Weak brakes & battery box confusion.

[Hay Dude]

Noticed trailer brakes are weak.
Battery box says “recharge” on battery, but battery is only 2 months old and electrical tester reads 12.4V
Brakes work, but don’t do a lot, even with brake controller fully cranked to 10.
The trailer is only a year old and brakes worked well when I first got it.

What should I start looking at? Wiring connections seem fine

 

[LittleBill21]

little confused, power for brakes are supplied by the 7pin, connected to the truck, through the brake controller, the battery onboard is for emergency pin pull.

most trailer brakes are manual adjustment, have they been adjusted?

 

[Hay Dude]

Yeah should have been more clear: there’s 2 issues
1. Battery box says “recharge” but tester says 12.4V
2. Brakes weak.
No, they haven’t been adjusted, but what would have changed that much from using it for a few months? It only gets used 2x per week. May have used it 15 times since I brought it home in March. The braking power dropped suddenly

 

[LittleBill21]

i don't know what a battery box is, your going to have to explain.

too tight brakes can get burned and wear quickly, other issue, is you had a grease seal leak, and the brakes are coated in grease, especially if they were greased using zerks and done improperly.

 

[dieselscout80]

I would look at the wiring for bad spots especially where the wires go into and out of the axle tubes.

 

[Hay Dude]

i don't know what a battery box is, your going to have to explain.

too tight brakes can get burned and wear quickly, other issue, is you had a grease seal leak, and the brakes are coated in grease, especially if they were greased using zerks and done improperly.

A trailer battery box is a small plastic box on the tongue of the trailer that contains a small 12V gel battery to actuate the brakes if the trailer becomes disconnected from the vehicle. It has “test” buttons you can push on the lid to provide information on battery status.

 

[LittleBill21]

A trailer battery box is a small plastic box on the tongue of the trailer that contains a small 12V gel battery to actuate the brakes if the trailer becomes disconnected from the vehicle. It has “test” buttons you can push on the lid to provide information on battery status.

well idk what voltage it deems rechargeable, is this battery charged when the 7 pin is plugged in? 12.4 is a touch low, not recharge low.

 

[Hay Dude]

Trailer battery box.

 

[LittleBill21]

thats fancy, make sure its charging. plug into the truck with it running make sure its over 13 v at the battery terminals

 

[Dftodd]

i don't know what a battery box is, your going to have to explain.

too tight brakes can get burned and wear quickly, other issue, is you had a grease seal leak, and the brakes are coated in grease, especially if they were greased using zerks and done improperly.

How do you grease an axle wrong with a zirc fitting??

If you just do 6 pumps of grease, fresh grease will never reach the outer bearing. There's a minimum of a 1/4 tube of grease capacity inside the hub between the inner and outer bearing on a 3500lb axle.

Excess grease will ooze out the outer bearing into the cap. So there shouldn't be much of a chance to build up enough pressure inside to force the grease past the lip seal.

I could see a failure if whomever installed the lip seal put it in backwards or lost the spring out of it.

But if the lip seal is installed correctly, then you can pump grease till your hearts content and it won't push past that lip seal and effect your breaks.

 

[LittleBill21]

How do you grease an axle wrong with a zirc fitting??

If you just do 6 pumps of grease, fresh grease will never reach the outer bearing. There's a minimum of a 1/4 tube of grease capacity inside the hub between the inner and outer bearing on a 3500lb axle.

Excess grease will ooze out the outer bearing into the cap. So there shouldn't be much of a chance to build up enough pressure inside to force the grease past the lip seal.

I could see a failure if whomever installed the lip seal put it in backwards or lost the spring out of it.

But if the lip seal is installed correctly, then you can pump grease till your hearts content and it won't push past that lip seal and effect your breaks.

it has been shown hundreds of times of bearing seals failing and coating the brake linings and everything else.

your suppose to lift the wheel and spin it while using the zirc fittings, I see literally 0 people do that, and using battery powered and air pressure grease guns, if you give it enough, you can blow the seal.

 

[Dftodd]

I would look at the wiring for bad spots especially where the wires go into and out of the axle tubes.

Most automotive wiring has a soy based coating. So critters love to chew on them. Especially if you live in an area where food sources are scarce.

My thought is corrosion in the plug since braking strength is based on the amount of voltage going to the magnets.

 

[Hay Dude]

It stopped braking correctly pretty suddenly.

 

[Dftodd]

it has been shown hundreds of times of bearing seals failing and coating the brake linings and everything else.

your suppose to lift the wheel and spin it while using the zirc fittings, I see literally 0 people do that, and using battery powered and air pressure grease guns, if you give it enough, you can blow the seal.

I literally do what you describe daily at work. I hit it with my pneumatic grease gun till grease starts to come out the the outer bearing.

The only time I've had failures is on older equipment where the lip seal is worn out and needing to be replaced. But that's usually caught when we do a periodic wheel bearing inspection on the unit and doesn't actually pump any grease to the brakes.

 

[nisaacs]

Pull the break away cable and see if the brakes lock up. Has the trailer been sitting for a month or two? High humidity will rust the armature/magnet and have poor brakes for a bit. Grounds are usually suspect.

 

[Dftodd]

It stopped braking correctly pretty suddenly.

Could be as simple as a bad ground wherever the brake wire ties to the frame.

I've also noticed that whomever they have at the trailer manufacturers doing the wiring, they seem to think that the wires need to be run guitar string tight.

That tends to cause the occasional gremlin as well.

 

[LittleBill21]

It stopped braking correctly pretty suddenly.

then its a wiring issue, or a grease on brake issue

 

[Hay Dude]

The brakes still work, but only maybe 20-30% power. Its only a 7k trailer, so the truck still stops it easily, but this needs to be fixed.

 

[LittleBill21]

if you have an amp meter, i believe at full power, each wheel should pull about 3 amps, this would help determine wiring or grease issue

 

[John0829]

I can tell you that when I bought my trailer a couple of years ago I had much the same issue. The brakes worked fine when I brought it home and for several trips after that then suddenly I not so good brakes. Turned out to be the cheap a$$ vampire splices they used to make the wire connections. Needly to say all that junk came off, solder and shrink wrap fixed my problems.