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-   -   How to reduce DC voltage? (https://www.askmehelpdesk.com/showthread.php?t=323083)

  • Feb 28, 2009, 06:54 AM
    StacyT69
    How to reduce DC voltage?
    Ive got a 48 volt golf cart and it has a 48v to 12v converter on it. For some reason I've got 20.5 v coming out of my converter and it keeps blowing my headlight. Is there an easy way to reduce this back to 12 volts without buying a new converter? The Headlight is 55 watts.. :cool:
  • Feb 28, 2009, 07:31 AM
    sarnian
    Hello StacyT

    First of all : + 48 Volts is provided by the batteries of the cart.
    To load the batteries you have a 48 Volts charger. And the cart has a 48 volt motor.
    So the converter you refer to seems to be reserved for the light and probably for some electronics also.

    A faulty converter could fail completely and provide 48 Volts.
    Your light already keeps blowing, but you do not want to run the risk other electrics or electronics to blow too.

    The 12 volt light at 55 Watts draws about 4,5 Amps. That is quite a lot for a converter to handle. So the converter is a heavy duty type.

    Any additional converter for the light only has to be of the type 48 to 12 Volt at 4,5 Amps, and that will be expensive anyway. And that still leaves the electrics/electronics in danger.

    Another - risky - solution would be to connect to the + 12 Volt of the battery bank, but that could harm the battery bank, as it would unload the batteries unevenly. In the end that could be even more expensive.

    Best advice is : just make sure, and replace the existing converter.
  • Feb 28, 2009, 07:55 AM
    StacyT69

    Thanks Sarnian, you are probably right.. However the 12 volts from the converter only run my tail light and headlight. The tail light is LED's so the extra voltage does not bother them.. The cart has 6 each 8 VDC batteries, so I cannot hook up to just one battery to get my 12 volts.. I'll take your advice and buy a new converter.. Thanks...
  • Mar 9, 2009, 05:48 AM
    Stratmando

    Hate that they used 8 volt batteries, 6 or 12 volts allows more options, check out the diagram on page 13:
    http://www.econogics.com/ev/Otis71jk_20060403.pdf
    Will see if I can find a good solution. 8 volt bulbs?
  • Mar 9, 2009, 06:46 AM
    Stratmando

    Haven't had luck with an 8 volt bulb, will try for a 16 volt bulb, here is something that can connect across 2 of your batteries in series:
    Voltage Reducer 16-18 to 12
    A 24 Volt bulb would work across 3 of the batteries in series.
    I would go with the Bulb over the converter, if possible.
  • Mar 9, 2009, 08:10 AM
    sarnian
    Stacy / Stratmando

    Although you can run small current applications from one of the battery taps (as selenoids), it is a bad idea to run lights from a battery tap, as the current draw will be high, resulting in some of the batteries being off-loaded faster than the others.
    See my first entry here : the lamp curent will be around 4,5 Amps.
    During re-charging this will lead to speeding up the destruction of part of the batteries, as there is only one loading current. It is in this situation not important if the actual total battery voltage is 36 or 48 volts.

    Although Stratmando's idea could work, it still requires another (high current) light lamp DC voltage converter (16 to 12 Volt at 4,5 Amps), as you only have battery taps at 8, 16, 24, 32, and 40 volts. Better than to replace the cause of all problems : the original converter itself.

    Another possible option is installing 4 new 12 Volt spot lights on the cart. But this is also problematic, as you would have to connect them in series - while none of these lights should have one of the connection wires connected to the cart body. It would work : three 12 Volt spot lights in series for a 36 Volt battery bank, and four 12 Volt spot lights in series for a 48 Volt bank. That way no converter is required at all. But that solution would be expensive also with it's four spot lights!

    Let me know if you require more info for installting that last proposal !

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