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Thread: Lithium Titanate Oxide Cells

  1. #11
    Senior Member John_Koorn's Avatar
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    Great write up Bob, thanks for sharing. Will be watching this thread with interest

    John K.

  2. #12
    Thanks John,

    Today I am back with some test results. What I have done is run my big machine in generator mode at a high input (around 7.5A) to charge the cells pretty quickly. So that we could have some sort of equality in gauging the results I did three runs each consuming 3AH into the machine. I did a discharge of 3A, 1.5A, and .75A so that we could have a look at the performance of these cells under various loads. I did say in the video a few times that this is not meant to be about looking at the charging efficiency of what I was doing. I ran this way simply to throw a large current at the batteries but I say it so that people not familiar with the machine will not misunderstand what I am trying to show here. I think I could do much better in fact if I did tune the machine to a more reasonable level but that may be for a later post.

    What I find very interesting about these runs was that I used the same amount of power to charge each time so we sort of know the battery pretty much was brought to the same level but on the discharge we got pretty much the same AH out at each rate, only the time varies because of the load current. My experience with regular batteries would tell me not to expect nearly the same output energy from a 3A pull to 10v as a .75A pull to 10v. I would expect to get quite a bit more from the lighter load but that is not the case in this test scenario at least.

    These cells are pretty amazing but I am not familiar with them yet. I do not know the best way to charge them or how to tune a machine for best performance on them, they are far different from LA in how they behave. I have no doubt that they can be fast charged with lots of current though. If they truly have the cycle life they claim then I am very impressed by them.

    Here are some charts of the run. First the CBA showing the three discharges:
    LTO_3ahIN_CBA.JPG


    And this was a chart running on a different meter showing both the charge and discharge. The primary was unhooked during the discharge cycles so that is why it goes flat on the chart.
    LTO_3ahIN.JPG


    And finally a video of this being done. It is kind of long, sorry about that.

    https://1drv.ms/v/s!AmzmftzD-V0mhneDlMLqkpcXKc4i

  3. #13
    Senior Member John_Koorn's Avatar
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    Hi Bob, looks interesting. I know absolutely zero about this type of battery but from the charts it looks like they are undercharged. I would've expected more than ~1.5Ah out of a new 2.9Ah battery.

    I'm not sure if pulse charging them is a good idea either. For example, I am working with 18650 Li-ion cells which have a specific CC/CV charging algorithm. At the moment I am charging them conventionally and logging some charge curves, just so I can get a baseline. Next step is to use them in a 3 battery switch to see how they perform (or not) there. I'm not planning at all to either radiant or capacitive discharge methods on them. Not suggesting you should do the same, but worth thinking about.

    John K.

  4. #14
    Quote Originally Posted by John_Koorn View Post
    Hi Bob, looks interesting. I know absolutely zero about this type of battery but from the charts it looks like they are undercharged. I would've expected more than ~1.5Ah out of a new 2.9Ah battery.

    I'm not sure if pulse charging them is a good idea either. For example, I am working with 18650 Li-ion cells which have a specific CC/CV charging algorithm. At the moment I am charging them conventionally and logging some charge curves, just so I can get a baseline. Next step is to use them in a 3 battery switch to see how they perform (or not) there. I'm not planning at all to either radiant or capacitive discharge methods on them. Not suggesting you should do the same, but worth thinking about.

    John K.

    John I said in the video but you may have missed it, they are not fully charged. These cells go to 2.8v per cell full so 16.8 would have been full, we were at about 14.6 in those runs. Now with that understanding think of what it says about performance. Even half charged those things put out 3A continuous. When I am using them for actual loads I charge them to about 15.25V which also is not full but I get a lot more out of them. I cannot go higher because the inverter will not take the voltage.

    I am with you on the pulse though. I read an artical somewhere that I need to find again that actually said the LTO cells do better on a pulse but I also know Mr. Bedini said it was not a good idea on other lithium cells so I'm not really sure but you are right to caution against it. I am about to install a 400 watt panel array to replace a few individual 50 watt panels I have so when I free up one of those 50's I am going to try charging these cells from that instead. I have a little buck converter that I can dial in to say 16v and hook to them.

    On a side note I am also working with some 18650's. I am about to put together some large packs with them. I saw guys making their own versions of tesla walls with them and it sparked my intrest. I am not doing anything that large but I have 200 cells that I plan to make into either two or four packs. I will post about those separately when I get working on them.

    I will also be posting very soon about my new Edison cells that I just got. I have a bunch of 10AH NiFe to play with. Thanks for your input.

  5. #15
    Senior Member John_Koorn's Avatar
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    Haha Bob, you got me. I should've watched the video first, but I was waiting until my lunch hour to do that.

    Wow, those cells have some pretty awesome power density. They do "fall off the cliff" pretty quickly at around 13v though. I think they will do great on solar. If you have a charge controller/inverter where you can program the min/max charge and discharge voltages you should be set.

    Good to hear you're working with 18650's too. I joined a DIY Powerwall forum where some guys are doing some amazing things. I'm not going that big either (yet, at least) but it is interesting. Maybe we should start a thread on that, don't want to hijack your thread here.

    Looking forward to hearing about your Edison cells too. I have a few that I bought second hand, I think they were used by the Japanese in the war. Start a thread on those too and we can share...

    John K.

  6. #16
    Hi Bob,

    Just watched your video. Very impressive performance out of these little cells!

    You remarked at one spot in the video about the wiggly graph curves with the CBA. I was having the same problem with my CBA and the voltage was lower on the chart than a separate volt meter directly across the battery. Turned out to be heating and voltage drop on the input connectors to the CBA. Someone else posted earlier about this happening to theirs as well. So I removed the connector and soldered the input wires directly to the contacts in the CBA. That cured the problem and I now get smooth curves and more consistent results.

    I thought at first that the CBA's internal circuity was going bad. Turned out it was only the connectors, which showed no visual evidence of making a bad connection.
    Gary Hammond,

  7. #17
    Quote Originally Posted by John_Koorn View Post
    Haha Bob, you got me. I should've watched the video first, but I was waiting until my lunch hour to do that.

    Wow, those cells have some pretty awesome power density. They do "fall off the cliff" pretty quickly at around 13v though. I think they will do great on solar. If you have a charge controller/inverter where you can program the min/max charge and discharge voltages you should be set.

    Good to hear you're working with 18650's too. I joined a DIY Powerwall forum where some guys are doing some amazing things. I'm not going that big either (yet, at least) but it is interesting. Maybe we should start a thread on that, don't want to hijack your thread here.

    Looking forward to hearing about your Edison cells too. I have a few that I bought second hand, I think they were used by the Japanese in the war. Start a thread on those too and we can share...

    John K.
    Yea I know in hind sight it was a little goofy to present these cells with half a charge as I did. I will make some full charge curves some time later and I might try charging on one of my SS builds instead. About the cliff at 13v, I noticed it too and it seems to be about 13.25 or so. Now I could remove one of the cells to bring that down but I did the 6 cells thinking that if I do not have to charge fully then it would be easier on the cells over the long haul. From what I know about any lithium it is the upper voltage that wears them out the most. Kind of the opposite of working with LA where we intentionally push them high.

    You have original Edison cells? Wow if that is what you have then please do post about them, or join in once I get a thread for mine started. I do not have the originals, I have the new Chinese plastic version. I had read all about the originals and wondered how that technology could have slipped away. The plates are not even part of the active material as I'm sure you know so other than changing electrolyte or physical damage there is nothing to go bad on them. Supposedly they will last 30k cycles or more.


    Gary,
    Thanks for the tip. I think I remember you talking about the deans connectors awhile ago too. I may have to do as you suggest. I have used those same connectors on my machines for awhile now and have not noticed any issue but on those I soldered them myself. Do you think it is the actual contact point in the connector or could it be a poor solder job on the CBA? I know that if you do not solder that little blade on really well these connectors can perform horribly. I found the trick is when soldering it on to strip the wire all the way back to be even with the plastic case and then solder all the way back to that point. It makes the whole thing nice and stiff so when you go to push the pin up in the housing you do not get any buckling which leads to poor connections.

  8. #18
    Hi Bob,

    Quote Originally Posted by BobZilla View Post
    .....................................Gary,
    Thanks for the tip. ......................................... Do you think it is the actual contact point in the connector or could it be a poor solder job on the CBA? ...........................
    I really can't say for sure, because I don't remember seeing any evidence of either arcing or poor solder joints on the contacts. It's been awhile since I corrected the problem by soldering the wires directly to the contacts inside the CBA. What I do know is that it has worked flawlessly since I did this!
    Gary Hammond,

  9. #19
    Anyone remember this old setup?

    SSBranchCircuit.jpg

    I have not run this SS in a few years. I got it out and re-did some of the wiring. It's running in branch output.

    In the picture if you look close you can notice the LTO batteries on the floor there. I want to do a post on these two starting from the same charge state but in this charge one was already way ahead when they started. I went back today and watched Mr. Bedini's videos in the SH Oscillator thread and this machine was what I had built back then trying to replicate his branch circuit. Damm I miss him and I didn't even know him.
    Last edited by BobZilla; 12-10-2016 at 10:35 PM.

  10. #20
    Hello group,
    I did a charge run on the machine from the last post in branch mode. It did very well but I am not posting the chart because I had to stop charging several times and then come back and turn it back on. These batteries are so small that I could not leave it running while away for fear of over charging so it was not a clean run. I will try to do another one and capture it for you to see all in one shot though.

    I can post the discharge from that run however. What we see here are both batteries connected in parallel to double the capacity. They were charged up to about 16.7v which is basically a full charge for a six series (2.8v per cell). These are supposed to be 2.9AH cells so I actually got more out than the rating. The discharge was done at 1A.

    I don't like posting this without a charge run to go with it but at least you can see the curve on these things.

    LTO_parallel.JPG

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