Adding gizmos

[FuzzWantsABus]

Hey all. When I first got the bus, I totally removed the driver's heater bay, the associated electrical panel, and all the switches. The vast majority of the circuitry was for school bus specific functions, like the lights & stop arm. In retrospect, I probably removed more than I should have. Specifically, the separate fuse boxes that were already wired for IGN, ACC, etc. I need to add in some things (backup cam), and put some things back that I took out (power mirrors and windshield wipers).

I have a nice fuse box, and I am just trying to figure out how to power it from the IGN feed.

I have located what looks to be a likely place to wire in the extra circuits-I don't know what to call it, but it looks somewhat similar to a main bus. See photos. My concern is that the cover for the posts clearly shows what is wired to each post, and it also shows an "x amps max." Also see photos.

If I am using the IGN post to add in 3-4 additional circuits, the amp draw could easily be more than the 4 amp max noted for that post. Is this a problem?

Is there another or different way to add in those circuits? My fuse box is currently wired directly to the battery feed.... Great for power, not so much great if something I add is drawing all the time and runs the battery dead.

Thanks in advance! I can take more photos or provide the wiring diagram if necessary.

[cadillackid]

the original electrical panel had 1 or 2 solenoids inside that box.. if you didnt throw the box and its guts away you may still have those..



it also had a couple strips with circuit breakers mounted.. this is a fantastic way of separating function and protecting every circuit..



the large wire ran from either the battery or the starter post through a big fuse (80 amp in my case).. there are 3 large wires.. 1 comes right from the starter post to a breaker bar directly.... that one has anything you want powered hot all the time... ( cigarette ports, clocks, dome lights?.. )



the second large wire goes to the input of a solenoid.. and the trigger or coil wire of the solenoid went to the IGN feed on that power bar under the left kick panel..

second large wire on the solenoid.. (output) goes to another relay bar... this pwoers anything you want when only key onto IGN position.. heaters, A/C, wipers, etc..



the 3rd large wire goes to the iput of another solenoid.. and the trigger of that solenid goes to the the ACC terminal on that power bar under the left kick panel.. out put of that solenoid goes to a relay bar which powers anything you want in ACCessory position.. radio, door motor, and the like..



each of the relay bars has in my case 10 or 20 amp relays.. (factory) anything with 12 gauge wire gets wired to a 20, anything wit smaller wire gets wired to a 10. each bar holds like 10 relays or so.



this gives you the ability to wire your accessories how you like.. this was typically done factory on most school busses, and I wouldnt change it. in fact if you tossed all those parts.. id be inclined to go to the junkyard and find some similar uness you wantto spend some $$ and buy new ones..



im sure others have done it in other ways. but I like the factory way.. all my circuits are protected and I can move items around easily by simply moving the feed wire from the switch to a relay on whichever bar i want it to operate from.

-Christopher

[FuzzWantsABus]

Thanks for the reply, CK. This is what I was afraid of. My bus WAS set up pretty much exactly like you describe, minus the relays, and I took it all out like an idiot. So now I have to try to recreate something similar.


Since what I'm adding back in is reasonably simple, I'll probably only wire one or the other, IGN or ACC. That being said, I don't know anything about solenoids.


Do they come in sizes? Amps? I don't have the old one to compare to, and googling "solenoid" is not terribly helpful, as there are so many results I have no idea how to narrow it down to what I need.


I'd also like to clarify a couple of things you said:


Is the relay you're referring to something like https://bit.ly/2AwBu2Y ?


I have something like https://bit.ly/2JmgH55 , but it's only for fuses. I'm curious as to whether you can use one relay for each fuse block, or if each individual circuit should be relayed separately? In doing some brief looking, something like this also exists: https://amzn.to/2z8K4mE


Thoughts/suggestions?

[cadillackid]

here is a solenoid.. you run a large wire (fused) from your battery or starter terminal up to the IN (one of the copper terminals)..



the 2 smaller terminals are the control coil.. one will go to chassis ground, and the other will go to that block under your kick panel.. if you want it to work in IGN and ACC then wire it to an IGN feed on that panel



then you run the other large copper terminal to the breaker panel or such that has your accessory switches.. (please fuse or breaker each accessory.. you still need a switch for each accessory.. the solenoid s just a big relay that enables the 'main' power so you can turn on each device.. if you cut power tothe solenoid then all devices on the down-side turn off..



you need to buy a continuous duty solenoid.. this is an example..



https://www.amazon.com/dp/B00BGTL9GI...9-d56d64501878

[FuzzWantsABus]

That makes perfect sense. Thank you so much! One last question....In doing what you described above, should there still be a relay between the fuse & the switch? Or the switch and the whatever-I'm-adding? Neither (because I'm guessing maybe the solenoid does that job instead)?


Thank you for your help and patience, Chris.

[cadillackid]

there defimitely should be a fuse or circuit breaker handling each switched item that you install. the wires you will be using for your accessories. like fans, radios, etc will be muich smaller than the main wires you hook to the solenoid. so you need to fuse them with smaller fuses.. if you use 12 gauge wire you can use up to a 20 amp fuse.. if you use 14 gauge wire you can use 10-15 amp fuses.. im not sure what happened to the wires you had going to your accessories like your heaters and such but most of them are 12 gauge..



here is an example of a single circuit breaker.. I dont have my bus torn apart to show you the multi bar.. but you can use a fuse panel like posted earlier would work.



https://www.delcity.net/store/12V-Au...hoCkmEQAvD_BwE


-Christopher

[FuzzWantsABus]

I think there's some confusion by what I mean by a "relay." I'm talking about one of these:


https://www.amazon.com/Absolute-RLS1.../dp/B0002KR9GG


My understanding is they're used to enable a low amperage circuit to switch on or off a higher amperage circuit (i.e. headlights). I'm trying to figure out how necessary it might be to use one, and if so, where it goes in the circuit-before or after the switch (in my case, all SPST, with the exception of the wipers). Here's some more info about them:


Automotive Relays and How They Work


As I recall, in the original wiring, there were none, although there are several mounted to the firewall. The wiring bundle is so massive in that area, I can't figure out what they're connected to. I'm wondering if the solenoid essentially replaces the function of a relay.

[cadillackid]

the relays mounted to the firewall are for chassis functions.. one is your starter enable relay.. one if the transmission modulator circuit relay and one is a fan relay (may not be used)//. at least thats what they are on my international.



most sachool bus accessories are wired direct to their switches unless its a high amperage circuit like the Bus Air-Conditioner .. if you are installing something that needs more than say 20 amos a relay is a great idea as high amprage switches arent as common as switches capable of 20 amps and below..



-Christopher

[FuzzWantsABus]

Okey doke. Sounds good. I'm off to Amazon! Thanks again for all your help and patience.