[RE-wrenches] Absurd battery question

[Zeke Yewdall]

 I think it's perfectly possible to do an open loop (no comms) system with
24 volt LFP's and the XW inverters, especially with the midnite classic
charge controllers.  They are more adjustable in my experience than some of
the other charge controllers.    The only somewhat reputable 24 volt LFP's
I know of would be the EG4 rack mount LL series though.  Much harder to
find than 48 volt options.  The LVD on the inverters will be too high,
which means you always have the chance of the battery BMS shutting down
before the inverter does.  And XW's will not dark start a shut off lithium
battery from any source.  I actually don't think the classic's will
either.  I've had to add separate small lithium battery chargers to a few
systems that the customers keep running the batteries all the way down in
to BMS shutdown.

I have another customer, also near Boulder, who I upgraded to LFP batteries
on his XW4548 inverter, similar vintage to your situation most likely.  And
by the time we were all done, I wished I'd just replaced the entire thing
with an AIO.  His batteries (discover) are quite picky with the XW inverter
-- works fine with the victron charge controllers and will sell to the grid
and all, but half the time they trip off line when charging from the
inverter for some reason we've not yet identified.  And, doing TOU billing
(since Xcel is charging around 3x as much from 5 to 9pm either already or
coming soon for most customers) with the XW is a much more clunky process
than with the AIO.  With the amount of money spent on labor and futzing
with the system over the past year and trying to get monitoring working and
all, we could have put it into the hardware of a new inverter with closed
loop comms with new LFP batteries....

Zeke

> ------------------------------
>
> Message: 4
> Date: Mon, 22 Dec 2025 13:32:54 -0700
> From: Chris Daum <Chris at OasisMontana.com>
> To: 'RE-wrenches' <re-wrenches at lists.re-wrenches.org>
> Subject: [RE-wrenches] Absurd battery question
> Message-ID: <011b01dc7382$28f91ef0$7aeb5cd0$@OasisMontana.com>
> Content-Type: text/plain; charset="us-ascii"
>
> RE:  Closed loop communications.  I have a customer who needs to replace
> his
> old AGMs; he's looking at getting something like 2500ah @ 24V and wants
> LFPs.  This is a battery based, grid tie system.  His equipment is a pair
> of
> XW4024s (Schneider - and he has NO interest in replacing his inverters) and
> three Classic (Midnite) charge controllers.  I'm concerned with integrating
> the LFPs with his old inverter, but his Classics, I believe, can be
> reprogrammed to accommodate the LFPs.  This system was installed around
> 2015
> so the equipment is not new - but it's basically been humming along until a
> couple of weeks ago, when there was a week of 60 to 90 MPH winds that
> killed
> the power for a while.  This is near Boulder, CO (at 9000 ft elevation).
> His system worked fine til his old AGMs gave out.  Their power was out for
> ~3 days, then came on for 2 days, then went out again for a couple of days.
> So he realized how undersized and old his batteries were.
>
>
>
> If he gets some new LFPs, do you think they'll work with this vintage
> equipment?  Any of your wonderful advice to pass along!?   I'm thinking the
> Classics can dial in the settings he needs.
>
>
>
> Thanks, y'all!
>
>
>
> Chris Daum
>
> Oasis Montana Inc.
>
> 406-777-4309 or 4321
>
> 406-777-4309 fax
>
>
>
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