[RE-wrenches] FLA battery problelm
Ray Walters
ray at solarray.com
Fri Dec 12 15:11:06 PST 2025
You must be quoting the 6 hr forklift discharge rate. That's actually
the HUP SO-6-85-17 which is rated at 845 amp-hrs at the 20 hr discharge
rate. The 20 hr rate is what we should be using most of the time for
off grid solar. The minimum charge rate for that battery is 68 amps.
That array could only do 50 amps on a perfect day, so immediately, your
array is undersized. Plus from the sound of it, they are just
chronically under charging/ over discharging the battery. I would
suggest doing a complete load profile of their daily loads, and
designing an array that can meet that load year round.
Renting an off grid home is always a mess. I started charging anytime I
was going to be brought into that situation, since I didn't design the
system for the new user. Just because it worked great fro the original
user, does NOT mean its going to be adequate at all for the average
American consumer. I'm guessing the array needs to be doubled in size.
Ray Walters
Remote Solar
On 12/12/2025 3:51 PM, David Coale via RE-wrenches 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> 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> 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> 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> 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
>>>
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