Tiborx8
Posts: 5
Joined: Sat Jun 08, 2019 11:15 pm

additional electric heater

Sat Jan 04, 2020 1:32 pm

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
Posts: 1070
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Re: additional electric heater

Sat Jan 04, 2020 2:07 pm

how many Amps can your 12V lithium provide, e.g. peak amps and also supply for an hour?
kiev = kenny's innovative electric vehicle

Tiborx8
Posts: 5
Joined: Sat Jun 08, 2019 11:15 pm

Re: additional electric heater

Sat Jan 04, 2020 2:29 pm

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
Posts: 55
Joined: Wed Nov 28, 2018 10:05 am

Re: additional electric heater

Sun Jan 05, 2020 12:39 pm

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
Posts: 5
Joined: Sat Jun 08, 2019 11:15 pm

Re: additional electric heater

Sun Jan 05, 2020 12:50 pm

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
Site Moderator
Posts: 3015
Joined: Fri Apr 27, 2012 4:22 pm
Location: Pittsburgh, PA

Re: additional electric heater

Sun Jan 05, 2020 1:37 pm

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.
"Bear" - 2012 Diamond White Pearl ES with QC - 2/21/2013
"Koorz" - 2012 Cool Silver Metallic ES with QC - 1/5/2015
"Photon" - 2017 Bolt EV LT in Orange with QC - 7/31/2017

Solar-powered since 10/10/2013

Tiborx8
Posts: 5
Joined: Sat Jun 08, 2019 11:15 pm

Re: additional electric heater

Sun Jan 05, 2020 2:12 pm

Thanx!

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

kiev
Posts: 1070
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Re: additional electric heater

Fri Jan 10, 2020 6:27 am

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.
kiev = kenny's innovative electric vehicle

Don
Site Moderator
Posts: 2926
Joined: Thu May 10, 2012 3:55 pm
Location: Biloxi MS

Re: additional electric heater

Sat Jan 11, 2020 2:57 pm

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
2012 iMiEV SE Premium, White
2012 iMiEV SE, White
2017 Chevy Volt Premier
2014 Ford Transit Connect XLT SWB wagon, 14,000 miles
1979 Honda CBX six into six

kiev
Posts: 1070
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Re: additional electric heater

Sun Jan 12, 2020 10:13 am

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.
kiev = kenny's innovative electric vehicle

Return to “Modifications & Accessories”