Controller with low voltage cutout??

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momofgcm
momofgcm Solar Expert Posts: 35
I have 2 systems that I need some kind of low voltage cutout protection. I want to disconnect the batteries from the loads (AC and DC) when they get to 50 discharge.

One system has (4) 123W (Voc 22C Isc 8A) panels and the other has (4) 208W ( Voc 36V Isc 8A) panels.

Can anyone suggest a good controller with some type of cutout protection for the batteries?

Kim

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,468 admin
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    Re: Controller with low voltage cutout??

    Quite a few Charge Controllers have voltage based Low Voltage Cutoff--However, voltage based is not really that accurate (depends on load, temperature, etc.)...

    The LinkLite and LinkPro Battery Monitors both have a programmable output that you can setup to drive a relay/remote power off switch for your loads.

    A new (to me) Battery Monitor, from Victron also has a programmable output you should be able to use for this purpose too.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • RWB
    RWB Solar Expert Posts: 168 ✭✭✭✭✭
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    Re: Controller with low voltage cutout??

    The Victon Monitor has more features for less money and is more accurate than the Link Lite Monitors. Just do a google search on LinkLite Battery Monitor install and problems and it should pull up some good forum articles.

    The Link Lite Pro was best but it has been discontinued so the Victron's features are for sure better than the basic Link Lite.

    A battery Monitor is the only way your going to be able to cut off the load by SOC reading only. Everything else is based on Voltage I'm pretty sure. I'm not sure if Bluesky's IPN Display has a SOC Relay output Cutoff or not???

    I have used the Victon's relay output to turn on an off a AC charger based on SOC Set point's and it worked just fine.
  • momofgcm
    momofgcm Solar Expert Posts: 35
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    Re: Controller with low voltage cutout??

    What is the best way to remove the loads from the batteries until they recharge?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,468 admin
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    Re: Controller with low voltage cutout??

    Some Inverters come with a "remote switch" interface. Makes it pretty easy to turn off the inverter.

    Turning off heavy DC loads is a bit more difficult. Relays work well, but can draw 6 Watts or so when energized (consuming more of your power).

    And, there are latching relays like this one (12 volt, 300 amps) for some $140:

    Blue SEa 7700 ML-Series Remote Battery Switch w/ Manual Control 12v DC

    Here is another Blue Sea product... A relay 12/24 volt that draws ~1.2 watts or so. A bit more expensive than the latching one above.

    Blue Sea has some interesting products... I am not sure how they would interface with the Battery Monitor for the latching products.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset