?'s About Wiring Work Lights On A Mahindra

[MUDONTHETIRES]

Hello All,

I've been reading all the posts about wiring work lights and I think I have everything I need to install some on my tractor but have just a few questions. First, let me tell you what I have. My tractor is a 2007 Mahindra 4530 4WD. For the work lights install, I have (2) 55 watt traps, 10 gauge wire, 14 gauge wire, (1) 30 amp relay, (2) 15 amp inline fuses and a switch. One 15 amp fuse is for the 10 gauge wire going to the battery. The other 15 amp fuse is for the wire going to "the other power supply".

Here are my questions:

1. Do the 15 amp fuses need to be 30 amp fuses and if so, why?

2. The wire coming from terminal 30 of the relay goes to the battery.
Where should the wire coming from the switch going to a "fuse panel" go if you don't have a fuse panel? At least I don't think I have a fuse panel. Please pardon me as I'm not very "electrically literate". Kennyd, you would be a great help here! I have supplied the wiring diagram for my tractor in pdf format below for reference if anyone has any ideas!

Thanks a million in advance!

 

[Mike058]

If my math is right, two 55 watt lights (110 watts total) draw about 8 amps at 13.8 volts. The 14 gauge wire should handle that just fine. (Seems it can handle 15 amps total) So your 15 amp fuses will be fine and you don't really need the 10 gauge wire. It's really stiff and can be a bear to work with.
Well the diagram's a bit bigger than I was planning on, but at least you can see it. Attach the 14 gauge wire to a positive volt source, doesn't have to be at the fuse box, you're using a separate fuse. Put your fuse in the line close to the source though. Use the switch, to ground the coil on the relay. Hook 30 and 85 to the battery, 87 to the lights and 86 to the switch. When you close the switch, the coil energizes, closes the relay and on go the lights.

 

[MUDONTHETIRES]

Mike,

I'll try that. Thanks for the great graph!

 

[POC]

Sorry to dredge this up.....but do you really need the relay? Can't you just run it straight through the switch?
Thanks,
Patrick

 

[mjncad]

POC: Sorry to dredge this up.....but do you really need the relay? Can't you just run it straight through the switch?
Thanks,
Patrick

Patrick:

Assuming the switch is rated for the current the lights draw; yes you can run it through the switch. However, automotive industry practice is to run heavy loads through a relay. Be safe and use the relay, they aren't that much hassle to use.

Mike058:
Re: ?'s About Wiring Work Lights On A Mahindra
If my math is right, two 55 watt lights (110 watts total) draw about 8 amps at 13.8 volts. The 14 gauge wire should handle that just fine. (Seems it can handle 15 amps total) So your 15 amp fuses will be fine and you don't really need the 10 gauge wire. It's really stiff and can be a bear to work with. Attachment 98945
Well the diagram's a bit bigger than I was planning on, but at least you can see it. Attach the 14 gauge wire to a positive volt source, doesn't have to be at the fuse box, you're using a separate fuse. Put your fuse in the line close to the source though. Use the switch, to ground the coil on the relay. Hook 30 and 85 to the battery, 87 to the lights and 86 to the switch. When you close the switch, the coil energizes, closes the relay and on go the lights.

Mike:

It would be better if your control switch was on the hot side of the circuit upstream of the relay instead of downstream as your wiring diagram depicts. Even though the switch will work as drawn, you still have juice running into the relay. In this case, you want the switch to de-energize everything downstream of the switch.

Mud: The wire coming from terminal 30 of the relay goes to the battery.
Where should the wire coming from the switch going to a "fuse panel" go if you don't have a fuse panel? At least I don't think I have a fuse panel. Please pardon me as I'm not very "electrically literate". Kennyd, you would be a great help here! I have supplied the wiring diagram for my tractor in pdf format below for reference if anyone has any ideas!

I've seen worse wiring diagrams than Mahindra's that you supplied; but I'm sure it has a fuse panel in spite of Mahindra showing each fuse separately, thus implying that each circuit has it's own inline fuse holder. I think Jeep used to use inline fuses many decades ago; but fortunately quit that silly practice. More than likely the fuse panel is behind the instrument cluster or hopefully it's like it is on my Deere....easily accessible via a removable cover below the steering wheel near the floor mat. Mahindra is showing the fuse as a rectangle with the text "10A," "15A," etc in it. That's how I was taught to draw fuses many years ago, and I still do to this day.

Matt

 

[snafukelly]

Can someone explain to me why that is not a short circuit in mike058's diagram?
Is the wire from 30 to 85 not creating a short circuit.
Someone please explain.

Thank you.

 

[Danno1]

.

No, it's not.

He's applying 12vdc through the fuse to the coil of the relay at term 85. Closing the switch in the lower center of the pic energizes the relay coil which closes the switch inside the relay. This sw needs 12vdc to turn the lights on. It gets that 12vdc from term 30.

.

 

[kennyd]

Can someone explain to me why that is not a short circuit in mike058's diagram?
Is the wire from 30 to 85 not creating a short circuit.
Someone please explain.

Thank you.

No short, it's just the battery + feed to the coil of the relay and to one side of the contact.

 

[Mike058]

Mike:

It would be better if your control switch was on the hot side of the circuit upstream of the relay instead of downstream as your wiring diagram depicts. Even though the switch will work as drawn, you still have juice running into the relay. In this case, you want the switch to de-energize everything downstream of the switch.

If I put the switch on 85, I'd have to run a 12 volt line to the switch and then down to the relay. By putting the switch on 86, I have to run one wire to the relay and find a ground for the other. I've found it's usually easier to find a ground point than a 12 volt source. I don't see any advantage to having the switch between the battery and the relay. When the switch is open, no current flows anywhere in that line regardless of what side of the relay it's on. If the switch isn't between the battery and the relay and I'm going to work on the relay, I can remove the fuse. But, the important point is, like you said, it will work either way. If you can sneak 12 volts from something else in the dash, run it to the switch and then down to 85. If that can't work. run a wire from 86 up to the switch and ground the other side. The other thing is to use the relay to keep the heavy wires short. Decreases voltage drop and saves money on expensive heavy gauge wire.

 

[mjncad]

If I put the switch on 85, I'd have to run a 12 volt line to the switch and then down to the relay. By putting the switch on 86, I have to run one wire to the relay and find a ground for the other. I've found it's usually easier to find a ground point than a 12 volt source. I don't see any advantage to having the switch between the battery and the relay. When the switch is open, no current flows anywhere in that line regardless of what side of the relay it's on. If the switch isn't between the battery and the relay and I'm going to work on the relay, I can remove the fuse. But, the important point is, like you said, it will work either way. If you can sneak 12 volts from something else in the dash, run it to the switch and then down to 85. If that can't work. run a wire from 86 up to the switch and ground the other side. The other thing is to use the relay to keep the heavy wires short. Decreases voltage drop and saves money on expensive heavy gauge wire.

I understand your points Mike; but look at any automotive or house wiring diagram, and the switch is always between the source of electricity and the load. You would have to use a lot of heavy gauge wire to make a big difference dollar wise and the voltage drop is not going to be as bad as you might think, especially when using the proper gauge wire for the load.

 

[mboulais]

I did something similar on my mahindra 4110. I have a relay wired into the "brights" when brights come on the relay passes power through a seperate fused circuit to two 55 watt halogens mounted on the roll bar.

 

[PILOON]

He guys, I beleive in the KISS system!

Simple wire to the switch and from the switch to the lights!
Most quality switches are rated for 10 amps and if you want to be fancy use a DPST switch (double pole single throw, ie on/off) and parallel the contacts.
While # 16 wire is OK, better #14.
Naturally a fuse or CB close to the power source.
Take the power from tractor buss bar if possible
(I wired aircraft for a living 'back then'.)

Also the relay will cost as much as all the rest!

Be sure to use heat shrink on all joints to keep out corrosion and tie off or clamp wires so that they don't rub and short out to ground.

 

[mjncad]

Also the relay will cost as much as all the rest!

Relays aren't that expensive, check out www.del-city.net

As far as relays in Canada being more expensive, the customs bureaucracy may be a big reason for that.

 

[MrMiller]

I agree with PILOON, keep it simple! The more parts you add the more likely you will end up with problems in the future. A simple switch to a fused battery source is all you need.

I personally never rely on just connecting to the chassis to "steal" ground. It always seems like a good idea but the connection always seems to fail eventually! (At least it has on every trailer I have ever used!)

I also wanted to point out that the circuit Mike058 showed will work fine but I would include a reverse biased diode across the relay coil (or other "snubber" circuit). When the switch opens the relay coil will generate a negative transient (large negative voltage spike) which can cause a decent arc in the switch and can slowly burn it out. Some automotive relays already have this built in and some don't.

Cheers,
MrMiller.

 

[Lammo]

OK. I want to add a light to my Branson 3820. The regular headlights are so low that they get blocked by the loader so I want to mount an extra light on top of the brush guard. I have a rearmounted light that came with the tractor that operates with a slide switch built into the light housing. In the interest of keeping it simple, can I tie my front light into the wiring for the rear light and have it controlled by the same switch? If so, what gauge wire should I run from the front light to the back? Thanks in advance for any and all advice.

Mark

 

[mbohuntr]

Short question, longer answer. Watts = volts X Amps. Watts / volts = Amps
Add up total watts (I always assume series wiring for safety sake for those who will question this.) Make sure all components will handle the amperage, amd use a slow blow fuse to take care of surges. (120 watts of lights / 12 volts = 10 amps... get it?

 

[PILOON]

Mark,
Yes in theory and use #16 or #14 wire.
In theory-BUT-check amperages.

Can your alternator handle all the amperage without drawing from the battery?
I say this because many CUT's don't have all that high alternator outputs!

Generally speaking you'd want total load to be at about 75% of the alternator output.
The other 25% is the reserve to charge your battery.
Also the majority of switches are rated at 10 amps, so you'd want the lighting to be at or below 10 amps otherwise you risk 'welding' the switch contacts.

I'm not a tractor electrical expert (but did wire many aircraft for a living) but on some that I have looked at I have seen 25 amp alternators, and that is not a whole lot, especially if you have a heater and start adding additional lighting.
Those heater fan motors can actually draw more than many lights.
Another item that is high draw is a rotating yellow beacon (dual sealed beams).

Getting to 'brass tacks', you really want to do an 'electrical load analisis' to best plan power management.
Barring that, an amp meter is never a bad thing to install.
In aircraft an amp meter acting as a 'load meter' made it permissable to add whatever we wanted as then the pilot could manage his loads.

 

[Lammo]

Thanks for the quick replies. I'm only going to add a single light, 55 watts I think but I'll double check. That would give me load of just over 4.5 amps (55 / 12 = 4.5833333333333333333333333333333). I'll see if I can figure out the wattage of the factory light and proceed accordingly. Thanks again!

 

[mbohuntr]

Very good point, Not only did miss that part, but I learned sumfin too. Thanks. I only run my rear trap work light for short periods, then make sure the battery has time to provide a full recharge. I hadn't considered the loading on the alternater . Some good advice there.

 

[mbohuntr]

That 4.5 amps is on top of the existing load your wire is handling...you might be just as well off running a separate wire and switch to avoid messing with your existing wires, and running either one or the other, thereby sparing your alternater.