openinverter forum

what do people favour for cabin heating ?

Ebay PTC heaters from breaking vehicles seems to be able to be had for a reasonable price, but I didn't see definitive articles on the wiki that detail how to drive them.

I see this new heater https://www.classicretrofit.com/product ... kll8w9LASS which whilst more expensive if fairly self contained and well documented.

What wattage is reasonable, that one from classicretrofit is max 1100w and they claim you should have 2 really.

thanks

for defrosting your windshield it should be enough. For cabin heating you need at least 5kW. With long winter at -10degC you should use fuel heater.

I have long been looking for an ethanol heater (so I can use bio-ethanol) and so far I have not found one that would be suitable for a vehicle.

Webasto has bio-diesel ones but they are too big and clunky for my 2-seater car...

I also looked into a heat-pump form a dryer but given I am as electrically gifted as a toad on cocaine I haven't found a viable solution yet.

I am leaning toward heated seats and infra-red sheets under the dash to make driving in cold weather tolerable (I plan on trying to use the car year-round) .

Ethanol burns clear, corrodes things quickly, and is harsh on a lot of hoses. You won't know you're on fire.

jrbe wrote: ↑Wed Jan 28, 2026 12:31 pm Ethanol burns clear, corrodes things quickly, and is harsh on a lot of hoses. You won't know you're on fire.

the same with hydrogen yeah...
In aviation fire onboard is the ultimate hazard. And knowing you are on fire and suppressing it is primary mitigation.
H2 people carrying drones are an IN but they have additional hazard that H2 can permeate into structure. Then it can burn so low that it can degrade primary structure before it is recognized.

This is why a propane heater could be more utility for you whilst still not exotic technology...
Others are Vevor Water heaters that are direct copy of the ebespracher oil heater.

If you want electric seats those are excellent choice and low consuming for effect. Usefull down to 5degC though...
Then there are 12V foil heaters for mobile homes. Thar will heat with IR surface and longer exposure at some 100W/m2. If you would want to utilize those you would have to make a system temp control which would keep heaters ON for the whole time and rely on heater surface instead of power.

Then there are PTC air heaters. You can easily get 800W 12V version from say VW Golf 7 diesel and use two in your car for better effect. But DCDC will suffer.
https://leafdriveblog.wordpress.com/202 ... preheater/
I never tested HV PTC heater. For me HV seemed too exposed...

Electric Water heaters...
I use 4kW Outlander CAN bus heater for great effect in car at winter.
https://leafdriveblog.wordpress.com/202 ... ev-heater/
Still if I turn fan fully on it will deplete temperature from exchanger quickly and heater wouldn't be able to produce enough Joules.... This is why I say you need 5kW electric heater for -10degC...

Then there are a DIY devices like converted 5kW washing machine heater. 230Vac version will produce 5kW at 360Vdc and be fine at that. What you need is confident temp control. 80degC thermostat switch is a must. You need to use either AC or 12Vdc never HVdc because it will smoke the switch when actuating it. Dicey but it can be done...
https://leafdriveblog.wordpress.com/201 ... er-heater/

You could use a DC SSR to drive the heater from high voltage. Later if you make a controller for the HVAC you can pwm power to it.
But some oe parts may have all this as part of it, some signals to turn it on / partial / off, and less headache.

https://www.ebay.co.uk/itm/257215013471 The kia EVs have HV ones.

jrbe wrote: ↑Wed Jan 28, 2026 2:12 pm You could use a DC SSR

That's what I did with the 3kW PTC heater from Feleten. An Arduino measures the temperatures and regulates them with PWM. SSR and PTC together cost around €250. The one from KIA looks good too. Does anyone know how it is controlled?

muehlpower wrote: ↑Wed Jan 28, 2026 5:20 pm That's what I did with the 3kW PTC heater from Feleten. An Arduino measures the temperatures and regulates them with PWM. SSR and PTC together cost around €250. The one from KIA looks good too. Does anyone know how it is controlled?

I think it uses a seperate controler which PWMs HV to what is needed. Because i could only see HV lines and thermistor on it. It must have a separate control similarly to tesla... Or its simply full 3kW and when temp is reached then HV relay is dropped.

f you look at all the pictures, you will see a 6-pin LV connection. Other offers also have a piece of cable connected there. I think there is either a CAN or PWM input and power electronics are installed. I found that on the internet. I don't know if it's correct.

muehlpower wrote: ↑Wed Jan 28, 2026 5:20 pm That's what I did with the 3kW PTC heater from Feleten. An Arduino measures the temperatures and regulates them with PWM. SSR and PTC together cost around €250. The one from KIA looks good too. Does anyone know how it is controlled?

I was going to look into Arduino for various things on my project... driving analog gauges, regulating heat etc...