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wrs last won the day on November 1 2017

wrs had the most liked content!

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About wrs

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    2nd Gear
  • Birthday 04/07/1968

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    92 E36 Coupe 3L Stroker
  • Mods List
    3L Stroker, M3 Shrick Cams, Link ECU, Full M3 Exhaust, MAF Delete, Fan Delete, 6-Speed Manual Conversion

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    Cars (Duh), High-End Audio

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  1. Here's the original 'Sealing Frame' gasket from between the heater box and firewall. This was the bottom left corner which happens to be where the leak was. It's pretty clear the seal has either failed or was never installed correctly from the factory. On the new install the seal has been checked and the sealing foam can be seen bulging out from the inside and from the engine bay so it looks like it has a good seal this time. Another give-away was when the old heater was removed it didn't take much of a push to get it free. On the donor heater I got from the wreckers a jimmy-bar was needed to pry it loose - it was stuck pretty good.
  2. Here's a couple of shots of the heater fitted in-car. The two red wires in a loop need an in-line fuse fitted as they're direct wired to the battery, currently with no protection. Ok for testing but not running live. Once fuses are fitted they'll be tied near the back of the loom and accessible when the kick panel below the glovebox is removed. The side of the glovebox clears the tallest parts on the PCB by about 5mm. It all just squeezes in where the old water pipes used to go.
  3. I already have a 140A alternator which is the biggest one available as a standard part for the E36. To go bigger might require a custom fit. The electric elements should use about 60A which is well within the 140A rating of the alternator. What I can't find out is if the 140A rating is continuous or short-term for peak loads with a somewhat lower continuous rating. With the heater running + headlights on high-beam + heater fan + other minor loads there could be close to 100A required. Knowing the continuous rating of the alternator would help give some certainty it will be ok or could fail. LED lights is a good option as long as they have the gadget to trick the blown bulb detection circuit. Hadn't thought of this as an option to lower power use...
  4. Here's a wrap-up of what I learned during the software testing and then in-car hardware testing. The PCB worked perfectly first time so no issues. The power supply was originally going to come from the heater solenoid +12V but this line is always live even with the ignition switched off. The power on this line also gets switched off when the drivers-side temperature selector is wound to maximum. The next issue which was minor was the logic levels for the solenoid on/off control were inverted. I'd assumed they were pulled low to activate the solenoid to let water flow into the heater core. However, the heater solenoid valves are always open and close when the solenoid is activated. This means the solenoid drive signals go low to turn off the heater instead of on. This was an easy fix - the advantage of doing all the control in software, the input on-state level was inverted. I ended up taking the 12V supply for the new PCB from the heater fan switch. The easiest access to this was on the resistor block that plugs into the back of the heater box. There's 4 wires for the 1,2,3,4 values on the heater fan speed selector switch. I added a diode from each wire to a common point so no matter what the switch setting was there's always 12V. Now the heater controls only come on with the fan switch and car ignition also has to be on first. If the engine isn't running the main power relays don't pull in because the battery voltage is too low. At idle only one heater can be used as the battery voltage sags too much due to the alternator not producing enough output at low RPM. From 1500RPM both can be run. You can certainly hear the alternator loading up though - will have to see if it toughs it out. Usually the heater will only get used if it's cold so the alternator will also get colder cooling air so hopefully it won't be a problem. I couldn't find much information about the alternator and what it's continuous rating is. If the voltage gets too low the FET's switch off and the relays open. There's then a 15 second time delay before the relays are allowed to close again and FET's turn back on. This is to stop rapid cycling of the relays. I did some more tests today to see how much heat is generated. With the fan on 3 there was a noticeable difference in the air temperature coming from the vents. It might be better than previously stated. The real test will be how long it takes to warm up the cabin in winter.
  5. It would be easy to modify for EV and higher voltages. The PTC elements are available in different voltage ranges. They don't series well being a PTC - the first one to go higher in resistance gets it. The FET's used in this design are only 60V rated but really low ESR. Higher voltage won't need as much current so using a higher voltage FET's with a higher ESR will give similar losses. The biggest problem with the current PCB is the voltage clearance between the tracks. For higher voltage you'd really want to use bigger clearances. For high reliability DC circuits I always use 'reinforced' creapage and clearance rules (4x the standard). Dead FET's are detected in the control logic and the relays are opened (a fault LED comes on). There's also redundant temperature sensors which will open the relays. The PTC elements will also max out at 210'C and power limit. Not that I'd want this temperature sitting in the plastic heater box - most likely would start melting things. 3 levels of safety should make it safe. It's all tested and working ok. The only problem I have is the control uP is active all the time, even with the ignition off. For now I've pulled the power plug from the PCB. It appears the 12V supply I've used from the heater solenoid is not switched. I'll have to find a switched source that comes on with the heater power. I assumed the heater solenoid power would be switched with the ignition - should have checked it first. This is the only error though. The heater control logic is working perfectly and heat comes out the vents. The heat is nowhere near as strong as the original water based radiator but I'd expected that. It's hard to tell now when it's already warm if it will be enough heat in winter. It's going to be much better than it was though - it didn't used to work at all. I can't check the current draw because I don't have a DC clamp meter anymore. I'll have to borrow one from work to test what the power draw is. I suspect it will be a bit more than 300W each side because the PTC elements actually have an initial negative coefficient so the wattage goes up until they hit about 160'C and then the resistance rapidly starts to rise. Since I'm operating them at 95'C the resistance is about 20% lower so I'm likely drawing 360W+...
  6. Eh?? I don't think you understand basic physics... Do you use your aircon for cooling - this is not really any better than electric heating? The aircon uses rotational energy just the same as the alternator... I don't really care what you think anyway. It's installed now so no going back...
  7. It's been a while - had to work over labour weekend so no progress for 2 weeks. I now have a week off work as days in lieu... Since HB day was on the Friday I got 4 days so took a days annual as well. The only thing left to do is test the software. I'll start this tomorrow and see how badly wrong it is. Following is some progress photo's. The new PCB fits where the old aluminum water pipes came out and headed towards the firewall. I've bunged up the two openings where the water pipes and aircon pipes came through. Where the old heater core used to sit also needed a plate fitted which worked out well because it's also where the cables now come out. A plate was fabricated to fit and then holes drilled for the cable entry. The cables that go out to the water solenoid on X35 and X10054 have been clipped off near the connectors and joined into the control cables for the new board. This means the original solenoid plug can be cut off or just tied off (at least it's not powered now). Side view showing how the board fits where the pipes came out. Original Plugs and new main power relays New Power Relays - the main power connection goes onto the unused tabs. Another view, looking from the front. Heater cores with all the wiring installed. The blue cables are shielded signal types which connect to the LT9701 temperature sensors clamped under the rectangular blocks of ally.
  8. The PCB is now partly loaded with the parts I had in stock. The remaining bits won't be here until mid next week. At least the software testing can begin...
  9. Can't understand how different dealerships can have such differences (>200%) in price... Yup, waste engine heat conversion into heat inside the cabin is close to 100% but then it all leaks out so effectively 0%. Otherwise you could turn your heater on for 5 minutes and then turn it off again and you'd stay warm for ever... Yup again to the alternator but the conversion of fossil fuel to rotational energy is around 30% then the alternator 95% so close to 30% effective efficiency conversion from fossil fuel to heat (not 10%)... We're also only taking about 0.6kW of energy, it's bugger-all. It's a project being done for the fun of it - I don't care if it's not particularly efficient.
  10. Where do you get heater valves for $280-300? The local BMW shop quoted $650+GST. I'm not charging the battery then taking the energy out - the heater won't turn on until the battery is above 13.5V which means the alternator is active. All the energy for the heater comes from the alternator which is about 95%+ efficient. The total fossil fuel to heat conversion is more likely 30% - still pretty rubbish + isn't using the already waste heat from the engine as you say. However, the project is in part about just doing a conversion with the added bonus of instant heat once the engine is running + no risk of a water leak from the heater core ever again. My solar PV on the house more than makes up for the fossil fuel use the electric heater element will use... Thinking about it though, the heater is actually 0% efficient overall. It makes heat which leaks out of the car so it's a total loss either way it's done.
  11. The PCB arrived today. The parts I didn't have in my left-overs box aren't going to arrive until next week... The new elements are mounted. Now the wires need to be properly terminated and a baffle added for the cables to pass through.
  12. Thanks, but the dash is coming out so I can change the sealing frame between the heater body and the firewall - it's leaking. I'm also doing an electric conversion to get rid of the risk of the heater core splitting sometime in the future. I'm 3/4 of the way there anyway since I had to strip everything to find the leaks. Had 4 in total - between the heater and firewall, from the heater core, from the fusebox/firewall and from popped bungs in the floor. 3 out of 4 are now fixed with the last one (heater/firewall) getting fixed when Ireplacing the heater with the second hand one converted to electric. The only leaks I didn't have were two of the most common ones - A-Pillar from the sunroof and door seal...
  13. Checked this too - dry as, so my original mod still appears to be working well. Was just about to seal up the gap and it started chucking it down again...
  14. Found it - nasty little bugger too... It's coming from the big plastic bung where the fusebox pokes through the firewall. You can see a drip forming. It's seeping in from all round the perimeter as well as where the cable comes through. Water goes down this gap in the metal round the engine bay and drops directly onto the electrical fusebox area. Since this is going to be near impossible to seal round the fusebox/firewall the only option is to stop the water getting into the engine bay. Why this gap is there beats me... I'll fill is with poos to seal off the engine bay and hopefully that's the end of the problem.
  15. Thanks, haven't checked this yet. I have a Link G4+ in this compartment and definately don't want water getting into it. I'll be checking this tonight for sure... Some years ago I did get water in this compartment due to the drain in the heater area getting blocked and water would flow into the ECU compartment when going round a corner. It fried one of the coil driver smart transistors and I thought I'd need a new ECU. However, the local BMW shop showed me to a box of old blown ECU's so I robbed a transistor to replace into mine. Got it going again using the robbed part. I thought I'd solved the water problem by gluing in a baffle to stop water ever getting in there again. Worth checking it's still working + to see if water is somehow getting back in now...