Custom Remote Start - Thermostat?

Hey forum, first post! I attempted to search the forum to see if there is already a thread on this - If there is my apologies, I could find none. I am in the business of shipping temperature-sensitive freight, and with some frequency, our drivers do overnight trips. I'm looking to have a remote starter wired to be controlled by a thermostat - That is, start the vehicle when it reaches a set point and run it until it falls below that set point. There doesn't seem to be a product that does this out of the box - There is one that I found that will "Hot start" with a maximum setting of 77* (already too hot for us) and will only run for a brief 5-minute period, once per hour - Or something to that nature. I believe this was a compustar. This will not be sufficient, we need to keep the cargo areas below 75* and it needs to continue to run as long as necessary to accomplish this, un-attended as the driver sleeps in a hotel. I imagine this can be accomplished with a third-party thermostat, either household-type 24-v or 220v (as for electric baseboard heat), with or without the use of transformers, relays, etc, but frankly I know very little about how a remote starter works. Is there somewhere within the wiring of a remote starter where a simple binary signal can be sent that will inform the system to run it's full "Yes, run vehicle" routine? Vehicles concerned are Ford Transits, Ram Promasters, and a Mercedes Sprinter, although I expect that's moot in this case because my assumption is that we'll have to install 3rd party remote starters (none are currently equipped). I would love to hear anyone's thoughts on this. Engine-off fuel fired heaters are quite common and inexpensive, but engine-off cooling involves installation of a generator and a whole host of extremely expensive modifications. I'm kind of shocked that a commercially available system that does this doesn't already exist (or if it does, it's hiding), surely I'm not the first person to run into this predicament? Even a very reputable upfitter in my area had no solutions to offer, other than the $16,000 generator upfit (which also involved hauling the generator on a movable shelf behind the vehicle). I thank you all in advance for any help you can provide!

My remote starter will run for 10 minutes before shutting down but it doesn't have any restriction for how long you must wait before remote starting again. You would need to have someone build a custom microcontroller interface that could use an accurate remote sensor (WiFi or Bluetooth connected).

Thanks eguru- Yes i'd thought of that too, my Ram truck will run for about that long as well (not one of the ones we're looking to upfit). That would probably be sufficient. Basically we just need the thermostat input to emulate the act of the remote being activated. If we need a custom interface as you say... What might be a good starting point to find someone to make such a thing? Definitely above my pay grade! Thanks

The interface can be fairly simple. Once you have all of your remote starters installed you will sacrifice one of the fobs for your project. The thermostat interfaces to a 2 second timer whose NO contacts are hard-wired to the start button contacts of the RS fob. Activate a relay using the vehicle's accessory power (which is only activated when vehicle starts). Use the relay contacts to supply 12V to the ignition wire. This will over-ride the RS timer (10 minute or whatever). Since you need to turn vehicle off when the setpoint is achieved, wire a set of contacts from the thermostat to cut power to the relay coil when temperature is less than the SP.

I looked around at some Viper manuals and observed that with a bit writer the hot start can be set from 40 to 130 in 10 degree increments. So maybe setting the hot start on one of those units to 70 degrees may work for your situation. Not sure the smart start limits for number of times but it seemed maybe like the setting was tied into timer start and could be set up to a max of 24. I have never installed one of those but perhaps Viper installers may be able to shed more light on whether it could be tailored to your needs. 4706v Install manual Steve G

Gotta say man... Pretty brilliant! Presuming a 10-minute run time, I'm pretty confident that we can get away without having to tune the off-cycle. We should be kosher to just cue it up to "Check" the thermostat every 30 minutes or so, and make the call to either start vehicle or not. Overnight hours the vehicle will cool quickly even on hot nights. Incorporating the start fob itself had never occurred to me. Thanks, I'll let you know what we come up with!

Iskidoo - I think I looked into this system before posting here, and I couldn't seem to find any good information about what this "Smartstart" actually does. It appeared to me at the time that the Smart Start would start and maintain a running engine until a desired temperature was reached, but it would still require a manual input for when to begin it's routine - In other words, it was still activated by the user, not the thermostat itself. The installer I contacted wasn't 100% sure, but he also believed this was the case. However, that could still be a very useful tool in conjunction with a thermostatic start, as it could maintain the run cycle until the set point was reached, eliminating the need for a second workaround to shut the vehicle off (eg, if my custom thermostat-start starts the vehicle at 75*, smart start would activate and run until it reached 70, rather than a fixed 10 minutes). Thanks for the heads up!

I was also looking at Amazon at some inexpensive temperature controllers that run on 12 volts. At the set temp it could be used to trigger the activation input that most remote starters have as an option. The input is typically tied to the output of some other alarm system or tied to door locks to trigger a remote start from pressing lock a few times on the OEM keyfob. This input could trigger anytime the temp controller sent it a turn on command. Here is an example of an inexpensive one but I'm not sure the reliability of these. Amazon 12v temp controller Seems that when the temp is achieved it will turn the cooling relay on and leave it on until the temp falls back down. The remote start input usually can be set to one pulse. I'm not sure if it would cause a problem if the controller was putting out a constant output on the wire that only needs a momentary pulse. You could try it and it may not be an issue. But if it was this relay circuit could be added between the controller and the activation input to change it from a constant to a momentary output. Constant to Momentary output Using this setup would make it more automatic rather than the smart start setup which would require a sequence of button presses to set it after everytime the vehicle was driven.Steve G

If a tune down cycle was needed it could probably be achieved using the same timer by wiring the heat relay switch from the temp controller to another constant to momentary circuit and then tying it to the brake shutdown input of the remote starter. Since it will also need to continue to work with the brake, the installer would have to diode isolate the 2 wires being connected to the brake. This probably wouldn't even needed but is just another option that I was thinking about. A toggle switch would probably need to be added on the wire to disable the low temp setting if you wanted the remote start to properly function in the winter. Otherwise the temp controller would constantly be trying to shutdown the remote starter when you actually wanted it to warm up the vehicle.Steve G

cabayo wrote: smart start would activate and run until it reached 70, rather than a fixed 10 minutes).

I don't think it would work like that. If you set hot start to 70 it would start probably at 70 degrees but it wouldn't shut anything down at 70. It would just start when it hit 70 and run for the amount of time that it was set for in the smart start settings. It's 12 minutes by default but adjustable from 1 to 16 minutes at option 10 in the "bit writer only settings" Smart start mode would also need to be enabled manually everytime you were done driving. I didn't see any option to keep it enabled automatically.Steve G