[RE-wrenches] New Lithium Batteries on Sunny Island System

[Zeke Yewdall]

I have done many systems with the Midnite charge controllers (and outback
and victron and others) with lithium batteries.  With the right voltage
settings they can work quite fine.  The Sunny Island inverter I am not
sure... it should be possible to set all of the voltage settings to work
with them, but I have never tried it with them. I have heard of people
doing this though -- one of the first lithium battery systems written up in
Home Power was a Sunny Island system with Discover lithium batteries if I
recall.  Lithium batteries do have a much flatter voltage curve than lead
acid, so guessing SOC based on voltage is even more difficult than with
lead acid batteries.  Some sort of AH counting SOC meter is very helpful if
doing an open loop lithium battery without BMS communications.

What would concern me from the scenario you have presented is that the
specs are for a lithium battery cell... not a lithium battery with a BMS.
I have built many lithium batteries for my own use out of cells by adding
my own BMS, but that's a whole nother level of fabrication compared to just
installing a complete battery.  And will most certainly not be UL9540
listed.  I would not install a non UL9540 listed battery for a customer
because of the liability.

Zeke

On Tue, Nov 25, 2025 at 1:05 PM <re-wrenches-request at lists.re-wrenches.org>

> Message: 2
> Date: Tue, 25 Nov 2025 07:31:40 -0800
> From: Jim Gowdy <gowdyelectriccambria at gmail.com>
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
> Subject: [RE-wrenches] New Lithium Batteries on Sunny Island System
> Message-ID:
>         <
> CAC+tiP7COiKi7BLMibm1L-Fm8pnBnirnMbFqSFLwJaQPsx70-g at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hello All,
>      I have a client that just got some lithium batteries and they have a
> sunny island inverter with a Midnight Charge controller.  I've heard and
> experienced integrating Lithium batteries into a Sunny Island inverter is
> challenging and could create problems.  Has anyone had experience with
> these batteries or installing lithium batteries with these components?
> Below are some details about the system so far.....
>
> System:
> 48v
>
> NEW BATTERY:
> China Aviation Lithium Battery CO.
> model: CA180F
> nominal voltage: 3.2v
> rated capacity: 180Ah
> rated energy: 576Wh
>
> Inverter:
> Sunny Island
> model: SI 4548-US-10
>
> CHARGE CONTROLLER:
> Midnight Solar Classic 150
>
> SOLAR ARRAY:
> N/A....it was dark when I was at the site so I couldn't take any notes
>
>
>
> --
> Jim with Gowdy Electric
> Cambria, Ca 93428
> business  805 927 2630
> cell  805 975 5279
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