Not For Everyone 12 Volt Sealed Relay & Base Bargain

Heavily loaded electric winch solenoid relays take a beating. What saves them is they are intermittent duty 600 amp rated. Much stronger coil, much stronger retractor spring.

I recently made a juiced up winch flyback filter for a forum member. But it dumps energy to chassis negative. (1) Motorola MR2535 reversed biased, two 1500 watt 16 volt TVS diodes. I also built a de-spiker for his Prestolite 160 amp Load Handler alternator, and then there were some 120vac clippers, and de-spikers for smaller alternators for some other members. Seeing stuff needlessly wasted just goes against my grain.

In 1981 I went "Ooooooo looky here!" A metal can 12 volt constant duty solenoid relay with silver INLAY contacts. Cost 400% as much as the same relay without the silver. I patiently explained to a customer that the relay MUST BE connected to ignition B, the circuit that plays possum when the key is twisted to the starter position. He nodded yes and grabbed the solenoid.

Four days later he returned. Placed the solenoid on the bench "Doesn't work" he declared. I took it apart right then and there. The silver inlays were destroyed. Molten and fragmented.

"You did connect it to the wiper motor parking power wire, right?"

"Nah.........Ignition is ignition"

The relay had boost-fed from his house batteries to the engine battery. It was rated for 80-amperes. It was supposed to be a charging circuit relay. With minimum contact resistance - voltage drop.

He wanted a cash refund. Two days later his personal check was returned marked insufficient funds.

And that...

Is why I am so grouchy about relays and solenoids.

MEXICOWANDERER wrote:
This is a good price if multiple items can justify the shipping charges.

The Tyco is a proven sealed unit. It lasts me years in continuous duty radiator fan duty.

https://www.parts-express.com/te-connectivity-tyco-electronics-12-vdc-5-pin-relay-spdt-20-30a-(formerly-bosch)--330-070

Try using a FREEWHEELING DIODE across the power contacts when an inductive load is being switched. Amazing increase in contact life.



Freewheeling or Fly back diodes and their function
Freewheel or Fly back diodes are used across inductive components such as coils to prevent voltage spikes when the power is turned off to the devices.

When power to inductive loads such as coils and inductors is turned off, there is a sharp voltage spike. The direction of this voltage is opposite to the applied voltage in accordance with Lenz’s Law.

When a current flows through the coil of a relay, the coil gets electromagnetically charged. The energy is stored in the magnetic field around the coil. When the power supply to the coil is interrupted and the current in the coil tends to decrease, the magnetic field discharges causing a surge in the voltage.

The voltage, thus induced, can jump across the contacts of relays connected to the coils. The sparks and arcing produced can affect the life of the contacts. The voltage spikes can also damage electronic components like transistors which may be driving the relay coils.

That's cool. Learn something new everyday.

Yeah, a reversed diode across the leads. Used that trick before. Like a shock absorber for spikes ;)

This is a good price if multiple items can justify the shipping charges.

The Tyco is a proven sealed unit. It lasts me years in continuous duty radiator fan duty.

https://www.parts-express.com/te-connectivity-tyco-electronics-12-vdc-5-pin-relay-spdt-20-30a-(formerly-bosch)--330-070

Try using a FREEWHEELING DIODE across the power contacts when an inductive load is being switched. Amazing increase in contact life.



Freewheeling or Fly back diodes and their function
Freewheel or Fly back diodes are used across inductive components such as coils to prevent voltage spikes when the power is turned off to the devices.

When power to inductive loads such as coils and inductors is turned off, there is a sharp voltage spike. The direction of this voltage is opposite to the applied voltage in accordance with Lenz’s Law.

When a current flows through the coil of a relay, the coil gets electromagnetically charged. The energy is stored in the magnetic field around the coil. When the power supply to the coil is interrupted and the current in the coil tends to decrease, the magnetic field discharges causing a surge in the voltage.

The voltage, thus induced, can jump across the contacts of relays connected to the coils. The sparks and arcing produced can affect the life of the contacts. The voltage spikes can also damage electronic components like transistors which may be driving the relay coils.

I sure will let you know. The double rating of the relay 40/30 is for NO/NC contacts but having 40 amperes go through a .250" push-on terminal is stupid. The people that manufacture these things should know better than play Moe Howard in the ad department.

Yep the old ------bait and switch trick. I'm wise to that. "Not born yesterday, born day before yesterday (Charlie Chan)"

Let us know what you find. I've been replacing a fuel pump relay in father in law's motorhome each year, looking for something sealed but not obscene in price. It sits all winter and he's about done with it.

When I see the pics in the ad that looks like it was "meant" to be sealed, but not advertised as sealed, I immediately think "seconds"

The ones that failed the tests or had a bad process, so find their way to ebay.

Then there is the "representative image, actual product may differ" trick that is common on ebay. What you get must match the description, not the generic pic.

Otherwise, I'd have a set or two headed this way ;)

I will be watching for your results :C

Agreed. But 99.9% of short life problems I have had with this style of relay proved to be "Open them up and find green and orange powder". Wet air entered and electrolysis did the rest. Most of my personal relay failures occurred in places where it would be impossible for rain or road splash to have entered the picture.

I have had Hella, made in Portugal relays fail, some from Denmark and many non Bosch relays fail mainly those marked made in Japan. In every case a Bosch Tyco relay also made in Portugal solved the reliability problem. The failure issue wasn't subtle. A genuine Hella relay less than a year old almost cost me an engine due to cooling fan motor malfunction. Every last one of the failures was green and red powder electrolysis.

Then I tried once again using non sealed relays, but applying a gob of dielectric grease on the relay base to seal against wet air. Much much improvement for customers who had purchased LED light bars. Same brand no failures. Months till failure versus three years no failure.

So when I saw the relay in the image I went "Aha! Someone learned their lesson". Ten cents worth of sealing makes the relay better than any gob of silicone dielectric grease I could apply.

My toad's fan has a Bosch relay now. But they are anything but inexpensive. The weak point of a Bosch relay is the relay base. It's exposed so more dielectric grease gets gooshed into the electrical terminal slots to seal them up. My "test lab" is hot humid marine air. Salty with a stiff onshore breeze. For testing it's ideal.

Because of the CRUMMY female relay base brass terminals all of these relays are vulnerable. THE weak spot. I would rate any of the Bosch style relays, even OEM Bosch with German base, as being suitable for 20 amps continuous and no higher. If Delco Packard fast-on terminals were employed the rating would do up but they will not fit the base.

I purchased a 50-amp sealed Bosch type relay and base. But instead of the relay contacts being .250" they are .375". Both cost me thirty dollars plus as a package. This is damned near the outright cost of a White Rogers tower-style 100-amp continuous duty relay. Lets not talk about garbage metal can continuous duty relays...

The best contact protection is gold flashing, not silver. But only the White Rogers tower relays seem to have it. The White Rogers is sealed. And it is thirty dollars plus.

Choose wisely. I am springing for the relays in the ad. We shall see.

I always wondered about the ratings on those- they are marked as 40/30 amp. I ASSume that it is 40 amps energized (n.o. contacts) and 30 amps non-energized (n.c. contacts).

I design instrumentation electronics that use relays. Sealing isn't always the best if the relay wasn't designed for it originally. Sometimes the internal plastics and potting materials outgas and foul the contacts. It's not usually a problem for power relays, but it can be if they don't cycle often (cycling scrubs the crud off the contacts). I would be wary of a no-name Chinese relay manufacturer. We have to do pretty extensive reliability testing for our instruments, and even relays from the name brand people have problems.

Your image resolution may not be as good as mine. The shiny black stuff on the bottom is potting material. The relay cap also seals along the bottom seal the bottom - seal the relay.