Is there a voltage tolerance that that should be taken into account?

rdemart44
rdemart44 Registered Users Posts: 7 ✭
in General Solar Power Topics #1
When running dc products i.e. a 9 volt transistor radio, 12 volt TV etc. how close do you need to get voltage wise not to have problems. As an example: lets say I want to run a 12 volt TV directly out of my charge controller which right now is 13.3 volts. Will this voltage be fine or do I have to get closer to the 12 volts?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Is there a voltage tolerance that that should be taken into account?

    Unfortunately the answer is: it depends on the particular device.
    Most things design to run from "12 Volt" auto source have a pretty wide tolerance, certainly +/- 10% from the usual 13.8 Volts (some vehicles run higher, some lower). Some 12 Volt inverters are notorious for shutting down from "over Voltage" is you EQ the batteries at 15+ Volts.

    What do you mean by running "directly out of my charge controller"? Is this a controller with "LOAD" terminals on it? Even so it will need a battery to provide stable Voltage levels (as discussed previously in another thread).

    In the RE world the absolute low end on a 12 Volt system is 10.5 Volts and the upper end for charging is usually 14.8.

    Sorry that's not a very definite answer. There are some things you can do if you think the Voltage might go too high, such as putting a diode in series with the power to knock half a Volt or so off. If it's a really critical device then some type of specific Voltage regulation would be in order.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #3
    Re: Is there a voltage tolerance that that should be taken into account?

    That is really hard to say... For example, some of the "12 volt adapters" (laptop, etc.) have been known to smoke when taken above ~14.2 volts.

    For an off grid power system, a 12 volt battery may see 14.8 to 15.0 or even 16.0 volts during some charging conditions (sub freezing battery bank, during equalization, etc.).

    13.3 volts is pretty much a "low" float voltage for a solar power system... Depending on the battery bank, you might need closer to 13.6 volts--And 14.2 to 14.75 volts for a flooded cell deep cycle battery is pretty much standard bulk/absorb set points.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • rdemart44
    rdemart44 Registered Users Posts: 7 ✭
    #4
    Re: Is there a voltage tolerance that that should be taken into account?

    The charge controller has a 12 volt cigarette lighter plug in it.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Is there a voltage tolerance that that should be taken into account?
    rdemart44 wrote: »
    The charge controller has a 12 volt cigarette lighter plug in it.

    :confused: I've never seen such a thing. Do you have a make & model so we could look up its specifications?
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #6
    Re: Is there a voltage tolerance that that should be taken into account?

    sounds like one of those C-Tire "power packs" that can be recharged from 110/12v/pv, last 2 through a cig lighter plug...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
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  • rdemart44
    rdemart44 Registered Users Posts: 7 ✭
    #7
    Re: Is there a voltage tolerance that that should be taken into account?

    It's the one that comes with the Harbor Freight solar panels which I think is 4 amps. It also has a 3,6,9 and two more 12 volt jacks.
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