Charge controller question.

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cizzi
cizzi Solar Expert Posts: 109 ✭✭✭✭
I noticed the sunguard charge controller from morningstar and some other smaller Amp rating charge controllers do not have + and - terminals for the load. While more expensive units that handle more amperage like the morningstar PS-15 have 2 screw terminals for the load.

My questions is really simple, on the smaller units like the sunguard that does not have the load terminals does that mean I can directly hook up my small loads to the battery terminals itself? Meaning it would have 2 wires on the + and 2 wires from the - ? (One set comming from the charge conrtoller and one set going to the load) ?

Can one of you confirm that this is correct?

Thanks,

Claudio Izzi
System Administrator
http://www.learningshells.com

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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Charge controller question.

    actually this is the prefered way to connect is directly to the battery. some controllers have a low voltage disconnect feature that would allow a smaller current of a rating that they determine that will automatically disconnect that particular load at a predetermined voltage point. normally there is not any protections from you running your batteries into the ground excepting those that have an lvd circuit. of course fuses and switches should apply too.
  • cizzi
    cizzi Solar Expert Posts: 109 ✭✭✭✭
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    Re: Charge controller question.

    So by connecting my load directly to the battery terminals there's no chance of running down my battery to the ground? How is that? If my load is pulling and my power is not being replenished from the panel wouldn't it still run it to the ground without a low power disconnect feature from the charge controller?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,476 admin
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    Re: Charge controller question.

    Typically, Low Voltage Disconnects are used with small, automatic loads, like landscape lighting and such.

    It is usually not efficient or easy to connect and control a large DC load using this technique.

    Depending on the size and usage of your system (and battery bank), you should really look into a battery monitor... They give much better information on the state of charge than a simple voltage measurement or watching an amp meter ever can.

    And if you have sealed AGM batteries, you cannot measure the specific gravity of your cells with a hydrometer.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Charge controller question.

    i was using a figure of speech there in that you could deplete them. only small currents that lvd circuits will kick out the load at a predetermined point so as to prevent it be drained 100%. i don't like them anyway as they set the voltage too low.
    the battery is capable of large discharges and your solar will only be capable of smaller currents to charge the battery so you should tap the battery posts for your loads. this is what most of us do, but there are some exceptions like i said.
  • cizzi
    cizzi Solar Expert Posts: 109 ✭✭✭✭
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    Re: Charge controller question.

    thanks!

    Claudio Izzi
    System Administrator
    http://www.learningshells.com