HEATED FRONT WINDSCREENS

[sebring]

I have to replace my cracked (front) windscreen on my racing S1 Elan and am considering installing a heated version.
Can anyone who has experience of these please comment on the following:
1. their effectiveness?
2. current draw? (i.e. continuous amps)
3. any problems/downsides/comments?

[Spyder fan]

I can answer 2 of your questions and partly answer the other.

This is based on the heated front screen fitted to my +2 and BMW Mini.

1: Yes they are very effective at demisting your screen prior to your cars demisting system warming up. Also very good at clearing ice from the screen on a frosty morning.

2: They draw a lot of amps (approximately 30, I don't know the exact figure) and it's for this reason that a timer relay needs to be in place to cut off the power after a set time so you don't drain the battery if you have other power hungry items like headlights or fans going. Start up the engine and switch on the screen and the engine note noticeably dips as the alternator takes the load.

3; The microfilaments embedded in the laminate are visible, you certainly notice them the first time you drive a car with one of these screens fitted, also there is a very slight vision distortion caused by the filaments heating and expanding the glass laminate sandwich. (it goes back to normal once switched off), I have never found this a problem, just an observation that's all.

I'm guessing that your racer doesn't run a heater/demister system so your problem with demisting is probably happening when you get a wet race? Therefore running the screen for the whole race will give your alternator/dyno a bit of a workout (less bhp?), 10 minutes is what my +2 is set to before auto switch off, but I have the same type of screen on the rear so I have double the power drain to consider. The Mini cuts off after approx. 15 minutes. Maybe if you do 15 - 20 minute races it's not a problem, but endurance racing might cause problems. A simple timer relay for 10 minutes duration may be the answer and a big easy to hit button to energise again if needed.

[miked]

See link for Ricky Evans. He has them. Have a word. I have not got one but when having a natter with him recall him saying about different configurations of the elements. Series and parallel. Mike


lotus-chassis-f36/heated-front-screens-for-elans-t25506.html

[patrics]

Hi,
I have one of the Ricky Evans one in my S4 and I think it works well - but only needed once during last years season.
The one I have, has a single element so doesn't need a timer but I guess thats means it will not be as fast at clearing the screen.
The one time I thought I was going to need it I put it on before any misting occurred and it stayed clear - does that mean it worked?

Regards
Steve

[toomspj]

I have a heated screen in my S1. It is absolutely brilliant for a wet race. Previously i had an S1 without heated screen or any real vents and spent wet races driving virtually blind - ok for 15 minutes or so, but not for 40 or 60 minutes.

I thought about wiring it via relays, but in the end opted for simplicity and just used a switch. The screen from Ricky Evans comes with two circuits (lhs and rhs) which i fused separately and i can choose to turn on one or both sides. I only use the screen when it is wet as it does draw a lot of current.

The one downside - if you are into close racing then when the screen gets peppered with gravel from the car in front putting a wheel off line, it obviously costs a lot more to change the screen out (i buy the standard screens for less than 100 pounds versus around 200 for the heated version).

Good luck

Paul

[sebring]

thanks for all the replies and links;

To those who have them in racing elans, do any of you have any idea what the current draw is? have you measured it 'in use'?
I note from the wiring diagrames given in the R Evans link, that a 25A wiring circuit is used with a 20 Amp relay - so presumably the current draw is somewhat less than this - any information based on personal experience gratefully recieved.
thanks again

[toomspj]

I haven't measured the current, but what i do know is that with a 40 A alternator, lights on and heated screen on and the car running in race mode, the battery voltage stays at around 13v.

I believe I used 2.0mm thin wall cable to wire it up.

I have found that a voltmeter is an excellent piece of kit to have in an Elan as it really helps diagnose issues.

Paul

[sebring]

Paul,

thanks v. useful - actually I now have a reply from R Evans, who has confirmed his units have a continuous draw of 17 amps, so your 2mm? thin wall cable would be just right!