Jr and I were doing pre-winter maintenance on his 2009 Mazda5 yesterday, and per routine I checked the block-heater plug with an ohmmeter.
It was open, which was no surprise, as after I opened up the replacement end I had installed a few years ago, I found all the connections badly corroded.
I cut off the plug and stripped back the conductors in the block-heater cable. One side was quite discoloured, from salty water wicking up the stranded wire. The circuit was still open (i.e. reading infinite resistance). I kept going until the resistance got down to c. 375 Ohms. Way too high. Stripped it back some more until the copper looked good. Now the resistance was about 114 Ohms. That still seemed higher than I expected, but within the realm of possibility.
I didn't have a good plug, so spliced in a grounded appliance plug and part of its cord for the time being.
I have been unable to find the rated wattage for this block heater, so don't know if the resistance is appropriate.
Let's round that resistance up to 120 Ohms to make the math easy. 120 V/120 Ohms = 1 A. (1 A)^2 * 120 Ohms = 120 W.
I thought a block heater was usually 300 W or more. I'm a bit reluctant to plug it in for fear of heating up the cord internally if there is still high resistance in the cord.
Thoughts?
Perhaps I should replace the entire cord (which looks like it would be a real pain, but so be it).
It was open, which was no surprise, as after I opened up the replacement end I had installed a few years ago, I found all the connections badly corroded.
I cut off the plug and stripped back the conductors in the block-heater cable. One side was quite discoloured, from salty water wicking up the stranded wire. The circuit was still open (i.e. reading infinite resistance). I kept going until the resistance got down to c. 375 Ohms. Way too high. Stripped it back some more until the copper looked good. Now the resistance was about 114 Ohms. That still seemed higher than I expected, but within the realm of possibility.
I didn't have a good plug, so spliced in a grounded appliance plug and part of its cord for the time being.
I have been unable to find the rated wattage for this block heater, so don't know if the resistance is appropriate.
Let's round that resistance up to 120 Ohms to make the math easy. 120 V/120 Ohms = 1 A. (1 A)^2 * 120 Ohms = 120 W.
I thought a block heater was usually 300 W or more. I'm a bit reluctant to plug it in for fear of heating up the cord internally if there is still high resistance in the cord.
Thoughts?
Perhaps I should replace the entire cord (which looks like it would be a real pain, but so be it).