Absorb time question

Started by Brirog, May 06, 2020, 11:29:54 AM

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Brirog

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

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 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

Brirog

Thanks for the info Larry, I will consider getting the WBJ at some point.

ClassicCrazy

Quote from: Brirog on May 06, 2020, 04:50:23 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 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable