Yes, the extension cord that connects the block heater plug to the outlet.

My first tool of choice for this project is my Kill-a-Watt, used as an ammeter (or watt meter) for the block heater. If I have to tear into the grill to check out the wiring, then I'll consider a DVM, possibly on an much warmer day.

 

Keep in mind the "killawatt" meter measures what goes into the AC/DC converter, (charger) and not what goes into the battery pack. If the OEM transformer (mine) was more efficient, maybe your "charger" is just consuming an extra 25-35 watts? Also not too extraordinary for each car to vary a little. Maybe if your charger puts out a little more, the battery can take a little more?

Mine is a 2005, built in 12/2004.

 

Good point I neglected to consider. Also I noticed a small fan running in the brick. I am actually considering disabling it.

 

With several new 2009+ owners here, I'd like to get this documented, maybe even get a how-to stickied.

I do have the 2009 manual. Maybe I can find that seat-belt connector there as well. I have the 24v PS, but need to get the connector to test, then run the wire from back to front.

 

I have an Enginer kit (4kwh) installed which sits above the HV battery. I have inserted a 60w battery heating pad from Napa between the two and it is set to turn on under 50 degrees F. It makes a big difference in battery performance on my FEH and uses little electricity. The other day my 10 mile drive to work got 60mpg in 25 degree weather.

 

A 60w heating pad is not an effective means to warm a cold battery, but sounds like just the trick to keep a battery already warm from a day of driving from cooling off overnight.

Plus, your plug-in battery will get warm naturally during the charge cycle.