Home› Battery/Electrical & Solar

AGM Battery (Renogy 100Ah) Maximum Depth of Discharge

jbajorjbajor Member Posts: 220
in Battery/Electrical & Solar
I am setting up my new Victron Smart Shunt  (IP65, 300 amp) and, in my research, seen MANY references to setting max discharge to 50% as well as 80% discharge (50% remaining charge and 20% remaining charge).  Clearly this makes a significant difference to the calculated time remaining on the battery for a given load. Are there any real world uses that you have had with respect to how far you allow your AGM battery to discharge without ill effect?  Where 50% is considered 'safe, I do not want to short change my capacity but I also do not want to prematurely damage my battery. What say you oh wise ones?  Cheers!  Jordan
Ultimate Toys Teardrop Camper
Volvo XC-40
SF Bay Area, California
· Share on FacebookShare on Twitter Share on Google+

Comments

  • pthomas745pthomas745 Administrator, Moderator Posts: 4,385
    There have been several interesting discussions on this subject in this group in the past. This thread is one of them, with some data on the various "depths of discharge" and life of the battery.
    A lot of this sort of info depends on the relative health of the battery, its age, how well it has been treated, etc.  All batteries will fade in amp hour capacity over time, and lead acid batteries, no matter how well they have been treated, are getting sketchy when over 5 years old. 
    The batteries mentioned in this thread (Trojan, Odyssey, Concorde, etc) were considered the "high end" AGM batteries of their time.  See if this thread helps, or simply adds to the "analysis".  

    2017 Outback
    Towed by 2014 Touareg TDi
    · Share on FacebookShare on Twitter Share on Google+
  • MarcelineMarceline Member Posts: 1,731
    edited December 10
    jbajor said:
    I am setting up my new Victron Smart Shunt  (IP65, 300 amp) and, in my research, seen MANY references to setting max discharge to 50% as well as 80% discharge (50% remaining charge and 20% remaining charge).  Clearly this makes a significant difference to the calculated time remaining on the battery for a given load. Are there any real world uses that you have had with respect to how far you allow your AGM battery to discharge without ill effect?  Where 50% is considered 'safe, I do not want to short change my capacity but I also do not want to prematurely damage my battery. What say you oh wise ones?  Cheers!  
    I hardly ever look at the "calculated time remaining on the battery." I think that data is a lot more useful when the controller is connected to a system where there is some kind of regular-ish load. I just don't think it's very useful when you have the compressor from a fridge (or the fan for a furnace) kicking on/off at irregular intervals. I mostly focus on the SOC (voltage) and the net amps consumed. Just my two cents.
    San Francisco Bay Area
    2013 CS-S us@gi
    2015 Toyota Tacoma PreRunner Double Cab
    · Share on FacebookShare on Twitter Share on Google+
  • jbajorjbajor Member Posts: 220
    I completely agree with you, however, how far will you allow your battery to discharge (lowest state of charge) for an AGM...  I currently am planning on not exceeding a SOC of 40% (less than 50% but sill more remaining than at an 80% discharge (20% SOV).  Sigh...  certainly MANY additional variable rendering it no trivial...  Just curious what other AGM owners have set there Victron Smart Shunt to..  btw, pthomas, that is a great thread!!  (albeit still not definitive but excellent food for thought!  Thanks all

    Ultimate Toys Teardrop Camper
    Volvo XC-40
    SF Bay Area, California
    · Share on FacebookShare on Twitter Share on Google+
Sign In or Register to comment.