Power Consumption
When the vehicles engine is not running the Heatshot unit is essentially switched off. The only part of the unit that is still active is its internal clock. This clock serves to monitor the battery voltage and detect the voltage increase when the engine is started. It then sends a signal to the micro processor to turn the unit on. The units internal clock will draw a very small amount of current in order to function. Typically this is 5 mA (milliamps).
When the vehicles engine is started, the alternator begins charging the battery and the voltage will raise above 12.8 volts. At this point the Heatshot unit’s internal clock recognises this and sends a signal to the microprocessor to turn the unit on. The micro processor then monitors the vehicles voltage and when it stops increasing and stabilizes, it turns itself on. This function is very important, as it means that by the time the Heatshot unit has turned on, the voltage and current that it needs to function is essentially supplied from the alternator not just the battery. Therefore, if the vehicles battery is not in the best condition, the unit will not draw vital power that is required to run the vehicle.
Once the vehicle’s engine is running and the unit has turned on, it will take a reading of the ambient temperature and also the temperature of the washer fluid inside the unit. It will then decide how many of its three heaters it needs to turn on in order to heat the washer fluid up to temperature within the 30 seconds.
In the most extreme conditions, all three heaters may be required to heat the fluid. In that case the total current draw for the initial 30 seconds would be 50 amps. However, if only two heaters are required, the total current draw for the first 30 seconds will be a maximum of 34 amps, and if only one heater is required the current draw will be 17 amps. Following the initial 30 second heating period, the unit will only consume 1.5 amps per hour.
It is possible to bespoke the unit. For example, if you have vehicles where a 50 amp current draw (even for 30 seconds) is an issue, we could supply you with units where only two of the three heaters function. This of course would reduce the current draw within the first 30 second to 34 amps. Note: If this option is used, it would mean the initial 30 second heating period would extend to 40 seconds.
There may also be some customers who cannot have the 5 mA current drawn when the vehicles engine is switched off (this is the current consumed by the unit’s internal clock as it monitors the battery voltage, referred to in our technical literature as quiescent current or dark current). If that is the case we can disconnect the internal clock and supply an additional cable to be connected to a switched live. This will turn the unit on and off instead of using the internal clock. This will mean that the quiescent current will be close to if not zero.