HV battery Oil pan pre-heating in winter

Maybe a stupid Idea, let' see the opinions.

Low temp affects fuel consumption on hybrid veicles harder than diesels and non
hybrids.

I believe transmission fluid plays a big role.
ATF WS has the following properties:
40°C viscosity 23
100°C viscosity 5.3
According to Hybrid Assist , In winter after 65 km MG1 is still at 65°C, being cooled by transmission fluid I guess that' s about a similar temp.

The idea is to stick an oil pan silicon pad heater rated 300w 240v, connected to the HV battery with a switch that opens at 220v to protect from overdischarge and a timer to start it 2 hours before morning commuting.

The pre requisite is to arrive at home with 60% charge the night before.

I know the battery is deadly, I was an electrician and nothing like that should be attempted without proper protection and safety measures. Unlike AC you don't feel DC you just die.

I installed a 2A fuse protected line coming out from the HV battery for reconditioning purposes and use it regularly.

Hit me

 

it was indeed unclear, I meant and now edited to MG1, yes the gearbox.

I thought about the AC outlet too, maybe it' s worth a try to see the effectiveness on mpg before making complicated mods.

However every cent saved in gas is a cent spent in energy bill, unless one has solar panels.

Similar to The advantage of a non plug in hybrid compared to plug in ones, you don't add costs to the energy bill

 

when I recondition the HV battery I apply a 400w load with light bulbs without errors

 

The prewarm would be at ignition off , 2 hours before commuting, not while driving.
Yes I'm aware of the danger.
I was thinking to use a butil cable, they are tough and resist to mechanical stress if hit by a shovel for example, I would run it on the ground and remove it before commuting, so not connected to the car body, the car is parked in my garden and fences are locked at night.

 

The idea is to use an over discharge switch to protect the battery, but it seems not easy to find for that kind of dc voltage.
The electricity would come from brake regen instead of the network, there are high taxes here on network.
At cold start MG1 and gas engine run anyway for the first 10 minutes to warm up the cabin in winter, and the byproduct will be an almost 60% charged battery.

Charging from 40 to 60% will warm up the battery as well, which is also desirable.

I' m trying to sell the idea, but all feedback is very welcome

 

link to undervoltage protection with manual and automatic reset:
https://a.aliexpress.com/_EvE7FXA

 

yes, a timer switch needs to be added before the undervoltage protection, I would propose start 2 hours before commute, cut off at 45% charge or 210v , according to Prolong user guide, it is safe to discharge at 400w rate up to 196v, so there is room to eventually discharge to 40% or 200v

 

My goal is to lower the oil viscosity to lower fuel consumption.

 

I' ve been searching a 230v block heater, apparently Toyota discontinued it. Any alternative available?

If not then the cheapest alternative is oil pan heater
I
€7,79 | 300W Engine Oil Pan Sump Tank Heater Pad 220V Universal Silicone Oil Heating Pad Engine Oil Tank Heating Plate Wear Protect Pad
https://a.aliexpress.com/_EJLFnsg


Has anyone done it before? If yes what is the maximum pad size that can fit on it?
I could go under and check but it's -4C now

 

I found cylindrical heating elements

€9,19 | DN15 1/2" Thread Tubular Heater Element 220V 0.3/0.5/1/1.5/2KW Cartridge Heater 15mm Tube Diameter Electric Heating Element
https://a.aliexpress.com/_EvZKWzI

what is the lenght and diameter of the toyota one?