Weak brakes & battery box confusion.

[dodge man]

As a rule a 12 volt battery should read a little higher than 12.4 volts?

 

[RustyA]

Fully charged 6 cell 12v battery should test for 12.6-13.2v at rest. Your tow vehicle should provide 14.2 running to recharge it when connected.

 

[John0829]

You said the controller works as it should on another trailer, good, truck is out of it.

In all likelihood the electronics in the box are not quite right in that it reports the battery needs charge at 12.4 volts when others may go down to 12.0 or lower before indicating a need for charge. Hook a battery charger to it for a little while and see what it shows after the voltage has been brought up.

Maybe the box is smarter than I think and it senses the battery will fail when a load is applied. Either way I have found these little batteries they use are not very robust especially if allowed to sit at a low voltage for long periods. On my trailer, which does sit for weeks at a time between uses, I added a plug for a trickle charger and setup a timer to the charger to bump the voltage once every couple of weeks. Batteries last longer now than they did before.

As for the weak braking, they worked fine and now they don't, it is a connection problem. Could be in the 7 pin connector but more than likely it is a splice or splices and the only way to fix it correctly is to crawl under it, unless you have a way to set the trailer on it's side, then solder and heat shrink all the splices, which if it is like most trailers there will be a ridiculous number of splices. And make sure the ground is clean and tight, preferably NOT a self tapping screw.

ALL of this has been said many times over the last 7 pages and until it has been done there is nothing more anyone can add except to add more pages repeating it over and over.

 

[hummertom]

Let's try to sum up all the above posts, that battery is a approx 4ah lead acid gel cell, it's marked "OK 3/23" that means it was tested then, not manufactured then, there will be a number on the top either stamped or cast into the plastic, you can figure out the date code or go to manufacturers website. Those type of batteries typically have a 3-5 yr lifespan depending on charging and use. That said 12.4 is a little low, should read min. 12.7 without load and charge at 13.2. That battery is only used for accidental disconnect of the hitch, your 7 pin provides power to the brakes thru the controller and charges that battery. Your possible points of fault are as follows and not in order of probability.
Controller
7 pin socket
wiring/ short to frame
unadjusted or lube fouled brakes
Worked construction for over 40yrs and installed and tested that kind of battery 1000's of times. Also chk the pad or shoe surface, if you are hauling heavy with a lot of braking they can become glazed which will give you bad stopping.

 

[Sid Post]

Yeah I know that. As I have said many times, I have 2 issues going on.
1. Breakaway battery box light reads recharge, but electrical tester says 12.4 volts. Thats one of the issues.
2. Brakes suddenly became weak. That’s the other issue.

I’m very aware the battery box is not related to the brake loss.

No offense intended! Reading a lot of posts in this thread suggests the breakaway battery matters so, I wanted to be clear for anyone not familiar with this that it only matters if the tow vehicle is not connected.

I have a couple of trailers that would be cost-prohibitive to own if a battery was required to have brakes. They don't see any meaningful use on public roads outside of agricultural use so, spending $40~$60 every time I need to use one just wouldn't work financially. Pretty frustrating as well to chuck a ~2 month old battery into the recycle bin.

The only trailer I ever had a problem within 100's of thousands of miles pulling trailers is one U-Haul 6x12 with a faulty hitch going across railroad tracks in a rural area. I am a hard stickler on good tires and brakes though, U-Haul doesn't give you a choice and they underrate their trailers to make them "legal" even though their size means they are routinely overloaded which is why you see so many of them upside down in the median of the Interstate.

 

[nyone]

Been there, done that!

Look for rust on the 2" receiver housing. In my case, the Dodge Ram 2500 came with a 2.5" receiver with a 0.5" spacer so it would accept 2" receiver components. That sleeve and the trailer hitch connection collected water and rusted, breaking the circuit to the trailer brakes in my case. Like a light switch some turned off I went from excellent brakes to absolutely nothing!

Your 7pin connector has a ground wire in it. So your hitch/ball shouldnt be the ground path.

 

[nyone]

Breakaway battery box light reads recharge, but electrical tester says 12.4 volts. Thats one of the

12.4v is a dead battery. It should be reading higher and more like 13+ if the vehicle is running.

 

[Hay Dude]

12.4v is a dead battery. It should be reading higher and more like 13+ if the vehicle is running.

Yeah, I know it’s marginal. New battery in late March. Hard to believe that far gone already

 

[LittleBill21]

12.4v is a dead battery. It should be reading higher and more like 13+ if the vehicle is running.

not even remotely

 

[Snobdds]

Split the ground coming out of the trailer brake to make a direct ground as close to the brake as possible. Then let the other side of the ground flow back to the control box as usual.

I make a dedicated ground at each light, break, etc. With lights I have to find either a screw or make and weld a tab to make a good ground.

Grounds on trailers are a pain.