About 60V,30A Voltage Regulator/Battery charger?

Discussion in 'General Electronics Chat' started by Qaisar Azeemi, Dec 19, 2011.

  1. Qaisar Azeemi

    Thread Starter New Member

    Oct 7, 2011
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    Is there any voltage regulator available in the market that can regulate the DC voltage up to 60V and can charge the 48V Lead acid batteries?

    I have used LM338K to make my 24V lead acid battery Charger with auto cut off circuitry sucessfully. now i want to make 48V and 36V battery chargers. Please help me about that.
    Thank you
     
  2. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    So you want an IC voltage regulator that can deliver about 1800 Watts:

    That would be a definite NO.

    I believe the LM317HV can handle input voltage up to about 65V but only at about 1A.
     
  3. Qaisar Azeemi

    Thread Starter New Member

    Oct 7, 2011
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    2)About LM338K is that they can be managed (Connected in parallel) to handle about 30A of current. since each LM338k gaurenty 5A Current delivery so to get 30A current at the output to charge 300AH or down to 200AH lead acid batteries can be designed.... since large heatsinks and cooling fans will be required in the housing.
    1) From the above description a power of 1800w will be managed.

    3)is there LM338K HV version IC available? that will be pretty enough for me to get my required regulated out put. :)

    OR

    are 30V Enough to charge a 48V battery? so an LM338K can be used to charge a 48V battery?
    kindly guide me about it.
    Thank you
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    No, 48v is not enough to charge a 48v battery bank.
    You would need at least 55v to charge a 48v battery bank - at the batteries themselves.
    Float voltage would be around 54.4v.
     
  5. strantor

    AAC Fanatic!

    Oct 3, 2010
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    do you really need a regulated supply to charge SLA batteries? I was under the impression you could feed them a rather nasty input and all is well.
     
  6. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    If you hold them in "float charge", the voltage has to be well regulated (and temperature compensated) if you want the batteries to live long.
     
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  7. SgtWookie

    Expert

    Jul 17, 2007
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    That much power would need at least a pre-regulator along with a mighty hefty regulation stage if it was going to be accomplished with (a) linear regulator(s)

    OTOH, I don't see why it couldn't be charged using an SCR-type regulation scheme. If one wanted to float charge in addition to the bulk charge, the SCR stage could be used as a pre-regulator for a smaller linear regulator; after all, it should not take much current to float-charge batteries -- that is, unless you have a shorted cell or two. Using an LM317 or LM338 for float charging would be acceptable, as the I-O voltage differential could be quite small. Since these regulators don't have a ground reference, they would not "see" that they were floating at ~60v above ground; they'd just see the I-O differential and Vref.

    Temperature compensation should not be too difficult; can be as inexpensive as a 2N3904 transistor wired as a voltage multiplier, thermally coupled to one of the battery positive terminals.

    The expensive part would be the transformer.
     
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  8. Qaisar Azeemi

    Thread Starter New Member

    Oct 7, 2011
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    Thank you sgtwookie. how can an LM338 be float at 60V above the ground? please explain the idea with diagram. thank you.
     
  9. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    Float charge is only the maintenance charge applied to fully charged batteries after they have been fully charged. The float charge keeps them topped off. Your spec for this device is:

    60V/30A

    which is what you need to actually charge the batteries.

    And, as I have said over and over, there is absolutely no way to build such a thing using IC regulators. If you try to build it uing a "linear" design, it will be about the size of a coke machine.
     
  10. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    I have a battery charger for 48 volt golf cart batteries. 8 six volts in series. The unit is about 12x12 x15 inches but it weights almost 50 lbs. It runs off a 20 amp 120 volt circuit, but I have successfully used it on 15 amp circuits. The max current output is just slightly more than 25 amps. If you could settle for less than 30 amps you could find such a simple linear charger for a simple price. It is sorta dirty voltage wise. Lots of noise spikes and a rough looking 2vac wave riding on it when under full load. It settles down to a much smoother DC voltage when not fully loaded with drained batteries.

    A small amount of concession on your amperage needs would net you a nice commercial unit for small change. I paid $149 for mine. Pictures are available if you feel you need to see it to believe such things exist.
     
  11. Kermit2

    AAC Fanatic!

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  12. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    That's a 48V/25A supply which is 1200W. That's about the highest wattage power supply you can run off standard 115VAC (single phase) wiring because after power factor and internal losses, the AC line current will be around 16A. The plate says "1700W AC WATTS" which is about 16A.

    The OP's target design of 60V/30A is 1800W, which would require the use of 208VAC three-phase to get the line currents low enough for standard wiring.
     
  13. Kermit2

    AAC Fanatic!

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    You don't need a 220vac outlet to get to 30 amps at DC voltages needed for charging 48 volt batteries. Though, as you say, having it so arranged would be less stressful on the AC wires as they would not be carrying full capacity amperage.

    :)
     
  14. Qaisar Azeemi

    Thread Starter New Member

    Oct 7, 2011
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    @Kermit2:

    do you have the schemetic of these chargers?
     
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