[RE-wrenches] Automatic Dark Start of Depleted Lithium Batteries

[Michael Morningstar]

I like where your going with this Jason

On Sat, Feb 22, 2025 at 5:08 AM Jason Szumlanski via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> I have been thinking a lot recently about the reasons off-grid systems can
> shut down, and working on strategies to prevent these nuisances that
> require manual intervention.
>
> Ideally, a BMS should never shut down due to low voltage/SOC because a
> properly programmed inverter should reach it's cut off well before the BMS
> decides it needs to protect the battery, especially where there is closed
> loop communication. But let's say that happens, where the BMS does make the
> DC battery output go to zero.
>
> It seems to me like the inverter should be able to start a generator, and
> then signal to the BMS that a charging source is available. But I'm not
> aware of any system that actually does this. The inverter should be able to
> wake up the battery. I can see this being particularly possible where one
> manufacturer is writing the code (I'm thinking Midnite AIO/Powerflo).
>
> Of course, the inverter would have to have power in order to do that, so
> if it's nighttime and there is no PV, the inverter power would need to come
> from somewhere. I have two thoughts. First, someone could manually start
> the generator, waking up the inverter, but they would not have to reset the
> BMS if the inverter told it to wake up. The second way would be for the
> inverter to somehow close the 2-wire start circuit upon inverter shutdown,
> restoring power to the inverter automatically.
>
> If those are not options, an external NO relay powered by the inverter
> output could be added to the 2-wire start circuit, perhaps with a time
> delay to return to the NO position to allow the generator to remain powered
> until the inverter does it's thing and starts charging the batteries.
>
> Anyway, my question is whether any inverter/battery combination out there
> works in a way that the inverter tells the battery there is a charging
> source available to wake up the BMS and reconnect DC power. And if not, why?
>
> Jason Szumlanski
> Florida Solar Design Group
> _______________________________________________
> List sponsored by Redwood Alliance
>
> Pay optional member dues here: http://re-wrenches.org
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> There are two list archives for searching. When one doesn't work, try the
> other:
> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:
> http://www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> http://www.members.re-wrenches.org
>
>

-- 

Michael Morningstar


Morningstar Electric Inc

PO Box 1494

Mount Shasta, CA 96067

530-921-0560

CSLB 1116835

mjmorningstar at gmail.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20250222/63c9d509/attachment.htm>