This is a mystery to me...

[openplanet]

...and I'm sure a smart person on this forum can clear it up.

I have 8 Crown 6v 370 ah batteries in series for a 48v system.  I've never been able to get the sg all the way up to 1.270, which is the manufacturer's spec; 1.250 is as high as I've ever gotten them, even after several hours of equalization at 62 volts.

I decided to do an experiment, and encountered something I don't understand.  I made the equalize voltage the same as the absorb voltage, 60v.  I also set the end amps extra low, 1a.  When the cc went to float because ea dropped below 1a I turned on equalization.  Lo and behold, amps (as measured by wbjr) went up to 8a and stayed there for several hours, no progressive decline.

Question: if absorb transitioned to float because at 60v current dropped below 1 amp, why would equalize be able to pump 8 amps into the batteries, given it was set at the same voltage, namely 60v???  I'm pretty confident I understand Ohm's Law, but this I definitely don't understand.  Thank you.

[Vic]

Hello openplanet,

Surprising to me that the Classic,  charging a 370  Ah battery bank would transition to Float at 1 A.

What is the time setting for Absorb?
Is it possible that the Classic went to Float due to Abs time expiring?

Just trying to get the discussion started.

Are you using the BTS,  installed on the side of a battery,  and plugged into the Classic?
Is  EQ set to use Temperature Compensation for EQs?
EDIT:  And what was the approximate battery bank temperature?

Thanks for the answers,  Vic
And,  is the EQ voltage set to  exactly the same voltage as Vabs?

[openplanet]

Not using time for absorb. Using end amps as determined by WhizbangJr.  I normally have that set at 7.4 amps (2% of battery ah capacity).  But as I mentioned, I set end amps at 1 amp in an effort to get the sg up to 1.270.  And it was just an experiment when I set the eq voltage the same as the absorb voltage (60volts).  I expected no change in amps when I started eq.  So I was surprised, and puzzled, when, after the Classic went to float because amps had dropped below 1, I set eq to START and saw amps go up to around 8.  I thought wait a minute...if 60 volts isn't able to push more than an amp into the batteries in absorb (hence the transition to float), why the heck would 60 volts be able to push 8 amps into the batteries in eq???

[Resthome]

Not using time for absorb. Using end amps as determined by WhizbangJr.  I normally have that set at 7.4 amps (2% of battery ah capacity).  But as I mentioned, I set end amps at 1 amp in an effort to get the sg up to 1.270.  And it was just an experiment when I set the eq voltage the same as the absorb voltage (60volts).  I expected no change in amps when I started eq.  So I was surprised, and puzzled, when, after the Classic went to float because amps had dropped below 1, I set eq to START and saw amps go up to around 8.  I thought wait a minute...if 60 volts isn't able to push more than an amp into the batteries in absorb (hence the transition to float), why the heck would 60 volts be able to push 8 amps into the batteries in eq???

Vic is correct the Absorb time setting still works with EA if the time is reached before the EA setting it will terminate Absorb. So what is your Absorb timer set to?

[openplanet]

Absorb time set intentionally high so that Classic will go to float based only on end amps.  10 hours.

[Vic]

OK,   fine,   BUT,  could you answer some of the questions asked above?

We know little of your system.

As an aside,   it IS possible that your Hydometer is not too accurate,  which might help explain your los-ish SG readings.

TIA,   Vic

[Matrix]

Ask Vic,  he will tell you I obsess over this subject    You many need to start with something in excess of 2.55v /cell.  Keep an eye on battery temp while doing this.    Unless I run 2.6v /cell I cannot get absorb to get me fully charged unless I have many hours.  I turn end amps off and if I run manufacture spec voltage for absorb it just keeps charging and charging at about 1-3 amps and takes a forever / if ever to fully charge.  I up the voltage and get there in about 2-3 hours in absorb from an SOC of 70%.

That said,   some where (maybe on this forum) someone   passed this on to me,  and I found it a good read. Perhaps it will help you?   

[openplanet]

OK Matrix, I'll set Absorb up to 2.55vpc (was set at 60v, will increase to 61.2) and see how that does.
(And Vic, I'll put details of my system in signature.  Thx.)

[Vic]

Hello openplanet,

Surprising to me that the Classic,  charging a 370  Ah battery bank would transition to Float at 1 A.
   ...

Are you using the BTS,  installed on the side of a battery,  and plugged into the Classic?
Is  EQ set to use Temperature Compensation for EQs? And what was the approximate battery bank temperature?

Thanks for the answers,  Vic

openplanet,    could you please fill us in on answers to the above?

AND,   if you are using a Hydrometer, what type is it,   what brand is it? "Type"  being,   glass tube with glass float,  or plastic case with a pointer thingie,  ...   or ?

Thanks again,   Vic

[Vic]

Hi openplanet,

Let me just add,   that all of us here are trying to learn.   So trying to figure out what is,  or might be happening in situations like yours (and many others)  is the real challenge.

Having data/information about the system and what are the operating conditions of the system at the time of an event  is very important.   Supplying this information is usually essential to discovery.

IMO,    Vic

[Vic]

openplanet,

Just in closing,   will   add an additional thought.

For the many of us who have ARST (Auto Reset at Midnight) turned ON;

If we change parameters,   like in the Charge menu,   those Charge parameters will (generally)  become active at the time that changes are made,   but,   if the change was not stored by pressing the Enter button on the MNGP,  that change will not remain on the following days.

Had wondered if changes in Veq,   EA, etc that you had made on day 1  were dismissed by the ARST   on successive days,  if that if ARST is enabled on the Classic in question.

Perhaps you have discovered something that would help explain the behavior that puzzled you   ...   Perhaps WE will never know.

Good Luck with your system.   Vic

[openplanet]

Vic--

I really apologize for the delay in replying to you, and I completely agree about the importance of background information for problem solving.  My bad!

*I AM using BTS, installed on the side of a battery (between two), AND plugged into the Classic.
*EQ is set to use battery compensation.  When absorb set to 61.2 battery temperature goes to about 32 c.

[openplanet]

Although my OP was about a mysterious upsurge in charging amps when (1) Absorb and Equalize voltages were set to the same value of 58 volts, (2) the Classic was in Float based on WbJr. end amps of 5a, and (3) I enabled Equalize...     the motivation for doing that experiment was that I'd never been able to get the SG in my Crown 370s above 1.240. 

A suggestion was made to increase Absorb to 2.5 vpc (60 volts on my 48 volt system).  THIS FINALLY GOT MY BATTERIES FULLY CHARGED.  I suppose I should have thought of increasing the Absorb voltage myself, but I didn't think of doing so because my Equalizations (normally set at 62 volts) never managed to accomplish a full charge.  Live an learn.  In case, thank you so much.  Once again this Forum proves so, so helpful.

I will now slowly lower Absorb voltage by .2 each week until I reach the point where SG is not showing full charge when in Resting, then I'll go back up by one step of .2 volts.  Make sense?  Thx.

[Matrix]

I would say you probably need to do an a Balancing EQ of the batteries at the max per cell allowed by the manufacture for several hours.  I would watch the SG of the cells every hour until the SG stops rising.  This could take 2-8 hrs.  after a full charge has been done.  (add water to any cells before EQ if needed)

Then using that number where the SG stopped rising in the lowest cell,  I would consider that fully charged SG and target that SG level for my solar absorb voltage / time / end amp SG number.

Just my .02