Water Heater

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Isaac96
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Re: Water Heater

Post by Isaac96 »

That's one of the first revision gate driver boards isn't it. Wonderful!
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Re: Water Heater

Post by johu »

Let's try quoting.
FJ3422 wrote: Tue Nov 10, 2020 9:14 pm As far as I know only the Tesla heaters have CAN. Most of the auxilary electric heaters have a LIN interface. You can pass the internal electronics and directy supply the IGBT's with a PWM signal, but this will also pass all the internal protections. Or find a heater that is originally PWM controlled. I just found such one; Search Ebay for "3M51-18K463-FB". Starting at € 10,- :)
I have it here, can you tell me how to control it?
Isaac96 wrote: Sat Nov 14, 2020 4:12 am That's one of the first revision gate driver boards isn't it. Wonderful!
Yes - 1st rule of DIY: use components that have been rotting in your basement for years :)
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Re: Water Heater

Post by FJ3422 »

johu wrote: Sat Nov 14, 2020 7:53 am Let's try quoting.
FJ3422 wrote: Tue Nov 10, 2020 9:14 pm As far as I know only the Tesla heaters have CAN. Most of the auxilary electric heaters have a LIN interface. You can pass the internal electronics and directy supply the IGBT's with a PWM signal, but this will also pass all the internal protections. Or find a heater that is originally PWM controlled. I just found such one; Search Ebay for "3M51-18K463-FB". Starting at € 10,- :)
I have it here, can you tell me how to control it?
Sure ! Just got back home after a few days spending in a hotel for work.

Control wires:
Black: +12V ACC (consumes ca. 20mA)
Brown: PWM signal, heater has internal pull-up. Freq. should be 150Hz (<140Hz or >160Hz did not work with mine). Fires from about 13% PWM-rate.

Heater is fused at 80A in a Volvo V50. Elements measure 0,50ohms cold, so around 80A max. current draw could match.
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Re: Water Heater

Post by arber333 »

FJ3422 wrote: Sat Nov 14, 2020 9:00 am Heater is fused at 80A in a Volvo V50. Elements measure 0,50ohms cold, so around 80A max. current draw could match.
That is a hefty current. I have tested similar VW heater with 55A cold. I think i got 60A for a second and then natural PTC tendancy droped this down to 50ish. That would be consistent with 1kW drain from 14V DCDC.
One needs to keep a steady airflow over the element to keep the PTC coefficient low and power high.
See here: https://leafdriveblog.wordpress.com/202 ... preheater/

So does this Volvo PTC have internal mosfet inside? Then you could just use one of theese for testing:
https://www.ebay.co.uk/itm/D4184-Isolat ... Swe~lcF-FR
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Re: Water Heater

Post by johu »

FJ3422 wrote: Sat Nov 14, 2020 9:00 am Sure ! Just got back home after a few days spending in a hotel for work.

Control wires:
Black: +12V ACC (consumes ca. 20mA)
Brown: PWM signal, heater has internal pull-up. Freq. should be 150Hz (<140Hz or >160Hz did not work with mine). Fires from about 13% PWM-rate.

Heater is fused at 80A in a Volvo V50. Elements measure 0,50ohms cold, so around 80A max. current draw could match.
Thanks! Awesome, it worked right away. Started drawing current at around 15% in a very non-continuous fashion (clicking noises from my power supply).
At 27% my 25A power supply overloaded like once 1 second.

So I will check in the car which duty cycle is needed to run at about 50A and generate that dutycycle with an attiny or NE555. Then I could tap into the feedback line of the heater servo and when it is open, start the PTC. Or maybe it's worthwhile to install a full CAN capable controller there and also run the water heater from that signal.
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Re: Water Heater

Post by johu »

So, PTC is in :) With the lights on I can turn it up to 50% dutycycle which is about 45A or 580W. Then I get 13.2V. At 55% I reach 50A but the voltage sags to 12.5V because the DC-DC converter is then fully loaded.
I get a mildly warm air flow, certainly enough for defrosting and with re-circulation enabled even heats the cabin a bit.

Will see how the DC-DC with downgraded fan works under full load, good thing is that heater is only enabled when it's cold. If I need more heat or run into problems I will attempt to use Arbers left over DC-DC.
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Re: Water Heater

Post by arber333 »

johu wrote: Sat Nov 14, 2020 7:01 pm Will see how the DC-DC with downgraded fan works under full load, good thing is that heater is only enabled when it's cold. If I need more heat or run into problems I will attempt to use Arbers left over DC-DC.
Good to know. I am still using it in my Pug, though i intend to replace it asap as soon as i repair the !¨$#* engine mount.
I guess there was a connection lost there for a second :)...

I would also really like to install 12V PTC heater, but i cant find the space behind the matrix. I guess that was done only on a later 406 with a diesel engine. It figures since diesel needs like 15minutes to heat up if you dont go directly to highway...

Now I have webasto and 5L of coolant overhead. So if i would use additional 2kW electric water heater i didnt really change anything. I would still need to consume;
Q = 5l x 4.2KJetc.. x 55°K = 1kWh of energy and use like 9minutes of time from 5°C startpoint in the morning...
Well i dont know if this would be worth it. Depending on my energy flow if i would consume 1kWh each 10minutes i would drain like 4 or 5Kwh on my way to work. Do you think that is acceptable in autumn temperatures? Certainly not in high winter...
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Re: Water Heater

Post by johu »

PWM circuit done :)

Runs on an attiny13 and simply attempts to keep the battery voltage above 13.2V with a P-controller. So turn the lights off for some extra heat ;) It will also counter the PTC behaviour to some degree. When sending 50% to the PTC element it will start out at 50A and drop to 40A. Now with the voltage regulation it will receive a higher duty cycle and remain at 50A.
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Re: Water Heater

Post by johu »

Extended the circuit a bit. I added a temperature probe from the Nissan PDM that I simply pulled up using the internal pull-up resistor (30k, roughly). That resulted in 1.22V @ 20°C and a gain of about 4 digits per 1 °C. So now I start throttling the heater at roughly 15 °C until it is completely disabled at 22°C.

Of course all constants must be re-calibrated when using this due to tolerances in clock frequency and resistors.
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Re: Water Heater

Post by johu »

All done and working :) Bolted a micro switch to the air flap servo. I observed when you set the inside cabin temperature warmer than it is, the flap will open all the way. When you turn off climate control the servo retracts just a few degrees. So had to bend the switch lever a bit so it would only be pushed when in "fully open" position. Forgot to take a picture unfortunately.
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Re: Water Heater

Post by Romale »

IMG_20210704_175657.jpg
IMG_20210706_133920.jpg

once I assembled a similar thing "in a hurry" from 600 volt 37 amp igbt transistors installed in parallel. with conventional current limiting resistors, the power keys did not close completely in a simple key mode and were very hot, so I added a locking driver from a small transistor to each and controlled the whole unit by simply feeding 15 volts controlled by a cheap temperature control controller from an incubator whose temperature sensor was inserted into the radiator of the heater. the setting was to turn on on demand and turn off when heated to 90 degrees, and turn off and turn on again when lowered to 75 degrees. thus, the temperature control made sure that the water in the heater was always between 75 and 90. this case was managed by a regular Nissan leaf heater, which I got for free when buying the engine. I took the native control board out of it, connected all the shades in parallel and got a 96c battery heater with a maximum power of 6kW. the water itself (antifreeze) was driven by a 12-volt Bosch pump system from some Mercedes (I use the same pumps to cool the inverter), the result was a very fast warm-up and it was very warm in the car even at -30 outside.
I took 15 volts from a small isolated dc / dc 12/15, which I left on the common radiator. I glued the walls to the radiator and filled the whole thing with a thermal compound, leaving only the input b- and output - for the heater and two thin wires for supplying 12 volts from the thermal control relay.

all this has been working perfectly for two years in one car

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