Is it safe to connect loads directly to controller ?

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abdoudiaw
abdoudiaw Registered Users Posts: 12 ✭
in Solar Beginners Corner #1
Hi,
I have a Morningstar MPPT controller 45amps.
I'm trying, in the middle of the day, when there is much sun, to let batteries charge with no loads, thus saving battery power for the night.
I would like to know wether it is safe to connect 12V devices directly to the controller, bypassing the batteries?
If yes, is it safe to do so while batteries are also charging?
Thanks a lot.
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #2
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    Re: Is it safe to connect loads directly to controller ?

    Could you explain how are you going bypass batteries and charge them at the sam time?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
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    Re: Is it safe to connect loads directly to controller ?

    There is no way to "bypass the batteries" nor is there any need to: if the power coming from the PV is capable of charging the batteries and supplying the loads that is what will happen.

    If the power is insufficient to do this, load demand will be made up by the batteries. When the loads go down charging will resume.
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  • abdoudiaw
    abdoudiaw Registered Users Posts: 12 ✭
    #4
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    Re: Is it safe to connect loads directly to controller ?

    Bypassing batteries, I mean directly connecting loads to the controller, not to the batteries.
    So basically we have two options:
    1-connect simultaneously batteries and loads to the controller
    2-disconnect batteries when there are loads connected to the controllers only if it is not safe to use option1
    Thanks
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  • abdoudiaw
    abdoudiaw Registered Users Posts: 12 ✭
    #5
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    Re: Is it safe to connect loads directly to controller ?

    Beside trying to save power, my real concern here is safety:
    is it SAFE for a device to draw power directly from the controller?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
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    Re: Is it safe to connect loads directly to controller ?

    There is no way to connect the loads "directly to the controller" electrically. It does not matter. It will not change the function due to the positioning of the connections.

    Considering that loads may have different current demands than the charging system can supply, it is best to connect the loads to the battery through their own fuses. For example a 60 Amp charge controller can put out 60 Amps but an inverter may draw 100+ Amps: the wiring from controller to batteries may be insufficient to handle the inverter (or other) draw.

    There are controllers that have 'LOAD' terminals. They are meant for low-current DC loads, and usually have functions such as low Voltage disconnect or low light connect on them. They are not for inverters or any load that may exceed the rated current (which is usually the same as the controller can output).

    You will accomplish nothing by connecting the loads to the charge controller's output terminals rather than to the batteries 'directly'.

    Without the connection to the batteries a charge controller will not output a steady Voltage and may not function at all. Your MS 45 MPPT for example will shut down with no battery connection. Again there is no reason whatsoever to do what you are suggesting.
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  • abdoudiaw
    abdoudiaw Registered Users Posts: 12 ✭
    #7
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    Re: Is it safe to connect loads directly to controller ?

    Crystal clear!
    I will not try that.
    Thanks a lot.
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