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  1. L

    advice on DC relais

    Hello, my e-scooter is based on 20s 40AH LiFePO4 prismatic cells and I charge it at 5A. I have an overcharging protection which I designed which is based on a relais between the battery and the charger which disconnects as soon as 1 cell reaches 3.6V. Unfortunately the relais contact kind of...
  2. L

    long charging cables

    my e-scooter is based on 20s 40AH LiFePO4 prismatic cells. Currently I charge it in the garage and so the external charger is very close with ~50cm cord. But I am moving to a new place with not possibility to have electricity in the garage, so I am thinking to keep the charger in the house and...
  3. L

    Connector for battery main leads

    Agree: better to connect the device in need directly to the output of the inverter. I still need your advice about the connector type between scooter battery main leads and inverter input. Requirements are: - safe so that the side connected to battery doesn't expose live wire - easy to attach to...
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    Connector for battery main leads

    I have a e-scooter fed on 20S LiFePO4 40Ah battery pack. I am thinking to use such power as a backup in case my house suffers from power outage from the grid. To do that I need: - a safe and easily accessible connector on the scooter connected to the battery main lead for 72V - a converter from...
  5. L

    Which battery chemistry for extreme climates?

    Winston LiFeYPO4 Battery are supposed to be particularly resistant at low temp thanks to yttrium. I have no objective data to prove it though, just reading from their website
  6. L

    Balancing a 20s battery back

    @999zip999 What is a battery nanny?
  7. L

    charge as you go

    Today I experienced an interesting phenomenon.... My e-scooter is powered by a mix of Winston 40ah and Wina 50ah LiFePO4 cells in a 20s configuration. I had a ~15km ride then I parked the scooter for the night at close to freezing temperature; then today I picked up the scooter and checked cell...
  8. L

    overdischarged wina LiFePO4 50ah cell

    Anyway even after this bad experience I am still convinced that it is better without BMS. Lets say that I destryed this cell, this is 60 Euro but I managed to get home safe and fast with my scooter even with this single cell at 0 Volt. If I had the BMS, the scooter would had stopped in the...
  9. L

    overdischarged wina LiFePO4 50ah cell

    So I removed immediately the cell that went down to 0 Volt; it is a wina lifepo4 50ah. It is also swelling. I managed to resuscitate it and so I charged it 10ah which is 20% of capacity and it held the charge for 1 week then it went down to 2.7Volt. Then I tried a full charge and I could push...
  10. L

    overdischarged wina LiFePO4 50ah cell

    Today I badly screwed up.... No BMS and overestimated my pack charge! On the way home I was noticing lack of thrust in my scooter powered by 20s LiFePO4. As soon as I reached home, I measured that one cell was 0 Volt, this is a cell I knew it was the weakest link. Immediately I put the pack on...
  11. L

    SuperCapacitor

    Today I put my idea to a test connecting the super-capacitor in parallel to the battery main leads: it didn't make any difference. So the problem is that when I ride, especially during acceleration or deceleration, the individual voltmeters that I have on every cell randomly show abnormally low...
  12. L

    greasy orange dirt

    This substance doesnt smell and in some places it is christallized looking like cane sugar. So consensus is for a leak. The cell is still performing well. Do you think there is any security concern? I dont have BMS but rule out any overcharge because I have developed a system that cut off...
  13. L

    SuperCapacitor

    Experts, on my e-scooter I have connected a cell-checker on every battery which give me real-time voltage reading. At times during acceleration, but also deceleration, they give very low reading, kind of unrealistic such as 2.6V, but only for one sample and then go back to normal. I suspect this...
  14. L

    greasy orange dirt

    Experts, it has been one year since I put version 2 of my Elettra2500 e-scooter on the road and now I have decided to open it for a thorough check-up. All looks good apart from a greasy orange dirt on the top of one of the Winston 40ah cell. Do you have any idea of what it can be? And above all...
  15. L

    voltage surge after vacation

    My mad! I made a typo in my first post: where I typed 2.28 I meant 3.28, 2.30 -> 3.30 The voltage reading is accurate, I measured with a second meter cell #14 and measurements are ok: 3.30 Volt idle and 3.6+ Volt under charge. This morning I gave it another try: - started with idle cell #14 @...
  16. L

    voltage surge after vacation

    I had a nasty surprise coming back from holiday..... My scooter is based on 20x winston 40ah LIFeYPO4 prismatic cells in series; before leaving for holiday I left the battery at roughly half charge, in pretty much balanced state and disconnected the main leads. After roughly 5 weeks I...
  17. L

    cell checker draw

    Experts, I am using three of these cell-meters to keep my 20S 50Ah LiFePO4 always under control. It has a ground pin and 7 cables to connect to a series of 7 cells to provide individual voltage reading: It works pretty well indeed. Considering a current draw of 35ma on the ground pin, I...
  18. L

    hellp with high-voltage-cut-off

    need help 'cause I am stuck with something I really cannot understand!! Last year I built a balancing system based on TL431 low voltage regulator for my 20S lifepo4 pack, so I bought 25x TL431 from mouser and all went well. Now I am building a high-voltage-cut-off also based on TL431 and very...
  19. L

    Disposing of LiPo

    want to revive this thread where latest post is two years old....hoping to hear there is a way to make good use of my fat old cells. So, now that my second build is on the road with a mix of winston, sinopoly and Wina LiFePO4 cells, I have twelve Wina 50ah cells from my previous build which are...
  20. L

    advise for opto-coupler

    I want to build an over-voltage-cut-off for my bulk charger for my 20S LiFePo4 pack. I am thinking of using TLV431 voltage reference for every cell: the TLV will drive the optocoupler. The first optocoupler to fire will switch a flip-flop which will disconnect the charger. I need advise on...
  21. L

    Did i fry my battery?

    Before the winter I put every cell of my 20s LiFePO4 pack in storage mode by pulling power down to 3.2V. A couple of days ago I wanted to revive the pack and started a bulk charge monitoring every single cell voltage every roughly half an hour. It all went well for 2 hours with all cells pretty...
  22. L

    under-rated charger: is this a scam?

    Experts, I recently bought this charger which is rated of output current of 1 Amp, but today I connected it to a LiFePo4 Wina 50ah cell and all that I can see is a miserable 0.6Amp :-( http://www.ebay.it/itm/221876225877 As you can see from the attached photo I just connected the charger to the...
  23. L

    concurrent/independent charging

    Experts, I don't know if concurrent or independent charging is the right term for what I am going to described, the fact is that neither serial nor parallel applies.... My new electric scooter will be based on a 20S LiFePo4 battery pack with following cells: - 8 winston 40ah brand new cells - 4...
  24. L

    pressure or not?

    How can it be explained why the LiFePo4 cell excersise pressure at high current? Is this related to charge, discharge or both? Thanks, Luca
  25. L

    pressure or not?

    Experts, after ending up with 12 badly swollen cells out of my 20 pack of Wina 50Ah LiFePo4 I have learned the hard way that this type of cell must be mechanically contained in order to put a uniform pressure to avoid swelling. I wonder if I should do the same for winston 40 AH or Sinopoly 40AH...
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