Hi, Joe. On 27/03/17 16:01, Joe wrote: >>>> I remember that when I bought this battery, I was advised to leave >>>> the charger plugged in for a little more than an hour after the >>>> charging level reaches 100%. And for the subsequent times, try to >>>> avoid having the charger plugged in when the battery charge level >>>> reaches 100%. So I was following that criteria. What do you think >>>> about that? >>> I would hesitate to contradict a supplier, but a lithium battery >>> charger should not permit overcharging. It *must* not, as there is a >>> serious risk of fire or explosion, not just a reduction of life as >>> will occur with other types. The maximum charge voltage must be a >>> fairly precise 4.20V per cell, and really the only practical way to >>> charge these batteries is to use one of many specialised integrated >>> circuits designed to do just that. >> I think he made that recommendation about disconnecting the charger >> when the charge reaches 100% because he thought otherwise would >> affect the battery life. > As I say, it shouldn't. Lithium chargers don't provide a continuous > trickle charge. Various sources on the Net claim that life will be > longer if you never fully-charge the battery, but with a laptop, you're > always going to be looking for maximum running time. Supposedly it's > best to store the battery for long periods half-charged, but then > whenever you need to use the laptop, you have about an hour to wait for > full charge. You can't win. Thank you for these observations. >> Very interesting what you mention in these paragraphs. So in this >> case a measurement on the battery would have to give a voltage >> between 3.0V and 4.1V per cell if the battery works correctly? > Pretty much. The discharge protection should come in about 3V, but > might allow discharge a bit further. There is little energy left in the > cell at 3V. Here's a set of discharge curves at various currents: > > http://www.richtek.com/battery-management/img/battery-discharge.png Thanks for the clarification. >>> Yes. The problem is that it's not possible to rig up a quick >>> charging test for lithium, or a dummy battery load to check the >>> charger. With other technologies, a current source powered from a >>> higher voltage, with a voltmeter, would give some idea of the >>> battery state. >> Do you think the problem might be in the charger? > Yes, certainly. That's why I said it's difficult to know what's going > on without either a known good battery or a known good charger. You'd > better hope it's the battery, as that is easy to fix... But in any case, whether the problem is in the charger or the battery, I suppose that to solve the issue I will have to change the part. I suppose if the problem is in the charger, the cost will be less compared to a battery. >> At the beginning I had thought that maybe not since the notebook >> works when it is connected. Although perhaps it could be that if the >> electronics that manages the phases that you mentioned before is >> physically in the charger, the problem is in the charger. > The external power for the laptop is separate from the charger > electronics. The charger must supply a defined current, and if some of > this were diverted to run the laptop, it would be difficult for the > charger to monitor the state of the battery. So the external power is > supplied to two paths, to the laptop electronics and to the charger, > with laptop power being taken from the battery when the external power > is not present. If I understood correctly, I think that here you was suggested that it could also be a problem related to another internal component of the notebook that diverts power from the charger to the battery for its charge. >>>> Perhaps the ultimate test is going to a business where they have >>>> original Lenovo components, ask them for a new battery to test it >>>> at the moment with the notebook and, if all goes well, then buy >>>> it. >>> Sadly, that's the only real test. >> >> Earlier I telephoned the supplier where I bought this battery and he >> offered to test (without cost) my notebook with a new battery for a >> full charge cycle to make sure the problem was in the battery. > You are lucky. Many suppliers have neither the equipment nor the > willingness to help after the warranty period. Yes, it is good that they have had that good predisposition. In fact, when I talked to them on the phone, I told them that if I saw that when I plugged in the charger, the charge led behaves correctly, I could assume the issue was on the battery and that would make the test a little quick. But the person I spoke insisted on doing a full load cycle so they would be reassured that everything works fine. Going there and back takes me at least three hours (plus the the time awaiting for full charge of the battery) so the trip would be a pain (not to mention go to leave the notebook for the test, go back, and go later for it). The alternative is that while the battery is charging, I stay there using the notebook to take advantage of the time :-) >>> Something worth trying if you have access to a voltmeter: the >>> battery pack will have at least three terminals, maybe more, and a >>> voltage should be measurable across two of them. The voltage value >>> may show a missing (shorted) cell. Discharged as far as possible, a >>> lithium cell should be around 3.0V, and fully charged, 4.2V. The >>> battery should be marked as to how many cells it contains. If you >>> get a reading of less than 3.0V per cell, there is almost certainly >>> a dead cell. Probably you won't get a conclusive reading, if the >>> charger thinks there's 38% charge, then the volts per cell is >>> probably higher than 3.0, which it can be if one cell is missing >>> but the others are well-charged. >> I have a multimeter, so I could try that. This is a 6 cell battery. >> Here [1] are the specifications of Lenovo in case this is useful. > So you're looking for 18V or more. But five well-charged cells will > give you 20V... This is very weird. I do not had any reading. The slots of the contacts are very thin (attached image) and I tried placing the probes horizontally, vertically and trying several combinations leaving one probe fixed and changing the position of the other, but without differences. I tried with the scale of 20V and then with the next one, but I did not have readings in any case. In fact later, to test the operation of the multimeter, I measured the charge of an old 9V battery and got a reading of 2.10V, so I do not think it's a problem with the multimeter. https://ibin.co/3H7uKkzIf4Ui.jpg Thanks for your reply. Kind regards, Daniel
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