[RE-wrenches] FLA battery problelm
Jason Szumlanski
jason at floridasolardesigngroup.com
Fri Dec 12 15:14:00 PST 2025
Yeah, 2.4 kW on a 32.6 kWh battery is a C/14 rate. It's barely going to tickle
the battery when the actual solar output is lower than optimal. Over time,
sulfation will take hold, and the internal resistance will continue to increase,
creating a snowball effect. It definitely sounds like chronic undercharging.
Jason Szumlanski
Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956
Florida Certified Electrical Contractor EC13013208
On Fri, Dec 12, 2025 at 5:53 PM David Coale via RE-wrenches
<re-wrenches at lists.re-wrenches.org [re-wrenches at lists.re-wrenches.org]> wrote:
> Thanks for the comments so far. The system consist of two Trace SW5548
> inverter couple into a 240 volt system. Batteries are 680 amp/h 48 volts,
> with 2.4kw solar and an Outback charge controller. The generator is a 7.5kW
> generator. When the inverters shut down, the charge parameter are reset to
> default, which is too low for these batteries. That said, this does not
> happen with the charge controller which does most of the charging, though this
> might not be enough in the wintertime.
>
>
> The voltage used to go up to 58 on bulk charge but now never goes higher then
> about 52 and the capacity is down.
>
>
> It’s always hard to tell from a distance what is actually happening at the
> site, so I am sue I don’t have the complete picture.
>
>
> Thanks,
>
>
> David
>
>
>
>
> > On Dec 12, 2025, at 1:38 PM, Jay via RE-wrenches <re-wrenches at lists.re-
> > wrenches.org [re-wrenches at lists.re-wrenches.org]> wrote:
> >
> > A few questions
> >
> >
> > What’s the charge capacity? Like how big is the generator and solar
> >
> >
> > How many amp hrs is the battery?
> >
> >
> > How are they determining they are not getting full?
> >
> >
> > What controller?
> >
> >
> > Is there a trimetric to keep tabs.
> >
> >
> > Given what you’ve said, I lean towards constant undercharging. Are they
> > salvageable? Possibly
> >
> >
> > I’d do a eq as high as possible from the oem. Take SG readings. Let them
> > cool a few days and do it again.
> > If you are seeing an increase in SG and leveling out of the differences then
> > keep going.
> >
> >
> > Depending on the size of the generator and loads and size of the bank it
> > could take a lot of hours of charging. So people run out of gasoline or hate
> > hearing the generator or figure 2 hours is enough.
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > > On Dec 12, 2025, at 11:34 AM, Jason Szumlanski via RE-wrenches
> > > <re-wrenches at lists.re-wrenches.org [re-wrenches at lists.re-wrenches.org]>
> > > wrote:
> >
> > >
> > > I second the chronic undercharging suggestion. We have a client with a 64
> > > kWh FLA battery bank that only has 2.4 kW of PV. When they bought these
> > > batteries two years ago, they thought they could solve all of their energy
> > > woes by just buying a bigger battery. It is astonishing how many people
> > > don't understand that batteries themselves do not generate electricity -
> > > they just store it. They must think it's magic!
> > >
> > >
> > > Anyway, with that kind of PV to storage ratio, they were probably barely
> > > getting past the internal resistance. The batteries are completely toast
> > > now, and the client is moving to LFP (with more solar per my demand).
> > >
> > >
> > > Jason Szumlanski
> > > Principal Solar Designer | Florida Solar Design Group
> > > NABCEP Certified Solar Professional (PVIP)
> > > Florida State Certified Solar Contractor CVC56956
> > > Florida Certified Electrical Contractor EC13013208
> > >
> > >
> > > On Fri, Dec 12, 2025 at 1:32 PM Michael Morningstar via RE-wrenches
> > > <re-wrenches at lists.re-wrenches.org [re-wrenches at lists.re-wrenches.org]>
> > > wrote:
> > >
> > > > Chronic undercharging, electrolyte dilution, lack of informed
> > > > equalization, and adding water without knowledge of the how’s, whys, and
> > > > when’s will kill those batteries in no time. I’ve pulled out to many of
> > > > those heavy bastards to count, most of them at a fresh young age
> > > > because the installer didn’t educate the clients properly.
> > > >
> > > >
> > > >
> > > >
> > > > On Fri, Dec 12, 2025 at 10:21 AM David Coale via RE-wrenches
> > > > <re-wrenches at lists.re-wrenches.org [re-wrenches at lists.re-wrenches.org]>
> > > > wrote:
> > > >
> > > >
> > > > > Hi Wrenchers,
> > > > >
> > > > > I have a client with an old off-grid Trace system and he is having
> > > > > trouble with the batteries. He has HUP Solar One FLA batteries that
> > > > > are about 4 years old, so they should be in good shape. The last set
> > > > > lasted almost 20 years with a fair amount of abuse.
> > > > >
> > > > > Here is he history and what I think is going on. 7/21 they got new
> > > > > batteries after about 19 years of use.
> > > > >
> > > > > 7/22 I get a call saying the batteries are not charging up all the
> > > > > way. When I check out the system, the batteries needed cleaning, and
> > > > > I found three low cells, and the charger settings were back to
> > > > > default, not set high enough to charge the batteries all the way (it’s
> > > > > always multiple problems). The client (now a new renter, new to the
> > > > > system) said he was filing the batteries once a month and experienced
> > > > > some overflowing when the batteries were charged up.
> > > > >
> > > > > I cleaned things up, reset the charging parameters and set up an
> > > > > equalizing charge to even out the cells. Hopefully this will fix
> > > > > things.
> > > > >
> > > > > 11/25. The client calls and said the batteries don’t charge up all the
> > > > > way and he is running the generator a lot and worried about getting
> > > > > though the wintertime.
> > > > > When I check things out, there are three bad cells and there is soda
> > > > > on the batteries. It is hard to get a good voltage readings because of
> > > > > the soda. Most of the cells are reading 2.1 volts under about a 40 amp
> > > > > load.
> > > > >
> > > > > Yesterday I check things out, and all the cells are reading between
> > > > > 1.93 to 1.98 under a 40 amp load in the morning, and I don’t find any
> > > > > bad cells. The charging voltage is never going over about 52 volts so
> > > > > the system is never getting fully charged up. The charge setting look
> > > > > OK, so not sure what is going on. This is acting like an old battery
> > > > > pack but these batteries are relatively new.
> > > > >
> > > > > My guess at this point is that maybe the batteries lost acid with the
> > > > > overflowing event and lost capacity. Maybe adding acid back in would
> > > > > bring them back up to working order. The SG measured at 1.150 or
> > > > > less.
> > > > >
> > > > > At this point the client (renter) has had enough of these battery
> > > > > problems and is wondering every morning if the batteries will last
> > > > > long enough to until the sun comes up. The renter is pushing for a
> > > > > replacement LFP battery, but there should be lots of life left in this
> > > > > battery pack.
> > > > >
> > > > > Let me know what you all think.
> > > > >
> > > > > Thanks,
> > > > >
> > > > > David
> > > > >
> > > > >
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> > > > --
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Michael Morningstar
> > > >
> > > >
> > > > Morningstar Electric Inc
> > > > PO Box 1494
> > > > Mount Shasta, CA 96067
> > > > 530-921-0560
> > > > CSLB 1116835
> > > > mjmorningstar at gmail.com [mjmorningstar at gmail.com]
> > > >
> > > >
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