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Building a battery Pack

Post in 'The Green Room' started by mass_burner, Oct 31, 2013.

  1. jharkin

    jharkin Minister of Fire

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    Not suprising, the load on the battery will ocnfuse the microprossessor in the charger and it wont know when to switch from bulk to absorb, etc.

    A system like your cars charging circuit can handle charging with a load because its a simple fixed voltage source. It just keeps the battery at 14.5 volts and supplies as much or as little current the battery will take at that voltage. As the battery gets full the current will just taper off to zero.

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  2. mass_burner

    mass_burner Minister of Fire

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  3. mass_burner

    mass_burner Minister of Fire

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    this charger recommends 6 - 50 Ah batteries. if i'm charging my battery pack, wouldn't that be a 105 AH battery. why does the charger care about the AH of the battery?
  4. woodgeek

    woodgeek Minister of Fire

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    because the trickle current is proportional to Ah.
  5. mass_burner

    mass_burner Minister of Fire

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    so could i use this charger on my battery bank as a whole?
  6. mass_burner

    mass_burner Minister of Fire

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    i think this is it: for AGM, do not exceed the C/3 rule:

    C (AH) / 3 hours = C/3 A

    so my battery bank would be 105AH/3=35A, or it would take 35A to charge it in 3 hours. so for C/7 (7 hours), I would need 15 A charge rate.
  7. mass_burner

    mass_burner Minister of Fire

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    Finally finished my rolling battery pack for now. Decided to go with 70 ah to start, can always scale up later.

    Attached Files:

    woodgeek likes this.
  8. woodgeek

    woodgeek Minister of Fire

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    Usually you wire parallel like this:

    [​IMG]
    to ensure they charge evenly....prob a 2 minute change.
  9. mass_burner

    mass_burner Minister of Fire

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    Hmmm. I would need to reposition the inverter toward the center of the top to keep the cables the same length. I was planning on using most of the top as a platform/table top for whatever. But I guess I'll have two smaller areas except one larger one.
  10. mass_burner

    mass_burner Minister of Fire

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    also, would I put both charging clamps on one battery, or 1 clamp on each each end?
  11. mass_burner

    mass_burner Minister of Fire

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  12. woodgeek

    woodgeek Minister of Fire

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    its a subtle issue, but yes, he is. The connectivity is obviously correct, but if you substituted the wires for resistors, the batteries would not charge evenly. I don't know how big an issue is, but hypothetically it becomes a problem when the resistance of the cables is close to the effective resistance of the batteries...and I could imagine that could be pretty low.

    For something to see light duty from time to time, you are prob aok. For an off-grid solar system doing heavy duty, I would do it the symmetric way.

    I don't think you should move the inverter, just make two longer cables. And I would charge it symmetrically also.....one clamp on each battery.
  13. jharkin

    jharkin Minister of Fire

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    Agree with geek. With parallel setup they typically run the positive to one battery and the negative to the other. In fact off grid folks try to avoid parralel as much as possible and run series. You avoid a lot of problems that way, no need to balance and if you ever get a bad cell its obvious in series.
  14. mellow

    mellow Resident Stove Connoisseur

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    I ran my batteries in parallel like woodgeek showed when I was doing car stereo competitions back in the day... way back in the day.
  15. mass_burner

    mass_burner Minister of Fire

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    thanks for the info, I will make the corrections. maybe is why my charger read 95% charged after I had a 1amp fan for 3 hours.
  16. mass_burner

    mass_burner Minister of Fire

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    I have a smaller xantrrex 600 HD pack and just replaced the battery. I am not happy with the charging rates (35 hours using house plug) and would like to charge the battery directly using my smart charger.

    Would there be any issues to adding cables directly from the battery out through the case for attaching to my charger?
  17. woodgeek

    woodgeek Minister of Fire

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    Not that I can see....so long as the Ah and chemistry are appropriate for the charger.
  18. mass_burner

    mass_burner Minister of Fire

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    Battery is 12v, 26 ah. My charger has built in step down amp rate to maintenance.
  19. mass_burner

    mass_burner Minister of Fire

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    So, this Xantrex pack has jumper cables you use to jump a car, 50 AMP. They plug into the side and are removable. The user manual says you can hook up the jumper cables to another battery and extend the capacity of the pack. So if the that's true, won't the battery in the xantrex be charged via these same cables by a charger?
  20. woodgeek

    woodgeek Minister of Fire

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    I would think so. Do you know the charger is SLA and not Gel Cell? I had a Jumper pack at on one time that was a bunch of NiCads strung together. I wouldn't want to use a Lead-Acid charger on that.
  21. mass_burner

    mass_burner Minister of Fire

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    The charger has a setting for AGM, GEL and STD. The battery is AGM, I just replaced it.

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