Battery advice and recommendation

I need to purchase replacement batteries for my 960W 24v Solar Back Up power system.
I was running 16 x Trojan T105 batteries for the past 8 years but the batteries now need replacing.
The batteries never got used or cycled as the whole system is only intend for back up power in the event of an natural disaster / earthquake or grid shut down etc.
I maintained the old batteries for the past 8 years, trickle charged them, equalized them when needed and filled them with distilled water when needed. 
They still look like new .. but the batteries aren’t taking or maintaining a charge anymore. So it’s time to replace them.

I’ve been considering either new T105’s or possibly the Trojan L16 or the Rolls S-550 as well.
What batteries would you recommend I purchase as replacements ? Would AGM batteries be a better choice for this type of solar back up system ?
I don’t mind spending little more if the batteries last longer.
Many thanks in advance. 


  • mcgivormcgivor Posts: 1,874Registered Users ✭✭✭✭
    edited September 2017 #2
    Welcome to the forum. You got good life with the T 105's, guess they died of old age since they weren't cycled, assuming 4 strings, using larger 1000Ah 2 Volt cells in a single string would be a better choice from a ballance perspective , AGM would cost more and relieve you of the watering, albeit they probably didn't use much in a float situation. Some manufacturers claim up to 20 years in standby use, under perfect temperature conditions such as  Hoppecke OPz, but the cost is about double what GC batteries are, for equal Ah., another option would be a forklift battery, very heavy though. Seems a shame they rarely get used, but that's not for me to judge.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • soloronesolorone Posts: 235Solar Expert ✭✭✭
    Price aside, how does the Tesla wall mount figure in this, I have an acquaintance looking at Hannah in Atlanta Ga for a system using the Tesla. 
  • AngliaUSAAngliaUSA Posts: 4Registered Users
    I am also looking into the TESLA option .. looking like close to $4k for 1.5KW lithium battery - with a 10year life expectancy .... I need to figure out the right new panels and new batteries for my existing electronics ....
  • AngliaUSAAngliaUSA Posts: 4Registered Users
    Trace DR3624 .. 3000W inverter - 24V .. WAS hooked up to 12 x 80W panels ... 960W total. Looking at 4 x new 300W panels and 4 x 6v L16 330AH Trojans ... ... trying to keep my cost down to $3k max and match the existing electronics to what I had ... 

    any thoughts or recommendations ?
  • mcgivormcgivor Posts: 1,874Registered Users ✭✭✭✭
    edited October 2017 #6
    Here's a suggestion, get yourself a grid supported inverter charger which has load shaving capabilities, run critical loads off the  inverter, during the day use  your excess solar production to support or partially support the loads since the inverter would have AC pass through capabilities. In the evening when peak billing occurs, program the inverter to allow battery power to support the grid, when peak billing terminats, grid power will recharge the battery at lower rates. In such a configuration you would actually be getting some payback from the batteries rather than them just sitting there waiting for an outage, of course they will still be available in such an event. Having a strictly backup system has little return and the expenditure for the batteries goes, for the most part, waisted, which is a shame, expanding your array would save you energy during the day, by offsetting grid consumption. Here is an example of a unit which will work for such an application, others are available, Magnum, Outback come to mind but I'm not personally familiar with them, although I understand they're excellent products.

    Of course I'm making the assumption there is peak billing by including load shaving, but advantage can still be achieved without, in the form of grid support, during the day. Some ideas to ponder.

    One could go further by selling back to the grid during the day, if loads are light, but that's a little more involved and of course if it is permitted by the utility.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • AngliaUSAAngliaUSA Posts: 4Registered Users
    Thanx for the suggestion ... if and when my Trace DR3624 dies then the inverter you suggest would make an excellent replacement. 
  • littleharbor2littleharbor2 Posts: 944Solar Expert ✭✭✭✭
    edited October 2017 #8
    Yes it will. It also gives you pure sine wave power, something your current inverter doesn't have. Bear in mind your inverter might just last you 20 years. Trace built some rock solid inverters in their day.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • 706jim706jim Posts: 205Solar Expert ✭✭✭
    My Trace DR1524 is now 23 years old and functioning perfectly. And with my electric fridge now runs 24/7
    Island cottage solar system with 1400 watts of panels, Trace DR1524 MSW inverter, Trace C40 PWM controller 8 Trojan L16's. My 25th year.
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