Break away safety cord

A vandal removed my break away cord while the trailer was in storage. The two 110ah batteries went completely dead. Fortunately, magnets and wiring on the tandem axels survived which is a miracle. I contacted the manufacturer and they told me the magnets are not really designed to withstand the continuous power of two house batteries and would withstand power from a small 10amp hour battery. The 10AH battery would run down before damaging the 4 magnets drawing 15-16 amps. They gave me a procedure to check the magnets which I performed and it was a miracle that they check out ok. Also the on-road braking seems normal. The wiring in my trailer is 10 gauge with a long run to dissipate the heat and the connections were good enough to not produce the heat that would fry the wiring. The battery lives have been reduced because batteries do not like to be totally discharged.
I am now considering installing a 10AH battery set up for the break away system to prevent this from happening again.

Had the cord get caught and pulled out several times while turning youst put it back in and no issues.
Frank.

Artum Snowbird wrote:
Thanks for the quick answers, and it got me thinking about when this happens. Most often it is when someone pulls out of the hitch without having it latched.

So, if then the brakes are on full... often one might not be thinking the best in that situation... KaTHUMP... how long until brake parts actually get damaged with full voltage on? Anybody with experience... did damage occur?

Essentially it is a resistance, and current flow through the resistance, and then the wiring should take the current without damage.

The first few days I got my first trailer I couldn't figure out why the battery kept dying. I did it three times. Pulled the switch and left it pulled. Drained the battery. No other damage I was aware of, but the batteries died fairly quick.

rhagfo wrote:

MainerBob wrote:
We had an occurence last summer where the cord got pulled by something in the bed by accident. By the time we realized what had happened we needed not only a new switch but all new brakes x4 and replacement of some fried wiring.

Wow, I had the same thing happen backing into a space, uphill blind side! Thought I had hit something BIG!
It only took the second time out of the cab to see the pin laying on the floor of the bed. I know trailer isn't going far when that pin is pulled!!!

Glad to know I'm not the only one that's happened to. Cost me big bucks to get it fixed.

The Break-a-Way switch is not designed to handle full power to the brakes for long term, just as the term implies "Emergency". Extended power through it will melt it. There's a picture on one of the forums of a switch that melted.

Trailer battery is wired directly to and thru the 'emergency brake switch'

When pin is pulled FULL trailer battery voltage goes to trailer brake magnets.
Trailer brake shoes will NOT engage until wheels rotate

FULL battery voltage is needed and required per Federal Law to engage trailer brakes in the event trailer becomes disconnected from tow vehicle

Pulling the pin when connected to tow vehicle can cause damage to tow vehicle brake controller due to back feed of full battery voltage.

MainerBob wrote:
We had an occurence last summer where the cord got pulled by something in the bed by accident. By the time we realized what had happened we needed not only a new switch but all new brakes x4 and replacement of some fried wiring.

Wow, I had the same thing happen backing into a space, uphill blind side! Thought I had hit something BIG!
It only took the second time out of the cab to see the pin laying on the floor of the bed. I know trailer isn't going far when that pin is pulled!!!

This question got me thinking. The other day someone was saying their measurement was 3.3 ohms, and he wondered whether all his magnets were actually connected. Could he not pull the cord, and then use the compass to see if there was a deflection on each wheel? Where does the emergency power come into the brake wiring?

Thanks MainerBob, that is certainly the definitive answer!

How long was it? Did you actually try towing the rig?

We had an occurence last summer where the cord got pulled by something in the bed by accident. By the time we realized what had happened we needed not only a new switch but all new brakes x4 and replacement of some fried wiring.