block heater ohms?

[JustinLee]

The block heater on my dads freightliner ohms at 10. 7. Doing searches, dodge rams fitted with Cummins should be around 20-25; so that 10. 7 seemed low. I checked his coworkers rig right next to his, 10. 4 ohms. The reason I ask is my dad has burnt several extension cords. One even melted both the male and female plugs. He has replaced the entire cord in his truck but not the heater itself but still burns them. His coworker has never had a problem.



Any thoughts?

Justin

 

[HBarlow]

I know nothing about Freightliner block heaters and don't even know if you are referring to a Cummins B5. 9 engine in a small FL MDT or any other truck diesel engine.

Just applying basic electronics I would guess that there are two elements in the FL's block heater and one is burned out and shorted to ground. That would explain why the resistance is half the normal resistance and also explains why the block heater is drawing too much current and burning out extension cords.

I would replace the block heater.

 

[JustinLee]

Both those trucks have detroits.

 

[CKelley1]

the 10 ohms is correct this will draw about 10 to 12 amps most extension cords are 16 gage and the plugs will get hot and do exactly what you observed just switch to a 12 gage cord and most of your problems will be gone, burnish off the oxide on the plug and use some bulb grease , electrical grease or nolox on the plug's and that will fix the rest

 

[Vaughn MacKenzie]

Yes 20-25 ohms gives you ~650 watts, which is about right for a Dodge Cummins block heater (I heard about 700W).

One at only 10. 7 Ohms would give you 1345W. That's a lot of juice, 11. 21 Amps like CKelley1 was saying. Add an extension cord and it'll cause you to drop voltage which means guess what. . . more current flowing. No surprise it's burning up the cords. Definitely need to have really clean terminals, and use the shortest cord possible. . . not more than 25' or so.

Vaughn