I have a solar charge controller with these specs:

  • Type: PWM-Type Solar Charge Controller, 30A, 12V/24V
  • Battery type: DC 12V/24V (auto-detect)
  • Charge current: 30A
  • Discharge current: 30A
  • USB output: 5V/2.5A maximum
  • Maximum solar input: 23V/46V
  • Equalization: sealed 14.4V / gel 14.2V / flooded 14.6V
  • Float charge: 13.7V/27.4V
  • Discharge stop: 10.7V/21.4V
  • Discharge reconnect: 12.6V/25.2V

I aim to use it to charge 2x 12V 7Ah sealed lead acid batteries. I fear that if the charge controller is able to output 30A to the batteries that will exceed the initial current of 2.1A on each of the batteries. Should I get more of the same, or a bigger battery? What size do you think is appropriate?

  • 1
    \$\begingroup\$ Repeated charging at twice the rated capacity of the batteries will shorten their service life. Does the controller have a current limiter? If not, add a current limiter to the controller input. See electronics-notes.com/articles/analogue_circuits/… for some example circuits. \$\endgroup\$ Sep 23, 2022 at 2:00
  • 1
    \$\begingroup\$ 30A, if the battery will accept it, will (probably) destroy the battery extremely rapidly. The manufacturer will supply a maximum allowed charge and discharge rate. For SLA's iots usually a fcation of their rated capacity (maybe C/10) \$\endgroup\$
    – Russell McMahon
    Sep 23, 2022 at 3:47
  • \$\begingroup\$ What are the specs of your solar panel(s). \$\endgroup\$ Sep 23, 2022 at 4:41


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