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Replacing a battery charger transformer with a audio transformer can I do it?

Discussion in 'Power Electronics' started by kboss76, Mar 20, 2021.

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  1. kboss76

    kboss76

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    Mar 20, 2021
    hi this question is for the one that has the answer,lol. I have a battery charger and the transformer is bad so I was going to swap it out with another transformer from a audio receiver can I do so without having a ton of issues if possible. Thank you in advance
     
  2. Hunter64

    Hunter64

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    Nov 20, 2018
    More information is needed. This litterally translates to "I have a problem, do you have a solution... please, please, please."
     
    dave9 likes this.
  3. dave9

    dave9

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    Mar 5, 2017
    Seriously, you didn't even mention what kind of battery (charger) !

    Probably not. The battery charger transformer for a typical automotive 12V battery is likely to be around 14VAC, possibly also a 7VAC center tap for 6V batteries while the typical transformer in a receiver/amp (assume you do mean it's got the amp built in too), is probably (roughly) over twice the voltage on the high current winding.

    As Hunter64 already stated, we'd need more info. It could be a low current charger, and you could have a receiver that isn't an amp (or is very low wattage) that has a lower voltage transformer, so not impossible for the variables to align but fairly unlikely.
     
  4. kboss76

    kboss76

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    Mar 20, 2021
    Its a Schumacher 2 10 50 amp and the transformer is out of a old Kenwood house receiver
     
  5. Nanren888

    Nanren888

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    Nov 8, 2015
    Short answer: unlikely.

    Unclear whether you mean a transformer for the input power of a piece of audio equipment or an output transformer intened for the audio signal.

    But, in general;
    Transformers change voltage and current into different voltages and current, they trade one for the other, voltage & current, in ways that don;t make or loose (much) power; that is obeying the laws of physics, as you'd expect.

    So to swap successfully, no damage to circuit or transformer; must match or exceed in voltage capability, must match or ewxceed in current capability, must match or exceed in the power handling capability, must match in ratio, that is the change effected,

    And yes, transformers come in a wide range of all parameters. Can't use a toothpick as a battering ram, &c &c.

    So, all things considered; unlikely to go well.
    Best to see if you can source a replacement part.
    Are you sure the transformer is bad? IF so, any idea what caused it to go bad? After all if there's a fault that destroyed the transformer, best to fix the fault before replacement.
     
  6. dave9

    dave9

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    Mar 5, 2017
    No, the transformer for the charger is higher current and lower voltage than the receiver, not even close.
     
  7. bertus

    bertus Moderator

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    Nov 8, 2019
    Hello,

    The charger can give peaks of 50 Amps:
    Schumacher 2 10 50.jpg

    A house receiver power transformer, even if it has a powerfull amplifier, will reach perhaps 6 Amps.

    Bertus
     
  8. Nanren888

    Nanren888

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    Nov 8, 2015
    Just to add to what bertus said. The suggested replacement is probably not sufficient power rating for a battery charger.
    Battery chargers tend to be required to handle lots of power to charge quickly. Other devices, usually less, so not sources of replacements.
     
  9. dave9

    dave9

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    Mar 5, 2017
    You could use a lower amp transformer assuming it's their unregulated, non-SMPS type charger, just won't charge as fast, and buying it may cost about as much as an entire ready made charger.

    Backing up a bit, did you measure the output of the transformer to know it's bad? If not, might be the diode(s) failed, or a thermal fuse in series, or given enough years operation, a thermal fuse in the transformer primary winding may have failed.

    If you were on a deserted island and that's the only transformer you have (from the receiver), and you happened to have a multimeter, you could even take off some of the secondary windings till the voltage dropped down to 14V or so, but in real life that is a tedious thing to do, keep unwinding and measuring voltage.

    Looking at a couple electronics surplus sites, I see that MPJA has a 12VAC, ~8A, 100VA transformer on sale right now for $15 +$7 S/H if you're in the continental US.
    https://www.mpja.com/12Vac-8333Amp-100VA-Power-Transformer/productinfo/35817+TR/
     
  10. Martaine2005

    Martaine2005

    3,309
    904
    May 12, 2015
    Iā€™d call him Lucky instead of Friday :)

    Martin
     
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