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Max charging for SLA battery?

  1. Jul 10, 2005 #1
    What is the max current for a rapid sealed lead acid battery charger?

    Most recommend 0.1C up to 1C where C = Ah rating. I have a max 30-32A regulated 13.8VDC power supply and the battery is 12V, 170Ah. Would charging the battery at the max 32A damage the battery?
  2. jcsd
  3. Jul 10, 2005 #2
    I dont think that the battery will draw the full 32A , in fact i am sure it wont..unless it is past , way past , its prime..
    13.8-12 =1.8V
    1.8/(internal resistance of battery) approx(.3 ohms) =6 amps..
    it should work fine, as it is...
    note :: it may draw more or less depending on the actual internal resistance and the amount of charge it allready has ..
  4. Jul 10, 2005 #3
    The power supply is current limited but I'm worried abt whether the 32A will cause damage to the battery(if fully drained)?
    Last edited: Jul 10, 2005
  5. Jul 10, 2005 #4
    does your power supply have an ammeter built in ?
  6. Jul 10, 2005 #5
    No but I can easily install 1
  7. Jul 10, 2005 #6
    what i mean is, if you were to measure the current , you wouldnt be damageing your Ammeter..?
    If not ,then try it with the ammeter installed and see what current the battery is drawing..
  8. Jul 10, 2005 #7
    so what is the max allowable current for charging? I can measure the current with a clamp ammeter.
  9. Jul 10, 2005 #8
    if you were to measure 6 A when when the battery is connected , you could leave it on for 28 hours ..
    170/6 = 28 approx..
    as you said at the beginning , 0.1c = 17A , but that is pretty high ...
  10. Jul 10, 2005 #9

  11. Jul 10, 2005 #10
    The few times I charged my motorcycle battery with a charger designed for an auto battery, I put the charger in series with the headlamp. Of course the charge time is much longer.
  12. Jul 10, 2005 #11
    I was wondering about that myself..
    but i'm sure cookiebar knows how to measure current..
  13. Jul 10, 2005 #12


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    I don't know why they wouldn't exist and I can't say I have actually seen one but using a hall sensor you should be able to measure DC amps with a clamp on meter. I have seen sensors that permanently go in-line for current measurement. They are a square donut type of thing that the wire goes through loosely. I can't see why this couldn't be adapted to a clamp on sort of thing. My two cents...
  14. Jul 10, 2005 #13
    Yeah, that seems to jog my memory.
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