TriMetric TM-2020: "Amp hours from full" display

SeanFSeanF Registered Users Posts: 6
Hello all--

Is there any reason why the TriMetric "amp hours from full" display would be a positive number? My understanding of its operation leads me to believe that it should be zero (fully charged batteries) or some negative number. I've read and (think) I understand the process by which the number is determined by the TriMetric, but I still see a positive number there occasionally, usually on weekends when the batteries get fully charged.


Thank you in advance!


4 x Trojan L16-H
4 x Kyocera KC-120
1 x Southwest Windpower Air-X turbine
Morningstar TS-45 charge controller
Exceltech 600 watt inverter
Xantrex C-40 load controller
TriMetric TM-2020 monitor


  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: TriMetric TM-2020: "Amp hours from full" display

    i hope i'm understanding you right on this and i will say in general about the trimetric. the trimetric tries to not only measure the amps lost from using your batteries, but also measures the same amps going back into the batteries. the problem is that it takes more current going back into the batteries to get it to be fully charged again due to efficiency factors. the trimetric does have provision for this efficiency that you determine for your batteries. if you don't set the efficiency factors into the trimetric or have misguessed the actual extra current that the batteies need, it will show a + or a - from full. this can be a guessing game as you rarely get it exactly right. even the battery temperature can swing the required current the batteries need to be fully charged. as i said it is a bit of a guessing game, but once you've found a good point to set it to, it does give an approximate charge condition. time and temperature can change that as well as a battery's ability to take or give current(aging for example).
    i do have the meter and since getting a controller with an ammeter for measuring the charging current and i know the general soc by the battery's resting voltage, i do not wish to use my trimetric any longer. the state of charge of any battery can be determined by its resting voltage better in my opinion than guessing at various charge efficiencies. this voltage can vary by battery type or manufacturer. if you are in the neighborhood then go with the meter as a general indicator of your charge and please don't take it literally as being exact. if it appears to get a wild swing that goes beyond that which you would normally see then investigate it. minor adjustments to the meter or resetting can be needed at times because of additive inaccuracies over time. i hope this covers all of the bases to your inquiry to the meter.
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: TriMetric TM-2020: "Amp hours from full" display

    Is your "Amp hours from full" set for automatic reset? See page 7 of the instruction manual:

    Jim / crewzer
  • SeanFSeanF Registered Users Posts: 6
    Re: TriMetric TM-2020: "Amp hours from full" display

    Excellent information -- thank you both! Crewzer, somehow I missed that tidbit while reading the manual X number of times...I think that will solve my problem.

    Thanks again!
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