Hey Everyone. I am looking for help and to see if it is possible to build a trailer light tester.
I work at a trailer dealership and right now we are testing trailer lights using an old plywood board with a 12 volt car battery and trailer lights attached to it with trailer plugs and switches. It is big and bulky.
What my plan is to find a way to make it small and more portable. I have a 20volt Dewalt battery and some old cordless tools that I have been able to salvage the battery attachment and + and - terminals from.
My hopes is to make a small case that I could put the circuits in as well as access for the battery to be attached when in use. I would like to have a few different plugs attached to the box for the different trailer hook ups (4 wire, 6 wire and 7 wire)
I was thinking to have LED's on the outside to indicate which light is being lit up (left signal, right signal, running lights and brake lights).
I would like to have the technician control the box by either pressing a button and it would have a time delay for him to walk to the back of the trailer and then it would perform the test or possibly by having a wireless remote maybe that he could take back with him and then press the button?
Please let me know if you guys could help me out The system needs to be 12v DC so I know I would need some time of converter to bump the 20 volts down to 12 correct?
You can get a buck converter to drop the voltage. The problem will be handling the amperage. The brake bulbs on my trailer are 55W each. 110W total divided by 12 gives almost 10 amps. Which I think you will be hard pressed to find one that can handle that.
I would look at using a battery box to improve the packaging on the current system.
It all sounds like a good idea, but the guy who built the old plywood board job with the 12v battery definitely had the right idea in the first place - use a proper 12v battery. A lightweight sealed motorcycle one should be just the ticket, and the extra weight is well-compensated by having something that works rather than lie around useless because the batteries are always flat. And you surely have the charger for it near at hand.
I'm betting you already suspect that the only 55w brake bulbs in the known universe are probably in reply #2, and are quite likely illegal, but you need to be able to handle trailers with more than one standard 6/21w anyway, not to mention heavy vehicles, so the comment about high current is not unreasonable.
I imagine this device being on an easel with the trailer sockets on a 2m lead and remotely controlled via bluetooth. I don't think you would need an Arduino at the remote end. The main unit would simply go through a programmed sequence on receipt of a bluetooth signal, i.e. the establishment of an auto-connect. The remote could be charged off the main device. The last thing you want is that to be flat.
I'm sure you could test for shorts and open circuit in the above programme.
Nick_Pyner:
I'm betting you already suspect that the only 55w brake bulbs in the known universe are probably in reply #2, and are quite likely illegal, but you need to be able to handle trailers with more than one standard 6/21w anyway, not to mention heavy vehicles, so the comment about high current is not unreasonable.
Sorry my bad. They are the back up bulbs. I knew there were two of them on at the same time.
Rather than a timer to let the operator move to look at the lights, just put a wide angle mirror infront of the lights and control box and operator can stay at the towbar end.
OR
Use an IR remote to cycle the control box as the operator stands in front of the lights.
Why do you feel the need to control the box? If it is going through a pre-programmed sequence then just let it do the sequence. LEFT, RIGHT, TAIL, BRAKE.
Of course you do need to think about the sequence a little bit. Common errors in wiring might include swapping left and right so your guys using the box need to be accustomed to always seeing LEFT first. Maybe go: OFF TAIL LEFT RIGHT BRAKE BRAKE+TAIL. By including some deliberate off time, you can identify the start of the sequence.
The hardest part is going to be building it into a box which is both rugged and portable. But not so portable that it leaves the site.
Checking trailer lights by yourself stinks. I like the idea of a wireless remote.
If you put a short battery in a longer battery box, that would leave space on the side and likely the top for mounting stuff. With the box longer than the battery, a portion of that space could be used to permanently mount the truck side connectors (3, 4, and 7 pin). Worst case is 7 pin with 6 signal wires. Use a 8 channel relay board to control the connection between the battery and the trailer. Since only one relay will fire at a time you may get away with a 5V relay board (I would roll the dice). Or you could find a 12V relay board and power it directly from the battery.
Hey Dezi, My trailer sits for months in storage at a time. More often than not I have a problem with my lights, when I hitch the trailer to my pick up. I was going to make a light tester also, then I found this one online for a little more than it was going to cost me to build. Here's the web address - https://trailerlighttester.net
Good luck!
Can you just run a small current through the lights and measure resistance? Sort of like a cable tester but terminated with light bulbs. You can also check for shorts and opens on wiring this way.
MotoJock:
Hey Dezi, My trailer sits for months in storage at a time. More often than not I have a problem with my lights, when I hitch the trailer to my pick up. I was going to make a light tester also, then I found this one online for a little more than it was going to cost me to build. Here's the web address - https://trailerlighttester.net
Good luck!
But that takes the fun away from building it yourself.
first, a CAN bus lamp is pretty common these days. not sure if you can just swap out the lamps. but, if that is possible, then you certainly do want to use an Arduino for this.
as was mentioned. a simple remote, you can get a 4 button as they are pretty common.
left / right / brake/ running light...
if you have a jump box, that would have all the power you need and the Arduino could be connected to it with a simple cable and then have the output for a plug.
you could have a simple plug and then use whatever adapters, or you might be able to have all the adapters hard wired and then you just pick the one you need for that trailer.
Getting past the bit of if the lights are working, Wolframore offered to test resistances. this is a great idea, it will help with possible bad wires. you could put in it test mode, the wiggle with wires along the trailer and if there is a bad section the resistance would change and send an alert.
I don't really see the need for any wireless arrangement, simply a 3 or 4 metre long lead.
As far as that goes, perhaps even using an Arduino is a bit over the top.
Whatever you decide, it might be good to remind you that most faults in trailer wiring come from bad earth returns causing feedbacks and you should perhaps give that some thought.
adwsystems:
You can get a buck converter to drop the voltage. The problem will be handling the amperage. The brake bulbs on my trailer are 55W each. 110W total divided by 12 gives almost 10 amps. Which I think you will be hard pressed to find one that can handle that.
I would look at using a battery box to improve the packaging on the current system.
Its much worse than that, a cold filament draws nearly 10 times the current of a hot one in a tungsten
bulb, so 55W 12V bulb will pull 40A or so peak.
You can either use an expensive current limited supply (the bulb will heat up anyway, just a bit slower), or
go back to using 12V battery (3S LiPo pack might be a possibility).
[ Most buck converters will not handle current overload gracefully, they will just shutdown to avoid
inductor saturation (which would put the input voltage directly on the output). ]
The system needs to be 12v DC so I know I would need some time of converter to bump the 20 volts down to 12 correct?