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    Are these lead acid batterys suitable to build a powerwall with?

    I dont see any severe problems in using these batteries. If they are only 3 years and have never been deeply discharged these sealed Lead-Acid batteries should be good to go! The worst enemy of LA is to deeply discharge them and keep them in discharged state for longer period. Then hard...
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    DC IR VS AC 1kH IR measurements

    @Wolf, if you are still looking for some logic-level Mosfet that will switch completely on at low Vgs (gate-source voltage) you have to look for the least Vgsth (gate-to-source threshold voltage) which is the voltage the channel starts to open (but still is not fully open). I collected a few...
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    Cause of heater-effect at around 4.0V and high self discharge at full voltage (4.2 ... 4.0V)

    Yes, your curve is very impressive and i am far behind your testing methods and experience with so many cells. I tested maybe a few hundred cells (600...800) so far, and my testing of IR is poor and only DC-method with very poor replication rate and accuracy. My best-IR tested cells are around...
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    Cause of heater-effect at around 4.0V and high self discharge at full voltage (4.2 ... 4.0V)

    Thanks for joining in, Wolf, and sharing your ideas. Honestly i doubt that the IR has really much to do with that abnormal heating at around 4.0 V when charging. I have many old cells with quite high IR (although i only tested them with the DC method, where the IR readings are always higher...
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    Cause of heater-effect at around 4.0V and high self discharge at full voltage (4.2 ... 4.0V)

    @Oberfail: thanks for sharing, very interesting. Prof. Jeff Dahn is talking about LCO-cells and special additives ("violin carbonate"?) that helps against the heating of LCO-cells. Not sure if heaters are mostly LCO chemistry - will have a look after that. I have the same experience with...
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    Cause of heater-effect at around 4.0V and high self discharge at full voltage (4.2 ... 4.0V)

    Hi all, you probably all know the problem of so-called "heater cells" that tend to get (very) hot when charging above a specific voltage? Typically this voltage (when heating starts) is around 4.0V - sometimes a bit lower, rarely higher. On the other hand there are cells, that don't keep their...
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    What is the average impedance of new 18650 cells?

    And if you talk of cell impedance or inner resistance (IR or Ri) you would normally have to specify if you refer to AC IR or DC IR - that can be (and normally is) a big difference! Actually the IR depends on several parameters: the frequency of measurement and the time of the load (AC or DC...
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    Grad Student Looking for Research in used Lithium 18650 Cells

    Hi Wolf, thanks a lot for this very detailed explanation and enormous data collection! Seems you really spent a lot of time in this investigation! The deviation from AC IR to DC IR is quite different with a broad spectrum. In general your finding with DC IR is ≈2X that of AC IR is true in my...
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    Grad Student Looking for Research in used Lithium 18650 Cells

    Hi Wolf, i absolutely agree Ri is an important parameter when investigating a cells SoH. Until now i did the Ri measurement manually with a classic DC-load method: Read Voc and read V(loaded) and calculate Ri using Ohms law - its quite simply. The disadvantages of this classic DC-load test over...
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    Account disappeared - and all my postings?

    O.k. i posted a link to a video of Andreas Schmitz, known as the Accu doctor in Germany. He invented a tool, called Lili, that tries to predict the condition of Li-ion cells (18650 typical used cells from laptops or ebikes) by some easy to elaborate data, e.g. data sheet of the cell and its...
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    Account disappeared - and all my postings?

    I still don't get why i was caught in "spamming" - what was wrong? Seems you still don't know? it just happened on the first day after opening my account - not a good start. Thats the first time ever, i had such an experience. I dont understand the post above - what can we learn from it? I am...
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    Account disappeared - and all my postings?

    Its not really satisfying when you cant find the cause of the problem. I am not aware of saying anything shabby or offensive, so i dont know how to behave the next time. When you take time to explain your experience and everything is gone without an obvious reason - thats no fun. So i hope you...
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    Account disappeared - and all my postings?

    I will think twice before i post here next time and spead all my ideas and experience. Quite dissapointed about that time waste ...
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    Account disappeared - and all my postings?

    Hmmm - but some with quite a lot of text. Maybe that was the problem? you should definetly check your anti-spam AI, seems over excited...
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    Account disappeared - and all my postings?

    My postings from yesterday are still missing. I posted in the Thread " Grad Student Looking for Research in used Lithium 18650 Cells" and some others - all missing I really wonder what triggered the spam??
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    Account disappeared - and all my postings?

    Why was there spamming? Too many posts? Maybe 3 or 4.
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    Account disappeared - and all my postings?

    The same as now: 'paddy72' - with exactly the same data...
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    Account disappeared - and all my postings?

    Hi all, i already registered yesterday and posted a few posts, but in the evening my account had disappeared suddenly!? I was not able to log in nor was my username (the same as now, "paddy72") found by the machine. Also all my posts seem to have disappeared. What happened here???
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