As a long time HUP dealer, I've dealt with stuff like that for quite a
while. FYI, HUPs are no longer being made, thanks to the tariffs.
As Steve mentioned, renters are Not the best off grid customers. They
really don't understand the system, and how to properly maintain it. My
guess is they have a bunch of phantom loads, extra junk plugged in, and
the system is never reaching full charge. 2nd, as noted, they are over
filling the water. I have several customers that get fixated on
filling, and forget to check SG, and actually fully charge the batteries
too. You didn't mention some key info: battery size, or array size. If
its a bigger HUP, it could take over a week with no loads to come back
up. HUPs have a minimum charge rate requirement that is very important
in this situation.
So, based on the age, this should be recoverable. It will take some
extreme EQing for possibly a couple of days. I'd EQ at 61 v for 2
hours. Monitor temperature and don't let the batteries exceed 95F.
Check SG. If you're not up to 1.265 on the lowest cell, EQ again.
Rinse/ repeat, until you get to 1.265. Then this renter may need to go
on an energy diet too, so this doesn't happen again. I've had so many
renters ruin good systems that worked for the original owners for
decades. They just leave stuff on, and it never comes to full charge.
Ray Walters
Remote Solar
On 12/12/2025 11:35 AM, Steve Higgins via RE-wrenches wrote:
The SW series inverters don't have non-volatile memory, so if the
renter discharges the battery below the low-voltage point, all
settings will be reset to default. That will definitely cause
charging issues.
If they were overfilling the batteries, this would push sulfate out of
the battery, diluting the acid mix and lowering overall capacity.
You can try adding more back, but it will require a lot of premixed
acid. It might help to drain 1/2 out and add back premixed 1.265-1.280
acid to correct. If the sulfate levels are already low and there is
mostly just water in the battery, corrosion can occur within weeks,
resulting in permanent damage.
Also, if you add too much or the sulfate has precipitated on the
plates, this will increase the sulfate in the battery and lead to a
significant loss of overall capacity.
My guess... is this battery is done for... You can try the above, but
you'll likely spend a lot of time adjusting electrolyte levels and
many hours of cycle charging to recover. Even if you recover to some
capacity, the SGs will always be "All over the place," and the bank
will likely remain questionable until they are replaced. In the
end, the "Renter" probably killed these due to lack of
interest/education...
Steve Higgins.
On Fri, Dec 12, 2025 at 10:21 AM David Coale via RE-wrenches
<[email protected]> 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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