Upgrading Heating System - Independent Battery Source

[Aerowhatt]

I’ve found my driving habits have changed since getting the “i”. I actually drive more now since it’s solar energy powered and I can go to the Mountains etc. pretty guilt free. Like everyone else in cold weather I would like to heat the car comfortably without having to give up range in the process. I can’t do the fuel parking heaters! It just rubs me the wrong way and I’m so done with handling fuel on a regular basis.

So here is my solution in process. I did some logging with Canion to see what I need to be toasty warm on the coldest windy days here. My solution is an electric supplemental heater. Before you tune out . . . it’s integrated into the existing system.

So I will be inserting an immersion heater element into the system on the return line to the stock high voltage fluid heater. The element I have sourced (slightly modified) will put out 1350 watts of heat running at 36 volts. A bit more than is needed to do the worst case job on average.

So changes to the existing system are minor. Merely splice the immersion heater housing in the return line after the reservoir under the hood. and add coolant to the tank to compensate for the additional volume. The element will be powered by a relay which which runs off the power to the stock heating system circulation pump. The power will come from a 36v 50ah LifePO4 battery that I have. Which is itching for a job to do. It will heat the car comfortably for almost two hours given the data I have collected. A snap disc thermostat in the relay coil wiring will keep the unit from over or under heating the fluid. Using the unit will be very straight forward.

Turn on the cabin fan as normal and select the lowest heating setting on the temperature dial. This activates the heating fluid pump (stock set up) and closes the relay on the added heating element. Only a minute or two and the inlet fluid to the stock fluid heating unit will be high enough to cycle it off. Cabin is heated using the normal dash controls for everything except the temperature setting which will remain at the lowest heat setting. To the driver the heat will function just like the temperature selector is set to the highest setting. Dialing back the heating amount with fan speed reductions as needed.

The added heater battery will charge with the car (L1 or L2), using the 12 volt system and a DC to DC up converter to do so. So no extra steps or cords involved. The car will take about 10% longer to charge. The battery has it’s own BMS and LifePO4 is one of the safest Li chemistries.

Looks pretty good on paper and I have some parts on the way. Time to work on fabricating and installing it will be the hardest to come by.
Unfortunately the dash will still show a range reduction with the heat on. But it will be wrong!

Aerowhatt

 

[Don]

Assuming the heat from your new element *will indeed* cause the OEM element to shut off and stay off, this sounds like a *perfect* solution!!

You'll never need more than an hour or two of heat, it recharges automatically as you charge the car and it's perfectly integrated into the stock HVAC system

Let us know more about the battery you'll be using - Where you got it and what it cost
I'll eagerly follow the way you go about this . . . . it sounds like something I may be interested in doing too

Don

 

[JoeS]

Aerowhatt, wow, I sure like the idea of not using fossil fuel! This is worthy of a separate thread and I'll be happy to start one for you and move the previous two posts over.

I'm very curious about your inline heating element - source/link? Other voltages available (e.g., 24v, 48v)?

Have you given some thought of where to mount your LiFePO4 battery pack? Make it easily removable for summer? I had mine (48v) sitting in the rear seat footwell when I had the auxiliary inverter charging setup to recharge my Sparrows at an EV event.

 

[Aerowhatt]

Assuming the heat from your new element *will indeed* cause the OEM element to shut off and stay off, this sounds like a *perfect* solution!!

You'll never need more than an hour or two of heat, it recharges automatically as you charge the car and it's perfectly integrated into the stock HVAC system

Let us know more about the battery you'll be using - Where you got it and what it cost
I'll eagerly follow the way you go about this . . . . it sounds like something I may be interested in doing too

Don

Yeah the OEM heating element is controlled based on incoming fluid temperature and the temperature selector position on the dash. If the incoming fluid is already hot the cars OEM element will stay off.

It wouldn’t help much to give my battery source. It’s too old and the source likely no longer exists. I got them directly from China about a decade ago. I used them as a range extender on my AGM powered electric motorcycle. Which I retired about 5 years ago when one leg of the front forks broke while riding it at (thank goodness) Low speed. IF I were buying a supplemental heating battery today I’m thinking I would try to get hold of a Yuasa (http://www.s399157097.onlinehome.us/PDFS/LIM50E_Modules.pdf) same cells as the car!

Aerowhatt

 

[Don]

I'm very curious about your inline heating element - source/link? Other voltages available (e.g., 24v, 48v)?

There are DC water heating elements of various voltages and wattages available - Boaters use them to dump extra solar or wind generator power into their water tanks for hot showers, etc

http://www.ebay.com/itm/Water-Heating-Element-Immersion-Water-Heater-Heating-Boiler-BSP-DC-36V-1200W-/321919616870?hash=item4af3e78766:g:dM0AAOSw~oFXMvd-

That one will work on 12, 24 or 36 volts at 400 watts per element

Don

 

[Aerowhatt]

Aerowhatt, wow, I sure like the idea of not using fossil fuel! This is worthy of a separate thread and I'll be happy to start one for you and move the previous two posts over.

I'm very curious about your inline heating element - source/link? Other voltages available (e.g., 24v, 48v)?

Have you given some thought of where to mount your LiFePO4 battery pack? Make it easily removable for summer? I had mine (48v) sitting in the rear seat footwell when I had the auxiliary inverter charging setup to recharge my Sparrows at an EV event.

OK with me if you want to create a separate topic for this perhaps "clean electric heating without loosing range" ???

The element is from Amazon and is a SS water heater element. It’s 12vdc and 600 watts. If you look closely at it though it’s two similar elements run in parallel at 12 volts and 50 amps. If the jumpers are reconfigured they can be run in series at 24 volts and 25 amps still yielding 600 watts. Putting V=IR to work and increasing the voltage to 36 volts gets us to 1350 watts at 36 volts and 37.5 amps. First concern is can the element operate at that High a level without burning out prematurely. The watt density for the original design purpose is extremely low and the repurposed element still has a low watt density compared to conventional 240 VAC electric water heater elements. I'll mount it inside a section of pipe (details as the project moves forward).

https://www.amazon.com/Dernord-600watt-Immersion-Submersible-Stainless/dp/B0182BETBE/ref=pd_rhf_sc_p_img_6?_encoding=UTF8&psc=1&refRID=4E48VNK97S9FRA4NMPCH

Placing the battery is something I have thought some about;

Packaged right it could likely fit under the hood (obvious advantages) Not keen on it being part of the crumple zone though and mounting and access would be a hassle.

One of the rear foot wells would be a good spot with few drawbacks.

Of course the rear cargo area. It would easily fit next to the spare tire still leaving some cargo space on top of both.

Since I use a rear cargo rack on the car with a locked aluminum tool box on it full time. That is also an option for me and what I am leaning toward most at the moment. Gets it out of the cabin and is easy to install/remove as needed

Aerowhatt

 

[JoeS]

Aerowhatt, I moved the related posts into this new topic. So, I looked at the 12v immersion heater and was wondering just what shape and how compact an inline container would be? Wouldn't need much volume as long as flow was maintained.

 

[Aerowhatt]

Thanks for moving everything.

I've done this kind of inflow electric immersion heater before for various purposes. The housing will be 2" dia pipe. The inflow enters at one end perpendicular to the heating element and exits at the other end (also perpendicular but in the opposite direction from the inlet). This gives lots of turbulence and mixing the whole length of the unit eliminating hot and cold spots for the element. Normally I would include a flow switch so that the element cannot energize without coolant flow. But in a moving vehicle it may not be the best safety solution for de-energizing the element if the flow were to be interrupted. Likely proper placement of the thermostat will work just as well and more reliably eliminating one part and some complexity. Nice thing about these set ups is they are pretty flexible as far as mounting orientation and not very large.

The most installation time and energy required will most definitely be the wiring.

Anyone see any problem with chassis grounding the 36V battery negative and just running a positive lead from the battery to the supplemental heater relay??

Aerowhatt

 

[Don]

The pipe could be a piece of PVC, couldn't it? That would make it very easy to fabricate

For those starting from scratch, it might be better to go with a 12 volt, 100 AH battery and use the 36 volt heating element which has 3 separate 400 watt elements. That way you could set it up where you have 3 different heat settings - 400, 800 or 1200 watts as needed by switching in additional elements using relays. Maybe . . . . that 12 volt battery could also replace the stock 12 volt battery and that would make wiring simpler and allow the battery to be mounted up front in place of the OEM battery??

I don't see any problem grounding the 36 volt battery to the chassis - I've done this on boats where the engine is a 12 volt system and the windlass and bow thruster run on 24 volts with everything grounded to the engine block

Don

 

[jray3]

Well, when I ran the numbers I concluded that a pound of hot water storage was worth more heat than a pound of LiFePO4 battery. Adding an additional hot water reservoir should be a bit more effort than the proposed in-line heater and battery.

Here's the meat of that old thread.
http://myimiev.com/forum/viewtopic.php?f=9&t=1874&p=15109&hilit=hot+water+reservoir#p15109

 

[Don]

A few of disadvantages to trying to stay warm with extra hot water

1.) You'd only have heat one way in your journey - At home where you've plugged in and are using the preheat, but nothing when the car sits all day in the parking lot and you have to drive home freezing.

2.) An additional disadvantage is that when you triple the amount of water in the system, you'd be making the stock heating system nearly useless if you tried using that on the way home - It would have to heat three times as much water up to 90 degrees or so before you saw any heat radiating into the car

3.) Your 'heater' would be constantly getting cooler the longer you circulate the water from the tank - You might be able to get 100% of the btu's available, but once the water cooled to 70 degrees or so, it's not going to feel like real heat coming into the car anymore

4.) With the tank mounted in the rear, you'll lose some of the heat circulating the water through long lengths of hose - True, the hose is probably in the car, but hose doesn't transfer heat to the air nearly as efficiently as the heater core does. Using additional water might not necessitate much additional wiring, but the additional plumbing would be more of a nightmare than the wiring, IMO

5.) With a battery heating system, your 'power' is available whenever you need it - With water, your stored energy is constantly decreasing even when you're not using it and by the time you need the stored heat, it might be gone

I would go with a fuel burning system before I tried additional water . . . . but the battery powered system sounds oh so practical :mrgreen:

Don

 

[jray3]

A few of disadvantages to trying to stay warm with extra hot water
.................
I would go with a fuel burning system before I tried additional water . . . . but the battery powered system sounds oh so practical :mrgreen:

Agreed, which is why I've only implemented it as a steel tank of hot water in the footwell, which maintains cabin warmth throughout the morning for errand running as it cools down all the way to ambient...
My morning commute is a net downhill run, so it helps regen, and the water could be dumped after cooldown if desired.

Back on topic, why go with the complexity of plumbing in another water heater and not just use an electric forced air or radiant panel heater? Having an aux battery with an inverter to power an off-the shelf heater would provide all the energy as heat (inverter waste heat generated in the cabin) and also allow use of more powerful 120 VAC items than most 12V plug-in inverters could manage. (Table saw, electric chain saw, hair dryer, etc..)

 

[Aerowhatt]

The pipe could be a piece of PVC, couldn't it? That would make it very easy to fabricate

For those starting from scratch, it might be better to go with a 12 volt, 100 AH battery and use the 36 volt heating element which has 3 separate 400 watt elements. That way you could set it up where you have 3 different heat settings - 400, 800 or 1200 watts as needed by switching in additional elements using relays. Maybe . . . . that 12 volt battery could also replace the stock 12 volt battery and that would make wiring simpler and allow the battery to be mounted up front in place of the OEM battery??

I don't see any problem grounding the 36 volt battery to the chassis - I've done this on boats where the engine is a 12 volt system and the windlass and bow thruster run on 24 volts with everything grounded to the engine block

Don

Interesting ideas for sure. Personally I like to keep designs simple and self regulating. Done right they do the job more efficiently than the operator having more choices.

Problem with the 12 volt being replaced by the heater battery is that the main traction battery is charging the 12 volt when in ready mode. So for all intents and purposes the traction battery would still be heating the car. The complications of interrupting that scenario are unknown and likely less than favorable.

Plastic pipe does make sense weight and ease wise. PVC would be marginal as it begins to melt around 160F. CPVC however, is rated to 100 lbs of pressure at 180 F and would be adequate for the application.

Aerowhatt

 

[Aerowhatt]

Back on topic, why go with the complexity of plumbing in another water heater and not just use an electric forced air or radiant panel heater? Having an aux battery with an inverter to power an off-the shelf heater would provide all the energy as heat (inverter waste heat generated in the cabin) and also allow use of more powerful 120 VAC items than most 12V plug-in inverters could manage. (Table saw, electric chain saw, hair dryer, etc..)

I started with electric infrared in my design process. The problem is that adding another separate heating system (of any type) takes more cabin space and does not take advantage of the flexibility of the air handling system already built into the car. More cabin space lost, less versatile, less effective throughout the vehicle. That was my conclusion anyway. Plus I want to do this thing with ease and repeatability. Likely not a good Idea to have 120V high amperage AC power in the cabin with you during a car accident either

Aerowhatt

 

[Aerowhatt]

I got the heating element. It's a bit smaller than I was expecting, which is a good thing (only about 6 inches long). I reconfigured the jumpers on it so that the two elements are in series instead of parallel. I did an emersion test with a three gallon bucket and the surplus 36V battery as the source. It heated the water right up in just a few minutes averaging 1368 watts of power during the test. Some actual boiling occurring right at the elements surface. So far so good.

Now to get serious about building the housing for it. Looking under the hood I'm thinking about mounting it before the inlet to the reservoir tank in the system. Thoughts or suggestions from those who have done fuel heaters and hose rerouting modifications is very welcome.

Aerowhatt

 

[Don]

Curious as to how warm (hot?) the threaded end of the element gets? Hopefully with the water carrying away the lions share of the heat the threads don't get so warm that you can't use the PVC

The triple element unit I posted the eBay link to *might* be a better choice - 1200 watts radiating off 3 elements as opposed to 1368 watts coming from just two??

*If* it turns out that you're getting a bit more heat than you really need with 36 volts (the thermostat cycling it off and on repeatedly) I may consider using your two element unit and running it on 24 volts - I suspect much will depend on the water flow rate. There are a number of assembled LifePo4 batteries on eBay intended for E-bikes which come with both a built-in BMS and a 120 volt charger - The following link (it expires soon) is for a 24 volt, 30AH unit with a 5 amp charger and sells for $387

http://www.ebay.com/itm/24v-30ah-Lithium-LiFePO4-Battery-5A-Charger-BMS-Rechargeable-Powerful-Electronic-/142198185213?hash=item211bac1cfd:gjUAAOSwPpFXMFSW

Don

 

[Aerowhatt]

The threads and wire connections on these things do get quite hot. That's one reason I'm going with 2 inch pipe so that there is room for a brass adapter between the element and the CPVC threads. This will be necessary for any decently adequate heat output for the application. the first foot of wire attached to the element has to be very high temperature rated wire as well.

The battery you referenced is fairly similar to what I am using. The problem with these is that they don't do very well above continuous 1C discharge rates. I know they probably claim more but so did the seller of mine. On my motorcycle I had these batteries run through auto reseting circuit breakers. If it pulled past 2C the breakers would trip (really felt that drop out accelerating up a hill). The bike could pull 275 amps peak which the odyssey AGMs could handle by themselves. The XR pack would be damaged pulling half that . . . So by going at least 40ah on the heating battery I'm keeping them at the 1C sweet spot in use.

You have to be careful with heating elements and voltage. The relationship is not strictly linear and can be a challenge. So if you used the element I'm using right out of the box (12V - 600W) and connect it to 24V it will pull 100 amps and run at 2400 watts. Particularly confusing when you have resistors (heating elements) in parallel.

When my son was young his bedroom was coldish compared to the rest of the house. At 2 years old you can't have a hot electric heater. All electric heaters run hot used as designed. By using a long 240V baseboard unit rated at 2100 watts And running it at 120V instead it reduced it's output to just under 700 watts. Which made it gently effective and hotish but safe to reach in and touch the element fins.

Reconfigure the element I'm using (series wiring the elements like I did) then run it at 24 volts and you get it pulling 25 amps and producing 600watts which would be two low to completely replace the OEM system performance in really cold weather. One reason that the OEM heating element is over 5000watts is to get heat fast. Probably the most important function of an auto heating system IMO. It's reasonable to use the traction battery to heat the water quickly then coast on continuous 600 watts supplemental heat from the added heating element and battery. You likely wouldn't loose more than 3 to 5 miles of range for that initial heat up twice a day.

I will certainly document how much the element cycles once It's all installed. I don't expect it to be much though. The OEM heater is averaging between 1000 and 1200 watts to keep the car ICE comfortable up in the mountains here.

Aerowhatt

 

[Lic]

I am using 60V20AH electric scooter battery and home small heater modified to work from 60V.

 

[Lic]

Here is idea how to use regular ventilating system and external battery. We need built heater from ceramic heater elements in size of air cabin filter and put it instead of filter.

 

[jray3]

Here is idea how to use regular ventilating system and external battery. We need built heater from ceramic heater elements in size of air cabin filter and put it instead of filter.

I like it, Lic. If you can fit a single ceramic element in the center of the air filter void, that may provide enough clearance from the plastics that could be heat-damaged. Yours is the simplest idea so far that provides a seasonally- removable secondary heat source that uses the stock fan, and it requires no plumbing mods. Just gotta get the installation and controls right to avoid a dash meltdown... Warning though, the twin ceramic elements in my electric RX-7 at 120 VDC don't make much heat. They'll warm the car nicely if given a 30 minute pre-heat and do a great job of keeping the windscreen clear, but there's no doubt why Mitsu cranked our heater all the way up to 5 kW!

BTW- with MR BEAN cold-soaked at 21 degrees F and and an inch of re-frozen snow on the windshield this morning, I tried out a hour of remote preheat rather than my usual 30 minutes of remote defrost. Utterly useless! During the few minutes between the end of heating and me entering the car, the small melted patch on the windshield re-froze, and the side windows had no more than a four-inch defrosted circle.
A double-dose of defrost would've had all windows clear and the interior toasty warm!