Hi all, I'm just wondering, how much current does a factory block heater (92 5.0v8) use and do they vary much between makes?

It's going to get cold tonight, and I want to plug both vehicles in, I leave mine in on a timer pretty much all the time, 15 mins on, 30 off, but I think tonight the other car needs to be plugged in too (and wonder if both can go off one cord/outlet)

 

I don't know what block heaters draw for current but here is a way to judge.
A 1000 watt heater at 120 volts ac would draw about 9 amps.
Two on at the same time would overload the normal 15 amp house line (2x9=18 amps).
I would set up two timers and set them so the heaters would never both be on at the same time as well as give the extension some time to cool between on times..
The length of the extension line and it's wire size is important to keep the voltage drop low, plug and extension heating to a low level and safe.
Use no less than a line of #14 wire size and preferably larger wire size.
The feed protection will normaly be 15 amp rated as well as the wiring and the outlet. Make sure the plug fits snuggly into the outlet so heating is kept to a min and prevent fire hazzard.

The most you could draw for either one or both heaters would be 15 amps. This would equate to 1800 watt TOTAL or SEPERATE.
I doubt the heaters are at that power level seperately.
Use judgement and not overload the circuit or the extension line and check temps at the plugups after about 10 min of operation to see what is happening..

 

Thanks Bluegrass. Good suggestions.

I had actually thought about alternating the timers like you said, although tonight it's so cold I think I'm going to have to leave them on - they are both plugged into an overload protected strip (not necessarily best practice I know) and all's been fine, in these temps the overheat risk may be reduced somewhat!

On another forum someone suggested block heaters on average are around 500w so I think I'm ok. When I unpack my stuff that's arrived from overseas, I'll be able to use my clampmeter to work out the current draw for next time

Thanks again.

 

I can't find any spec on power consumption, current rating, or resistance for the block heater, but I doubt it's anywhere close to 1,000W (9A). I've already sold the only one I had, so I can't measure it.

I'd guess it's closer to 200W than 1KW, but probably less than 100W, so it should be safe to have several plugged into 1 outlet or extension cord. If you have a cheap multimeter, you can measure yours.

 

Not saying it's the one in yours, but looking up the options on my truck, I found this:

LIMITED PRODUCTION OPTIONS

* FRONT LICENSE PLATE BRACKET (LPO) NO OPTION KIND 153
* CARPET/FLOOR MAT DELETE *Replaces STD carpet w/black vinyl mat* (LPO) *CREDIT* NO OPTION KIND 16G
* HD BATTERY CREDIT (REQ: 531 HD Elect/Cooling Group & LPO 41H Engine Block Heater) *CREDIT* NO OPTION KIND -CRED1
* ENGINE BLOCK HEATER -inc: 600 watt element, HD 72 amp-hour battery *Recommended when minimum temp is -10F or below* (LPO) NO OPTION KIND 41H
* PRICED DORA NO OPTION KIND C09


BTW: 1200 Watts (two of the above heaters) would draw 10.9 Amps. The conversion is Amps=watts/volts or 10.9=1200 / 110 While in the states, 15 amps may be normal for wiring (14 gauge), in most northern climates, 12 gauge (20 amps) is used. Just make sure that your extension cord is rated for the circuit.

 

Indeed, they vary from one model to another, but most of the Ford units are 600 watts.

-Joe

 

I was curious what mine pulled after reading this thread...so let me explain how I did it.

I have a manual transfer switch installed on my house so if the power goes out I can select 8 circuits to run off of a backup generator. Each side of the panel has 4 circuits and below each set of 4 is a watt meter in 100 W increments.

I fired up the generator and plugged in the 240 VAC cord and transferred the dedicated fridge garage outlet to the generator. I unplugged the fridge (it wasn't running anyway) to get an accurate reading and when I plugged in the truck the gauge went to 700 Watts. Upon doing a conversion I am pulling 6.25 amps at 120Vac which I know that generator makes perfectly still from my volt meter I stuck in the outlet too (with a load on the generator).

The needle on the transfer panel was right on the 700 watt mark with no fudge room. Now that I have done this I wanted to see what my cost per KW is. My city charges $0.07 per KWh, and when converting completely down it would cost approximately $0.05/hour to plug in the truck.

I am not sure if these block heaters turn off when they reach a certain temp or if they just stay running 100% of the time. Obviously if they reached some kind of set point your cost to plug in the truck would drop as it cycled off and on.

I am having issues with my engine warm up times and I park inside. So when I back a 50 degree truck out into the 5 degree air, the engine cools off as it runs thanks to that huge *** belt fan and I have been debating plugging in the truck inside the garage for a week to test warm up times like this or if it even makes a difference.

Just thought I'd throw this at ya!

 

They sell this thing called a kill-a-watt at wal-mart for like $20...it tells you the watt draw of whatever you plug into it. It's useful for when your entire second floor only has two outlets, both on the same circuit and you just bought a big-*** TV.

I learned it as the PIE rule in high school physics, like everything in that class it was 10x more complicated than it needs to be, like
P(power in watts)= I(intensity in amps) * E(electromotive force in volts)

or, more simply, watts =volts*amps

Both your heaters will be fine on the same circuit, at the same time providing nothing else is drawing off it. Worst comes to worse, the breaker pops, you reset it, that's why they're there.

 

If your house has HBO's (head bolt outlets) for the outlets that are outside exposed to the weather (and they are required by code) then you should be fine to plug both vehicles in, most HBO's are 20a. The block heater never cycles off and it cannot overheat the coolant because of the natural circulation of the coolant, if the coolant were to get hot enough the thermostat would open and then the heat would be dissapated that way.

 

use a dc clamp on amp meter

 

its a block heater that plugs into an AC outlet
most outlets in your house are on 15A breakers but the garages in most are wired for 20 amp breakers so you can run aircompressors and such. so plug it in the garage and dont worry about it. if your wirings good then you should never have a problem

 

it's been a long day- i had dc voltage in the brain from the variable speed motot i just replaced in a furnace-let me correct my post,use a ac clamp on amp meter-phil

 

dont worry about it bud, we all have those days.

 

On my 97 I have the stock block heater plus 2 100W pad heaters (one on the oil pan and the other on the transmission pan and I have never had a 20a breaker open while I was plugged in even with a 1000W halogen light plugged into the same outlet.

 

Since we're on the subject of block heaters, I'd like to know if I have one, and where it is. I've got an 02 with the 4.6L engine. I can see an orange electrical cable coming out of the engine, and it looks kind of like an extension cord. The problem is, I can't see where it comes out of the engine, or where the other end is. I can see all this from under the truck. I don't know if it is a block heater, but since all the other wiring is black, I assumed this was the block heater.