How to Install a Blocking Diode

Tricia Lobo

Blocking diodes are one-way valves used in electrical circuits. When building your own wind dynamo chargers or solar power systems to charge batteries or create AC power, blocking diodes can be extremely important to prevent charge from flowing backwards, draining your battery bank.

Blocking diodes are not of use in preventing overcharging of your battery bank.

When there is low wind, in the case of a wind dynamo, or at nighttime, in the case of a solar panel, a blocking diode becomes particularly important.

  1. Acquire a blocking diode capable of blocking the maximum possible current that your generator can produce -- this is the theoretical maximum that could ever flow backwards from your batteries.

  2. Wire the generator or solar panels to the 12-gauge AWG cable. Connect positive terminals to the black wire and negative terminals to the white wire. Connect green wire to the motor/panel casing, to serve as a ground. Wire the AWG cable to the blocking diode.

  3. Wire the blocking diode to the charge controller, which is configured precisely for your voltage and motor settings according to manufacturer's instructions. Wire the charge controller both to a dump load, which will avoid overheating of your batteries in the event that too much current is sent towards your batteries, and to the battery bank. Your blocking diode will function to prevent current from flowing backwards from the charge controller.

  4. Tip

    Since your blocking diode does not prevent too much charge from flowing downstream to your batteries, the use of a dump load is necessary.