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DIY Solar panel setup on a budget

Discussion in 'Hobby Engineering' started by Mathuisella, Oct 15, 2013.

  1. vk2fro

    vk2fro Member

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    Madi is good, I have watched a few of her videos. In one she even toasted a class T 150A by accidentally shorting that 280Ah 48V bank :p
     
  2. Current

    Current Member

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    So, how are those super capacitors going
     
  3. Recharge

    Recharge Member

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  4. Recharge

    Recharge Member

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  5. ernie

    ernie Member

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    Seem like a video to support his own higher prices.
    The key point is that a "grade B" cell is for all intents and purposes, is indistinguishable from a "grade A" cell, and still gives the end user thousands of charge cycles.

    - Ernie.
     
  6. Recharge

    Recharge Member

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    he even said you'd not notice until well after warranty ran out. heh
     
  7. Sunder

    Sunder Member

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    I actually don't know what the cut off is between Grade A and Grade B cells, but I was playing with hobby LiPos about 12 years ago for electric bikes. Back then BMSes existed, but not really for Hobby LiPo. You actually balanced the battery during (or rather at the end of) each charge.

    This gave you visibility of stuff the BMS normally hides from you. The premium stuff you basically just charged and it was done. The balancing phase would take a couple minutes at most. The cheap LiPo would drift quickly. You'd charge, and it would spend 10-20 minutes balancing. After a few months, it might spend hours balancing.

    It's not just the balancing time though. Most BMSes top balance, which means when one cell reaches "full" it bleeds off a bit of energy and and keeps charging. Then two cells hit full, and it bleeds them off etc. Which means one weak cell in say an 8P (24v LiFePo4 battery) means that 7 cells are wasting energy and being cycled unnecessarily. It will kill off the pack faster.

    Not 100% defending him. Almost all my batteries are using cheap Chinese cells. But he's got a point. I now buy 10-20% extra cells and I go through a couple weeks of testing and discard both weak and overly strong cells before assembling the actual pack. Having cells which are not consistent is a real problem that will not be visible for the first few months at least, but that 10 years you were expecting might only be 3. And that 100Ah you were getting day 1 might only be 80Ah after a few months, with a strangley low round trip efficiency (because the BMS is constantly burning off excess energy to balance).
     
  8. Recharge

    Recharge Member

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    hmmm informative and interesting to learn.
     

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