Gotta Learn Why?

Fixing installs with relays in this field on big draw is a NO NO, I used them back in the day with installing door locks on car alarms & Etc. This type of build needs to use a solenoids. Please remember this isn’t a bandaid for using cheaper wire. You still must run the correct gauge. Got to test them systems reguarly to see when the system is getting weak.

Here are the facts on the why and why nots.

When you’re building a 12V softwash setup, controlling high-amperage pumps the right way matters. Both solenoids and relays are switching devices — but they’re not equal.

• Relay: An electromechanical switch. Designed for lower-amp automotive circuits (lights, fans, stereos).
• Solenoid: A heavy-duty contactor. Built for high-current loads like starters, winches, and pumps.

Both use a small trigger wire to control a larger circuit, but the build quality and amp capacity separate them.

Why Solenoids Are Better

1. Amp Handling
   • Relays: Usually rated 20–40A continuous, short surge only.
   • Solenoids: Commonly rated 80–200A continuous, designed to handle huge surge amps without welding contacts.
     → Pumps surge 25–35A on startup. A solenoid shrugs it off; a relay struggles and fails.
2. Duty Cycle
   • Relays are intermittent-use — not designed to cycle under constant load.
   • Solenoids are continuous-duty rated, perfect for pumps that run long spraying cycles.
3. Contact Size
   • Relay contacts are thin, and arc easily when switching under load.
   • Solenoid contacts are thick copper or silver alloy — less resistance, less heat, longer life.
4. Voltage Drop
   • Relay = higher internal resistance = voltage loss to pump.
   • Solenoid = larger contacts = lower resistance = more volts delivered to the pump motor. That means less heat and longer pump life.
5. Environment & Durability
   • Relays are small, plastic-cased, not sealed for chemical/marine environments.
   • Solenoids are metal-bodied, often sealed, designed to handle heat, vibration, moisture, and chemicals.