DC Voltage Regulation

kelly
kelly Registered Users Posts: 11 ✭
in General Solar Power Topics #1
My battery bank is nominally 12V, but it will vary a lot based on what my solar charge controller is doing. I have a Co2 detector that is designed with a 110 AC wall plug that converts power to 12V DC to run the device. I don't have any idea what will happen to this thing if I try to attach it directly to my "12 V" batteries. I don't want to run the power through an inverter and back through the device's transformer. Is there a device that can take 12-15V variable power and deliver a consistent 12V?
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #2
    Re: DC Voltage Regulation

    Welcome to the forum Kelly.
    While I don't know the actual voltage output from your AC adapter, guess what - - - - the vast majority of such AC adapters often are unregulated and their outputs can be substantially higher than their rated output. I've often come across 9 volt adapters putting out 11 and 12 volts. Likewise I've seen 12 volt adapters outputting 15 volts.
    Most devices fed by such adapters can handle higher than rated voltage.
    That said, I again state I don't know your particular unit. Too bad you didn't have a good DC volt meter you could use to check the actual voltage coming out of your adapter.
    And yes, I know the common adapter voltages will drop somewhat under load, but many times there is little load, so the voltage stays higher than rated.
    You PROBABLY won't have a problem connecting directly to your batteries, but I can't guarantee that.
    It's sort of like predicting which 120 volt AC devices will operate OK on MSW inverters and which ones will emit smoke and die. Pretty much trial and error.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #3
    Re: DC Voltage Regulation

    Is this a CO2 carbon dioxide detector or a CO (carbon monoxide) detector?

    At least for CO (carbon monoxide) detectors, you can usually buy ones that will run from four AA batteries (that you replace every ~1 year). I would do that rather than trying to connect to your battery bank. Would be cheaper and more reliable.

    Note that CO detectors need to be replaced every ~5-10 years--The CO sensor degrades over time (and exposure to CO gas--The detector is actually a chemical "battery" that uses the CO to generate the detection signal).

    Here is one for less than $20:

    http://www.homedepot.com/p/Code-One-Battery-Operated-Carbon-Monoxide-Alarm-KN-COB-B-LPM/202756110?N=5yc1vZbmgk

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    #4
    Re: DC Voltage Regulation

    I agree with all of the above, but if you want to regulate approximately 12V to exactly 12V, look for a boost/buck DC-DC converter on ebay.

    I am available for custom hardware/firmware development

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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #5
    Re: DC Voltage Regulation
    waynefromnscanada wrote: »
    Welcome to the forum Kelly.
    While I don't know the actual voltage output from your AC adapter, guess what - - - - the vast majority of such AC adapters often are unregulated and their outputs can be substantially higher than their rated output. I've often come across 9 volt adapters putting out 11 and 12 volts. Likewise I've seen 12 volt adapters outputting 15 volts.
    Most devices fed by such adapters can handle higher than rated voltage.
    On the other hand, some really want to see the nominal power.
    I had a wireless mike receiver with a wall wart power supply. When the original supply died (wire broke, of course, right at the source end), I tried replacing it with a universal supply.
    What I found was that the receiver did not work with the universal set to 12V. Too high a voltage, so I had to set it to 9V instead.
    Basically the variation is too wide to handle unless you measure the actual output under actual load.
    SMA SB 3000, old BP panels.
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