[RE-wrenches] Absurd battery question

[Steve Higgins]

Hey Chris,

You can do 'Open Loop' comms with many of those legacy inverters...    The
only real issue with the Open Loop comms is that he'll need to pay more
attention to them than you would in a closed-loop system.   Every so often,
depending on how hard he works them, he may need to separate the parallel
strings and balance them (Charge to complete 100%) every 6-12 months.

The only real issue that I've found is the SOC%, which means those Context
inverters will never be accurate, so there is a learning curve on that.

Don't want to be a sales guy here, but we do offer some 24V LFPs that would
work for this:  https://rollsbattery.com/battery/s24-150lfp/

You can run up to 6 in parallel.

We do offer 12V models that can be set up in 2S4P. Using the S12-300LFP,
you can use four parallel strings.   They should be wired with bus bars and
breakers to make balancing easier.

Here is an idea of how they would be wired...

[image: image.png]


Feel free to let me know if you have any questions...

Happy Holidays!


*Steve Higgins* *⋅* *Technical Services Manager*
*t* +1.902.597.4020   *m* +1.206.790.5840
*f* +1.902.597.8447   *e* steve at surrette.com
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On Mon, Dec 22, 2025 at 12:50 PM Chris Daum via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> 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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