Can you help shed some light ?

   / Can you help shed some light ? #1  

Mark_in_NH

Veteran Member
Joined
Mar 4, 2002
Messages
1,554
Location
Moultonborough, New Hampshire
Tractor
New Holland TC35D w/ 16LA FEL
Ok everybody, I need a little guidance in the 12 volt electrical department. Being the son of a Master Electrician, I feel a little stupid not being ably to figure this one out. But a little Humility never hurt anyone, so here goes.
The used canopy that I recently installed on my JD 950 has 4 amber lights on it, one on each corner. Wanting to make sure that they all worked, before I ran any wires and made any permanant connections, switchs etc. this is what I did.
I properly grounded all 4 lights to the bolts that hold the canopy to the ROPS, these bolts thread directly into the factory holes in the ROPS, there are no clamps. I hooked a wire directly onto the Posative battery terminal and ran it to the back of the tractor for temporary connections.
Now comes my befuddlement. I can connect ANY TWO of the 4 lights and they come on at full brightness, if I connect the 3rd and/or 4th light EVERYTHING goes very dim. /w3tcompact/icons/hmm.gif
There has to be a simple and logical explanation for this, I have done my fair share of automotive wiring, fog lites, driving lites, wigwag flashers, trailers etc. but this one has me stumped.
My plan / intention is to hook the 4 lights up to a wigwag flasher, but I need to make sure that they will all work properly first.
 
   / Can you help shed some light ? #2  
It sounds like the wire is too small to carry enough current. The resistance of the wire acts like a non-adjustable dimmer. If you hook all 4 lights up, they should all be very dim (unless the wire burns off, then they won't light at all). Do you know the wattage of the lamps? If so, divide the wattage by 12 and that will be the current. You probably need #12 or #10 to run them - 10 is bigger than 12, and they are good for 30A and 20A..............chim
 
   / Can you help shed some light ? #3  
Sounds like your ground is not as good as it should be. You might try running an extra wire to get a better ground.
 
   / Can you help shed some light ?
  • Thread Starter
#4  
Chim,
<font color=blue>It sounds like the wire is too small to carry enough current</font color=blue>
That is a distinct possability, I will do some math this weekend to see.

Ed,
<font color=blue>Sounds like your ground is not as good as it should be</font color=blue>
I was thinking same thing, so I have already tried running a seperate ground directly from the battery. No change /w3tcompact/icons/frown.gif
 
   / Can you help shed some light ? #5  
Mark, the first thing is to make sure that each individual light is grounded. You should probably disassemble the lights and clean any screws and/or holes that provide ground. It is almost better to run a seperate wire to ground the light. Probably 75% of 12V wiring probles are due to poor grounds. If you are also planning on putting work lights on the canopy you could use a terminal block for all the grounds. Also use an electronic alternating flasher as it is not voltage dependant as is a 537 mechanical flasher(as voltage drops the flash rate slows dramatically). One last thing, di-electric grease on the bulb sockets and any connections will prevent corrosion( regular grease acts as an insulator and shouldn't be used). Hope this helps and any other questions just ask.

Bill C
 
   / Can you help shed some light ? #6  
sounds like if the above solutions don't work, maybe you are getting the 3rd and 4th lights in series with the first two. A series circuit wil make the bulbs burn half as bright as they should be. Just a thought.
 
   / Can you help shed some light ? #7  
<font color=blue>One last thing, di-electric grease on the bulb sockets and any connections will prevent corrosion( regular grease acts as an insulator and shouldn't be used).</font color=blue>

Sorry but I think that this is backwards. A "dielectric" is defined as a nonconductor of direct electric current.

Jack
 
   / Can you help shed some light ? #8  
There are a number of different "goops" that are useful to have around for work like this. Good to use on battery terminals too. Penetrox, CU/AL Aid, NO-Alox and others can be picked up in electrical supply houses or even Home Depot. They are all pretty similar, and a pain to get off clothing.............chim
 
   / Can you help shed some light ? #9  
I have to agree w/ Chim. You grounded each light to the frame, that should give you a good ground.

If you ran your hot wire to light 1, then light 2, then 3, etc. in series, you probably aren't supplying enough current to run all the lights. To run all 4 in series you probably need 10 guage wire but it's really difficult to say no knowing the amperage requirements of the lights you are trying to light.

Other than changing to a larger diameter wire, you can run 2 sets of wires [in parallel] (as you seem to be able to run 2 lights off the wire size you are using w/ good results) or go to a smaller (dimmer) light that doesn't require as much current to light.

mark
 
   / Can you help shed some light ? #10  
The problem with running the lights in series is voltage drop. You will get a voltage drop at each light, with 4 lights the same wattage, you will drop @ 3 volts at each light. You will have 12v to first light, 9v to second light, 6v to third light, and only 3v to the forth light. All the lights should be run in parallel so they each get 12v.
 

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