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WisDesign

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About WisDesign

  • Birthday August 7

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  1. The box ended up being just under 22" wide at 21.75". Cool to see you're making good progress as well! Having all the bodywork done already makes things a bit stressful as we're loading heavy batteries in and out of the car... !
  2. So I thought I was well on my way to completing my 4th battery for my 1968 1600-2 restoversion. Unfortunately, on closer investigation using the foam core mock-up I had built, we realized that the freshly installed rebuilt brake booster and master cylinder created a not-so-insignificant interference. The photos below show the basic idea of the front battery pack sitting under the hood, above the motor and transmission. When we previously checked this position, the brake booster was not installed... doh! After drowning my sorrows for an evening, I started playing "what if" scenarios with the LG lithium-ion battery sub-modules. We realized it was really the width of the complete battery pack that was the problem, but we had some room to grow vertically if I could come up with another workable configuration. Part of my challenge in this new configuration was self-imposed. I am proud of the fact that I had managed to thermally couple the heat sinks on the cell module to the aluminum base plate of the previous battery design, thus using the entire aluminum enclosure as a heat sink for the battery pack, which would improve performance, reduce thermal gradients, and extend the life of this passively air-cooled battery. With a 90 degree rotation of the cell module, I'd need a new thermal sinking strategy. With more red wine (or a nice West Coast IPA - can't remember), one quickly emerged. I would rotate the modules 90 degrees on their long side and create vertical aluminum heat sink plates inside the pack to achieve the same thing as the top and bottom plates of the "short box" design. Before we set off down this path, we smartly modified our mock-up to ensure this new configuration, which cut about 5 inches from the overall width, would work. And... it did! We gained room in all the prior interference concerns and were even able to drop the pack overall a bit. With that confirmed, I set about designing and building the new enclosure... Since there would be less pressure on the heat sinks compared to using gravity to press them to the thermal plate, I decided to use a thermal gap pad in the interface to ensure good thermal conductivity between the cell module and this plate. It's the bluish-purple pad below. This made tolerancing my box build a bit trickier and in the end, I used some spacers between two of the cell modules to take up some gap and maintain pressure against the sink plates. Here's a shot of the final configuration. The one section of 80/20 that runs down the pack creates a nice 20mm gap that allows me to run the BMS and CANbus cabling from front to back as these cell modules have voltage sense connectors on both ends as they use double-ended cell terminals. The cell monitoring boards mount to the back of the cell modules and are more accessible through the back cover over the short box design should they need servicing in the future. Quick check was done hooking up 12Vdc and CAN to the master BMS and checking on the display and laptop that we've got good communication with all the cells and thermistors. All good! The completed "tall box" battery. The handles will help for installation. They can be left in place or removed once I've got the pack installed. Haven't decided on that detail yet. I also paid extra attention to sealing this enclosure during the final assembly as it will live under the hood. All of the panels have silicone "gaskets" and the connectors are fully sealed. Should water eventually find a way in, the terminals are coated with dielectric grease and power terminals covered with moisture sealing mastic. Here's a comparison between the tall box and short box batteries. The tall box was a bit fussier to build, but is a bit more efficient in use of space and materials. In the end, it's helpful to now have a couple of different battery configurations for future builds and various space constraints we are likely to run into. I promise my next blog post will have more "car stuff" than batteries...Onward! Thanks for reading. -Brian.
  3. WisDesign

    WisDesign

  4. Ooooh... keep me posted on the Vintage Air solution. I've got no plan at the moment for such driver comforts...
  5. First of all, let me say that I am thankful for a forum in which we can have a friendly exchange of ideas. Anybody just thinking about, interested in, or actually building a conversion is more than alright in my book! Not because I doubted anyone, but out of my own curiosity, I ran my own spreadsheet on the Tesla small motor solution and it looks like a very good solution. At 274Vdc nominal, you're around 78% of nominal voltage for a full pack, so base speed on the motor should fall around the same percentage. Agree that you will land around the 200hp mark at the wheels and the bonus is that the gear reduction and differential should be overbuilt for that power level. The 54kWh battery seems adequate to hit that peak power level/current at less than 4C discharge, although I noted that they require some form of cooling if you intend to run them at over 1C continuous (54kW), which would only be the case if you were taking the car to the track. I think the only downside is that it's a bigger tear-up to the chassis to fit the motor/gearbox unit in the rear and you may end up with a unique solution on spring rates based on how the front/rear weight distribution turns out (same can be said with my solution though). IMO - What really matters in end when it comes to performance is rear wheel torque and power-to-weight. The motor torque is pretty inconsequential if you don't understand the intermediate and final drive gearing. In the case of the Tesla small motor, the single, fixed ratio is 9.34:1 with a peak motor torque of 330Nm. This provides 3082 Nm / 2273 lb-ft of rear wheel torque up to the 5100 rpm base speed (my assumption - could be wrong), which will come at about 40mph and then begin to taper off. Compared to my solution of integrating the 4-speed gearbox, the Tesla solution looks like a pretty darn good way to go. However, I'll have a 257Nm motor coupled to a 4-speed and differential that will provide a 14.72:1 ratio in 1st gear = 3782 Nm / 2789 lb-ft of torque, but only up to about 20mph before it begins to taper off. It remains to be seen if the drivetrain turns to shrapnel at that input torque though. Second gear will provide a more manageable 1500 lb-ft of torque, and carry me up to ~90mph, so I'm guessing this is the gear that will see the heaviest duty cycle. Third is for the highway and Fourth is for the Salt Flats... For me, I've had experience in many direct drive and gearbox coupled electrics and I still enjoy the feeling of rowing through the gears and having a bit more control over the vehicle. For example - gear selection also influences the amount of regen you'll receive as you let off the throttle, similar to downshifting a gas engine as it's the mechanical ratio slowing the wheels. It is novel to me that you can apply the latest electric drivetrain technology and still retain the romance of driving a vintage car. My Dad's electric MGBGT has the stock four-speed and a racing clutch and it's pretty fun to drive. I wouldn't race a Tesla with it, but that's not really the point of the car for him or myself. To each their own, but I thought I'd provide a bit of my own justification. I'm anxious to see these builds completed as they represent different approaches, but are both seemingly being pursued with a lot of passion and consideration into making a high quality conversion. On that note... better get back to it!
  6. I think there is more than one "right" answer depending on what you're trying to achieve. If you've got a plan to do it better... I say go for it. I'd love to follow your build as it sounds like you've got a ton of experience with these cars and I'd learn a thing or two! My hesitance to go all in on the Tesla route is based on the fact that the performance of that drivetrain is based on having a very large capacity (70-100kWh), 400Vdc battery to provide it with power. It seems that many in the conversion world like to quote the specs of the Tesla motor in terms of what it is capable of in a Tesla and avoid the fact that they have far less battery voltage and capacity supplying it, which will certainly limit its performance. I can understand the sex appeal of the Tesla system and I imagine most customers don't really care what the peak power is. I just wanted to try something different by engineering a custom solution for the car. I reserve the right to be completely wrong on all of my opinions...
  7. Brian here. Working on a 400Vdc conversion of a 1968 1600 as Geoff mentioned. Yes - I'm retaining the 4-speed. At present, I've got a 3.91 ratio open diff, but have been keeping an eye out for a LSD. Check out my blog. I am building this up as a "kit" so that others could do the same in the future. I'm also keeping track of my costs along the way. It's not cheap by any stretch, but I doubt anyone here got into vintage cars as a way to save money. Let me know if you've got any questions...
  8. Thanks for the compliment! Back at ya! I think I already follow you on Instagram, but I'll double check. That's an awesome amount of battery capacity for such a small car, well done. What is the total voltage? I'm happy with the EMUS system so far, but won't know for sure until I do the full integration. The ability to reconfigure the output pins in their software is pretty handy and its clear that this is not their first "go" at a BMS. I believe they've been around since 2009 or so. The CCGM (cell can group monitor) can monitor a 16S string, which works perfectly for the LG modules I'm using. Not sure how Tesla does their series strings. I know they've got a ton of those 18650s in parallel.
  9. While the battery shown below looks identical to the other I posted, it is, in fact, a newly built battery. As a reminder, I need 4 of these in the car to get to my full pack and roughly 32kWh of capacity, which should be good for over 100 miles of real-world driving range. They will be configured with 2 in series and 2 in parallel to reach the desired voltage and capacity. Lithium-ion batteries are amazing in a lot of ways, but require careful management to ensure the best performance, safety, and longevity. To that end, it's critical to have a battery management system (BMS), which measures and reports on the cell voltages and temperatures and makes some calculations based on that voltage and measured current over time (coulomb counting) to predict a State-of-Charge (SOC). The multimeter is displaying 170Vdc, half of the pack's total voltage at roughly 30% SOC. The BMS in my system is made up of cell monitoring units which measure voltage on each individual cell and provides the data over a CAN bus which is wired into the circular connector on the outside of the front plate. I recently received the small display that pairs with the BMS system to provide some of the available data to the driver. I was curious to see how it all worked, so I hooked it up and ran through the available screens... Overall, I'm really pleased with the display. It's clean and simple with a single rotary button interface and displays the information I'm concerned about - i.e. State of Charge (SOC), Pack Voltage, Pack Current, Low cell voltage, High cell voltage, Average cell voltage, and pack temperatures. It's an OLED display, so the brightness, viewing angle, and overall visibility is really nice. You can see the "master" BMS control unit in the background. This is what aggregates the CAN bus data from the batteries and provides the output over serial to the display. The BMS unit is highly configurable through their software, so I'll be able to map the output pins to the various functions needed to drive contactors relays, water pumps, etc... . My current plan is to mount this display in the center console above the stereo slot somewhere. I've been searching the forums and blogs for ideas...! Let me know if anyone has a suggestion...
  10. Oh yeah... my trick to getting the glass clean was to use a razor blade to scrape decades of hard water and whatever else stains off of it!
  11. Ah ha! Our little ev conversion club is growing! Pretty cool that we're each taking a different approach to the powertrain components. I've shied away from the Tesla stuff, but I totally get the attraction and the parts are becoming more and more available with their success. I'm using a BMS from EMUS with Cell Can Group Monitors for each of the battery sub-modules. The BMS has configurable outputs that should allow me to drive the instruments. They also have a discrete display unit. I'm not really interested in a giant touch screen in the cockpit...
  12. Thanks for the feedback and tips, Geoff! Definitely helpful and I'm sure I'll be coming back to you with questions once I'm actually trying to get everything working. Very helpful to know someone out there that's already tackled some of these challenges!
  13. A small, but significant milestone was made in the refreshing of the instrument cluster for my 1968 1600 restoversion (electric conversion). Here's what we started with... older model cluster with all black gauges and cloudy glass... the plastic surround and bezel rings were in pretty good shape though. I've always been a fan of the earlier model "silver dollar" gauges and even the late model "cross-hairs" gauges, so these were my least favorite option. I did some hunting on eBay and found a silver dollar cluster that had the plastics poorly re-painted, but the gauges still looking pretty good. While I like the silver dollar gauges of the older cars, the additional chromed bezels and dash surround edge is a bit too "Buck Rodgers" for my personal tastes. So, I was able to combine what I had with the eBay cluster to come up with something that I think will fit the car and achieve the look I'm after. I spent the most time cleaning the glass and then trying to figure out how to get those [email protected] inner bezel rings, which I repainted in flat black, to hold it all together correctly again. I also broke one of the speedo glasses while cleaning as it slipped out of my hand onto the concrete garage floor and shattered... so I was lucky to have had a spare! Here's how it turned out. It was nice to have a "mini-project" that could be completed in a couple of weekends and provide some much needed feeling of progress! Can't wait to get this installed into the refurbished (by JustDashes) 3-piece dash! This also commits me to figuring out how to get these gauges to function with the converted drivetrain. The speedometer is no problem as it's mechanical, but the tachometer, fuel level, and temp gauge could be a bit of a trick. I'm pretty sure I can convert outputs from my BMS controller to drive them, but I'm sure there'll be some challenge there that I'm not anticipating. I'll also be augmenting the gauges with a small LCD display to indicate battery parameters. At the moment, that display is destined for the center console. I'd like the interior to remain pretty minimalist as I love that about these cars. I know not everyone will agree, but my premise is that the electric drivetrain should make the vintage driving experience more "refined" rather than trying to make a 50+ year old car act like a modern Tesla... i.e no giant iPad tablets in the cockpit! Hope everyone's using this trying time to do what they love around the people they love and get some progress made on their projects! -Brian.
  14. Yeah... I assume that most are surprised by the weight based on how light lithium-ion 12Vdc starter batteries and the like are compared to their lead-acid counterpart. However, in most of those applications, the battery is just providing a burst of power. In this case, we also need it to provide a lot of energy capacity to keep you moving down the road as long as possible.
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