KID controller operation and electrolyte stratisfication

[nlt999]

Hi!

Do I understand correctly that each morning, when the sun wakes up the KID, it automatically starts a 3-stage charging cycle (Bulk, Absorb, Float)? 

If that is true, would that not be enough to prevent long-term stratification of the electrolyte in flooded batteries left unattended for long periods of time??

If a WBJR is installed on the KID and working correctly, when we look at the KID WBJR status screen where it shows the net current into/out of the batteries, if the KID is in Float mode and there is enough PV power available to balance the loads, should we expect to see ZERO Amps showing on that status screen?  (in other words, the Float charge current would be just matching the current we are drawing out of the batteries at any moment)

From anyone's experience using the KID with WBJR, when in Float mode what variation is typical in the net current reading on that WBJR status screen?

Thanks for any comments!  Nick

[SM-Viper]

Nick,

You should see a value of about .5 amps in float. That is the float charge to the batteries. Hope this helps.

-Sean

[Vic]

Hi!

Do I understand correctly that each morning, when the sun wakes up the KID, it automatically starts a 3-stage charging cycle (Bulk, Absorb, Float)? 

If that is true, would that not be enough to prevent long-term stratification of the electrolyte in flooded batteries left unattended for long periods of time??

If a WBJR is installed on the KID and working correctly, when we look at the KID WBJR status screen where it shows the net current into/out of the batteries, if the KID is in Float mode and there is enough PV power available to balance the loads, should we expect to see ZERO Amps showing on that status screen?  (in other words, the Float charge current would be just matching the current we are drawing out of the batteries at any moment)

From anyone's experience using the KID with WBJR, when in Float mode what variation is typical in the net current reading on that WBJR status screen?
Thanks for any comments!  Nick

Nick,

You are correct about the daily charge sequence.

It is my opinion that Stratification  will not be the main issue with your L-16 batteries  --  from the info posted elsewhere,  seems to me,  that that the main issue could well be water consumption,  with no one there to replace the water,  and that the KID is doing a timed Absorption each day that has sufficient amount of PV power,  from the settings that the KID is using,   posted elsewhere

>EDIT:  Will add,  that,  given the very long period until the batteries can again be serviced,  AND,  that the KID does not yet have Auto EQ,  or Skip Days,  you have fewer options,  than you might want,  in  a perfect world.<

A  Flooded battery that has just completed a full charge,  and is being Floated at a manufacturer's nominal,  temperature compensated Vfloat  will require some current flowing into the battery,  to maintain Vfloat. (I have noted this in another Thread here).

For the Flooded banks here,  this temperature compensated nominal maintenance current (at a reasonable,  and manufacturer-recommended Vfloat),   is almost exactly 0.3% of nominal 20-hour Capacity.  Larger batteries will need higher currents to maintain Vfloat,  and a higher Vflt can result in a higher maintenance current.  The Deka L-16s at the site may behave a bit differently,  as they have a different temp comp value (--3 mV/C vs --5 mV/c for my batteries).    Stratification might well affect this maintenance current,  at least,  somewhat.  Stratification is not easy to measure (generally).

A considerable amount of battery charging will occur at a nominal Vflt,  on a battery that has NOT completed a full charge,  just prior to the application of Vflt.   This can be observed when using Skip Days (on the Classic),  but the KID does not yet have Skip Days.

The above is from observation of several Flooded banks in use here.

Vic

[Vic]

Hi Nick,

In my previous Post,  have assumed that you have NOT set an EA value,  and the Absorb time will be fixed ...

DID you set an EA value?  In your ReBulk Voltage Thread here,  and the similar one on Wind-Sun,  you have not listed a WBjr EA setting ...

Thanks,   Vic

[nlt999]

Vic, you are right....... we do NOT have an EA setting at this point.  As I mentioned in another post, the installer put our WBJR in backwards, which we only discovered a day before my brother had to leave for the season.  I therefore have the WBJR disabled until we can get it reinstalled correctly next summer.  As a result we are relying on a fixed Absorb-time setting, which I set to 30 minutes due to a post I read on the other site.  The Absorb voltage is set at the lowest-end of Deka's recommended range (from their renewable energy charging recommendations chart), 28.8V

We are hoping that these settings will get us through the off-season and not destroy the batteries.  The batteries have survived well for the last 4 off-seasons when we were using 170W of panels and a Morningstar ProStar-30 PWM-type controller.  That controller and panel combination maintained the batteries well for the unattended 9 to 10 months an only required topping off the water at the beginning of the summer, and during the active season.

Thanks once again for all your inputs!  Nick

[Vic]

YEA,  YEA,  yea,  Nick,

Sorry,  had already forgotten about that ...  been away for a day and one half and already forgot this important piece.

And,  did not know that the batteries were seasoned.

Well,  all that one can do,  IS all that one can do.

Sorry about the forgetfulness.    Good Luck.

[Mtn Don]

If that is true, would that not be enough to prevent long-term stratification of the electrolyte in flooded batteries left unattended for long periods of time??

Not sure on this... it's just theorization.

If the system is idle, no current draw down by anything except for the slight draw for the Kid itself, should there not be any stratification going on at all? The battery is just sitting there, in cold storage (good).  But on the other hand if there is some stratifying occurring a float charge is not enough to prevent that. It takes enough current to cause some good bubbling to mix electrolyte.  In spring / summer when the system is put back into service an EQ should likely be performed to get things stirred up and be certain. In normal day to day use if the PV array is sized large enough the normal replacement charge should also keep things stirred up.

Be interesting to hear from someone with extensive L-16 experience about whether or not dstratification could be an issue over a winter siesta, but with a daily bulk-absorb-float.

[tecnodave]

To all,

I'm way too late to chime in on this but let's be clear about stratification. 

This is caused by inactivity.

Basic chemistry:   1.260 specific gravity battery acid is heavier than water. When left not disturbed the acid will stratify leaving a more concentrate at the bottom of the cells and less concentrated at the tops. This happens when you have no significant loads and resultant low charge levels which do not stir the acid through the breakdown of water into hydrogen and oxygen.

The cure.....regular equalization which raises the voltage enough to cause the bubbling and gassing associated with the breakdown of the water therefore stirring the acid.

I do a simple test for stratification:     After resting for a while I read and record every cell with a good hydrometer.  Then I use a turkey baster to stir the acid. The baster has a much larger volume so it sucks up more mixture. After several minutes I use hydrometer again, recording each cell, and comparing with first reading.  If the specific gravity has gone up......sure enough I have stratification


Since the kid does not yet have auto eq. You might want to look into one of the high frequency desulfators.....these do much of the same process but by using spikes of voltage to de sulfate which does stir the acid solution.

td