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  1. R

    Are Prius cells worth anything?

    Ok, Thank, I let him know.
  2. R

    Are Prius cells worth anything?

    My son just picked up a wrecked Prius Hybrid. He said it is totaled. Are the battery packs worth anything?
  3. R

    I failed a kilovolt contactor.

    https://www.digikey.com/en/products/detail/te-connectivity-aerospace-defense-and-marine/5-1618388-8/2362831 The contactor runs directly off of 48v pack. Max voltage is about 54v. Spec says 60v is max input. I noticed the contactor was running very warm. I let it go and after 3 months the...
  4. R

    Seplos BMS "Output Short Circuit Protection"

    Yes, I understand that it is entirely possible to design a BMS that could defeat the hardware overcurrent protection. My point is that it is not a good idea to give a microprocessor based circuit the ability to turn off hardware over current. Over the years power engineers have been reluctant...
  5. R

    Can someone layman math me on PWM controllers?

    Are you all set with the math now? If not I can put page together and post.
  6. R

    Can someone layman math me on PWM controllers?

    Most charge controllers use the Buck topology. Current out of the controller can be quite a bit higher than the input current. There is plenty of application notes concerning the buck controller.
  7. R

    Pre-charge resistor seems crazy

    Inductor may cause other problems
  8. R

    NEC wire color Q

    I was going to ground it, but I will rethink it. Thanks for the input.
  9. R

    NEC wire color Q

    Yes. I was aware of color requirement, but could not find clause again. I'm in the 2014 NEC. I ordered the correct color wire -white- but they shipped black.
  10. R

    Why such puny active charge balancers?

    I don't know exactly what it is other than a commercial application. I think active deign will be needed.
  11. R

    NEC wire color Q

    I read in NEC that grounded array systems use white for the negative. I can't seem to find that clause. Anybody know where it is?
  12. R

    Fuse Types? Why is it a big deal?

    Fast fuses can also keep components from rupturing during a supercurrent event.
  13. R

    Buried line from panel to house

    NM is Southwire non-metallic conduit-down 18". 1" conduit with 5x #10awg. 2 Red, 2 white and a green. White is for grounded PV system. Green not required, but thought it might come in handy to tie MOVs to service enterance ground. Current is about 17amp in the #10 so I am not concerned with...
  14. R

    Buried line from panel to house

    Yes. I hope I don't have to do anymore digging after this! But if I do conduit will help
  15. R

    Buried line from panel to house

    Thank you - the comparison should be just what I need. Yes, conduit is the flexible NM type from Southwire.
  16. R

    Buried line from panel to house

    I am picking out wire for underground run. I think either one of these would fly. The stuff is a little pricy - glad it's only 150' run. I just want to get some more eyes on it before I pull out the credit card. I will probably go with nassaunationalcable.com as they are close. Comments are...
  17. R

    Why such puny active charge balancers?

    Do the smaller passive balancers work ok? I have to wonder if a few hundred ma of balance current is enough to do the job.
  18. R

    Precharge circuit.

    Yes, looks like about 20W to keep them nice and toasty. A series resistor might tame that down some.
  19. R

    Store temperature in ice?

    Why use ice? Because water is inexpensive? Why not use liquid Sodium or parafin?
  20. R

    laying out pcb for inrush limiter

    I recently did a 1000A/600V solid state DC breaker for a client. I used a fet to do inrush. It is actually quite easy. The gate voltage is controlled through a stiff source. The drain current through the fet is controlled as a function of the voltage across it and the heatsink temperature...
  21. R

    laying out pcb for inrush limiter

    It is not just the contactor. BMS and fast fuse can also be problems. Do you have link to the solid state contactor?
  22. R

    Overhead wires - panels to charge controller

    Here in New Hampshire (The Granite state) we have a lot of ledge to deal with so running wires underground may be difficult/impossible. To complicate matters I have a large stone wall between point A and point B. I am thinking a combination of underground and overhead. I have two panel...
  23. R

    Batteries going out of balance while charging.

    They charge each pack up to full so that they are top balanced at the end of each charge cycle. The Boeing batteries are K2 cells. NMC if I recall correctly.
  24. R

    Batteries going out of balance while charging.

    I think you mis-understood my question. If each 12v pack has it's own charger then the packs will never be placed in parallel. I bring this up because we took that topology a step farther with the airliner packs. We did a large pack for Boeing. 8S/26P. We used 8 individual chargers so never...
  25. R

    Batteries going out of balance while charging.

    Can you use two chargers? Scrap the 24voltish charger for two 12voltish chargers.
  26. R

    Why not to use Daly BMS with MPPT controllers

    Yea. would need a minimum load. Vicor produces buck converters that are open loop. They are called intermediate buss converters.
  27. R

    AIMS charger: observations and quiescent power draw

    Have you taken a look at the input current waveform of the charger? I am curious how close it resembles a sinewave. There should be a fast acting fuse between charger and cells. Battery University has some obnoxious engineers who think they know more than they do :)
  28. R

    Class T vs ANL fuse

    I have DC rated breakers that should clear anything but a short. The arcing is taken into account when the breaker is designed. The class T will clear a short circuit before the transistors blow into fragments. I've designed large 3 phase industrial inverters for a long time. I get the point.
  29. R

    Growatt, tell me I'm wrong

    i have seen Growatt shut down on high voltage without any indication what happened. I queried sig solar but they had no clue. They asked for a bunch of useless information. I told him I thought it was the power supply shutting down because of high voltage. Changed over to LiFePO4 and prob...
  30. R

    Class T vs ANL fuse

    I used a class T to clear under short circuit. I put a breaker in series with a lower value to protect the wire. The only way the class T will ever clear is with a short circuit. That is just another way to do it with maybe a little more margin before the expensive fuse clears.
  31. R

    EVE 280Ah cells. are they stock USA?

    Is anyone stocking the EVE 280 cells or comparable here in USA?
  32. R

    60mv Voltage deviation one cell

    maybe better to run them up and down a few cycles before you add balancer.
  33. R

    Inverters

    https://www.meanwell-web.com/en-gb/dcdc-converters/24_-_1,24/all-output-current-a/all-output-power-w/12/ l like the Meanwell products very much. If you haven't picked out a 12v/24v boost converter take a look at these guys. These products come from the good China - Taiwan. (EDIT: I have...
  34. R

    OK ... Which Resistor to Use?

    Yes, the resistor should be sized for the 20 or 30 watts or so that the power supply will draw before the inverter turns on. If the resistor is too large in value the power supply will blink - as the bus voltage decays. In other words the reason the power supply blinks is likely caused by the...
  35. R

    OK ... Which Resistor to Use?

    I expect your power supply is booting up and causing blinking. Try the 4 ohm resistor. Power supply should come up and stay up. Then it is time to short out the resistor. If you have an auxillary power supply output on your inverter you could use this to pull in a relay and short charge...
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