battery is charged before being exhausted?

Answer: the calculation of battery life is based on complete cycles of chargeing/discharging. The life of a lithium battery is generally 300-400 cycles. You do not need to worry whether the battery is charged for a cycle once the AC supply is connected. Only a complete cycle of charging/discharging counts as a cycle when calculating battery life.

Incidentally, this supplier did not include the plastic 10mm shim that's required with this battery. Fortunately I had a spare from an old dead battery. I suppose the battery will fit in place without the shim, though.

[pgoelz]

Had something interesting happen the other day to my two month old (4 cycles) non-OEM Chinese replacement battery in my X61s.

Laptop has been used on AC exclusively. Battery manager has been set to charge at 90% and stop at 95%. The charge level has dropped from 95% to 90% every five days or so and the charger has brought it back to 95% as expected.

The other day I needed it portable so I unplugged the power supply and started walking into the next room. Almost immediately, I got a low battery warning…. after less than 60 seconds on battery power.

I plugged back in and sure enough, battery manager said I had 4% left. This is after saying I had >90% prior to disconnecting the power supply. I plugged the supply back in and observed as it charged normally from 4% up to 95% over the course of a couple hours. Several times during the charge, I unplugged briefly and observed that the charge level was the same on AC vs. on battery.

After recharging I ran on battery for about an hour and the battery gauge behaved as expected.

I then performed a battery meter reset. At the end of the discharge cycle, when it said it had a couple percent left, the pack voltage reported as 13.44V (3.36V/cell). End of discharge on Li cells is 3.0V unless they have a built in safety margin.

Not sure what happened…. it was as if the pack was never charged and eventually self discharged to near zero even though the charge indicator and charge level both said it recharged each time it reached the 90% setpoint. It is also subtly different from the sudden death I experienced on my OEM pack. That pack went from maybe 80% charged to hibernate with no battery warning. This Chinese pack went from >90% charged to a low battery warning, so perhaps the failure mechanism isn't the same.

I am wondering if there is a flaw in the concept of these smart batteries. I think they are trying to keep track of the energy removed and replaced instead of simply looking at the pack voltage. Using the pack voltage as a charge level indicator is not as precise (but not that bad) but it would never need to be “reset” and it would never lose track of the state of charge. This could also explain the sudden death syndrome where the battery reported it was fully charged one moment and dead the next. We are all assuming it is a problem with the cells but what if it is a problem with the state of charge algorithm / circuitry?

Paul

[John H]

Had something interesting happen the other day to my two month old (4 cycles) non-OEM Chinese replacement battery in my X61s.
...
The other day I needed it portable so I unplugged the power supply and started walking into the next room. Almost immediately, I got a low battery warning…. after less than 60 seconds on battery power.
...
Paul

I had a similar experience with my X60s 4cell a couple months ago, and it returned to 'normal'. I wrote it off to a bad connection from not being inserted exactly right. Hasn't happened again.

But, meanwhile, the new chinese copy 4cell I got yesterday is only charging up to 76%. I've done two discharge/charge cycles.

I was sorta thinking that maybe the charge monitor didn't realize it was a new battery and mistook it for the old 4cell which was only getting up to about 60-70%. I'll check further, later.

It seems to me that X60s batteries are problematical. I've never had these problems with T60, T40 or earlier systems.

the Lenovo refurb prices are looking better and better.