Auto-close roof in rain

[sk93]

I got thinking at lunch today...

Our cars have a rain sensor, used to detect rain for the autowipers.
Depending on the current draw of that thing, how feasible do you think it would be to utilise it in a circuit that's linked to the roof-close button?
Obviously, if it's a good draw, then the only benefit would be a dead battery, but there are after-market detectors available for next to nothing (£4 example)

I don't forsee any issues with the circuit, as you could hook into the led indicator light to detect when the roof has fully closed (led extinguished)
and by-passing needing the key to operate the roof can't be that hard... can it?


Anyways.. what are peoples thoughts? would it be a cool addition, or does anyone know of any major hurdles I've missed?

 

[WLH]

Some year ago I remember reading somewhere that there was a company sold the necessary parts to make that work. As I recall it was pretty expensive. Most roadster owners that I know don't leave the top down unless they are going be nearby and have the car in sight.

 

[Breaker]

Does the roof on the 1st gen cars close when the car is moving? If not, what's the point! :wink:

I never leave the roof down on mine when parked and never will.

 

[cj10jeeper]

Aside WLH's comment about not leaving it iunless sight and no prospect of rain, etc. then let's look at this as a project - say for the hell of it.

I can see it as being possible if a few obstacles can be overcome:

The rain sensors won't be active unless the ignition is on so you'd need to either have a separate rain sensor wired in permenantly 'on' or switched when you want to set the system.

The roof requires the button to be held down to activate it, so you'd need something like the Reinhold one touch module that once touched replicates the button being held signal.

From thee I guess all you need to do is have the sensor send it's signal to your new box of trick that in turn activates the one touch module.

If you're competent to build a simple circuit board I'm sure it could be done.

I would not worry about battery drain. It'll cycle it many times without any negative battery impact.

 

[PawnSacrifice]

If we've any chance of selling this to The Dragons we're going to need some safety mechanisms:
1. Something like they have on lift doors so you don't trap anyone’s appendages
2. An electronic perimeter of some sort to ward off traffic light window cleaners
3. Tw*t detector to disable the system when that friend of a friend who thinks he’s funny but really isn’t chucks water on the car to set it off

However, with my luck I'd end up trapping some sort of wildlife in the car which, startled and scared, would urinate all over the place before trying to dig / gnaw its way free. For that reason, I'm out.

 

[sk93]

As I've said before, I am quite content leaving the roof down in the company carpark.. at my dad's pub... or in the girlfriends confined carpark. There is zero chance of anyone misbehaving with the car, so the only concern I have is the elements.
I'm sure there are others who leave the roof down as well

I reckon you could use a SPST switch against the existing "hold the button" style roof, using the feed to the "indication LED" as the cut off indicator (once the light circuit looses voltage, the roof it up, so open the switch) for a 555 timer or similar, so we shouldn't need the reinhold module afaik.

Ideally, I'd like to use the in-built sensor, as a: its already there and b: it'd be nice to keep this mod looking "oem" from the outside.

I think I may have a crack at this, just need to get my hands on the Z4 wiring diagrams.
I can get the TIS, but I don't believe they contain said diagrams do they?
Do you know where I could obtain them?

 

[sk93]

If we've any chance of selling this to The Dragons we're going to need some safety mechanisms:
1. Something like they have on lift doors so you don't trap anyone’s appendages
2. An electronic perimeter of some sort to ward off traffic light window cleaners
3. Tw*t detector to disable the system when that friend of a friend who thinks he’s funny but really isn’t chucks water on the car to set it off

However, with my luck I'd end up trapping some sort of wildlife in the car which, startled and scared, would urinate all over the place before trying to dig / gnaw its way free. For that reason, I'm out.

:rofl:

A question about the roof-closing-by-keyfob-mechanism-thingy - does this detect things getting stuck / in the way? If so, I may have to look into how it achieves that. If not, then no need, as I'd only be replicating another system

Tw*t detector would be good tho.. maybe have the light sprays rotate 180 degrees...

 

[cj10jeeper]

I think a lot of the ebay sellers of TIS bundle in the WDS package. Certainly I have it.

Using the feed to the LED sounds like a good thought, but out of my knowledge zone on those electronics.

How would you keep the rain sensor active as the car hibernates after 15 minutes?

 

[sk93]

My father's been a hobbyist sparky for decades, so SOME knowledge has rubbed off, and, of course, I have him as my "phone a friend" choice... which helps

The hibernation thing is something I need to investigate (hence looking up the drain factor).
The other sensor I posted (the £4 special), runs from a single 9v battery, and lasts for weeks on just that, so must have a very low power consumption when not triggered.
If the oem one is of similar drain, then I'd look into having it hard wired, similar to the stereo's memory power feed.

However, I believe the technology used between the two is dissimilar (i think the £4 relies on the water making a contact between two points, wheras the OEM uses infrared to detect alterations in the window's reflectiveness (AFAIK!).

The more I think about it.. the more it sounds like the oem sensor may be too power hungry to be on whilst the engine's not :/

 

[PawnSacrifice]

I'm a real numpty with this sort of thing, but getting around the hibernation mode - I'd expect the alarm to run off of a seperate circuit? :| (please be gentle if that's a really dumb point!)

Reference the keyfob auto cutoff... I would imagine that assumes line of sight to the car?

 

[sk93]

The alarm would indeed run off a seperate circuit, but with previous experience to alarms, I'd be hesitent to use its power feed, as they often monitor input voltage / current and go off if they detect a spike / dip.

RE keyfob: I guess it does, but can you actually stop the autoclose?

 

[Zed Five]

My friend's mercedes has this option on his sunroof... autoshuts when it rains. 8)

- just a shame it's a merc then :wink:

 

[srhutch]

Though this had been discussed before.....

http://www.z4-forum.com/forum/viewtopic.php?f=2&t=11480&p=172337&hilit=+auto+roof+rain#p172337 :wink:

 

[sk93]

interesting thread, but looks like it died off.. any idea if it went further than that?

I tried to hook up the ammeter to the rain sensor last night, but the freezing cold and lack of decent light in the garage meant I was unable to even get the plastic cover off the sensor!

So instead, I stuck together a basic circuit to work for against one of the many rain detectors maplin and RS sell:

T1 - 2SC1061
T2 - 2N4403
T3 - 2N4401

R1 - 500
R2 - 10k
R3 - 1 meg
R4 - 1k
R5 - 1 meg

C1 - 470u/25v
C2 - 100u/16v
C3 - 100u/16v
C4 - 0.1u/3v
C5 - 1u/3v

ZD1 - 3.6v/ 1/2w


it works straight from the car's 12v source, and has next to no draw until the rain detector is triggered, at which it only uses 3v anyway

The next bit of the circuit (the roof opertion bit) probably needs to run a 555 timer chip, using the roof status LED feed as the reset trigger.. I need to check the voltages etc for the switching, after which I'll knock up the next bit.

Obviously, I've not tested the circuit yet (I've not even built it), but it looks relatively sound to me

 

[Andy]

However, with my luck I'd end up trapping some sort of wildlife in the car which, startled and scared, would urinate all over the place before trying to dig / gnaw its way free. For that reason, I'm out.

:lol:

Excellent idea - yes this was covered before but I think you're further on already.

is there also an obstacle in that the ignition needs to be on to operate the roof buttons? I've just had mine reset to go up with the key (therefore ignition off) but im not sure how you'd tap into this rather than the buttons.

wish i could add something more constructive than that but will follow this thread with interest if it keeps going - mine also spends it's life with the roof down everywhere it goes.

 

[lacroupade]

However, with my luck I'd end up trapping some sort of wildlife in the car which, startled and scared, would urinate all over the place before trying to dig / gnaw its way free. For that reason, I'm out.

:lol:

Excellent idea - yes this was covered before but I think you're further on already.

is there also an obstacle in that the ignition needs to be on to operate the roof buttons? I've just had mine reset to go up with the key (therefore ignition off) but im not sure how you'd tap into this rather than the buttons.

wish i could add something more constructive than that but will follow this thread with interest if it keeps going - mine also spends it's life with the roof down everywhere it goes.

Andy what buttons are you pressing to send the roof up out of interest?

 

[sk93]

it's an obstical in some respects, but as it is definately possible for it to be bypassed (as in the keyfob method), it's not going to be impossible, but until I start pulling off bits of plastic, I'm not sure how much of a ballache it'll be :?

just knowing I'm not the only one who leaves his roof down and would like the "safety" a mod like this would offer is enough for now

 

[PawnSacrifice]

8) ... I'd need pretty spectacular avatar to carry that off!

 

[Andy]

twas the idea of you killing things in your roof.. shame i didnt get the quote right and i can't be arsed now 8)

i mean roof up with the button, had this programmed at an indi.

 

[sk93]

you have seen the Street KA advert that was banned, which has a similar vein to your convo? lol