Absorb Time

[Jrosado99]

I have a 48v system. 360w*10(3600w PV array) for a 375AH battery bank.
Battery parameters by manufacturer(with temp sensor)
Absb/Bulk: 60V
Float: 54V
EQ:62.4-63

I have the classic 150v.

How do i make sure that the temp is set correctly so i can use the given parameters of charging ?
I recently check the controller and it showed a SOC% 100 but it was still in the absorbing time. My question is... is it safe to the batteries to still absorbing while on 100%?
In the whizbang J. What is the meaning of the efficiency?
I haven’t set end amps because the battery manufacture told me not to. According to him, the battery likes to absorbing.
I have the classic manual but in my opinion i haven’t found something that teaches me how the controller perform in a daily basic. I just want to understand the controller.

[boB]

I have a 48v system. 360w*10(3600w PV array) for a 375AH battery bank.
Battery parameters by manufacturer(with temp sensor)
Absb/Bulk: 60V
Float: 54V
EQ:62.4-63

I have the classic 150v.

How do i make sure that the temp is set correctly so i can use the given parameters of charging ?

Welcome to the forum !

This parameter should be supplied by the battery manufacturer.  For regular flooded lead acid batteries it is -5mV  for each 2V battery cell.

I recently check the controller and it showed a SOC% 100 but it was still in the absorbing time. My question is... is it safe to the batteries to still absorbing while on 100%?
In the whizbang J. What is the meaning of the efficiency?

Staying in Absorb while at 100% is fine.  Normal a lot of the time.   You need to have some time in Absorb to keep the batteries from sulfating and wearing out sooner. 

Even if the battery gets to 100% state of charge.  BUT if the time in Absorb is long enough (a few hours typically), then that is usually the most charged they are going to get.  This is why, even if the SOC doesn't quite get to 100%, the system has to assume the battery is then 100% charged at the end of Absorb and when it goes to Float after those few hours in Absorb, it forces the SOC to be 100% charge.  That is sort of an automatic self-calibration.

The battery doesn't get very much amp-hours returned to it after the first hour or two of Absorb.  Absorb is mainly for maintaining the batteries' health and to keep sulphate off of the plates and to keep that would-be plate insulation from hardening and reducing the capacity of the batteries.

The efficiency that you set for the State of charge calculation has to do with the fact that when you pull out a certain number of amp-hours energy from the battery, you have to put more amp-hours into the battery to replenish those amp-hours pulled out when it discharged.

That efficiency is typically somewhere in the 90% range.  That is amp-hour charge efficiency.

Some will also talk about energy efficiency which is sort of different and lower percentage than amp-hours efficiency.   That lower figure has to do with, partly, from that energy that went into your Absorb charge cycle above and beyond putting in the last few amp-hours and maintaining the anti-sulfation health of those battery plates.

The Absorb cycle technically does not have to be done every single day and it has been said that doing a long Absorb every single day can reduce the battery life.  I am not sure exactly what that interval has to be BUT I have been told by one reputable battery manufacturer that they found it COULD go as long as one month without Absorbing and still be OK.

I haven’t set end amps because the battery manufacture told me not to. According to him, the battery likes to absorbing.

OK.  Then I would do what they say and stick with the Absorb cycle as best as possible with the available solar energy.

Ending amps is an automatic way of ending the Absorb cycle earlier than it would end if just left to the timer, as set in the Classic.

As your battery is charging and goes from Bulk MPPT to Absorb and sits there at the Absorb voltage, the current just naturally goes down to some minimum value required to keep the battery at that voltage.  That's the current it takes at that voltage to do that maintenance charge that keeps the plates from sulfating.  It just takes extra energy  (voltage X current X time)  or  watt-hours to do that.  That energy is part of why the energy charging efficiency is lower than the amp-hour efficiency.

If the manufacturer says to Absorb for a certain amount of time, then do what they say.  But some days the sun doesn't shine enough to get that Absorb done by solar PV.

I have the classic manual but in my opinion i haven’t found something that teaches me how the controller perform in a daily basic. I just want to understand the controller.

This forum and the folks that are on here can help you with a lot of these questions.

They live with the Classic and similar systems and are better with day to day operation, usually.

[billmill]

Hey bud,  I'm a one year newbie and have a 48 volt system too. I just joined the forums and wish I would have a year ago.  Enjoy the learning curve.

[Jrosado99]

Thank You All.