Author Topic: Absorb time question  (Read 162 times)

Brirog

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Absorb time question
« on: May 06, 2020, 11:29:54 AM »
Hello, I have a 750 W solar array (3 x 250 watt panels) 30 Amp MPPT Kidd charge controller with battery temp sensor and a 24 Volt battery bank consisting of (4 x S6-460 AGM Rolls Surrette batteries).
Does anyone know what the absorb time setting should be for these batteries? Also, does this value need to change taking colder weather into account during the off season?

Tx

ClassicCrazy

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Re: Absorb time question
« Reply #1 on: May 06, 2020, 03:17:50 PM »
Do you have the Whizbang and a shunt installed ?
Those are good options to really know what is going on with the battery. That way you can know that you are putting back in what you are taking out of the battery and get a good estimate of its SOC - state of charge.
Rolls should have some details about Absorb time for their batteries.  2 hours is a good place to start.  If you have the Whizbang you can use Ending Amps instead of Absorb time and that can be more flexible to what your batteries need.
The temperature comp sensor and setting will raise the Absorb and Float voltages as the batteries get colder to keep the batteries properly charged. As far as changing the absorb time - it might be a good thing to do but really depends upon your usage and what you are observing happening with your batteries.

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

Brirog

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Re: Absorb time question
« Reply #2 on: May 06, 2020, 04:50:23 PM »
Thanks for the info Larry, I will consider getting the WBJ at some point.

ClassicCrazy

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Re: Absorb time question
« Reply #3 on: May 06, 2020, 05:48:19 PM »
Thanks for the info Larry, I will consider getting the WBJ at some point.

Whizbang is well worth it - not too long back people  used to pay a lot of money to get something like the Trimetric meter to count the amps going in and out of the battery.  It really is the best way to know how much power you use and charge too.
Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie