pauly v.100
Well-Known Member
variable speed fan control from Flexalite
Relay Enclosure
- Thread starter RedFish
- Start date
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variable speed fan control from Flexalite
slantsixdan
=..=
Whether you make your own relay bank or buy someone else's (or go junkyard shopping), be careful if you feed a bunch of relays with one single input wire. Not only must it be of adequate gauge to handle the maximum possible current load from all relayed loads that could be operated simultaneously, but it also must be adequately protected against overload. That means a thoughtfully-selected fuselink, fuse, or circuit breaker which needs to be placed within a couple of inches of your power takeoff point (where the feed wire connects to line voltage) -- otherwise you have a length of unprotected high-current wire waiting to cause major fireworks if something pinches, cuts, or chafes it. Also keep in mind that the more circuits on a common feed, the greater the consequences of a failure in that common feed. Of course you should protect each and every load separately, but even that doesn't guarantee against a cascade failure. It does happen. Example: you've got a nice, tidy relay bank with a single feed wire bringing power to the #30 (power in) terminals of your relays for your electric fan, your low beam headlamps, your high beam headlamps, your A/C compressor clutch, and your ignition and alternator field circuits. One hot night as you are driving along, your A/C compressor clutch field coil develops an internal short and for any of several plausible reasons its own fuse or circuit breaker fails to open the circuit. The circuit protection on the main feed wire opens and
poof
you're without high beams, without low beams, without radiator fan, without ignition and without charging. At night. While still going 70 mph or whatever. And it's probably a Saturday at 10pm so nothing's open, and it's probably raining.
Me, I prefer to specify individual feeds, each with its own protection, for each relay. It confines the consequences of a failure. Lose your low beams? You've still got high beams to get safely off the road. A/C compressor clutch field coil dead-shorts? You have no A/C but everything else still works. Obviously this can get physically cumbersome if there are a lot of relays and you're trying to feed them all from a common existing take-off point (such as the battery positive or alternator B+). In cases like that, the thoughtful approach is to have a short high-current main feed supplying a fuse- or breaker box, one fuse or breaker per relay, then feed each relay off that box.
It is possible to go too far in either direction when planning out electrical upgrades. The idea is to strike a practical balance between minimising the consequences of a failure (one relay for each and every individual load...left low beam, left high beam, right low beam, right high beam, etc.) and minimising the likelihood of a failure (minimum parts count one relay for all headlamps).
Me, I prefer to specify individual feeds, each with its own protection, for each relay. It confines the consequences of a failure. Lose your low beams? You've still got high beams to get safely off the road. A/C compressor clutch field coil dead-shorts? You have no A/C but everything else still works. Obviously this can get physically cumbersome if there are a lot of relays and you're trying to feed them all from a common existing take-off point (such as the battery positive or alternator B+). In cases like that, the thoughtful approach is to have a short high-current main feed supplying a fuse- or breaker box, one fuse or breaker per relay, then feed each relay off that box.
It is possible to go too far in either direction when planning out electrical upgrades. The idea is to strike a practical balance between minimising the consequences of a failure (one relay for each and every individual load...left low beam, left high beam, right low beam, right high beam, etc.) and minimising the likelihood of a failure (minimum parts count one relay for all headlamps).
pauly v.100
Well-Known Member
Thanks for the input Dan. the main power source to the relay bank does have a fusable link, also theres a fusible link in the fan connection. I wish i was more savvy on electrical things but, well advised or not, everything powered through the relays is double fused. The aftermarket wiring I'm using provides fused power to the relay feeds and they're fused again in the relay box.
Hope that makes sense, that was the easiest way for me to wire it.
btw, be contacting you soon for headlights and maybe 3rd brakelight.
1 relay- low beams
1 relay- high beams
1 relay- elec. fuel pump
1 relay- elec. fan controller
...leaves me with one unused relay for future add ons.
let me know if I have anything wack!
btw, 140 amp tuff stuff one wire alt.
thanks again- pauly
Hope that makes sense, that was the easiest way for me to wire it.
btw, be contacting you soon for headlights and maybe 3rd brakelight.
1 relay- low beams
1 relay- high beams
1 relay- elec. fuel pump
1 relay- elec. fan controller
...leaves me with one unused relay for future add ons.
let me know if I have anything wack!
btw, 140 amp tuff stuff one wire alt.
thanks again- pauly
Part of the reason my relays are so close to the alternator is the main power supply. The water tight maxi fuse holder ( barely seen in the pic ) has approx. 6 inches of #6 AWG lead each side Reaches just to the distribution block under the cover. Ample space for more relays. 2 more planned are heater blower motor and a/c clutch. Relays and connectors are all the same type/size so they are interchangeable incase one should fail.
I would temporarily forfeit the horns for low beam lights if the need should arise. Only the relay connectors are labeled.
All connections are continuous unbroken wire from female relay connectors' terminals to those female terminals at the component end. All in all, I'm pleased with the setup.
I would temporarily forfeit the horns for low beam lights if the need should arise. Only the relay connectors are labeled.
All connections are continuous unbroken wire from female relay connectors' terminals to those female terminals at the component end. All in all, I'm pleased with the setup.
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