Designing a Low Voltage Disconnect that accommodates the Classic 150

[5 Minutes 2 Midnite]

So I've been over on the Arizona Wind & Sun forums in a discussion about how to improve the existing LVD I incorporated in my new system. My LVD is designed to drop power to ALL equipment in the event that battery voltage falls below a certain level.. including the cc (the contactor interrupts one leg near the battery).

Several folks on the AWAS forum have commented that you really should disconnect the solar input from a cc before dropping battery power to it.

I suspect that there would usually be no or minimal solar input in the case where this backup relay would trip, but I'd like to verify what importance there is being sure the Classic is disconnected from solar voltage before being powered down. Given the way everything wires up to the Magnum MMP mini panel in use, it's not going to be an easy task rewiring the battery input to the cc upstream from the inverter.

thanx

[ClassicCrazy]

Did they mean don't disconnect the Classic first and the PV second ? Couldn't you just put another relay in to disconnect PV input at the same time  ?

Larry

[5 Minutes 2 Midnite]

<<Did they mean don't disconnect the Classic first and the PV second ?>>

Yes. Exactly.

<<Couldn't you just put another relay in to disconnect PV input at the same time  ?>>
Yes. Definitely. But before doing so I wanted to see if there was a need for the extra relay. I am curious what Midnite's opinion is on this.

thainx
jim

[Halfcrazy]

The issue I see is, The Classic would stay running from the PV array and try to power the inverter (Look like a battery to the inverter).

What I would do if it were me would be to set it up in 2 stages. Stage 1 drops the inverter only at a low Vbat and Stage 2 then drops the classic. This does two things, 1) it stops the Classic from back feeding the inverter and 2) it gives you a chance for the Solar to try and charge with no loads

[5 Minutes 2 Midnite]

What I would do if it were me would be to set it up in 2 stages. Stage 1 drops the inverter only at a low Vbat and Stage 2 then drops the classic. This does two things, 1) it stops the Classic from back feeding the inverter and 2) it gives you a chance for the Solar to try and charge with no loads

As it happens the best solution recommended by a NAWS member is to not use a contactor for LVD, but to instead turn the inverter off by triggering its remote OFF switch (in the case where it does not turn itself off first). I will use my JDL-404 as the trigger. So now that the contactor disconnecting the battery is out of the loop, your suggestion naturally comes into play. If you see what I mean.

Thank you both.
jim