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mechman600 07-05-2012 02:08 AM

Project: The Electric Booger (budget EV conversion - '92 Mazda MX-3)
It has officially begun. Today I commandeered the wife's parking spot in the garage to officially begin ripping and tearing.

To clear things up, it is a 1992 Mazda MX-3 Precidia. Booger green. The plan is to build an ultra-low budget EV, using cheapness to my advantage. Much inspiration from the ForkenSwift and ElectroMetro:

For the main bits so far, I have a 72V SePex motor (6.5"X18"), Alltrax 72V (450A) controller and 13 free lead acid battery cores from work, among other things of course.
My parts collecting thread is here:

My conversion blog is here: Project: Electric Booger

Can you count the missing pieces so far?

With a baby due in a few weeks and my obsession with motorcycling (and the currently beautiful weather these days), it may be a slow go, but I will be sure to post here. I owe it to the EVers in this forum that provided so much inspiration.

Here are links to highlights of this thread

Motor/Transmission adapter complete:
Motor/Transmission installed, front battery racks:
Rear battery racks:
First commute in the Electric Booger:
Commuting to work video:
New Battery Pack:
PWM field controller installed:
Final charging solution:
TO DO List after one year:

euromodder 07-05-2012 07:17 AM

Good luck with the build !

3n3rgystar 07-05-2012 08:07 AM

LOL, nice name and you already got alot parts ahead in the game!

mechman600 07-12-2012 02:21 AM

The ICE is out.

I thought I would need to borrow an engine lift, but it turns out this one goes out through the bottom. Do you think my car lift would be safety approved?
Didn't think so.:)

FXSTi 07-12-2012 07:03 PM


Originally Posted by mechman600 (Post 316598)
Do you think my car lift would be safety approved?

OSHA is a small town in Wisconsin.

ron 07-12-2012 10:44 PM

4x4s are rated I think. it also helps to have a large set of wrenches

UFO 07-13-2012 11:45 AM

Yikes! Don't get underneath that, even with the engine out it will hurt if it falls on you. Good luck with the build.

mechman600 07-18-2012 11:50 PM

The other day I hauled the transmission, electric motor and chunk of aluminum to work, where the mating of the motor and transmission will take place. The transmission was absolutely filthy from an engine oil leak and took a good 15 minutes of steam cleaning to get it spotless.

Today I started work on adapting everything together. First off, I am mating the transmission to the keyed shaft side of the motor. Originally this motor was coupled on the opposite end where there is still a gear on the end of the shaft. Unfortunately, the opposite end (the end I want to couple to) has only three 5/16" threaded holes to mount the motor. You can see the three tiny holes around the edge of the motor face.
Not strong enough. I usually prefer overkill. So today I performed some precise measurements and drilled three 21/64" holes into [what I figured was] the thickest part of the face approximately 5/8" deep. Turns out I was right, as I did not go through the motor face anywhere (and get aluminum filings inside the motor). I tapped the holes 10mmX1.5 and made up three short studs.
Studs are the strongest when torquing into aluminum. I will Loctite the studs into the motor face and torque it up to the adapter plate with nuts. Metal on metal instead of torquing into aluminum.

mechman600 07-18-2012 11:57 PM


Originally Posted by 3n3rgystar (Post 315394)
LOL, nice name and you already got alot parts ahead in the game!

Yeah, the only thing I am missing is a proper vacuum pump system for the brakes and the potentiometer for the throttle.

Anybody want to donate parts? HA!

mechman600 07-23-2012 02:23 AM

Well, three days ago my wife gave birth to our second child, another girl. So a week off work for me, helping around the house, keeping things under control (as much as possible, anyway....). Surprisingly enough, I have been able to get into the garage to tear apart the Booger some more.

First off, the exhaust system: gone. That was easy. Like....five minutes. A few bolts and a bunch of rubber hangers. That's it.

Secondly, the gas tank: gone. Less easy. But it is official that this car will never ever consume petroleum again. No turning back now.

My boss is building a Miata powered Caterham from scratch and wants the fuel pump, so that will be my first parts sale from this thing, even if it's only for a box of beer. Unfortunately the engine has 280K km on it, so I doubt there will be any takers on that.

mechman600 08-14-2012 11:13 PM

I have been messing around with the adapter plate the last few days. The motor is mounted up to the plate.
All it took was a 2-1/2" hole saw and a few drill bits in the drill press.

The adapter plate is huge. Way too big. I will eventually saw it down for sure and maybe use a chunk of it for a heat sink for the motor controller.

Here is the transmission input shaft with pilot bearing stub:

And here it is after the pilot-bearing-stubectomy, thanks to the cutoff wheel on my die grinder. It took all of about two minutes to complete:

mechman600 08-29-2012 06:47 PM

One thing to report: I did in fact receive my 1" keyed hub in the mail:
And I did in fact weld it to my splined clutch centre:
Did I weld it straight? I sure hope so. I fitted my new 1" keyed hub to the motor shaft and much to my dismay, in very "Princess Auto-esque" fashion it fit quite loosely to the motor shaft. No precision here, folks. So when I tighten the set screw, it pulls the coupler to one side of the shaft so that it wobbles a tiny bit (0.010"-0.020" or so) when the motor is spinning. Hmm...that's not good.

So here I sit on an 11 day holiday at our Hacienda in Osoyoos, trying to think of what I should do. And here's what I have come up with: I will discard the set screw on the motor shaft portion of the coupler to allow the coupler to float on the motor shaft. The clutch splines of the coupler fit quite snug on the transmission input shaft and there is no radial movement of the coupler there, so the coupler's radial position will be located by the transmission input shaft only and the motor shaft will float in the opposite end (the loose end) of the coupler.

There will not be an issue with the coupler moving fore and aft because I welded a washer between the 1" keyed portion and clutch spline portion inside the coupler to prevent it from moving.

The question is, should I put grease between the coupler and motor shaft to prevent the key from wearing out as the coupler moves around on it? I don't know. It will definitely work, but longevity has now become a giant variable.

puddleglum 08-29-2012 08:18 PM

Not to be a killjoy, but I don't think your plan to leave out the set screw is a good idea. There is not a lot of surface area to drive on with a key and keystock is not that hard to start with. I have seen a lot of key failures caused from loose set screws, and often times the keyway in the shaft and the coupler are damaged as well. It's your call, but I think you should find a better fitting coupler.

mechman600 08-29-2012 10:22 PM

Thanks for the advise. I am guessing that the most torque going through this coupler will be 40-50 ft/lbs with minimal torsional vibration. I had guessed that a 1/4" key would be able to handle this, but maybe not.

For those non-Ecomodder types, and for a bit of extra EV commentary, I have also started a conversion blog here, for those interested:
Project: Electric Booger

Daox 09-04-2012 11:42 AM

Its good to see this project progressing!

I would have to agree a solid motor coupling is essential. The more slop the more its going to not only wear out your coupling, but your motor and transmissions bearings.

mechman600 09-06-2012 01:34 AM

Thanks for the coupler advise. I agree that a good fit is essential. So today I finally set out to figure out why my one inch keyed hub fits so loosely on the motor shaft. Let me remind you that in a previous post, I blamed Princess Auto (the local surplus store) for what I assumed was a poor quality, mis-machined part.

Out came my 0-1" micrometer and inside bore gauge. It turns out that the Princess auto piece is exactly one inch ID. It also turns out that the motor shaft is .982" OD. What this means, ladies and gentlemen, is that the shaft is not one inch in diameter, but 25mm. I didn't know they came in metric sizes. Weird. Back to the drawing board.

I am going to ship the whole thing to my friend Matt (a machinist) by the weekend - motor, a new 7/8" hub (that he can lathe out to fit the motor shaft. Wait, didn't I return one of those already?!) and clutch center. When he is finished, it will definitely work. So again I wait.

My apologies to Princess Auto. I will never doubt you again.

mechman600 09-08-2012 08:00 PM

Yesterday I purchased the last of my bits. I finally found a cheap vacuum pump that will work well for my brakes, a Volvo vacuum pump. Turns out that their turbocharged cars (and there are a lot of those) all use a vacuum pump for the brakes. Used - $55.
I also purchased a vacuum switch, PB-6 style potbox (with idle micro-switch), pre-charge resistor and a couple of 400A fuses from Cloud Electric.

Today I did some measuring and chopped the motor shaft shorter so it will be about 1/8" from the transmission input shaft when everything is bolted up.
The new coupler should be ready in a few days. I hope. Then all will bolt together nicely. I hope.

mechman600 09-11-2012 08:00 PM

Yesterday I took care of my power steering issue. I have converted it to armstrong steering. As strong arms will do all the work. Sorry, bad joke.
The hose is joining the input and return of the steering rack, basically just to keep crap out.

mechman600 09-15-2012 08:07 PM

The other day my buddy Matt (the machinist) redid my first adapter attempt. Here is a video of the nice true adapter spinning up:
I supported the transmission in a garbage can so the input shaft was pointing up and set the motor (bolted to the adapter plate) onto the transmission to trace the adapter plate out. A few minutes of drill press time and a lot of sawing and here is the result:
I spun it up to check for strange noises and all is well.

However...much to my dismay, I realized something today. This motor has a gear on the end opposite the transmission, and this end has an exposed bearing. It appears that this end was originally the drive end and was immersed in the oil of some sort of gearset. You can see the o-ring that sealed oil from leaking out. There is probably an oil seal on the motor shaft on the armature side of the bearing.
I have already come up with an end cap to seal it off so it is not exposed to the elements, but I need to figure out how to keep this bearing lubed. One way is to fill it up with grease and every once in a while remove the end cap to put more grease in. The other option is to make a small oil fill plug on the end cap that maintains a level of oil just above the bottom of the bearing.

What to do...what to do...

ron 09-15-2012 11:26 PM

have your bud machine a cup that seals on the oring and fill it with some 5-20 motor oil , that option sounds the best . in the future you may find a use for that extended gear.

mechman600 09-17-2012 03:43 PM


Originally Posted by ron (Post 328107)
have your bud machine a cup that seals on the oring and fill it with some 5-20 motor oil , that option sounds the best . in the future you may find a use for that extended gear.

I already came up with a cap using some 3" hose and a hacked up Peterbilt shock absorber. Pictures to follow. I will probably go with 75W90 gear oil since that is what this bearing bathed in until now.

Today I went to my USA mailbox and picked up my:

1. PB-6 potbox. It will work brilliantly for my purposes. The idle microswitch trips just off idle before the pot resistance starts changing. I will use this microswitch to turn the field power on and off (remember - I'm attempting to power a sepex motor with an Alltrax series/PM controller here!). This safety redundancy will ensure ultimate safety in case my Alltrax decides to weld itself into a closed circuit.

2. 2-400A fuses. One in the high amp wiring, one in the glovebox for backup.

3. Used Volvo vacuum pump. I already hooked it up to the brake booster, gave it 12 volts and pumped the brake pedal repeatedly (and quickly). This vacuum pump easily keeps up, so I will not need to make a vacuum reservoir. And that's good news.

4. Vacuum switch. It will tee into the brake booster vacuum supply and will turn the vacuum pump on and off through a relay.

mechman600 09-18-2012 04:40 AM

Here's the finished bearing end cap. I used a piece of 3" hose, a couple of clamps and I hacked and welded on the outer dust cover off a Peterbilt rear shock absorber. I drilled and tapped it for a plug that will set the oil level in the cap and it can be rotated to adjust the final oil level once installed in the car. I filled it with a couple ounces of 15W40 diesel engine oil. After a few hours nothing leaked out.
My buddy Matt (the machinist) advised me to go with oil instead of grease to lube the end bearing because of the high speeds it will be spinning. Grease would probably just fling out, causing a dry bearing situation. Dry is bad.

mechman600 10-04-2012 12:24 AM

The motor and transmission are installed and ready to go.
I had to fabricate a mount for the passenger side end of the motor to keep the engine/transmission angled correctly.
I also completed the front battery racks. I made them out of 1" angle iron and 1/2" square tubing.
Here are the five group 31 underhood batteries installed for fitting purposes. I am pleased to announce that they fit beautifully!
I am going to run ATF in the transaxle. The manual specifies ATF only for ultra low temperature climates, but considering this motor will not have much power, I'm not worried. The thin ATF should help with reducing driveline friction a tiny bit.

Daox 10-04-2012 09:50 AM


Originally Posted by mechman600 (Post 331955)
I am going to run ATF in the transaxle. The manual specifies ATF only for ultra low temperature climates, but considering this motor will not have much power, I'm not worried. The thin ATF should help with reducing driveline friction a tiny bit.

You might not have massive amounts of power, but you will have fairly decent torque. 450A on a 6.5" motor is going to give you around 70 ft/lbs which is about 70% of what the stock engine had. I'd recommend going with what the mfg recommends. You aren't going to loose much by staying with a thicker oil.

mechman600 10-06-2012 04:23 PM

Thanks for the advice, Doax. I agree with you on all things except the 70% of ICE torque one. There's no way the 1.5 had 100 ft/lbs! Probably more like 70-80. Therefore, your advice holds even more truth.

However, I have a bunch of ATF laying around, so I am using it temporarily for low speed testing and whatnot. Simply put, I was in a massive hurry to test this thing out and didn't feel like running to the store to buy gear oil! Here's a video:
I have also completed the rear battery rack:
That's right, no more back seat. My choices were to keep the useful trunk and use the useless back seat for batteries or keep the useless back seat and use the useful truck for batteries. It was an easy decision.

Next the control system and battery cables. Test drives by next week?

mechman600 10-08-2012 02:10 AM

Here's the pile of batteries installed in the rear battery rack:
The old girl is a little saggy in the back now with 480 lbs of lead in the back seat. It took about 45 psi of air in the rear tires to get rid of the bulges. Corvair style.

I also think I figured out my heater situation. I was going to replace the heater core with a ceramic element from a 110V heater, but I soon realized that removing the heater core in this car is a huge pain in the butt. However, I discovered that the heater fan is on the passenger side and connects to the heater box with a plastic pipe that can be removed in about 10 seconds:
There is a 1875 watt hair blow dryer on sale at Canadian Tire for $10 right now, and I think I will be able to dissect it and stuff it into this pipe, minus fan, powered by my entire pack voltage. It won't know the difference between AC and DC will it?

And to continue the eternal EV conversion gag of installing the charging plug in the ex-gas cap:

mechman600 10-08-2012 11:08 PM

Today I went out and bought the $10 blow dryer. I dissected it to get the heating coils out of it. Built into the coils is a bimetallic temp control switch and a thermal fuse for safety.
I mounted it into the plastic tube connecting the heater fan and heater box.
For a test, I turned the heater fan on and plugged the blow dryer coils into 120VAC. In a matter of seconds, the Booger's heater was blasting heat much better than it ever has (not a huge feat considering the coolant thermostat was stuck open ever since I owned it). I ran the heater for about 10 minutes. No funny smells, burning, melting or fire. I pulled it apart to make sure and all is well. It looks like the solution for heat was quick, cheap and painless after all!

mechman600 10-14-2012 12:03 PM

Lots of updates to catch up on.

1. Traction wiring is finished. I was able to find enough used 4/0 truck battery cable to do the job. Overkill, but awesome.

2. Control system wiring is finished. I am powering the field windings with 12/24V with a toggle switch on the gearshift (through a relay, of course). I am also using the potbox idle switch to turn the field power on only when the go pedal is pushed. I was able to find a decent sized diode to wire between the field terminals to eliminate the massive spark that occurred every time I turned the field power off.

3. The six Mastercraft 10/2A battery chargers are installed.

The first test drive was a fail. I remember watching a Ben Nelson video when he was trying his electric motorcycle for the first time and it went backwards. So I guess you can say I "pulled a Ben Nelson" on my first attempt. (Sorry, Ben). I put it in reverse to back off the ramps and the car lurched forward. So I backed off the ramps in first gear. forward gear and five reverse gears - that won't work. It turns out that I had mixed my field polarity up, and thankfully didn't blow up my field spike suppression diode.

Test drive #2 happened last night. It was a very short one around my townhouse complex, getting up to a whopping 20 km/h, but I did experience a massive "EV grin" that took hours to subside. My initial thoughts are that I believe I have succeeded in powering a sepex motor with a series/PM controller.

More updates/pictures/video to follow. Hopefully soon.

Here's my insurance papers now:
The lady at the insurance place was nice enough to change the fuel type for me.

mechman600 10-15-2012 01:26 AM

Today I was running power wires for my heater when I suddenly got a highly unexpected 72 volt shock. My ratchet was on a contactor lead and my elbow was touching a chassis bolt.


I thought I had very carefully isolated the traction wiring from the chassis... My multimeter showed a 72V difference between the chassis and traction positive. After a few moments of scratching my head, I decided to unplug the system voltage meter I installed last night and recheck. Once I did, there was no more voltage reading between chassis and traction pos. So my $8 four wire volt meter is not isolated and eventually will have to be chucked for something different.

Or is it something I should even worry about?

mechman600 10-15-2012 04:00 AM

I just got back from a fairly lengthy test drive. I am blown away by how well my electric car works. Yes, I can officially say those words out loud - "my electric car". I was actually nervous about going out with it. Would it break? Leave me stranded? Catch on fire?

I left the field voltage switched to 12V the entire time. I found that on 24V, the field relay got smoking hot and started making hissing noises. I have never heard a relay make hissing noises before, but I know that's a bad thing. I believe it is a high current problem, not a higher than-designed-for voltage problem.

In most EV conversions, you usually start off in second gear. But I found second gear far too weak, so I got used to taking off in first and switching to second at about 30 km/h. It seemed to top out at 60 km/h in second and I didn't bother with third because of lack of space, but I am confident that it will easily exceed my goal of 70 km/h.

After one lap around the block I started to get confident, so I kept driving around and around, turning here and there. I probably drove a total of 10 minutes, and not with economy in mind. When I got back to my garage, the system voltage still read 73.6 volts, which means I hardly put a dent in the battery capacity. So I have a feeling that my 20 km range goal might be a possibility.

The power brakes work amazing. There was no difference between being powered by a Volvo vacuum pump and being powered by vacuum from the old ICE.

How quickly does it accelerate? Not very quickly, but it accelerates and that's all that matters. You have to realize it is now a 3200 lb car with about 25 horsepower (on a good day).

When I got back to the garage I quickly opened the hood and checked to see how hot the motor is. Remember that I have a very small motor here and I am asking it to do a lot. The motor was definitely warm, but I could easily hold my hand on it, so things are looking good there too.

Stay tuned for more pictures and video in the next while. Now I just can't wait to drive it again!

Daox 10-15-2012 09:33 AM

Woohoo, congrats on going for your first good run! :thumbup:

Ryland 10-15-2012 09:44 AM

As far as the motor getting hot, the outside is not as much of an issue as the brushes and commutator getting hot, 350F/175C is about where it will start to cause damage.

mechman600 10-15-2012 12:00 PM


Originally Posted by Daox (Post 334160)
Woohoo, congrats on going for your first good run! :thumbup:

Thanks! Man, what a feeling. You watch all these YouTube videos of guys excited to be on their first EV run but it is a feeling that I could never have imagined. Never before has such low speeds been so thrilling!


Originally Posted by Ryland (Post 334161)
As far as the motor getting hot, the outside is not as much of an issue as the brushes and commutator getting hot, 350F/175C is about where it will start to cause damage.

Thanks for that info. 350F seems really hot to me. I will carry my infrared temp gun with me and stop to get an armature temp reading, especially after going up the hill on the way from work.

I also installed my hair dryer heater and wired it in last night. I wired it in so there is no way it will get power unless the heater fan is on. I turned the heat on for about 10 minutes and it blows...well...warm air. So it isn't as hot as with the ICE providing heat, but it is warmer than no heater. As long as it keeps the windshield clear, I'm happy.

As an experiment I am switching the 72VDC heater power with a regular old 12V 5-pin relay. After ten minutes it was slightly warm to the touch, but that's it. I also switch the 72 VDC key signal to the controller with one of these relays as well. I am concluding that at least to 72 volts, these relays work fine, keeping in mind that I am still using 12V on the control side (pins 85/86).

mechman600 10-17-2012 12:09 AM

Today was my first commute in the eBooger. It was a smashing success.

12V is not enough for the field in my sepex motor. Too little start off torque and it has to rev much too high to make decent power - the shift from first to second at 6000+ RPM. Plus, I can hear arcing brushes at higher revs. As soon as I switch to 24V field, the brush crackling sound goes away.

I measured field current today. It turns out that the field windings are 1 ohm. 12V = 12.5A, 24V = 25.0A.

I still have a major problem with a massive voltage surge from the field whenever the relay goes open. I tried to eliminate it with a large(ish) diode across the field terminals, which helped, but it's still there. When the field relay opens on 24V, the arcing lasts a few seconds and the relay gets smoking hot after a few on/offs.

I decided to run pin 87a of this relay to ground so the field surge goes straight to ground. At 24V it seems to have cured the arcing. However, when I tried 36V on the field, as soon as the relay opened sparks flew, and stink filled the air. Not good

What do I need to eliminate this voltage spike completely? What resistors, capacitors, diodes, etc. do I need and how do I do it?

How many amps can I safely give the field?

mechman600 10-17-2012 12:59 AM

Here's a thought: couldn't I buy a tiny 72V/100A controller to control the field current?
Controller Kelly 24-48V 50A Super High Efficiency #KDS48050E

jakobnev 10-17-2012 03:01 PM


I suspect the electric motor will heat your tranny less than an ICE would, so ATF shouldn't be a problem even if your climate is warmer.

Daox 10-17-2012 03:34 PM


Originally Posted by mechman600 (Post 334612)
What do I need to eliminate this voltage spike completely? What resistors, capacitors, diodes, etc. do I need and how do I do it?

I don't think you can eliminate it completely. Some additional super fast (transil) diodes are what I have always heard suggested.


How many amps can I safely give the field?
It might be best to take the motor apart and see what gauge wire the field wires are. From there you can at least get some idea how many amps they can take.

95curd 10-17-2012 11:21 PM

nice bulid! looks like it's coming together real nice. Are you planning on any luxuries like radio and AC?

mechman600 10-19-2012 01:00 AM


Originally Posted by 95curd (Post 334799)
nice bulid! looks like it's coming together real nice. Are you planning on any luxuries like radio and AC?

The car never had AC. But it does have a fully functional 6-CD changer in the trunk (a la 1992).

-Top Speed on flat ground (so far): 80 km/h and still accelerating. I just haven't had the opportunity nor the space to do a true top speed run yet.
-Range: I have no idea. But it gets me to work and gets me back from work without putting a dent in the system voltmeter's reading.
-Charging time: after 6.5 km (with a big downhill) commute to work, three hours; after the commute home (with a big uphill), four hours.

A question that I have been asked three times in the last two days is:
"Have you thought about putting an alternator on the drive axle so you can charge the batteries while you drive?"

Oi. As a response, I usually refer to this video:

Field Power Problems

Yesterday I installed a larger relay to turn the field on and off - a relay that closely resembles a starter relay on some Ford vehicles. Now that the field power is being interupted with the larger relay, there is no arcing or funny relay noises even with 48 volts going to it. I seem to have solved this arcing issue for the time being. I am not sure the field voltage choice relay will last very long with the amount current I am forcing through it (it is merely a plastic, square 40A 5-pin relay) but I guess I will have to find out the hard way. I do have a spare relay in the glove box after all!

The other day I measured field current, which for power curve sakes is probably a more important figure than field voltage. But it turns out that the field winding resistance is exactly one ohm, so 12.5V applied = 12.5 amps, 25V = 25 amps, etc. Now I am at 48V for start off, and it makes quite a difference in torque. Most times I can take off from a stop in second gear.

Battery Diagnostics

I was originally going to install six small digital volt meters in an array to monitor each battery pair. I even bought a bunch of meters off eBay. However, in my great haste to get this car on the road I left them out. But it turns out that detecting bad batteries will not require individual volt meters.

Yesterday I charged the batteries after my commute home from work. I noticed that it took one pair an extra hour to charge, and one of these two batteries was making bubbling sounds. The next day when I got to work I immediately unhooked these two batteries from each other and measured their resting voltage. The one that had been bubbling while charging was a full volt lower than the other, so I charged it, removed it and load tested it. Yup, toast. 350 amps instantly brought it down to 7 volts. A battery should be about to handle half its cold cranking amps (these are 700CCA batteries) for 15 seconds and still be at 9.6V or greater. I quickly found a replacement in the core shed at work, tested it (9.8V on a load test) and replaced the dud. One the next full charge all of the chargers turned off within 15 minutes of each other. Problem solved. I guess this is another advantage of using individual 12 volt battery chargers.

Alltrax Controller

A buddy of mine lent me his remote inductive ammeter so I could monitor motor current. I am proud to say that Alltrax does not lie in their specs of 450A for two minutes and 350A for five minutes. On the way home from work yesterday I floored it all the way up the long hill. When I reached peak voltage (which is also peak power) and the current started to fall (57 km/h in second gear) I shifted into third and it held 450A all the way up the hill while still gaining speed. I am highly impressed with this controller.

Other than a little bit more tweaking and tinkering, I believe I can truly say that this project is quickly coming to a close. Today I finished my control panel that looks much better than the gaping hole under the radio:
I absolutely love the old school red LED numbers. Dr. Emmett Brown would indeed be proud!

The extra meter in the centre will be the voltmeter for the 12V accessory battery. The switch on the right is the heater switch and the switch under the system voltmeter will be used to turn the voltmeter on and off. This switch is my solution to the fact that the [super cheap eBay] system voltmeter is causing a shared ground between the chassis and the traction system. I plan to power this voltmeter with a 9 volt battery through this switch to eliminate this problem.


I did use it today. It was pouring rain outside and about 10C. It was merely a ploy to keep the windshield from fogging up and it completely worked. When I got home I put the inductive ammeter on the supply wire: 7 amps. 72V X 7A = 504 watts. Not substantial, but it's better than nothing!

Here is a picture of the organized mess formerly known as the engine compartment:
I hope to have some videos soon. Until then, you will have to be patient!

mechman600 10-22-2012 12:47 PM

Battery Woes
The last few days I have been trying to get my battery pack in as good of condition as possible. This is relatively speaking, of course, because these are all used "dual purpose" group 31 batteries taken out of heavy trucks.

Last week I replaced one battery because after it took forever to charge, it failed my half CCA (350 amp) 15 second load test, sagging to 7.0V. 9.6V is minimum for a good battery.

The next day I went out for some errands on an 11 km long run and I barely made it home because the pack was sagging so hard by the end (down to 49V on acceleration at one point!). So the next day after driving to work and before charging, I gave each battery a 200 amp load test and found all batteries sagging to 10.3V-10.8V except one that was sagging to 8.5V, so I replaced it.

Now I have one battery that performs well, but once charged drops in voltage to 0.2V below all others. It slowly discharges and takes it's "buddy" down with it unless I keep the car plugged in, and then the charger cycles on and off to keep these two fully charged. Today at work I will swap it out for my very last free spare battery and hope for the best.

I am not sure what I will do if (or when?) the next battery lays an egg because my free battery supply is dwindling. I hope that the batteries I murdered so far were faulty all along (which is likely because they were removed from trucks for a reason) and that they are not being prematurely murdered by my car. I guess I will know soon enough.

If these Paccar Dual-Purpose batteries cannot handle duty in my electric car I may start replacing them two at a time with new deep cycle batteries from Interstate Battery. Through my work I get a smoking deal at Interstate and I would have 30 month warranty that way. But I wonder if I should replace dead ones with new as they fail or just pull the pin and drop $1000 on a new pack so I can just forget about it and be happy....

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