I have a solar panel charge controller with a load terminal that disconnects when the battery (12V car battery) goes below a certain voltage (9V). I have connected a winch which draws a maximum of 15A to that load terminal. I can start the winch in some instances, but often not.

I assume it is because the winch draws high current when starting, causing a voltage drop below the 9V cutoff and that in turn causes the load terminal to be disconnected from the battery.

Apparently, these load terminals are only meant for small loads like a light. But I wonder if I could just add a capacitor to "support" the battery at winch start to ensure the voltage doesn't drop too much?

Answers to this question suggest this is possible. I also read about inrush current limiters, but I'm not sure if this would be the right application.

If the capacitor approach works, would I put it in the battery circuit or the winch circuit? Is there any risk to damage components? Any hints on how to determine sizing of the capacitor?

I could just connect the winch directly to the battery but there are other loads like lights prewired in that circuit and I would like to take advantage of the automatic disconnect to prevent the battery from discharging too low.

  • \$\begingroup\$ "I could just connect the winch directly to the battery". Yeah, that's exactly what I'd do. Leave the other loads connected via the load terminal. \$\endgroup\$ – Finbarr Apr 5 '18 at 16:41
  • \$\begingroup\$ That would require some extensive rewiring. If a cheap and simple capacitor would solve my problem that would be much easier. \$\endgroup\$ – ignerant Apr 5 '18 at 17:01
  • \$\begingroup\$ It won't, you will need a VERY large capacitor to make any noticeable difference. \$\endgroup\$ – Finbarr Apr 5 '18 at 17:02
  • \$\begingroup\$ @Finbarr I see, guess I'll have to bite the bullet and rewire. \$\endgroup\$ – ignerant Apr 5 '18 at 17:28

Your Answer


Browse other questions tagged or ask your own question.