HELP-Settings, Charging Issues and other Stuff

[Vic]

OK Garret,

This report is "most excellent"!

Glad that you found that errant temp reference.

ALL battery manufacturers that deal directly the end users,  at least on some battery models push the edge of the envelope regarding Capacity.  In the western countries,  especially in the USA,  bigger is always better,  and some of us are always looking for MORE.

Personally, would much rather have Surrette use 1.265 filling electrolyte,  vs what many other manufacturers do -- use 1.280 SG electrolyte,  and 80 C for Capacity ratings,  although,  Surrette may have changed from 25 degrees C to 27 like some others.   The battery biz is full of specmanship,  and  the more straightforward companies can be left in the dust (become un-competitive)  if they do not stretch a few things,   IMO.

FWIW.  Looks like you will have a very nice Backup power system.

Have fun with it.    Vic

[Vic]

Thanks Garret for that paper ...  will try to look at it this evening.

Some Flooded batteries,  especially the very tall ones like Fork Lift batteries,  have used pneumatic bubblers low in each cell to help agitate the electrolyte and reduce Absorb voltage and time requirements,  as well as reducing the need for frequent EQs,   FWIW.      Thanks again,   Vic

[Vic]

Hi Garret,

Now that you have found the main issue with getting your new batteries fully charged,  a couple of things;

Your 30 Vabs could probably be reduced to 29 V,  or a bit less.

And you could probably do any EQs at the low end of the Surrette-recommended range -- about 31 V,  at least for starters.

From memory,  thought that your Vfloat was 0.1 v above the spec,  yea,  this is a nit,  if correct.

Also,  your End Amps (from WBjr Shunt),  should probably be set to a higher value.  FWIW  the Surrette banks here use about 0.9% of 20 hr real nominal Capacity,  when not deeply-cycled.

Initially,  we all just wanted to see you get those batteries fully charged.   Now that you have,   the smaller details could matter more.

Have Fun,   Vic

[Garret]

Hi Vic

thought that your Vfloat was 0.1 v above the spec,  yea,  this is a nit,

Thought the 0.1 V above the recommended float setting both innocuous and a good fit since my measured terminal voltage based on the Classic output was 0.1 V less.  Also on the Magnum charger, the float voltages only come in 0.2 V increments, so it was either 28.2 or 28.4 V.

Your 30 Vabs could probably be reduced to 29 V,  or a bit less.

I will back down on the absorb.  29 V does seem a little more middle of the road.

The whole problem definitely stemmed from too low an absorb voltage, which in turn was strongly influenced by the incorrect reference voltage setting of 10C.  Selecting 10C vs 25C is a difference of 900 mV, not trivial.  That could also explain the lower than normal charging currents observed in absorb and the total lack of gassing. 

From the article I sent you, one of my conclusions would be that stratification due to inadequate mixing from electrolytic evolution of H₂ and O₂ may be more detrimental in the long run than risk of positive plate erosion.  So a little gassing during the absorb phase may be beneficial.  Just my unseasoned opinion. 

Anyway, as a newcomer, I'm almost expected to trash my first set of batteries, right?

Good sun yesterday.  I cycled the batteries down to about 60% and recharged from the Classic using my current settings.  Would agree, had to bump the WBJr end amps to 3 or it would not make to to float.  Attached is my ending gravity which I verified by direct SG measurement.

Cheers

[vtmaps]

inadequate mixing from electrolytic evolution of H₂ and O₂ may be more detrimental in the long run than risk of positive plate erosion.  So a little gassing during the absorb phase may be beneficial.  Just my unseasoned opinion. 

It's not an unseasoned opinion... it's a fact.  And you need more than just a little gassing.  Stratification builds up during charge and discharge.  Only a long absorb or EQ eliminates it.  Every day that you don't get to 100% SOC is a day of deepening stratification.

An interesting strategy, recommended by some manufacturers, is to slightly undercharge on a daily basis, and then weekly do an EQ to really stir up the electrolyte.  This will result in fewer hours per week of high voltage charging with its resulting gassing and corrosion.

Whether or not the manufacturer recommends it, that's what most of us off-gridders do... it's not often that I get to float more than a few times per week.

--vtMaps

[Vic]

OOPPSsssssssssss ... just lost a post.

Stratification also causes positive plate erosion,  at the bottoms of the plates.   One needs gassing for a full charge,  and more gassing yet for good mixing.  This erodes the plates,  but is necessary for healthy batteries.

You could test to see what is the required Vfloat for your system -- you really want to just barely keep your batteries fully charged.   Floating also causes plate erosion.

Have been Skipping days of full charge on banks here,  using Skip days.  And on days Skipped,  am running 50.5 as Vfloat (about 25.25 on a 24 V system),  to avoid much of the recharging of the battery that comes with customary Float V.

IMO,  reducing Vfloat below recommended levels is not an a problem,  unless one needs every bit of battery Capacity to run through the nights,  or as reserve for low sun days,  etc.   FWIW,   Vic