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S_Davis's avatar
S_Davis
Explorer
Oct 08, 2020

Max amp draw

What is a max amp draw for a pair of Trojan T105s? I am trying to figure out wire sizing.

27 Replies

  • S Davis wrote:
    What is a max amp draw for a pair of Trojan T105s? I am trying to figure out wire sizing.


    more than likely the max current you will stuff in them to charge will be greater than the max current you pull. But you need to consider both cases. And both will depend on what you have. 50A charging is not unreasonable with a good charger, 6V jars don't like more than about 30-50A longer term draw. Disadvantage of GC is higher internal resistance which affects battery voltage on larger draw.
  • Overdraw means plates heating and warping
    That in turn causes gassing meaning hydrogen and oxygen plus acid. AGM batteries excel at extended CCA performance.
  • Max short circuit amps? You need a fuse to take care of this concern.
    Realistic peak draw during use? I give the pair 75 to 90 max.

    Note the T105 specifications prominently gives the 75 amp rating in minutes. This is where I get my numbers.
  • Bobbo's avatar
    Bobbo
    Explorer III
    To figure out the "max amp draw" that the batteries are capable of, drop a crescent wrench across the terminals. :B To figure out what size cabling you need, calculate the max amp draw of your RV.
  • Ok thanks, I have 1/0 DLO cable rated at 260 amps and the wire run is under 5’ to a 600 amp buss bar for each pair of T105s. Sounds like this will work.
  • That "depends" :) IMO think about 150 amps for a few minutes of microwave time as long as the batts are above 75% SOC. (inder 75% the inverter will see 11 volts and alarm), and you can charge them no sweat at about 80 amps to start with, where Bulk will last only a few minutes before amps taper.

    So IMO go for #1 AWG at under say five feet each for pos and neg to the 2000w inverter. Use same gauge for the series link between the two 6s. If you have to go longer than five feet each, then go fatter.

    the 80 or less charger can have #4 AWG, but you can also wire the charger over to the inverter on short wires and then they share the (maybe fatter) inverter's wires.
  • See page 10. I believe Trojan answers your question.

    https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf

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