additional electric heater

[Tiborx8]

hello All,

it may not be a new idea - i read about an immersion heater install into the return line from 2016 - but i came to an even simplier/more effective idea I would like to discuss here.

i would insulate the heater reservoir and install an immersion heater (controlled with a thermostat) into it. Further more i would also modify the heating lines in a way that I would completely switch off of the OEM heater under the car - i would use heater coolant pump current as a trigger for the immersion heater. So all in all, I would disconnect the coolant pipes from the OEM heater, would also disconnect the HV cables from it and made a coolant circuit as short as possible: heat echanger-pump-reservoir(heater)-heat exchanger.

I have a 12 v Li-ion battery pack large enough to run an immmersion heater for one hour - due to the thermostat, it will be a longer running time - we use the car for short trips, anyway.

i would not charge the 12v additional battery from the existing 12v battery during the heating - just would connect it at the beginning of the car charging.

All in all, it is a similar idea than what was discussed on the Forum in 2016 - just maybe even more effective mod.

I am not an expert in any way - so all thoughts are welcome.

 

[kiev]

how many Amps can your 12V lithium provide, e.g. peak amps and also supply for an hour?

 

[Tiborx8]

Hello,

as I am building 18650 packs (I mean: built a few already) and currently have about 600 used cells, I can build a suitable pack to practically any demand. Of course, these older cells cannot provide more than 0,5-1C discharge so larger discharge demand means larger pack..

I would still prefer the 12v idea rather than the 24-36v volt as one converter less in the circuit..

 

[WReed82]

Hi,

The significant advantage to going with higher voltage is your wires don't have to be as heavy.

Compared to 24V, 12V requires twice as much copper.
36V or 48V requires even less copper.

Thanks and good health, Weogo

 

[Tiborx8]

Thanx for the feedback!

yes, less current requires thinner wires.

Anyone knows how much coolant is circulated in the heating system? That would give a clue at least sizing the immersion heater.

My other concern: is the OEM heating element is used during air conditioning? I am not familiar with the AC process...

 

[PV1]

Heat and air conditioning are two completely separate systems. The heater circulates water from a water-based heater element through the heater core and back to the reservoir. The air conditioner is a conventional, refrigerant-based system that circulates refrigerant between the condenser coil in the front of the car and the evaporator coil in the cabin ductwork.

When the car is in READY mode, the heater only operates when the fan is on and the temperature knob is in the red zone.

I have the service manual, but I don't see a spec for heater loop coolant capacity.

 

[Tiborx8]

Thanx!

This way it seems that the idea is possible - at least theoretically. Tomorrow I will have closer look of the heater..

 

[kiev]

The owner's manual gives the refill capacity for the hot water heater as 2 Qt or 1.9 L including 0.4 L in the reservoir. That seems really small, but i guess that's the case for a tiny car.

The FSM indicates there is a drain plug on the bottom of the heater, so you could drain and catch to measure and compare with the spec.

 

[Don]

I just don't see any 12 volt heater as being very practical. The OEM heating element is over 4Kw and even a 1Kw 12 volt heating element would draw about 100 amps from a 12 volt source . . . . and using only 1Kw isn't going to get you a meaningful amount of heat, let alone defrost - It might take a long time to get the windows clear. . . . . . and how long can your used 18650's put up with a 100 amp draw??

You say you use the car for short distances - What's wrong with using the stock heating system just as it is??

Don

 

[kiev]

Using 2L of water and a 1kW heating element, it would take about 6 minutes just to heat the water by 50 degrees C.

Then you look at the heat loss due to recirculation thru the heater core and the desired volume of air to be heated.

The interior volume is 2.4 m3 or 2400 L, so there is about 3 kg of air. To heat that by 20C takes 59 kJ to come from the core exchange. Not sure how long that would take.

 

[DBMandrake]

The built in heater in the car actually peaks at 5.5kW during warm up, although it typically settles down to about 3kW once the selected flow temperature is reached. (The temperature knob controls the flow temperature of the water through the heater matrix, not the cabin air temperature - it's up to the driver to manually adjust the heater temperature to regulate the cabin temperature)

Even with this power available it takes about 5 minutes to heat the heater fluid from 0C to 60C (maximum) so it would take an eternity to heat at 1kW, and there's a very strong chance that you simply wouldn't be able to get the heater matrix up to a useful temperature at all with 1kW with cold exterior air blowing through it. If you can't get the flow temperature up to at least 40C you're wasting your time, as this is the lowest setting that will give any useful warmth in winter conditions. (Enough to keep the window clear)

I agree that a 12 volt heater simply isn't up to the job, especially with the added layers of inefficiency of having to heat a loop of water and then heat the mass of the heater matrix itself.

If you really need the extra range and heat in winter a better (although not very PC!) option is a small Diesel/Petrol based heater to heat the heater fluid circuit. A number of people have installed them now and you can get nearly summer range in winter by using one. I was on the verge of installing one myself however the combination of the high up front cost and a recent decision to sell the car this year has nixed that plan.

 

[Tiborx8]

So,

for heating while driving: one working solution is the 12v infrared heating film (high temp model) on the floor, in the doors and behind the front seats, plus heated seats and steering wheel.

If someone is after the traditional air heating: all previous posts took it granted that the loop with 2 liters of coolant in it and going under the car and back is granted - nope. There is a possible mod to add a coolant valve used in ice cars to close down the heating matrix while the engine coolant is too cold. With it, it is possible to close down most of the existing coolant loop hence increasing the efficiency of the water heater.... as a water heater, for example, the cabin pre-heater used in the BMW X3 and some bmw minis can be used - I already picked one up together with a ford heater valve - when i build them in, I will make a post about it. as the heater valve is only controlled by a 12v soleaoid, when the HV battery needs heating, it can automatically open the loop.

 

[Don]

I suppose you may be able to come up with a solution which could slightly improve on the efficiency of the OEM system, but IMO it would be amazing if you could make very much of an improvement - The engineers at Mitsu were certainly concerned with squeezing out the maximum range possible while keeping the occupants at least semi-comfortable and their expertise really shows throughout the car - They're not incompetent by any means so improving on what they came up with won't be easy

Your big problem is - Power. A 1500 watt household heater running on 12.5 amps of 120 volt AC power would not do much to keep the car warm while driving 30 mph through 30 degree outside air . . . . you just need lots more power than 1500 watts to do the job, which is one reason Mitsu chose to get that power from 350 volts DC and not 12 . . . or 24 . . . . or even 36 volts DC. Getting 2Kw from 18650 cells for an hour is gonna take a BUNCH of cells. If you preheat the car at home before you leave, then 2Kw of heat might keep it semi-comfortable until you got to where you're going, but then getting into the cold car an hour later for the trip home . . . . you're still gonna be COLD. Whatever your plans, I would not disable the OEM heating system, that's for sure. If you do, make sure you can easily get it back to a stock configuration

If I lived where it gets cold, I would have bought a little diesel heater long ago. They're cheap, not too hard to install, they use the existing liquid system and OEM pump and they give a TON of heat for very little fuel consumed - A 2 liter fuel tank would probably last for a weeks commuting. Several good threads here on the installation of them from our Canadian friends and a few others

Don

 

[jray3]

I'll echo Don's comments, adding that I ran the numbers a few years back and concluded that a preheated hot water bottle carries more Btu/lb than even fully charged LiFePO4 batteries can. That water bottle could be in your lap, a lumbar support, or as advanced as a custom metal tank on the floorboards. I used an old steel outboard motor fuel tank as a hot water bottle a few times in experimentation, but didn't need it on my short commute at the time. Now my commute is too long for the i-MiEV, so my wife uses the car daily in local errands- allowing full heater use without stressing over range or battery life.

-Jay

 

[drcat]

That's not an awesome solution but I have a 150W 12V made-in-china heater aiming my wind glass. It defogs the glass from inside pretty well combined with the main fan at slow speed but its still cold in the car. With a heated seat its less or more acceptable for driving but no comfort still.
My c-zero has also a 900W / 220V heater installed by previous owner with a plug on the rear bumper. I think what if I'll connect it to H/V lines and re-wire inside to deal with 360 volts instead of 220.
It produces a decent amount of heat for comfortable driving and won't affect mileage significantly. Except for the fan type - it seems needs AC not DC but its not a big deal

 

[Tiborx8]

I suppose you may be able to come up with a solution which could slightly improve on the efficiency of the OEM system, but IMO it would be amazing if you could make very much of an improvement - The engineers at Mitsu were certainly concerned with squeezing out the maximum range possible while keeping the occupants at least semi-comfortable and their expertise really shows throughout the car - They're not incompetent by any means so improving on what they came up with won't be easy

Your big problem is - Power. A 1500 watt household heater running on 12.5 amps of 120 volt AC power would not do much to keep the car warm while driving 30 mph through 30 degree outside air . . . . you just need lots more power than 1500 watts to do the job, which is one reason Mitsu chose to get that power from 350 volts DC and not 12 . . . or 24 . . . . or even 36 volts DC. Getting 2Kw from 18650 cells for an hour is gonna take a BUNCH of cells. If you preheat the car at home before you leave, then 2Kw of heat might keep it semi-comfortable until you got to where you're going, but then getting into the cold car an hour later for the trip home . . . . you're still gonna be COLD. Whatever your plans, I would not disable the OEM heating system, that's for sure. If you do, make sure you can easily get it back to a stock configuration

If I lived where it gets cold, I would have bought a little diesel heater long ago. They're cheap, not too hard to install, they use the existing liquid system and OEM pump and they give a TON of heat for very little fuel consumed - A 2 liter fuel tank would probably last for a weeks commuting. Several good threads here on the installation of them from our Canadian friends and a few others

Don

Don, I think it is time to change paradigm of car cabin heating as the ice power is over. What i am talking - and doing - about is not new - see the post here, for exmple:

https://chargedevs.com/newswire/new-heating-concept-increases-ev-range-and-enhances-passenger-comfort/?fbclid=IwAR1OYQWNWAz0GnxfOsWaSpfV_t73oCoRbPEYSNdBaQtsMDaXsZw1hXV-8EE

Mitsu engineers actually made not such a brilliant job in my view - at least in some way. One clear shortcoming is heat insulation of the cabin, the other is - but it may be due to the time the design was - clearly the heating solution. Infrared heating in the past years are well proven in all areas - from homes through stadiums to churches - that they can solve a heating problem where heating the air takes too much of energy. It is not just me saying that - it is a fact.

As for the high power need of a close-circuit water heater - it is clearly not a parking heating solution. The dc-to-dc converter in the car can charge the 12v battery by 1.5kwh max, so 0.5 kwh can be easily covered by the Dc-to-Dc converter during travel. As I wrote, I don`t believe it would heat up the air in the cabin - why would it be needed as the infrared film does this job - but could defog the windscreen and the front side windows.
This combined heating could work indeed in my opinion - the infrared part of it I don`t think so, I know so.
Best regards.

 

[GarryIno]

Hi...the more up to date electric vehicles can be modified to warm the lodge prior to moving off. This should just be done while the vehicle is as yet connected as clearly the warming will utilize battery power. On the off chance that you are just utilizing the vehicle for a short excursion, you will most likely be OK, in the event that it isnt connected, yet you do need to utilize an electric vehicle in an alternate manner.

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[jray3]

With depths of snow preceding the depths of winter, my folks in Colorado came up with a nice solution for supplemental heat that involves no vehicle modifications or load on the traction battery. They use an Ecoflow Delta Max power station to run their camper on 120 VAC out in the wilds, and that 2 kWH portable battery and inverter unit fits nicely behind the rear seats of an i-MiEV too. Besides ballast for winter traction, it is now powering two Lasko MyHeat 200W forced air heaters that are mounted atop a weighted plastic jar that fits in the center cup holder. I was surprised at how potent only 200W of directed heat can feel in subzero weather, and with 2 kWH capacity, the Ecoflow battery can provide either 5 hours of continuous heat on HI (EVen while parked), or it could run our L1 EVSE for over 2 hours, providing about 8 miles of range. That's a nice winter driving accessory and while not cheap at $2100, might be attractive enough when considering emergency backup power and other year-round uses. The Delta Max is also expandable to 6 kWh, and their newer PRO version can recharge from EVSE.

The manufacturer is pretty mum on what components are actually inside the box, but the photo at this link seems to confirm a 48V system (15 LiFePO4 in series), so adding your own extra capacity or using it to run a small vehicle, etc. seems feasible.
https://ecoflow.com/products/ecoflow-delta-pro-portable-power-station