Trailer Bypass Relay Current Draw

[jonrev]

Just wanted to know if anyone who'd fitted a TEB7A/S bypass relay had noticed the current it draws when not in use. Fitted mine up as per instructions (nicely soldered connections) and noticed a loudish click when I fitted the fuse. A relay inside the unit was obviously pulling in. "Oh bother" I thought and checked all the wiring- all seemed OK. Checked the outputs from the relay to the towbar socket and none were live so the relay didn't seem to be switching any circuits. One by one I disconnected all the wires to the unit till just live feed and earth were still connected and still it pulled in when I connected the fuse. I tested the current it was drawing and it was around 14 milliamps. All I'd read about these bypass relays said quiescent current was less than one milliamp.

At this point I emailed Towequip the supplier. Got a phone call back from them very quickly but they were not able to say whether this was normal for one of these units or not. Eventually offered to send me a replacement in case my one was faulty. This duly arrived and I tested it only to find exactly the same happened.

So OK a decent car battery should handle a constant 14 milliamp drain for a longish while so probably wouldn't cause problems even if the car was left standing for a week or two but:- If the battery was a bit dodgy and the weather a bit cold it certainly wouldn't help. Also it means there's a relay inside the unit that's pulled in 24/7 doing nothing but using battery power and getting hot- Why? It doesn't make sense.

My solution is now to fit a switch in the live feed from the battery and try to remember to switch it off when I'm not towing. Not as per the wiring instructions but I'll feel better! Maybe I'll change to an ignition switched live at some stage but would be interested if anyone else has noticed a similar 'feature' with their unit.

PS. Much praise for Towequip. Admitted they were not electronic engineers and just sold and fitted the units they were supplied but were very quick to deal with my enquiry and extremely helpful.