Coolant-to-heat candles for electric vehicles. Utilize preheating

Hi!

Winter is just around the corner, and I've been thinking for a long time about implementing a timer-controlled external electric pre-heating system to protect the engine.

A.T.U. offers a type of immersion heater (230V) for this purpose, which is (now here's the thing!) screwed into the coolant expansion tank. What a shoddy solution! This tank is only connected to the engine with hoses that are about the thickness of a finger! How can heat possibly flow without a pump?

But through this forum (big praise for the expert articles), I learned that modern diesel engines already have an electric coolant heater installed: the 3 heating elements!

Here's my idea: You could use an external 12V power supply (from a cheap transformer) to pre-heat your car in the winter using a timer. The question is whether the natural water circulation will be sufficient in the long run, or whether a small electric pump needs to be installed in the small heating circuit.

By the way, how many watts do the three candles consume, or how much electricity do they draw (for reference)? I've already located mine.

And one more thing: Did I understand correctly that when it's cold, the large cooling circuit is completely closed or inactive? Is this also the case when the car is stationary? (If the coolant bypass valve is controlled by the vacuum system, it's possible that the large cooling circuit could be active even when the engine is idling. This would require an electrical...) The auxiliary heater is very inefficient because it heats the surrounding area through the large radiator.

thank you in advance[/b]

These 3 candles are standard taper candles.

As a guideline for cold candles (in a 4-cylinder engine), I know of 60 amps.

So, we would have 45 amps for the 3 candles.

They are located near the engine exhaust outlet, facing towards the interior, which is not ideal for heating the engine because the heat would be released into the interior.

Furthermore, it will be difficult to consistently deliver 45 amps, as a standard charger from a hardware store may not quite be sufficient .

m;

Hi,

Have you read the article about the CALIX preheater?

Okay, I'm ready. Please provide the German text you want me to translate.

The part is either screwed into the engine block or the oil cooler line (depending on the version - see product description). The pre-heater from ATU is also installed in this way. I am not aware of a preheater in the surge tank.

Thank you for the response.

Don't worry about the 12V power supply. You don't buy something like that at a hardware store.

In my parts bin, I still have a collection of transformers. If there isn't a suitable one, I'll just get a cheap halogen transformer. It's cheaper than buying a completely new electrical component. Preheating.

Regarding the issue with the flow direction: Perhaps an electric water pump could be used, which pushes the water in the wrong direction for preheating? However, if the interior fan isn't working and there's no airflow, not much heat is likely lost through the heater core, so the pump could also run in the correct direction. Of course, it must not have significant flow resistance when stationary.

Supplement: I just found a 12V transformer with 42A (500 watts) for 39 euros. So, that's great . For the cable to the car, I'll use a thick speaker wire, I have some left over. Or I could take the transformer for a walk (it weighs 4kg), let's see which option is cheaper.

@Bertil: Yes, I've read that. However, I find the idea of using heating candles more elegant because it eliminates the installation work required for an auxiliary heater, especially since I don't have a lift or ramp nearby.

ideeAlist wrote:

Don't worry about the 12V power supply. You don't buy something like that at a hardware store. In my parts bin, I still have a collection of transformers. If there isn't a suitable one, I'll just get a cheap halogen transformer. It's cheaper than buying a completely new electrical component. Preheating.

... to completely ruin your car's electronics with alternating current... Have fun...

Don't mess up the electronics. The headlights are disconnected from the vehicle's electrical system when the engine is off. (The relay contact is open).

Even if operated incorrectly, there's no risk of 'frying the electronics'; the 12V AC is simply connected to the vehicle's electrical system. The worst-case scenario in this case would be that the fuse in the transformer blows (a short circuit of the AC voltage through the vehicle's electrical system, potentially causing magnetic interference). Saturation caused by direct current can also trip the fuse for the spark plugs. (depending on which fuse trips first).

To avoid such a mistake (after all, I have a girlfriend ), I can install a changeover relay that is controlled by the external 12V~. Okay, so: Disconnect the 12V wire - the relay switches to connect to the vehicle's internal power system.

Have fun, but I think it's all a bunch of nonsense.

1. Alternating current has no place on board.

2. And this is crucial: the glow plugs are only activated when the engine is running, ensuring sufficient coolant flow. Without this flow, the heating effect will be minimal because the coolant will evaporate at the glow plugs. Furthermore, it's questionable how long they would last before burning out.

greetings
dieter

Hello,

The natural water circulation might not be sufficient for the heating power (~500W). However, you could integrate an electric pump into the water circuit, as is commonly done with auxiliary heaters. You might find a pump like that on eBay for a low price (e.g., from a defective auxiliary heater).

The large cooling water circuit is opened by a purely thermo-mechanical thermostat, meaning it is normally closed.

You would also need a temperature regulator to prevent your water from starting to boil. While it might take a very long time (or even be impossible) to achieve this with 500W and a pump, if the pump fails, it will become quite unpleasant.

Furthermore, I would definitely use the additional relay you suggested to prevent any accidental misoperation. (In my opinion, it could even be a weak relay that interrupts the connection between the motor control unit and the glow plug control unit).

I, however, have some concerns regarding the lifespan of the additional glow plugs. While the installation is relatively simple, it's possible that occasional replacements might be necessary.

However, it remains a semi-professional solution, and you may end up experiencing more frustration than enjoyment. But you have to decide that for yourself.

Regards,
-Private vehicle, featuring a genuine heater and a homemade mobile phone remote control.

@dieter

1. Alternating current has no place on board.

Why not? (Reasoning) And what do you understand by 'on board'? In my case, the alternating voltage will only be present at the (spark) plugs, which are isolated from the vehicle's electrical system.

Or another question: What advantage would for heating purposes be gained by rectifying alternating current? I only see disadvantages here: losses in the rectifier, and costs associated with the rectifier.

Regarding the flow: Yes, there will probably be an electrical component involved. A pump is needed.

ideeAlist wrote:

Don't mess up anything with electronics. The headlights are disconnected from the vehicle's electrical system when the engine is off. (The relay contact is open).

You can't avoid the grounding connection!
You are creating a wonderful induction on the engine block, which then affects the electronics that are not separated from the battery (including...). The LiMa regulator, also known as the "alternator regulator," is "not affected at all."
The currents there would make the activity too dangerous for me. The slightest issue (like moisture...) and things get complicated, and no amount of protection will help.
Furthermore, I would first test what happens when the glow plugs are subjected to alternating current. Since it's not a purely ohmic resistance, unwanted "noise effects" can occur.

The Calix/Waeco heater is sold as a double-insulated device for a reason. In this setup, the chassis ground is connected to the protective conductor. However, the AC circuit and the DC circuit are otherwise completely separate.

Therefore, the transformer connection is connected directly to the main mass of the spark plugs. (direct mass connection) This prevents any current from flowing through the motor block.

If the electronics can handle 200A of starter current (which is overlaid with a massive amount of electromagnetic interference from the starter's commutator), then it probably won't have any problems with the spark plug current either.

The inductance of the glow plugs is negligible at 50 Hz. However, a soft-start feature using a thermistor is recommended for a gentler startup.

Alright, let's build it.

Under normal conditions, there's nothing wrong with it, but if it gets wet, you're in for trouble.

Okay, but first I need to look for an affordable electric pump. I've already found a cheap one that I want to connect in parallel with the radiator or the engine block (in the engine compartment).

Condition: The radiator is blocked by the heating control knob (set to 'cold') via a shut-off valve, so that water only circulates through the engine block.

Question for everyone: Is this the same thing with the heating control knob on the dashboard?

Regarding the spark plugs: Perhaps I don't need to run them at their full rated voltage. How about trying a 5V operation? A cheap PC power supply is well-suited for this purpose, as its waste heat can also help to slightly warm up the interior.

So, um...

The heating system is air-based, and the heat exchanger is always flowing with fluid.
The main cooling circuit is regulated by a thermostat (located in the water pump), which opens at around 80 degrees Celsius. So, it's completely irrelevant to you.

A pump would be advisable...

But honestly... what do you need 500W of heating power for? That's ridiculous.

The Calix heater has, if I recall correctly, a power output of 800-1000W. It's not exactly impressive.

A standing heater is bubbling away with 5.2 kW of power...without an electrical connection .

@bertil

50A is not a concern, even with alternating current. If the grounding strap has a connection, it will receive the current much earlier when starting. If he makes sure not to connect both the transformer and the vehicle's electrical system to the spark plugs simultaneously... and even then, the engine control units can handle quite a bit. At least initially, the battery would absorb the current, which would likely blow the fuse in the transformer before anything else. I doubt induction in the spark plugs is a significant issue at 50Hz.

However, a 50A wiring system is not straightforward. Finding suitable connectors was a challenge. A 63A CEE connector is somehow too large .
'Driving the transformer around in the car? Hmm... but it would have to be absolutely waterproof (230V!!!). So, IP68 with a corresponding connection to the outside...'

CU Gremlin (with a heater that loudly announces its presence to the neighbors).

Hi,
Even air-based heating systems can have a water valve that, when in the "cold" position, prevents the air from being heated. That doesn't really matter if the fan isn't working.
500W or even less is really very little. You have to turn it on hours in advance. A welding transformer probably covers the power requirements best. Possibly a switching power supply from a really large server.

Hi,
Even air-based heating systems can have a water valve that, when in the 'cold' position, prevents the air from being heated. That doesn't really matter if the fan isn't working.


logisch. but I really can't think of any current VAG vehicle that still (or again) has something like that
A TDI definitely doesn't have that. Just imagine the cold water shock if you suddenly want it to be warm. The TDI would never heat up like that .


CU Gremlin.