[RE-wrenches] Remote battery disconnects

[Bradley Bassett]

Wiliam,

I designed a system for this using the MidNite RT breakers. They use 24VDC
to trigger them, but you must then open the 24VDC to them once they have
tripped or it will burn out the coil in the breaker. What I designed was a
48VDC to 24VDC power supply and a EPO button that is normally open. We have
both of these, the N.O. button is rare. The power supply is from OutBack.
Then once the breaker has tripped the power is no longer supplied to the
switch or RT breaker. It does require a manual reset of the breaker. I've
attached a drawing of this.

Brad
AEE Solar

On Fri, Jan 27, 2023 at 12:54 PM William Miller via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Glenn:
>
>
>
> As I wrote, a DC disconnect is required.  Here is an excerpt from the Q&A
> with the building official:
>
>
>
> 4.   Will you be requiring an external disconnect to disconnect the AC
> output of the inverter system from premise wiring?
>
> Yes, as required per 230.85
>
> 5.   Will you be requiring an external disconnect to disconnect batteries
> from the inverters?
>
> Yes
>
>
>
> If the DC disconnect was not required I would not be wasting everyone’s
> time with my post.  I try to be careful about that, researching on my own
> before posting and trying to make my questions very clear.  I also try not
> to embarrass myself with dumb questions, but that does happen occasionally…
>
>
>
> William
>
>
>
> Miller Solar
>
> 17395 Oak Road, Atascadero, CA 93422
>
> 805-438-5600
>
> www.millersolar.com
>
> CA Lic. 773985
>
>
>
>
>
> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
> Behalf Of *Glenn Burt via RE-wrenches
> *Sent:* Friday, January 27, 2023 11:46 AM
> *To:* William Miller via RE-wrenches
> *Cc:* Glenn Burt
> *Subject:* Re: [RE-wrenches] Remote battery disconnects
>
>
>
> Does the AHJ really want the batteries disconnected from conductors, or
> does he really just want the inverters to stop operating and producing AC
> within the house?
>
> Obviously there is a big difference here and it may be changing as the
> code evolves.
>
>
>
> -Glenn
>
> Sent from my 'smart'phone, so please excuse typos and spelling errors.
>
>
>
> ------ Original message------
>
> *From: *William Miller via RE-wrenches
>
> *Date: *Fri, Jan 27, 2023 2:26 PM
>
> *To: *RE-wrenches;
>
> *Cc: *William Miller;
>
> *Subject:*[RE-wrenches] Remote battery disconnects
>
>
>
> Friends:
>
>
>
> We have a large-ish residential off-grid system install coming up.  The
> AHJ has said they will require a remote battery disconnect.  I suspect
> there will be fire sprinkler controls and a pressure pump that would become
> inoperable if this system were engaged.  In this case we will apply for a
> waiver.
>
>
>
> The last time this was discussed here as far as I can find was October of
> 2020.  At that time no one suggested any specific battery disconnect
> equipment.
>
>
>
> To further clarify my needs:  There will be 4 or 5 Radian 8048 inverters
> (5 or 6 4/0 battery circuits, ~350A each) and two 175 amp PV recombiner
> outputs.  That is 6 poles of high amperage DC disconnects.
>
>
>
> The battery array will be either a UnigyII VRLA or a lithium of a brand
> yet to be determined.  In the case of lithium we will look for a system
> that can remotely enable a BMS shutdown.  In the case of a VRLA lead-acid,
> we will not have that luxury.
>
>
>
> I have done some considerable research and have not found viable, high
> amperage, remotely activated shutdown equipment.
>
>
>
> I am wondering what hardware others may be using to achieve remote battery
> disconnecting in these types of cases..
>
>
>
> William
>
>
>
> Miller Solar
>
> 17395 Oak Road, Atascadero, CA 93422
>
> 805-438-5600
>
> www.millersolar.com
>
> CA Lic. 773985
>
>
>
>
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