Solid state relays

[Emmalina]

Since the solid state relays are now so cheap I have started mounting them on all sorts of things. Mainly dc pumps or solenoids (gas) These things remove the arcing of contacts and infinitely improve the life of water pumps. In the box of failed pumps 90% are due to the pressure switch failing . I would seriously ask people to look into it as the pump manufacturer isn't going to.

[Lake-Effect]

Interesting. Perhaps those failed pumps have inferior contacts or relays. I would be a little concerned that solid-state relays might be more vulnerable to a lightning strike, but you might be on to a great idea for extending the life of those pumps.

[Emmalina]

Originally Posted by Lake-Effect

Interesting. Perhaps those failed pumps have inferior contacts or relays. I would be a little concerned that solid-state relays might be more vulnerable to a lightning strike, but you might be on to a great idea for extending the life of those pumps.

Think if lightning strikes least of your worries would be a 5 dollar relay ! They all had original pressure switches.

[Dockhead]

I have some solid state relays on board. It's news to me that they are "so cheap". I paid a pretty penny for mine. They are great -- silent, efficient, and extremely long-lived.

[Sailmonkey]

Originally Posted by Dockhead

I have some solid state relays on board. It's news to me that they are "so cheap". I paid a pretty penny for mine. They are great -- silent, efficient, and extremely long-lived.

If you buy the “Inkbird” or “Mysweety” brands on Amazon they’re cheap.

Otherwise they’re $40-$60 a pop.

[Emmalina]

Its only a mosfet with an opto isolator and a plastic box $5 for 40amp or $10 for 80 depends where you are I suppose.

[redneckrob]

The one thing you need to be careful of with solid state relays is that they generally fail closed, while traditional relays fail open. In some cases this is a distinction that makes no difference, in others it can be a potential big deal.

[stormalong]

I use automotive headlight relays. Cheap, plug into sockets and are available everywhere. The contacts on most pump pressure switches can't handle the starting current of the pump motor.

Since I use the same relay on a bunch of pumps I have fewer spares to carry.

[NevilleCat]

For numpties can you explain how you would insert them into the water pump circuit please.

[Lepke]

SS relays are cheap on ebay, but higher amp rated are bulky compared to the usual auto relays I use.

[stormalong]

Originally Posted by NevilleCat

For numpties can you explain how you would insert them into the water pump circuit please.

It is very simple if you understand basic electric principles. The relay coil is powered by the pressure or float switch and the pump is powered through the relay contacts.

If you don't understand this you need to get someone who does to set it up for you.

[Emmalina]

Originally Posted by stormalong

I use automotive headlight relays. Cheap, plug into sockets and are available everywhere. The contacts on most pump pressure switches can't handle the starting current of the pump motor.

Since I use the same relay on a bunch of pumps I have fewer spares to carry.

Also a good solution but noisy and no led indicator but cheap yes.

[NevilleCat]

Originally Posted by stormalong

It is very simple if you understand basic electric principles. The relay coil is powered by the pressure or float switch and the pump is powered through the relay contacts.

If you don't understand this you need to get someone who does to set it up for you.

Thanks, I understand now.
And thanks for sharing your valuable advice and experience in the same positive and non-condescending manner (S) I have sadly come to expect from this forum.
Though badly burned, I still win because I no longer need to pay $100 per hour for someone to install one for me.

[stormalong]

Originally Posted by Emmalina

Also a good solution but noisy and no led indicator but cheap yes.

Noisy? How often are you triggering it? The pump noise will be much greater than the relay.

[donradcliffe]

I used one of the cheap ones to trigger the air horn on a racing start timer I built. It controls a 15 amp draw with the 20 ma output of an Arduino. It has been living on the committee boat for over 2 years with no problems. I am pretty sure that if I short the output it will let the smoke out and fail open.