OK, light Friday evening entertainment. Here in the UK, a retired friend has a non-pc but very well cared for Range Rover 4.6 HSE. However, it developed a fault in that it would regularly discharge its (new) battery after 2 nights in his garage. Trips to auto electicians/workshops failed to reveal anything, meters, alternators, etc nothing discharging. So what was it? and I have a bonus question for the correct solution.
(No giigling!) but I reckon JB folk are a breed apart
OK, quick thread, and I guess Mr Lid has been researching. Electronic smog is indeed the answer, his newly installed weather station was sending 1 minute humidity readings over air, they in turn were trying to activate his central locking ..
For a real prize, what specific item caused my Ferrari owning friend's alarm to activate around three times a year?
The Memsahib's VW Polo had the same problem. We'd got a new battery from Halfords due to previous one leaking. The NEW battery also leaked!!!! Took it back and got another one. That's been fine, up to now!!!
If the receiver for the central locking wasn't such a crap one (but they ALL are!) the central locking would probably not have noticed. So that the system can be as cheap as muck, the receivers are around 700kHz wide and the transmitters are somewhere in that bandwidth. This actually led to German car manufacturers attempting to get all other Short Range Devices (SRD) banned from the 433 MHz frequency range. They did get somewhat short shrift on that at the CEPT (European Conference of Posts and Telecommunications) committee.
Some 20 years back, I worked in the group that made a load of the integrated circuits for them. The car manufacturers just refused to pay for anything but the minimum performance - they were even upset when the use of superegeneritive receivers (which radiate interference like the clappers) were banned.
Might be some fun round Weymouth during the Olympics - there will be some transmissions on the frequency during the sailboat racing.
On my beemer it was the "final stage resistor". A french made part (Valeo) that caused massive amounts of trouble. It was a simple part to swap out. Check that the ventilation fans aren't constantly blowing - a simple bit of toilet tissue "blowing in the wind" over the air vents, after everything is switched off will tell you quickly if it's the rouge part.
Exactly the same thing on my mate's BMW. It was slightly more subtle because it did its thing intermittently after he'd checked everything was off and locked the car up. Only discovered what was happening after he'd linked up a recorder overnight to monitor the voltage/current draw.
On my wife's Clio the overnight battery drain was traced to a worn through ignition circuit wire intermittently shorting out against a metal brake pipe. bit of tape and some cable ties sorted that one out!
I didn't mention that the unlocking/locking radio receiver shouldn't draw any more than 5 milliamps. That means (if it hasn't any current saving circuitry built in) it should take 8 days and 16 hours to deplete the battery by 1 amp-hour.