[RE-wrenches] Odd battery charging behavior with Outback inverters

[Mac Lewis]

William,

This is a very timely question, I have been seeing the same thing.  I also
don't allow any Flexnet interference in charging.  I went to investigate a
site yesterday and figured this one out.

It turned out that the Flexnet was uncalibrated by about 1V on the low
side.  This was a Lithium site and so there was not significant absorb time
and that 1 V is very significant.  The solar controller and Radian were
calibrated properly so it looked on Optics as though we were never getting
full but we were.

The Flexnet is a real mixed bag.  Its great to have the info but I don't
like the difficulty of calibration (loose nuts in the casing) and that the
Mate defaults to using its voltage meter.  We try to calibrate these as
closely as possible.

One thing I've noticed when I'm following up others work is that the
majority have incorrectly wired/programmed Flexnet DC.  They will not have
the appropriate shunts activated and so the system constantly reads 100%.
A lot of these systems are installed using Outback prewired panels (Im not
sure who builds these).

If your customer is savvy, you can have them unplug the cable from the Hub
that feeds the Flexnet.  If the voltage changes significantly, then the
calibration could be the issue.

Please keep us in the loop on what you are finding.

On Thu, Jan 11, 2024 at 9:46 PM William Miller via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Friends:
>
>
>
> I got a call from a client inquiring as to why his generator was starting
> every morning, even though no one was staying at the property and there was
> decent, albeit winter, sunshine.
>
>
>
> While looking into it I noticed that when his generator did run the
> battery voltage did not stay at absorb level for the prescribed time period
> as set in the battery charging settings.
>
>
>
> Outback tech support said that, lacking a better theory, it might be
> possible the FNDC could be affecting the charge settings.  I do not allow
> FNDCs to control generator run, so this seemed unlikely.  However I had no
> better idea and am being not much of a fan of the FNDC, I agreed to unplug
> it.  There was no change in the generator charging voltage profile made by
> this.
>
>
>
> I got curiouser and started looking at other Outback sites.  All of my
> normal Outback off-grid systems with both Radian and VFX inverters are
> exhibiting the same problem.
>
>
>
> I know this is kind of in the weeds, but that is what we are here for,
> right?  I made a little web page about this issue to easily share
> information and graphics.  Here is the link
> <https://millersolar.com/MillerSolar/case_studies/38-Radian_Charging/Outback_Charging.html>
> .
>
>
>
> This issue has serious implications for my clients.  The charging profiles
> seen are not good for these batteries.  Eventually the deficiencies in the
> charging regime will shorten the life spans of very expensive batteries.
>
>
>
> I am not very informed about lithium batteries, but I would be interested
> if this profile is bad or not for lithium batteries.
>
>
>
> I am hoping this is not a design or programming defect.  I would be
> interested in any shared experience.  Maybe some of you could glance at
> your Optics displays and see if you are seeing the same thing.  All input
> is very much appreciated.
>
>
>
> William Miller
>
>
>
> Miller Solar
>
> 17395 Oak Road, Atascadero, CA 93422
>
> 805-438-5600
>
> www.millersolar.com
>
> CA Lic. 773985
>
>
>
>
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-- 



Mac Lewis

*"Yo solo sé que no sé nada." -Sócrates*
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