Brake away switch battery on a cargo trailer

[sljkansas]

I just bought a used cargo trailer that has a small rechargeable battery on it. the battery is only putting out about 5 volts. I guess I need to charge it. My first question is can I charge it with a regular battery charger on the low amp setting?

Question 2. How do I keep it charged when not in use?

The disconnect cable is missing but the plug is still in it.can I just replace the break-away cable or replace the complete switch assembly.

[jrnymn7]

Here it is:

Original

Here's a replacement:

Replacement

That's just a little guy. At that price, just replace it. There appears to be several replacements available, including an AGM version.

Or build a new tray and go with a larger battery.

[sljkansas]

There is (was) a switch inside the trailer, but the switch is broken. This will be an easy fix.

The battery is a sealed lead-acid, rechargeable. Label on battery reads- WP4.5-12 12V4.5ah

I have a little wiggle room in the batterybox What size would be a good match?

[WyoTraveler]

Some cargo, stock and horse trailers also wire internal trailer lights to that battery. If yours is wired that way you may want to buy a heavier duty battery for replacement.

[sljkansas]

The trailer does have electric brakes. I did have to drop the setting on the controller when I first hit the brakes on the truck, it locked the brakes on the trailer and they do work with the brake controller on the truck.

I'll look for a solar charger and mount it on the trailer to keep the the battery up, and may add a couple of LED lights in the trailer.

Thanks for the help.

[RoyB]

You probably should determine if you have Electric Brakes or Hydraulic surge brakes. Having an installed battery and break-away cable probably tells you that Electric Brakes are installed. All of your SAFETY LIGHTS are powered by the Truck Battery when the trailer cable is hooked up.

Most utility trailers have the SURGE BRAKES as they do not require a BRAKE CONTROLLER in the truck to use them. Keep in mind that most states DOT have towing laws that stipulate that trailer brakes (separate from tow vehicle brakes) are mandatory when the trailer exceeds a certain weight limit.

ETRAILER is good place to buy parts and systems for all things trailers...

You should be able to charge your depleted 12V Battery using a 120VAC battery charger. When you connect your trailer cable to the truck you may be able to tap the truck 12VDC line and this would trickle charge your trailer battery when in use...

Your utility trailer battery should hold a charge for a long time when sitting as there will not be any parasitic drains to run down the battery.

[jrnymn7]

If it's a 12v battery, pretty much any 12v charger will do. (If it's a 6v, use a 6v charger). Just keep in mind you do not want to charge at higher than a C/4 to C/3 rate. It's likely not a deep cycle, with its 20hr rating clearly indicated, so you should try to figure out roughly what its 20hr rating is, if possible. Otherwise, go with say 4 amps, to be safe.

Some "smart" chargers will not initiate a charge on heavily depleted batteries... I think anything under 6v(?) is deemed 'deceased'. At 5v, you need to baby that thing back to life. Start out with a 2a trickle, and see how that goes. Should take a couple days of slow and easy to get it ready for "normal" charging. DO NOT hit it with high amperage or voltage from the get go. That comes later.

As for future maintenance... take your pick. A small solar panel may be in order, or just charge it up on occasion... but do keep it charged up, or it will sulfate terribly. In fact, you will likely need to de-sulfate it, if and when you are able to get it charged up. (Remember to monitor water levels in all cells).

Post what battery it is, and what you have available in the way of chargers, and several here can help you thru the process.

[Grandpere]

At 5 volts I doubt the battery is going to take a charge, but yes you can use a regular battery charger only I would use a high amp charge to attempt to break down the sulfation that has occurred inside the battery plates.

I would replace the whole assembly, probably the reason the cable is missing is that the pin is rusted in the socket and the cable broke while trying to remove the pin. If you can get the pic broke loose and pulled out put a light film of lubrication on it and put it back in and get a new cable. If you go with a new assembly, pull out the pin and put on a light film of lubrication so keep it from seizing up again.