EV Demister/Heater Selection

Technical discussion on converting internal combustion to electric
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TooQik
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EV Demister/Heater Selection

Post by TooQik » Thu, 06 Jun 2013, 02:31

I've been reading up on the various options for replacing the demister/heater for my EV build and searching the internet for other options and found the following two websites/products:

Speedy Air Spares

12 Volt Customs

I'm particularly interested in the Speedy Air Spares unit. Does anyone here have any experience with either of these two products, and if so are they able to share how well they work (or don't)?

Look forward to your feedback.

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coulomb
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Post by coulomb » Thu, 06 Jun 2013, 04:53

TooQik wrote: Look forward to your feedback.

I haven't used either of these, but 600 W is pretty tame for heating, and 50 A is pretty heavy for 12 V. It's really better to have a heater that runs off the main pack, if at all possible.
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EV Demister/Heater Selection

Post by Bryce » Thu, 06 Jun 2013, 14:54

I would strongly suggest using the old water heater core with a water heater - the MES-DEA water heaters in particular. All-in-one unit, built-in protection, runs off main pack. No adaptation of heating/ventilation system required, jut plumb it into the old heater lines. Nothing else is as simple, or quick to install. All the alternatives are either (and usually all) of:
mostly ineffective
draw way too much off a 12 V battery
fire risks
bloody complicated to install

As for the cost of the MES-DEA unit - is cheap compard to collecting all the bits for any other option, plus save HEAPS of grey hairs and time to install.

(And no, I don't sell them! Just have had experience with the other systems and the pain they cause. Would never go back after using the MES DEA units).

Cheers
Bryce

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EV Demister/Heater Selection

Post by TooQik » Thu, 06 Jun 2013, 23:53

Thanks coulomb and Bryce.

Even though there is a lot more work involved with a ceramic heater type replacement for the water heater core, I'm leaning this way as the ability to get heat quicker appeals to me.

Granted 600W is not enough for a full blown heater, but if I were to use this purely for demisting/registration purposes would it be sufficient? My thought is to replace the entire system with a reverse cycle air conditioner unit down the track.

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Post by Johny » Fri, 07 Jun 2013, 05:08

My heater is variable so I tried it tonight and 600w is OK if soley directed at the screen. It depends where you are I think.

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Post by TooQik » Fri, 07 Jun 2013, 05:51

Thanks for that Johny. That's really going above and beyond, I really appreciate you doing that and posting the result. Image

I should state I'm also in Melbourne...think I need to update my profile details.

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Post by 4Springs » Sat, 08 Jun 2013, 00:19

TooQik wrote: Thanks coulomb and Bryce.

Granted 600W is not enough for a full blown heater, but if I were to use this purely for demisting/registration purposes would it be sufficient? My thought is to replace the entire system with a reverse cycle air conditioner unit down the track.

I had the same idea. I put in a 12V Demister initially, and I have my eye on a reverse cycle aircon unit for the future.
This demister is 180W, and all I can say is that it is just adequate. The engineer looked at it, laughed, and ticked off that section. As a demister on cold days it does the job, slowly and with a lot of noise. If there is mist when I get in the car it takes about 5 minutes to clear it by itself (a rag is quicker). Any heating benefit is lost because I also have to have the original fan on to keep demisted. I drive in a coat, and need to get myself a pair of driving gloves. I think the two that you linked to would be much better.

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EV Demister/Heater Selection

Post by Bryce » Sat, 08 Jun 2013, 16:44

Hi there - to put the MES unit in perspective: I currently drive a car with a ceramic heater, and yes it is a reasonably quick (and positively thermonuclear when it gets going) but at the expense of a significant drop in driving range. (And slightly annoying if you want less that summer resort temps!). MES DEA unit is not much slower at it only contains a few litres at most, and heat range is in the realm of the old car heater. MES unit reduces the range around 15 - 20%. My current unit reduces it by 40% :(

Would still recommend a water heater (and preferably the MES DE unit) over a ceramic one.

Cheers
Bryce

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Post by acmotor » Sat, 08 Jun 2013, 18:08

Reverse cycle aircond, while good as a heat pump with something like 3:1 thermal kW out for electrical kW in, has a brick wall problem with ambient temperature. Namely that when the evaporator (i.e. outside part when in heating mode) reaches freezing (zero deg C) it literally freezes the condensation on it and blocks up. No airflow. Heat exchange stops right when you need it most. Image

The evaporator will often block at as high as 10 deg C ambient (since it is colder than ambient) depending on design, airflow, rain etc.
Many reverse cycle airconds will automatically reverse for a while and thus apply heat to melt the ice and clear the evaporator. This ends up as no win as the ambient temperature gets lower.

This has lead, I think, to all commercial EV manufacturers using the water heater 'kettle' (like MES) design as they are aiming at a -40 to +60 deg C world market. This is the case with the iMiEV. It runs a 5kW water heater ! Yep, you know when that is on. Fast heat but 20% reduction in range with ambient down near zero. The heater cycles once warm and average power would be around 1kW.

If you select defrost, the iMiEV runs both the aircond and heater flat out. Incredible fast defrost. But consider the power consumption before hitting the button.

Actually, the most useful item is the electric heated driver's seat. (fortunately off 12V not 330V !) It draws 120W from memory.
If you are doing an EV conversion then heated seats are a good move ! Image
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EV Demister/Heater Selection

Post by PlanB » Sat, 08 Jun 2013, 21:57

Audi (towards end of the clip) seem to have gone to a lot of trouble with integrated thermal mangement.

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acmotor
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Post by acmotor » Sun, 09 Jun 2013, 01:13

Audi heat pump still has to use a kettle as backup. In this case the kettle is part of the battery/controller/motor thermal loop. Still just needs raw kW when it is -20 deg C outside.

Well not a lot of trouble really. It is just the sort of management that is required in future technolgy.

Co-generation and Tri-generation in large buildings is one example.

One day your fridge, freezer, house heating ,house cooling, HWS, PV cooler, oven whatever will be integrated into one thermal management system.

Yep, an R8 electron would be nice !
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EV Demister/Heater Selection

Post by 4Springs » Sun, 09 Jun 2013, 16:14

acmotor wrote: Reverse cycle aircond, while good as a heat pump with something like 3:1 thermal kW out for electrical kW in, has a brick wall problem with ambient temperature. Namely that when the evaporator (i.e. outside part when in heating mode) reaches freezing (zero deg C) it literally freezes the condensation on it and blocks up. No airflow. Heat exchange stops right when you need it most. Image

The evaporator will often block at as high as 10 deg C ambient (since it is colder than ambient) depending on design, airflow, rain etc.
Many reverse cycle airconds will automatically reverse for a while and thus apply heat to melt the ice and clear the evaporator. This ends up as no win as the ambient temperature gets lower.
I had wondered about this, especially for cold foggy mornings when there is a lot of moisture in the air. I wonder if it could be mounted in some way that it gets the (potentially slightly) warm air from the motor?
We use reverse cycle airconditioning to heat our home, and it certainly has no problems with sub-zero conditions outside. It goes into a defrost mode every so often, but only for a short time, and only once every few hours. If I'm only driving the 15 minutes to work, would it ice up in that amount of time? Who knows, but it would be an expensive experiment.
Has anyone used these
acmotor wrote: Actually, the most useful item is the electric heated driver's seat. (fortunately off 12V not 330V !) It draws 120W from memory.
If you are doing an EV conversion then heated seats are a good move ! Image

You've convinced me, I've just ordered one through ebay. $76 for two seats, about 60W per seat on high, but it also has a low setting.

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EV Demister/Heater Selection

Post by TooQik » Sun, 09 Jun 2013, 17:59

Cheers everyone for your input.

Seems that a combination of two of either water, air and reverse cycle heating would be the best solution ie. a/c and water, a/c and air or water and air, rather than a single heating type.

Obviously whatever the solution battery capacity will always come into the equation...well, unless ugg boots, long johns and ski jackets are the solution. Image

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Post by TooQik » Sun, 09 Jun 2013, 18:36

Acmotor's comment about the kettle got me thinking, a lot of workplace offices and homes now use instant boiling water devices. In the office I work at we have Zip products. I had a look at the Zip website and they have a product named (fittingly) the Zip Autoboil which comes in a 1.5kW rated unit (smallest). Has anyone here considered using the heating elements out of one of these to get engine temp water to the standard heater core? Or is this really just a long winded way to achieve what the MES-DEA units Bryce suggests already do?

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Post by Bryce » Mon, 10 Jun 2013, 15:32

Hi there - in short, that is a long-winded way to do what the MES unit already does, as it comes as one unit with built-in circulation pump, over temp and fluid flow fault sensing with alarm output and cut-out. (Well, at least the RM4 version - the other comes without the pump). Just connect to the Anderson connector for traction voltage and the 3 pin connector for 12V input and alarm output and away you go! Comes in 2000W to 4000W versions with a variety of traction voltage ranges.

Jeepers, I should get a job selling the things ... (which I don't!).

Unfortunately they went out of production in 2012, but Metric Mind in the US still seem to have some for $290 (half what I paid from them before that!!).

Supposed to be a new version in 2013, but have yet to see it.

Cheers
Bryce







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EV Demister/Heater Selection

Post by TooQik » Thu, 13 Jun 2013, 02:51

Thanks Bryce.

Speaking of Metric Mind, I'm waiting on them to release their new high voltage fluid heater, the MMC4000HV, to see what sort of price they'll be asking. Looks interesting from the specs they've published.

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Post by Peter C in Canberra » Fri, 10 Jan 2014, 23:17

I have a 900W resistance heater in my converted car and it is barely adequate in a Canberra winter. The rest of the family say it is not adequate at all. It is slow to defog the windscreen. The aircon defogs very quickly so I am glad I got that going. It makes a big difference having 4 passengers breathing out water vapour vs. one driver only.
A 12V heated car seat kit takes much less power and works well.
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