12v Mattress heating pad woes
Last night was kinda chilly. An hour before climbing into bed I, plug my 'watts up' meter inline with my mattress heating pad, crank it up to 7, check out the amp draw, and see it is only half of n...
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Well the specs claimed a 6.2 amp draw, but due to the increasing voltage drop as the connections heated up, the current dropped along with the voltage.
My powerpole modifications made it a steady 6.8 amps which is not 50% over the baseline 6.2a, but perhaps the engineers expected the voltage drop and the resulting drop in amperage too.
But since they recommend these for truckers and they say to turn on the mattress heating pad a few hours before turning off the engine, they would have to figure in battery charging voltages making it to the ciggy receptacle. Even with 2 volts drop across the ciggy plug from 14.4 that leaves 12.4v which is all my ciggy plug was ever really fed. Could there really be so little overhead engineered into such a device?
I am not accounting for the 5 feet of 18 awg cable I cut off between controller and ciggy plug. Certainly the voltage across that 5 feet between plug and controller, which I did not measure, was also significant.
I hate to be one of those people fishing for what I want to hear and dismissing any opinions that do not do so. What I want to hear is that the failure was likely caused by 3 winters of use and abuse my my 220 lb frame wearing out the wiring. I don't want to hear that I have to artificially limit the current by planned voltage drop into a replacement pad or risk premature failure.
I wonder if I can determine if the failure was wear and tear related, or if it was induced by me reducing the voltage drop through a shorter circuit path and elimination of one of the poorest ubiquitous connectors ever designed.
That extra 5 feet of 18 awg wire was always in the way. I was glad to be rid of it. I'd hate to think its elimination was the cause of the failure.
I wonder what the life expectancy is for such a device.
I'd consider 120v models now that I have a Quiet PSW inverter, but I really liked this 12v unit, while it lasted.
My powerpole modifications made it a steady 6.8 amps which is not 50% over the baseline 6.2a, but perhaps the engineers expected the voltage drop and the resulting drop in amperage too.
But since they recommend these for truckers and they say to turn on the mattress heating pad a few hours before turning off the engine, they would have to figure in battery charging voltages making it to the ciggy receptacle. Even with 2 volts drop across the ciggy plug from 14.4 that leaves 12.4v which is all my ciggy plug was ever really fed. Could there really be so little overhead engineered into such a device?
I am not accounting for the 5 feet of 18 awg cable I cut off between controller and ciggy plug. Certainly the voltage across that 5 feet between plug and controller, which I did not measure, was also significant.
I hate to be one of those people fishing for what I want to hear and dismissing any opinions that do not do so. What I want to hear is that the failure was likely caused by 3 winters of use and abuse my my 220 lb frame wearing out the wiring. I don't want to hear that I have to artificially limit the current by planned voltage drop into a replacement pad or risk premature failure.
I wonder if I can determine if the failure was wear and tear related, or if it was induced by me reducing the voltage drop through a shorter circuit path and elimination of one of the poorest ubiquitous connectors ever designed.
That extra 5 feet of 18 awg wire was always in the way. I was glad to be rid of it. I'd hate to think its elimination was the cause of the failure.
I wonder what the life expectancy is for such a device.
I'd consider 120v models now that I have a Quiet PSW inverter, but I really liked this 12v unit, while it lasted.
