I just got my 3 part "kit" in the mail.
Here is what I have learned so far:

The block heater is rated 400 watts at 115 VAC.
( Stamped on the brass heater itself )
It runs on AC power right from your house plug.
There is no converter for this device.
It is just like a light bulb, without the glass cage.
The filament touches the coolant water.
It makes heat from a direct short, basically.
Without the water, it would glow orange like a toaster.

I put a watt meter on mine when I plugged it in, just the block heater alone. It was pulling 435 watts from my garage outlet.
I measured my garage outlet and it was 124.7 VAC.
This means the block heater draws 3.5 amps.

Then I plugged in the AC/DC converter by itself.
Under no load, it was putting out 23.5v DC.
Under no load, and not attached to the car, the transformer was taking 3 watts just sitting there ( 3 watts just going into heat ).
Then I attached it to the car, and it took just 5 watts total.
( 2 more watts than not connected )
So not much was happening with that transformer under these conditions:
My HV battery SOC was about 50%.
My HV battery temperature was 22'C ( 72'F )
I tried it both with key on, engine off, and key off. Same result.

The engine block heater is "dumb". No thermostat. No Electronics.
The engine block heater gets hot anytime it is plugged in.

The AC/DC converter (120 VAC to ~24V DC ) is smart.
There are some electronics somewhere that tells it to come on only when needed.

As far as I can tell, the block heater, and AC/DC converter can be used separately. There is one "Y" cable, but you can use either branch of the Y you wish, or both.

The "Y" Cable with the household plug cost me $49.10 via mail order.
The 400 watt block heater cost me $26.79.
The AC/DC converter cost me the most, $80.70 and is probably going to be the nearly useless ( or used-less ) part out of the bunch!

In a couple of months, I will have zero degree days, and will measure the HV battery temperature before and after. Based on the brute size & weight of the AC/DC transformer, it can probably put out 2 amps. 2 A at 24v is 10% the wattage of the block heater, but then again, you don't want a battery pack at 120 degrees in the morning like you do with your engine coolent! ( Plus the engine has a lot more mass, and the specific heat of water is very high, so the numbers make sense. )

-John

 

FYI you need a 14mm hex ( I used a 1/2" socket driver with a 14mm Allen tip, you need something that beefy ) to remove the EBH plug.

You need a 24mm socket to install the EBH into the hole.

I had both on hand, and swapped them out really quick.
I lost 12oz... a pint tops of coolant.
Yes, some trickled down my arm, but I wore an old water repellent jacket I didn't mind getting dirty and was done with the heater part in about 2 minutes. It was easiest to lie on my back and work up. I had the car on stands to give me... 9-10" of additional clearance.

Now, on to the wires! ( which are pretty much plug n play )
-John

 

As we now know, the FEH must be warmed to a minimum temperature to
allow EV driving, or engine shut down at stops. In years 2005
through 2007 this equals an engine temperature of 140'F to allow
engine shut down. It has been reported by at least one owner, that
the minimum temperature for EV in 2008 is 160'F.

Also, the HV battery needs to have certain temperature conditions met
for optimal performance. ( 50'F to 85'F )

If owners purchase an optional "Engine Block Heater"
kit, this kit contains 3 parts: 1.)The block heater (120v 400-435
watts), 2.)The 120v AC to 24v DC (50 to 75 watts)converter that feeds
24 volts into the large battery in the rear, and 3.)The wire harness
with house plug and "Y" splitter for the 120v power. 2008 owners
report they do not get the 24v part, but I have not confirmed this.

While the 24v converter is listed in the Ford parts list as
a "charger" it appears in real life it is simply a HV battery warmer.
Several test uses have not increased battery state of charge, but
have increased HV battery temperature.
Last night was cool, but not cold at my home. Outdoor was about 32'F
(0'C, had frost) at dawn, and my lightly insulated garage was about
45'F.

I had a timer turn on my block heater for 2.5 hours before my A.M.
commute. When I turned the key this A.M. my engine temperature was
104'F before I started the car. This allowed me to go into EV within
3/4 of a mile at 35 miles per hour this morining. Outside was at the freeze
point.

But I noticed something else that concerned me. As soon as I turned
the key this A.M. my Air Conditioner also turned on! On a hunch, I
used the FEH diagnostic test and checked my HV battery temperature.
My HV battery was 32'C or 90'F after sitting all night in my garage
that was about 45 degrees! ( The battery requests cooling above
about 85'F ) So it appears if you use the Engine Block and battery
heater in excess, on days that are not that cold, there comes a point
when it becomes counter-productive, even harmful. Now, it would take
140'F or higher to physically ruin your HV battery, but why even bake
it at 100'F if you can avoid it? After less than a minute, my
battery was under 30'C and the A/C went off and stayed off. The
battery air vent opened and sucked in 0'C outside air, and my battery
was to 25'C within 2-3 minutes.

So what have I learned?
The block heater by itself pulls 400-435 watts ( based on home
voltage of 115-125 VAC ). I physically measured 435 watts and my
home was 125 volts at the time.

With the HV battery heater plugged in at 72'F, still, total draw was
435 watts.

With the HV battery heater plugged in at 45'F, the wattage draw for
both components was 510 watts, indicating 75 watts going to the rear.

At 45'F, more than 2 hours of "plug time" is counter-productive.

Thought you all would like to know.
I just installed this last weekend, so
I'll report more data as days get colder.
-John

 

Well I guess you confirmed what the "HV charger" does. Sounds like we just need the basic block heater and not the "HV charger" part.

 

I am a bit surprised that the battery got to 90'F in 2.5 hours.
I may have to recind my previous statement that the HV battery heater is smart enough to come on only when needed. I've only done it one time, but it looks like it was not smart enough to know when to shut off.
-John

It looks like the car needed to "learn" or something.
In the future, the battery only went up about 60 degrees.

 

The battery heater may be a self regulating strip heater. The heater element resistance increases when it gets hot, so it draws less current. And that produces less heat.

These are simple, inexpensive self regulating heaters that would make a lot of sense in out battery heater application!

 

I know you said the wiring is plug and play but could you please explain where the wires go, what is entailed in running them. I don't have access to a manual so any help would be appreciated. I can only find a photo of the wire by the coolant bottle and am unsure even which wire goes there. I don't want to run into a snag and have the car down longer than necessary and have the little lady upset with me. Thanks in advance.

 

I'm on a business trip, and my photos are at home.
However, the wires come with a foil heat shield for the parts near the engine.
The wires go up between the engine and the firewall and over the top of the engine. It was kinda obvious to me once I had them in hand.

Mine came with a couple of clips and it was obvious where the clips went.
The plug goes over the top of the radiator, and the plug goes down in front of the radiator, about to where the front license plate is.

HTH, ask if you have any specific questions.
Wish I had the photos... darn.....

 

Hi John,
What about the wires to the HV battery, where do they go?

 

The 2005-2007's came standard with the 24v HV battery heater wires in place as standard equipment. What was "optional" and required installation was the 24v DC transformer that plugs into the 120 VAC home wall plug.

The 2 small gauge wires came with the car, and went from near the windshield washer fluid tank, to the small 2 wire jack on the HV battery pack... the small jack that is empty on your car.

Do this:
If you have the block heater, figure out by watt meter, or ammeter how much power your "plug" draws.

A block heater by itself will draw 400w to 425w.
A block heater + battery heater will draw 500w or a little more.
Hence, I figure the battery heater componet, if factory installed, draws roughly 75 watts.

It would be cool if it was built into the 2009, but I doubt it.
John