[RE-wrenches] VFXR3648A battery charging

Sun Dec 14 11:12:15 PST 2025

Jerry/Wrenches:

I have another almost identical system on Optics.  The other system charges
correctly.  I compared all of the settings and found one difference:

On the problem system the Grid Input was set to Generator.  On the
functioning system it was set to Support.  This should not matter because
Input Priority is set to Generator on both.

In the Mate, both system are set with identical parameters.  The Generator
type is AC Generator.  Even though this should not apply the DC Absorb
Voltage is set to 76 on both.

I changed the one different setting: Grid Input from Generator to Support.
If the Support setting does not fix the problem it is time for a factory
reset.

I did note the coincidence of a charge limit of 52 VDC on the two threads.

William

Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985

*From:* Jerry Shafer [mailto:jerrysgarage01 at gmail.com]
*Sent:* Saturday, December 13, 2025 2:01 PM
*To:* RE-wrenches
*Cc:* William Miller; Steve Higgins
*Subject:* Re: [RE-wrenches] VFXR3648A battery charging

William,  wrenches,

As l am sure you know the pv comes from the CC  and the gen charge cones
from the inverter., I would suggest digging into the mate and look at the
setting in the inverter, make sure you have it set to gen not grid and all
your settings are gen. Resetting would be way down the list to do.

Fun times

On Sat, Dec 13, 2025, 1:53 PM Steve Higgins via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

The other setting that could affect this is the DC Generator Setting in the
AGS menu.

For a Normal 48V system, this is generally set to around 70volts... Many
see this and panic and set it down.  Even if you have DC Gen set to no,
it'll still affect charging.

This screenshot is assuming 24V...

[image: image.png]

If they have the DC Gen set to 52 volts, it'll charge to 52 for a time and
then shut off.

*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 Sat, Dec 13, 2025 at 1:17 PM William Miller via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

Jay:

Thanks for that.  I always thought re-bulk only applied if you had 24/7 AC
input which we do not.  I made the adjustment and we will see what happens.

William

Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985

*From:* Jay [mailto:jay.peltz at gmail.com]
*Sent:* Saturday, December 13, 2025 12:11 PM
*To:* william at millersolar.com; RE-wrenches
*Subject:* Re: [RE-wrenches] VFXR3648A battery charging

You have to set the rebulk volts higher, higher than what ever you start
the generator.

Say 56 or so.

Jay

On Dec 13, 2025, at 11:56 AM, William Miller via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

Friends:

I have a client with one VFXR3648A inverter off-grid with PV and a
generator.  The inverter is set to bulk at 58.2 VDC for 2 hours but when
the generator is required the voltage never gets above 52 VDC.  The PV gets
the voltage up to the 58 volt zone reliable.

The original generator was a portable of about 3 Kw.  I thought it was not
providing enough RMS power so we upgraded to a Kohler vertical shaft 12 kW
air cooled unit.  The problem is still the same:  The bulk voltage of the
batteries never gets above 52 VDC.

On my next visit I plan on resetting the inverter to factory defaults.
Other than that I am not sure what to try.  I have little luck reaching
Outback tech support in the last year so I am hoping someone here can
provide some advice.

Thanks in advance.

William

Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985

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