Horse trailer draining car battery

[diamondrockharvey]

Seems like my Ifor Williams trailer is draining the battery on my BMW X5.
Just having the trailer hooked up to the electrics is draining the battery and I have been stuck twice now with a horse on the back and no power to start the car! Anyone else experienced this? I have used the trailer previously on my old car and never had an issue and my friend has also used it and her car was fine so I don't think it is the trailer?? I am wondering if unhooking the electrics whilst not travelling would help and then just connecting it whilst driving? Or if it is the tow bar electrics that need looking at? The battery is fine when just day to day driving so I sure it is just when it is hitched up that it is a problem. Can you plug the electrics in after you have started the engine and then unplug before you stop the car engine?? I am wondering if that is the solution? As only seems to drain when the car is left off at a standstill. Any thoughts appreciated.

 

[Honey08]

OH is a mechanic and says connect it up when you've started the car, unplug it while standing. Also, for the battery to drain, something is draining it - interior light in trailer etc. Best to ask your local garage to check perhaps.

 

[Toby_Zaphod]

Check the wiring on your car's tow bar. Many towbars now require the wiring to go through a relay to the tow cars electrics & shouldn't be straight wired into the car's electrics without the relay. If you haven't been wired through a relay then that may be causing you the problems.

 

[diamondrockharvey]

Thank you both. No lights are staying on. Will get tow bar wiring looked at!