NorCalFJ100
SILVER Star
Hey thanks so much for this. Subscribed!!!!!!
Learn Electrical Troubleshooting ! (1 Viewer)
- Thread starter MrMoMo
- Start date
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these are great videos and are helping me very, very much
Have you noticed that a lot of those black relays, like you show in the video, burn out or go bad after some use? I've been told it's because they're not continous duty relays. A napa clerk showed me a solenoid that I installed for aux lights. It's installed up near the battery in my 80 series and I can hear it click even in the driver's seat with the engine running, if there's not too much other noise going on. Don't get me wrong, the black relays work, just don't last for continous use with higher amp equipment.
Edit: Come to think of it, it's not the load that kills them - it's the relay is just not designed stout enough to be energized continously and eventually fails to work.
Edit: Come to think of it, it's not the load that kills them - it's the relay is just not designed stout enough to be energized continously and eventually fails to work.
Last edited:
MrMoMo
That's not rust, it's Canadian patina...
- Thread starter
- #49
As I mentioned in the video, not all relays are created equal. Of the two in my hand, one is rated at 30A, the other at 40A though they look identical, and I suspect neither of them would do that continuously. (Actually, I believe they are rated 20/30A and 30/40A meaning the normally closed circuit is rated for 20 and the normally open is rated for 30 (or 30/40 per the second relay) So you can see from this that two identical looking relays used in two different ways, one can have a rating of double the other...
The amp rating though, is a separate circuit from the coil. The coil doesn’t care how many amps are flowing through the contacts.
The two relays I had there are definitely cheapos. I’d trust them for about 1/2 of their rating. If you bought a true “Bosch” relay, it would probably handle the load just fine. Also, most relays are not sealed, which means you are going to get crap (water/dust etc) inside, which is going to affect the contacts over time. Driving over rough roads can also damage the hair like wire that runs the coil, which could lead to premature failure.
The nice thing about cheap relays is exactly that - they are cheap. I pick those ones up on sale for about $5 with the holder. Buy them in bulk or online and I’m sure you can get them for way less. If you are using it for a more critical circuit, it may be worth either over sizing the relay, or at a minimum going with a good quality brand name. Worst case, you can put two relays in parallel, and double the current carrying capacity of the switching.
