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I have ordered a few of the cheap relays on amazon in the past. Wasn't really impressed with the longevity. They are really cheap inside as well. Was looking for a name brand fused relay but having trouble finding them. Anyone know of a source?
That's an interesting relay design - it's the first time I've ever seen one with a built-in fuse like that. That being said, I would never use one regardless of brand. Fuses are not designed to protect the device they're connected to (gauges, amplifier, exhaust cutout, or whatever), they're designed to protect the wiring going to that device. You never want more current flowing through a wire than it's designed to carry, causing it to heat up and possibly cause a fire. So, you should ALWAYS put the fuse as close to the power source as physically possible or at any point where the wire size gets smaller (splices or power distribution blocks, etc.). That fuse on the relay means that the wire supplying power to the relay is not protected. The only case where this would be acceptable is where the power supply wire is already fused and the output wire is smaller gauge than the input wire thus requiring additional protection. This is extremely unusual and still not necessary since you can just replace the existing fuse on the input wire with one small enough to protect the output wire.
Bosch is the originator of the common 4-pin and 5-pin relay (hence why they're called Bosch-style relays) and their product is still considered among the best. However, if you're having longevity problems with relays, perhaps it's not the brand but rather the design that's the problem. Look for diode-protected relays which have an internal diode to protect against arcing and contact damage. When using that type of relay, the low current (relay coil) 12V power must be connected to the 86 terminal and ground to the 85 terminal (reversing them defeats the purpose of the diode). As far as I know, all Bosch relays come with the internal diode these days.
Hella is a less common but good quality brand for relays as well.
Thanks, I went with this Cole unit to try. Has the diode you mentioned. I liked the simplicity of the built in fuse is all. Not super worried about destroying any sensitive electronics in this case.
Its used to power a 12v dc pump 7-10a peak. And I only run the pump for 5-10seconds at a time. So not super bad load wise. Its triggering methanol injection with a boost switch.
08-13-2024 | 01:59 PM
Any name brand "good" fused 12v relays out there? 
