I am in the market for a 16'-20' tandem dual goose neck dump trailer. Based on my bad experience with electric brakes on a PJ 27' + 5' trailer I have concerns going ahead with the purchase. Despite numerous tow vehicles and brake adjustments the brakes on my current trailer will not lock even without a load. Loaded there is little braking effort on the trailer. Is this typical of electric brakes? Air is not an option. Advise is appreciated.
Are any of the brake controllers you have available digital? Something like a Tekonsha Prodigy will show "short" or "not connected" of it's not seeing what its supposed to. Sounds like you have a bad ground or blue (trailer brake) wire somewhere in the system, maybe even in the plug. I would check both wires from the trailer plug on back through the furthest brake and even run new wire for all. If the wires run through the frame anywhere or through the axle tubes it could be in there too. With the controller set to max, you should have a 12 volts under heavy brake pressure on the blue wire at the furthest brake in the line.
x2 on the ground and the voltage to the brakes. I would suggest looking at electric over hydraulic. There is a hydraulic pump on the neck of the GN that supplies fluid to the disc brakes on the wheels. Much better system than those finicky magnets! I have a 20GVW trailer that brakes very smooth and strong with them.
I had a three axle gooseneck that would easily lock all six wheels empty, and loaded to 20K+ on the deck had more than enough stopping power. If you're concerned though the electric over hydraulic systems like redneckracin says are another option. Something else that can be an issue with the electrics, unless something's changed in the last few years, NONE of them have any effect in reverse. Climbing a steep hill and then having to back down, you find out real quick if your tow rig's brakes are good and if you have enough hitch weight on the drive axle.
I agree with the common electrical issues listed above. On my most recent tandem dully goseneck I went to 12,000 lb axles. The brakes are much better than on the 10,000 lb axles I had before. They are bigger and way more durable and long lasting.
One thing I forgot to mention are the magnets themselves. You can adjust the brakes up all you want, but if the magnets are worn enough good braking is not going to happen.
Or if somebody put the backing plates on the wrong end of the axle, seen that.
There are also a number of trailers where the wiring is simply not large enough to carry the current of electric brakes. And- the notes about the electric over hydraulic disc brakes- good advice. Easy to service, work great. Expensive to buy. One note on them, have a battery mounted on the trailer. I have seen cases where the disc didn't work well just because the actuator couldn't get enough amperage through the cable. Or if it did, the truck's fuse blew and you lost it all. Have a battery on the trailer, and use the truck's Batt circuit to charge it.