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  1. Solarsail

    Index of 12 electric VTOL's

    Interesting. Let's say we use 72" propellers, and we have 6 of these. How many kW do we need to lift 450 kg?
  2. Solarsail

    Battery pack selection for self-launching glider

    @kubark42 Any new developments on this interesting project?
  3. Solarsail

    DeWalt 20V Max 3.0Ah Battery Pack Teardown & Analysis

    Mystery solved. The 3rd pin in the tool is the battery pack thermistor. As long as the thermistor is cool (i.e. resistance high), the tool is happy and works. Insert a 47 kohm resistor between B+ and the 3rd (thermistor) pin on the tool. Tool will not work without this resistor. Also make...
  4. Solarsail

    DeWalt 20V Max 3.0Ah Battery Pack Teardown & Analysis

    That is a good idea and exactly what I want to do. Could you please tell me the value of the resistor, and is it between the middle pin and ground or middle pin and B+? Thanks a lot Flippy!
  5. Solarsail

    Suggested battery capacity for 30 min flight?

    Three phase AC motors seem to have efficiency above 90%. But the propeller efficiency is probably 50% to 65%.
  6. Solarsail

    Blackfly AEV

    Well thanks, there seems to be some live flesh in the cockpit. The architecture is very creative, in that it is an eVTOL that does not require a tilting mechanism. I wonder about the stability of the aerodynamics. If the front (or rear) wing is affected by turbulence, there is no compensating...
  7. Solarsail

    Battery pack selection for self-launching glider

    Can you also plot the graph for 18s LFP and 16s LCO without diode? Could you also draw pack voltage on the chart? I wonder if you have included the internal resistance in your simulation. The LFP cells will have 1/6 of the IR of the LCO cells. I think this will assure that at high C, 5/6 of...
  8. Solarsail

    Battery pack selection for self-launching glider

    ....
  9. Solarsail

    Battery pack selection for self-launching glider

    For a hybrid pack, I would recommend 14s LCO and 16s LFP. 14 * 4.2 = 58.8 V. 16 x 3.7 = 59.2. If you parallel them without the diode, you get 58.8 / 16 = 3.675 for the LFP which is perfect. You can then use one charger, and two BMS. You can still use a bunch of diodes in parallel to isolate...
  10. Solarsail

    Battery pack selection for self-launching glider

    Well, if your concern is spontaneous combustion, then forget about the hybrid approach and you will have to stick with the A123 26650 (M1A). In which case 15 kg will give you roughly 1.56 kWh, and 47 kW. This should check all your boxes. These cells have high cycle life. BTW, you mention...
  11. Solarsail

    Battery pack selection for self-launching glider

    Packs should of course be removable, but not necessarily portable. Carrying them to charge makes little sense, even if they are 15 kg. Easier to pull a cable, or install an EVSE where the glider is parked. In a post above I calculated the power needed for 170 fpm climb. Let's say MTOW is 300...
  12. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    No problem Ennoid. I am out of here. I will just have to reply to that self-appointed thread pillock though. Haha, you are wrong. Put six 24S BMS in series. Now try to charge all with one 100V charger. You can't. It will blow up. If you knew how, you would have explained it. With a...
  13. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    Ennoid -- I found a method to serial string the BMS and charge all modules with a single charger simultaneously. No contactors, relays, or isolation needed. No timesharing required.
  14. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    Have you even read the thread? It is not Ennoid complaining. It is Flippy dictating what I can post and turning insulting and ad hom. I have no issues with Ennoid -- he has a great product and I plan to be one of his customers. I see serial insults by Flippy is not derailing the discussion...
  15. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    Where have I asked Ennoid to put the power supply on his BMS board. Please supply link. All I asked is to put the CCCV circuit consisting of a few capacitor and one inductor and one fet (the very last block of a charger) on the board and there is a very good reason for that if you are dealing...
  16. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    Don't have to be insulting or pedantic, if you have a point. Are you trying to make up for Flippy's gaffs? "Does not generate heat" is not the same as 0%. Any reading of the 2nd law will tell you that 0% is impossible. What I said obviously means that relative to the object at hand, the heat...
  17. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    If I read this correctly, you are suggesting a single BMS for the whole pack of 6 to 9 modules? With 1200V fets multiplexing the balance lines from each module and the power lines? That does not sound practical. If you are suggesting one contactor and one BMS per module, then I would like to...
  18. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    This is Flippy's comment. Is that what he said? 1) Again, I am not suggesting the power supply to be on board. I am just suggesting the CCCV function be on board! I can see that a 5A CCCV function on board may pose a fire risk to the BMS and the cells. But is it more than the BMS itself...
  19. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    Well, I am strictly speaking of your 24S model. It has a much wider market than skateboards. The skateboard market will be dominated by the Chinese in due course if not already. Of course there will always be a small DIY contingent like fish in a fishbowl. But the multi-module and EV market...
  20. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    You still don't understand the issue of charging serial modules, do you? An enhanced BMS is the right solution to this problem. I never said my pack is 900V. I said if you put 9 modules in series you get 900V. My pack is about 300V. It is most likely 2p4s or 3p3s. Each module being 100 to...
  21. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    Ahhhh ... so you admit to how confused you are and don't even know the basics of serial / parallel circuits. I think you should get some help as stuff that me and Ennoid discuss is way above your head. You have no solutions, except to rudely tell people to shut up. You don't even know what...
  22. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    Please stop being condescending. No need for that, in particular you have not understood the issue. What basics is it that I don't have a concept of? That electric potential results in a current? Please explain. Who gave you the authority to tell members here what they can ask or not? And...
  23. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    I think you are confusing a CCCV charger with a power supply. A 5A trickle CCCV charger can probably be built in under 100 grams. Why is this important? Because you don't want to be hauling 6 or 9 separate isolated charger boxes and all the associated cabling and connections when flying from...
  24. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    6 x 15 is fine for me and many others. Prove me wrong Ennoid. Can someone explain Flippy's comment? It sounds nonsense. I understand it is not an easy job to add four more ports to the 24s, but in case you have not manufactured the board yet, then it should still be in the realm of...
  25. Solarsail

    Open source BMS for 48V to 400V lithium-ion battery pack

    ??? :?:
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