| Owner | Joe | ||||||||
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| Location | Phoenix, Arizona US map | ||||||||
| Web/Email | WebPage | ||||||||
| Vehicle | 1989 Toyota Corolla GTS Got it used on Craig's list with a seized motor - only $300! | ||||||||
| Motor | Netgain Impulse 9 Series Wound DC | ||||||||
| Controller | Cougar? Revolt? Not sure what the final name 144V 500A model This is the DIY controller created by Paul Holmes - very impressive, works incredibly well! | ||||||||
| Batteries | 24 US Battery 2200, 6.00 Volt, Lead-Acid, Flooded I tested 120V for a couple weeks and decided to go for 144 since I had the space for more batteries. The car is heavy, but voltage sag and battery amps are much less. | ||||||||
| System Voltage | 144 Volts | ||||||||
| Charger | Quickcharge 144V 20A Seems to work well, just as the specs say. It's big though, so I just have it sitting in the garage as of now. Currently developing a switch mode charger on my own... | ||||||||
| Heater | 2 Ceramic heaters in series. 144V across one seemed to be too much and it'd 'pop' and only draw a few amps. The two now draw around 10A total and create a modest amount of heat, good enough for AZ. | ||||||||
| DC/DC Converter | 350W Also works well. I forget the brand, but it brings the system up to 13.5V and pumps some amps into the accessory battery to keep it charged. I haven't seen the accessory battery drop below 12.2V (open circuit). | ||||||||
| Instrumentation | Paktrakr for battery amps and voltage Digital Voltmeter for controller input voltage - this will measure battery volts once the contactor closes, but when I turn on the breaker, I can see the voltage rise slowly on the caps and let it level off before starting to drive Battery/Motor digital Ammeter - from a 50mv shunt in the motor loop and another in the battery loop. I have a relay and toggle switch to switch between the two - I try to keep the amps low. I also have a temp probe in the controller heatsink since it'd be nice to monitor in the AZ summers. The Curtis I had didn't take kindly to the heat and was often in thermal cutback mode. The Revolt seems to handle it really well with lower heat generation and thermal mass. I'll see operating temps in the 50's on hot days. | ||||||||
| Top Speed | 70 MPH (112 KPH) Pretty easily to 55-60 in 3rd. I put it into 4th once and got to 70 with room to spare, but didn't want to push it with fairly new batteries. | ||||||||
| Acceleration | Enough to easily keep up with traffic. The killer is waiting 4sec for the motor to spool down from 5.5k to 3k to shift from 1st to 2nd (might put the clutch back in, or develop a motor brake to spool down quicker). Starting in 2nd is possible, just slow out of the gate. | ||||||||
| Range | 65 Miles (104 Kilometers) Not sure yet exactly. As of now, a 20mi trip dropped the SG from 1.265 to 1.230 and a 44 mi trip dropped SG to 1.190 or so, or about 55% SOC. My longest run so far has been 54 mi to about 50% SOC. This is the typical trip out to the school and back and luckily, it's mostly highway with only modest hills. | ||||||||
| Watt Hours/Mile | 230 Wh/Mile Based on amps and volts while cruising on the highway. Don't have instrumentation/recording ability to measure a whole trip, so this is likely higher when considering accelerations and hills. | ||||||||
| EV Miles |
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| Seating Capacity | 5 adults | ||||||||
| Curb Weight | 3,740 Pounds (1,699 Kilograms) Weighed at the scrap yard. 2060 lbs on the rear end. | ||||||||
| Tires | Goodyear Integrity, 185 70 14 I wanted B381's but couldn't justify the high price to get 'em installed. The GY's are the ones that come on the Prius and, while an awful tire for poor weather, are supposed to be pretty good for rolling resistance. I have them inflated to 55 psi. | ||||||||
| Conversion Time | Got the car at the end of May '08. Driveable around town and to work in Jan '09. Still a lot of work to do... | ||||||||
| Conversion Cost | 300 for the donor car 2400 for batteries 7000 for conversion parts ~1000 for tools (welder, drill press, stuff I wanted anyway) Labor: I'm guessing around 200 hours | ||||||||
| Bought the car in May of 08 and began tearing it apart that summer. Ordered parts in August and started putting things together. I'd say most of the time was put into testing and wiring the electronics to control the 12V stuff and building battery racks. Got the car moving around late November and finally road-worthy in Jan '09. 01-14-09 As of today, I have driven just over 100mi all EV with around 10 cycles on the batteries. I just got the heater working and was able to put the glove compartment area under the dash back together. The driver's side needs a lot of work still. Plans to do: Finish wiring various switches Install Paktraker Upgrade tires Upgrade brakes Fabricate/install grill dams Fabricate/install engine compartment splash guards Check for caliper rubbing Wheel alignment Replace rear speakers Investigate homemade on-board charger 1-18-09 Have had the paktrakr working for a few days now. Works well, but i'm having problems with recording the data stream under high acceleration similar to others. I've ordered several EMI suppressors, so we'll see how that works. At 60 mph, it appears to be pulling between 60 and 160 amps, depending on going uphill or downhill. at 100 amps, the reserve capacity from the USB website is 80 minutes, which would equate to 40 miles to 50% SOC. I'm almost there without doing any efficiency mods, so we'll see what happens. It'd be impressive to get down to 75A for 115 mins of reserve capacity. I did record a charge cycle though. The quickcharge charger put out nearly 30A at first (good thing it's on a 30A breaker) and once it reached the cutoff voltage of 2.4v/cell, it held that for 3 hours. I did notice that the current only dropped to 4A, and that was after only 90 min. I might try to proportionally timed gassing mode. Also, just weighed it at the crap yard - came it at 3740 total, and 2060 on the rear end making the weight ratio .81 to 1. Came in a little heavier than I expected, but subtracting 1550 lbs of batteries, 150 lbs for the motor, and about 100 for battery racks and cable, 1900 lbs is about right for the glider. 2-5-09 Been monitoring the set of 4 new batteries that I added to bring the system up to 144V. They're a few cycles behind the rest, so they discharge a little further than the others and re-charge a little quicker. I'm hoping this gets better with time, as a contact with USB suggested it will. Another range data point: 20 mi trip to visit the parents, consisting of 4 mi surface streets and 16 mi highway (at 60mph, 55 up hills) brought SG down to ~1.225 on these newer cells. According to the charts, that's around 70% SOC. My solid state relay for controlling the heat element failed, and of course it failed 'on'. I suspected it might happen from what others have said, but it seemed to be such an elegant option. Pretty bad to fail after only a few cycles. Next option might be some sort of small contactor, but it's pretty warm in PHX anyway. Went to a parking lot and brought some equipment to calculate rolling resistance. I wanted to see if I could quantify the change when I upgraded to better tires. These were the originals that I got the car with, but pumped up to ~44psi (10 over the max). I used a mic to record the audio as I coasted over a metal bar. From the digital audio, I could get a decent time measurement, and using the wheelbase of the car, I could calculate speed. Then, by measuring the distance the car rolled, I could calculate an acceleration (assuming it was constant) and a drag force, and ultimately the coefficient of rolling friction. Anyway, it ended up around .0103, which seemed right in line with typical tire results. According to some testing I read, the B381's are at 0.006, 40% lower friction. I'll repeat the experiment when I get a hold of a set and compare. On another note, still haven't gotten the paktrakr to record un-jumbled data. 4-12-09 I've spent most of the recent time working on a portable switchmode charger. Currently, i've made a 'dumb' charger that'll work up to 15 amps before getting too hot. Once I get up to 25 amps, I'll work on making it 'smart'! The longest trip so far was a 44 mi trip, mostly highway, at 55mph up to Scottsdale and back. The trip brought the batteries down to about 55% SOC based on SG readings. I routinely make the 35 mi round trip to my folks' place without issue. I haven't put it into prime time for the 52 mi round trip down to the school and back as i'd like to have a portable charger before venturing too far. I picked up a couple of sheets of coroplast for splashguards and belly-pan for 20 buckas apiece, but it's just sitting in the garage. I got the controller heatsink thermometer working. Seems that it operates about 15- 20C above ambient. On a 95F day, it did start to limit motor current to 375 amps for a bit, but went back to normal after cruising a mile. Temp reading was 45C. I decided to go with Goodyear Integrity's for tires since they were about half the price as the B381's... A lot of reviews show that this is the OEM tire for the Prius and users often complained of losing mileage when changing tires. So far, I haven't noticed much of a change in performance, though it appears that I'm cruising at the same speeds with the same motor current. Presumably, since the tires are a little larger, this means I'm cruising about 5% faster for the same current draw (torque). I put in a battery current shunt and a relay/toggle switch to switch between motor current and battery current using the same meter. Unfortunately, the shunts aren't exactly the same (despite both being 500A 50mv shunts) and the battery amps are reading about half the actual value (as checked with my clamp meter). I'm going to work on a opamp circuit to scale this reading up to the correct value. I'll have to start working on some form of AC as it's already getting pretty warm. I also keep putting off upgrading the brakes. Conscious driving hasn't led to any problems so far. 6-10-09 Not sure what the deal with the battery loop shunt was, but now it's reading correctly. Maybe there was some contact resistance in the wiring or connections somehow? Anyway, it reads accurate to an amp when compared to my clamp meter, so I'm happy. Biggest surprises so far: keeping amps at or under 200 while accelerating is actually pretty easy, and amps vary wildly with just a small change in accelerator positioning. Once, I gunned it to accelerate into the carpool lane and it peaked over 400A at around 116V - that's 46kw or about 62 HP! Also, drove the furthest on a charge to date. 54 miles round trip out to the school and back. The trip was about 8 mi city driving with the rest of it highway. Cruising battery amps at 55 mph were from 80-100 while I tried not to exceed 150A up the modest hills. Cruising voltage started at 141V and ended at 136 while resting voltage started at ~153 and ended at 146. I didn't measure SG, but based on how it's been behaving, I'd put this at a little above 50% SOC. Temperature was about 90F, which is cool for June, but nice for floodies. I've also noticed that some of my terminals have been getting warm, almost too hot to touch. I've heard about EVer's lead posts melting, but lead's melting point is about 600F! I don't think it's that bad, but I also noticed that the few cable connectors that the battery supplier made with O connectors were much cooler, only barely warm. I concluded that this was because the OO cable in a O connector was very tight and made a very solid crimp and that the OO cable in OO connectors were pretty weak using the hex crimper they have. I picked up a hammer crimper a little while ago to make some of my own cables, but hadn't used it yet. I took one of the already-made cables in my battery string, removed the heatshrink, whacked it in the hammer crimper, painted some liquid tool handle coating stuff on it and reinstalled. Voila! Ran very cool when compared to the others! So, I'm slowly re-doing all of those original hex crimps. I picked up a seat cushion that has a fan to circulate air through seat and back area. It's ok, but I'm still scheming for some sort of AC. Other current projects are the DIY charger and I'm thinking about making an AH counter. 7-9-09 It's getting warm! I've concluded that the Curtis controller tries to limit itself to operating around 50C. Now that the ambient temp is 43C, I notice that it will very quickly go into the 1.5khz mode to reduce the heat losses. this tends to keep the operating temperature to 50C when cruising on the highway for a while. This temp goes up when doing a lot of city driving and accelerations - up to 53C so far. So, that's only 10C above ambient, but it's in the lower frequency mode A LOT! I can see when it switches modes on the heatsink thermometer - it'll drop 1.5C degrees when going from 15khz to 1.5 khz, and then go back up when it goes back. This explains how the heatsink temp could reach 50C when it was still cool out - it wasn't going into thermal mode yet. Now that it's hot, it just stays in the low frequency thermal mode more often. what's bad about the low frequency mode? first, you can hear it, and second, I think it's pretty high stress on the capacitors due to higher ripple current. Nevertheless, i'm excited to soon be receiving the DIY controller from Paul Holmes. It's the same specs as the curtis, but has a lot less heat losses (on paper at least). I hope it works well! I'm also working on adapting a window A/C unit to use the evaporator in the dashboard. so far though, I've only picked up the A/C unit for 100 bucks at home depot. 9-11-09 Got the new controller! Woohoo! Works well and reliably delivers power. I suspect things are ok as far as heat dissipation, but things get pretty warm after a lot of city driving or high amp freeway driving. Bench tested the A/C and it worked! Perhaps not as great as original, but temps down in the 50s with the fan on high for about a 60 deg delta T. I've gotten all the mechanical stuff installed less hoses, so once that's all set just gotta work on the electrical stuff. I'm working on an inverter to convert my high voltage DC to AC for the compressor. If it works like expected, I should also be able to control the speed of the compressor so i can just turn it down instead of cycling it on and off. 10-23-09 I've been testing the DIY controller for a couple months now and it's worked superbly. There's been a couple glitches, but that's what beta testing is all about! With some software revision and some minor hardware additions, I think its performance far exceeds the Curtis. This is more so I can remind myself, but if you subtract 3000 from the total miles driven, that's about how many miles are on the new controller. The guys at AZ Auto and Air were awesome with assisting me in my A/C endeavor. As of now, all the mechanical stuff is installed and working - I just need to finish the electrical part of it. It's not perfect, but I think it will do the job. As far as range is concerned, I've driven out to the track and back many times now without issue. Recently, I did notice that the voltage under load is much lower than previous. Towards the end of drive, it's down to 132V at 80A rather than 136 or so. Two things I think contribute to this: It's a lot cooler now than when I first started making the drive - averaging 70F vs 95F, and I had just watered the batteries, so the electrolyte was more dilute. I think those initial range tests were when the cells were about ready to be watered, so it was more concentrated. 10-4-09 I had a battery that died a couple days ago. I had my eye on this battery for a while now - it was leaking acid out the top at first (caused a mess of the battery rack) and a month or so ago, I noticed that the SG in one of the cells was 50pts lower or so. I equalized it separately, but that didn't help. I though some just leaked out, so I thought about adding acid at some point. But, before I could do that, I was about 3/4 of the way through my commute and the paktrakr was showing only about 2V under load while the others were almost at 6. I stopped and bypassed it and noticed it was really warm. It was just past the year warranty, but the battery shop sold me a new replacement for $25, so I can't really complain. It's all back together now, and running well. I also tested my AC compressor inverter/controller and it works well! I just need to fix a glitch in the software, maybe add a boost regulator circuit, and install it in the car. | |||||||||
1989 Toyota Corolla
“Corolla EV”
Last Updated 11-21-2009
Copyright © 1997-2009 by Mike Chancey