Startup Timer for Heater

**Anshu** · 12-08-2007, 02:42 AM

Hey,
As we have set into winter I have the same problem with my carputer as last year. My usb support doesnt work in the cold. So long story short, I think im going to buy a 12v heating blanket and put that ontop of the computer so that I can get some instant heat when the car boots up. But I dont want this running all the time. I need someway to have it power up for lets say 120 seconds and then turn off, only being triggered by power input. I did a search for timers but it all seems on shutdown.
Any thoughts?
Thanks in advance!

**nobb** · 12-08-2007, 05:03 PM

When you say usb support, is it the built in usb that isnt functioning or are you using a separate usb pci card? Does you computer still bootup and everything else work? With a heater, you will have to wait atleast several minutes for the components to warm. Maybe a cheaper and more practical alternative is to just try adding a another usb pci card that works in the cold.

**Anshu** · 12-09-2007, 01:53 AM

No its in the in built usb. I think your saying to add another card. Its a laptop setup so theres no way to go about doing that. I think by adding a cheap heater, it would reduce the number of reboots etc. The heater should be warm in one min so ok. And coupled with remote start will be ok.
Anythoughts on the timer?

**h3rk** · 12-09-2007, 02:32 AM

so, every time that the 'heater' is going to turn itself off, the car and the computer will be running correct?

You could use the fusion brain. (keep in mind the brain will not activate anything until the computer is up and running)

Power the 'heater' trough a normally open (87) contact of a 12 volt relay(call this relay A).

Relay B (activated by the fusion brain) is in series with the coil side of Relay A, such that Relay A only turns on if ignition is on and fusion brain hasn't turned on Relay B (connected to normally closed contact 87a).

Relay B is controlled by the fusion brain, and can be set to turn on a set time after the program automatically starts(some xml'ish skin writing is required, but in this case will be very easy).

Relay A
85- Accessory wire
86- Relay B (30)
30- Fused source for heater
87- Heater, and maybe a led saying that the heater is on
87a- Nothing

Relay B
85- }pin connector to brain
86- }pin connector to brain
30- Relay A (86)
87- Nothing
87a- Ground

Then, through the skin you tell the brain to turn off X time after program initiates.

You could also do it with capacitors and resistors, but 2 minutes is a long time for that.

And then you'd have a bunch of more outputs and inputs you can set to control with your computer

if you're in to that sort of thing.

Edit: another thought:

Use something like a neutral safety switch, so that when the car goes in to any position other than park, or neutral; Relay B picks up and turns off Relay A=> heater.

But that opens up the need to have a third relay as a lock in so that the relay A will pick up while starting up the car, but will not turn on when the car is parked but not turned off.

**Anshu** · 12-09-2007, 02:47 AM

interesting. that could just work. or even better if I had the brain I could just set it to turn on using a temp sensor or something.
my only concern is that because the brain is USB, will it not work if the computer is not giving a usb signal hence killing the entire plan? otherwise Im sold, I was actually thinking about going fusion for other reasons!

**h3rk** · 12-09-2007, 03:00 AM

I specifically wrote my recommendation taking the fact that the brain does (*almost) nothing when the car is off. The way I specified it, it wouldn't kill your plan.

*almost refers to the fact that you can set digital outputs to turn off a specified time after the computer shuts down, iirc.

**Anshu** · 12-09-2007, 04:55 PM

Im still somewhat confused. Sorry.
Wait I think I may just have understood it. In simpler terms the when the car is on but the computer on the pad would be on. When the computer comes on and runs for x period(lets say enough to safely know its not going to freeze again) then the brain turns off the pad. thats genius.
sorry for not understanding the first time.
So thats a viable option, do you think that would be alot better then using a similar system but instead of time turning on relay B it was a temprature controlled sensor?

**GoHybrid** · 12-09-2007, 06:34 PM

i think this is way easier than you're making it. Just use a thermostat switch calibrated for your favorite temperature to operate the heating blanket relay. It sounds like what you want is to maintain above a temperature as long as the computer is operating, as opposed to raising it for a short time on startup.

This is just an example of the type of switch you are looking for. They have bimetal discs in them that trigger after reaching a certain temperature threshold and come in all shapes and sizes and temperature ratings.

So for example, same ambient air temp is 0 degrees celsius when you get into your car - you need heat, so you would have a thermostat switch that breaks when ambient temp reaches 20C. So you give your relay coil ignition power and put the thermostat switch inline with that, and then heavier gauge constant 12V through the relay to the blanket. This way you've got a blanket that gets you to operating temperature, always turns on when it's cooling off too much, and never stays on when things are warm enough, and is always off when the car is off.

Probably not more than $10 worth of parts not counting the blanket.

**Anshu** · 12-09-2007, 08:03 PM

seems to make sense. however a quick google search didnt show much of where I could get that part. is that like a mouser or a radioshack kinda thing?
Cheers

**SKiTLz** · 12-10-2007, 12:24 AM

Originally Posted by GoHybrid

i think this is way easier than you're making it. Just use a thermostat switch calibrated for your favorite temperature to operate the heating blanket relay. It sounds like what you want is to maintain above a temperature as long as the computer is operating, as opposed to raising it for a short time on startup.

This is just an example of the type of switch you are looking for. They have bimetal discs in them that trigger after reaching a certain temperature threshold and come in all shapes and sizes and temperature ratings.

So for example, same ambient air temp is 0 degrees celsius when you get into your car - you need heat, so you would have a thermostat switch that breaks when ambient temp reaches 20C. So you give your relay coil ignition power and put the thermostat switch inline with that, and then heavier gauge constant 12V through the relay to the blanket. This way you've got a blanket that gets you to operating temperature, always turns on when it's cooling off too much, and never stays on when things are warm enough, and is always off when the car is off.

Probably not more than $10 worth of parts not counting the blanket.

This sounds like a much better idea than my $120 temperature controlled relay i was going to buy.