Diluted electrolyte and low SG

[SolarMusher]

Hi all,
I have a problem on a rolls battery bank (flooded/700Ah/48V), which had been overfilled up to the top last November. Gravity reached 1.245 with a few 1.250 after 12 hrs 64V EQ last week but yesterday it was showing a low 1.230 after a full charge and 100% SOC (no loads). After a month, and several charges/discharges, cells are still at top level with too much water. PV is 3 kwh, Classic is 59.2V with a Whizbang end current set at 9A and 3hrs absorb time, gen is set to auto-start at 70%/100% (for now I’d like to avoid draining these batteries deeper). I’m afraid that this guy would end to kill these batteries when powering large loads (inverters are Magnum PAE 8.8kwh) with such a weak gravity. Of course this guy had been warned and the bank was performing great when installed, but…
I’m wondering what the real state of charge of these batteries is and what would happen when a diluted electrolyte drops too frequently under 1.200…? So what could I trust in, SG or SOC or nothing in this unusual case? What would be better, longer absorb time or frequent equalising to try to evaporate all this water?
Any thought appreciated.
Happy new year.
Erik

[Halfcrazy]

Hm. If nothing is spilling out than that means all the good stuff is still in there. If the level is not dropping it would appear to me that the batteries are not being charged enough? I may give a call to Steve at Surrette and get his opinion.

Ryan

[Vic]

Hi Erik,

Assume that these batteries are two strings of L-16s (?).  L-16s do not have very much reserve capacity for electrolyte fill,  such that the amount of dilution  is not that great.

Agree with others,  that raising the Vabs somewhat,  and perhaps a somewhat more frequent EQ should do the trick of ridding the cells of excess water.

On the wind-sun Forum,  you did mention the concern about freezing vs the lower SG.   Since I am a Californian,  have not had to pay much attention to this.

Agree with Ryan,  that if there was NO overflow of electrolyte,  then It is just a matter of time until the excess water is eliminated from the cells from normal Absorption and EQ.

The 5000 series Surrettes DO have more reserve area for electrolyte,  so if these batts are in the 5000 series,  the amount of dilution (before overflow)  is somewhat greater than for the 4000 or 4500 series Surrettes.

Opinions,   Good Luck in the New Year.     Vic

[SolarMusher]

Hi Ryan,
I was thinking that setting an absorb charge on time only, for 4 hours or more could help evaporate a bit of water but it's snowing every days here and sunny absorbing days are only once ot twice a week so it's gonna take a long long time to get it right, I could also set the gen on absorb time for long time. My concern is the loads that this guy could draw from this weaky bank without damage.
If SG is 1.225/30 when full with 9amps EA, obviously it could drop easily under 1.200 when supplying large loads even if the gen start at 70% SOC (if not too cold, -32/37°c and below for the next days).
The only advice I could give him would be: don't use your system until everything is right but I'm pretty sure that he'd disagree, it's a new house that he wants to enjoy.
Yes, Ryan if you could give a call to Steve at Surrette it could help. Right now, I'm scratching my head with snow, cold and doesn't see what I could do to get it right before it's too late.
Erik

[SolarMusher]

Hi Erik,

Assume that these batteries are two strings of L-16s (?).  L-16s do not have very much reserve capacity for electrolyte fill,  such that the amount of dilution  is not that great.

Agree with others,  that raising the Vabs somewhat,  and perhaps a somewhat more frequent EQ should do the trick of ridding the cells of excess water.

On the wind-sun Forum,  you did mention the concern about freezing vs the lower SG.   Since I am a Californian,  have not had to pay much attention to this.

Agree with Ryan,  that if there was NO overflow of electrolyte,  then It is just a matter of time until the excess water is eliminated from the cells from normal Absorption and EQ.

The 5000 series Surrettes DO have more reserve area for electrolyte,  so if these batts are in the 5000 series,  the amount of dilution (before overflow)  is somewhat greater than for the 4000 or 4500 series Surrettes.

Opinions,   Good Luck in the New Year.     Vic

Hi Vic,
I've posted a reply but couldn't find it  .
Yes, we are talking about two strings of  Rolls S-460 serie 4000 (700Ah/48V), Classic whizbang and Magnum PAE End currents are set to 9amps EA with 3hrs absorb time. I was talking about freezing because of the gen starting battery which was located inside the gen and could prevent the gen from starting at 70% SOC when low temps. I've solved this problem by doubling battery capacity and put it in a box inside a heated shed where the rest of the system is located, it starts great now even when low temps. These 12V starting batteries are charged/floated from a SunSaver mppt 15A from the 48V bank, works fine, still want to add a relay connected on daylight aux1 to make it work like PV. Vic, do you think I could safely use 60Vabs (higher rolls setting) for sometimes with a 4 hours absorb to evaporate this water a little faster.
Erik

[tecnodave]

Erik,

If I could throw in my two cents, I often stir the electrolyte in my L-16's by pumping fluid with a turkey Baster , if I have a high level I pull some out and save in one of my distiller water containers.  This will also help prevent sulfation due to the stratification. That said I am a very hands on type of person and maybe can explain how I get 10 years out of my batteries. I measure my s.g. every two weeks and chart it to be able to predict trends that will lead to a failure. I also use a refractometer. This is based on my being from Alaska and the knowledge that stratification of the electrolyte will lead to freezing of the batteries. This is usually fatal as the separator plates are crushed when this happens. In Fairbanks we used a winter battery which had a normal s.g. of 1.320-1.340 these were built by Alaska Husky Battery Co. of Fairbanks that would not freeze at 70 below which is normal in Fairbanks for 90 days in the winter. These batteries were parked with the snow tires in the summer as they could not take the heat of the Fairbanks summers.

Educating people about taking care of things is one of the major issues of off grid power, electricity is easy to me but changing people's mindset about it is a different matter.

tecno

[SolarMusher]

Erik,

If I could throw in my two cents, I often stir the electrolyte in my L-16's by pumping fluid with a turkey Baster , if I have a high level I pull some out and save in one of my distiller water containers.  This will also help prevent sulfation due to the stratification. That said I am a very hands on type of person and maybe can explain how I get 10 years out of my batteries. I measure my s.g. every two weeks and chart it to be able to predict trends that will lead to a failure. I also use a refractometer. This is based on my being from Alaska and the knowledge that stratification of the electrolyte will lead to freezing of the batteries. This is usually fatal as the separator plates are crushed when this happens. In Fairbanks we used a winter battery which had a normal s.g. of 1.320-1.340 these were built by Alaska Husky Battery Co. of Fairbanks that would not freeze at 70 below which is normal in Fairbanks for 90 days in the winter. These batteries were parked with the snow tires in the summer as they could not take the heat of the Fairbanks summers.

Educating people about taking care of things is one of the major issues of off grid power, electricity is easy to me but changing people's mindset about it is a different matter.

tecno

Hi tecno,
Fully agree with you!
That's the problem here, this guy is living in town and would like to have the same way of life in his cottage (very nice cottage indeed!).
Erik

[dgd]

Erik,
Four L16s at a remote repeater site were kept filled to overflow by a local service tech who was told to check battery levels on each weekly visit. He ignored the instructions in manual how to do this.
This went on for over a year until I visited. It took several eqs and 3 months to get sg back to normal.
They didn't seem any worse for experience.
Dgd

[SolarMusher]

Hi David`

Erik,
Four L16s at a remote repeater site were kept filled to overflow by a local service tech who was told to check battery levels on each weekly visit. He ignored the instructions in manual how to do this.
This went on for over a year until I visited. It took several eqs and 3 months to get sg back to normal.
They didn't seem any worse for experience.
Dgd

Hello David,
Good to know that you had success to bring them back to life. It's the worst part of the year here to have this kind of problem on an unattended system: one or two sunny days a week with a max four hours of sun to charge a bank, snowing for the rest of the week with pannels covered and if not enough, add cold temp that could prevent a gen from starting and this winter is particularly tough. If there was wwoofing in solar I would like to swap my place for a few monthes  . I'm pretty sure that it would not be  a great problem  for the rest of the year, just have to wait. But the worst is to come when the owner will be there (tomorrow) with family and low capacity batteries and propane genset at -34/37°c. I think I'm gonna take a three days dogsledding ride... .
Erik

[Westbranch]

Erik, don't you have a 700 Km trip to make soon?

[SolarMusher]

Erik,
Four L16s at a remote repeater site were kept filled to overflow by a local service tech who was told to check battery levels on each weekly visit. He ignored the instructions in manual how to do this.
This went on for over a year until I visited. It took several eqs and 3 months to get sg back to normal.
They didn't seem any worse for experience.
Dgd

David, did you see these L16s below 1.200 SG when you checked them the first time you visited the site?
I had noticed very low SG around 1.150 before charged and equalized which could be explained by voltage and SOC that didn't match SG no more. I think that it could be "safe" to use such a weak system until large loads are not used and SG doesn't drop and stands below 1.200 for too long. It would be interesting to test SG when the system hits 70% SOC (gen start), after EQ I had it at 1.245 max (8hrs) so I guess/hope it should be at or close to 1.200 at 70% SOC.
Ouch! -40°c this morning  . Hot water is frozen inside with stoves x2 runing...
Looking desperately for WWOSFing (world wide opportunities in solar farming, Hawaï prefered) .
Erik

[dgd]

David, did you see these L16s below 1.200 SG when you checked them the first time you visited the site?
I had noticed very low SG around 1.150 before charged and equalized which could be explained by voltage and SOC that didn't match SG no more. I think that it could be "safe" to use such a weak system until large loads are not used and SG doesn't drop and stands below 1.200 for too long. It would be interesting to test SG when the system hits 70% SOC (gen start), after EQ I had it at 1.245 max (8hrs) so I guess/hope it should be at or close to 1.200 at 70% SOC.
Ouch! -40°c this morning  . Hot water is frozen inside with stoves x2 runing...
Looking desperately for WWOSFing (world wide opportunities in solar farming, Hawaï prefered) .

Hi Erik,
The L16s were those Trojan types in the red containers, about 420Ah. They were new in 2011 and AFAIK overfilled from Oct 2011 to Aug 2012. When I visited the remote site in Sept 2012 the SG was extremely low, can't remember exactly what. I thought the batteries were dud and informed the owners they needed replaced.
I was told that it would take a couple of months to get replacements and arrange transportation etc (helicopter lift into rugged terrain, hut on hilltop).
The genny had limited fuel so could not be left running.
So the batteries had to keep working for a while further.
There was six 185watt Suntech panels to MX60. So I arranged two additional 240 watt PVs, reset MX60 to 70amps and adjusted the absorb and float up by about 2 volts and had the regular tech do an EQ at 32v every 3 weeks on his maintenance visits.
Fortunately summer and longer days were coming so the batteries were getting way overcharged - this didn't concern me as I thought they were probably ruined.
When I revisited following Feb the L16s were at normal SG and working as expected.
I lower the A and F by a volt and left them at that, EG every 8 to 10 weeks.
They have been good ever since, now C150 plus battery connected 500watt turbine, genny has not started last 6 months...

I suppose we were lucky because summer temps were high, nothing below 5degC
I would agree with your light load usage and keeping SG at least above 1.200

dgd