Re: "Racing" the Duff Beer Electric Car

Fixing my earlier charger math, each charger uses 9.5A of 120v , so 1140w of input power to produce 1008w of charging power, so 88% efficiency. This thing should get much better MPG than the last iteration.

Currently it's on jack stands with pieces scattered all over the shop. You get a LOT of wrong parts when you order stuff for this car. Luckily I found an old Chilton's manual on eBay so I have pictures of what the correct parts are supposed to look like.

Everybody grab your brooms, it's shenanigans!

52 (edited by jrbe 2017-01-24 08:28 PM)

Re: "Racing" the Duff Beer Electric Car

This is very cool! You mention doing the regen braking from a button. Some motor controllers can use throttle position kind of like a manual transmission ice car. 0 tps is full regen (of where you set it), that tapered down to maybe 20-25% which is like coast / maintain, then 25% to 100% is some ramp of power / acceleration. Drivers get a dead spot feeling when starting off from a stop but feels more natural at speed I would think. Unless it has a smart ice like tps / regen "map" that takes speed into account.
If your controller can do tps proportional regen it may be easier to train all of the drivers to use (maybe help them actually use regen more consistently) and less jarring when it kicks in.

-Killer B's (as in rally) '84 4000Q 4.2V8. Audis never win?

Re: "Racing" the Duff Beer Electric Car

I broke down and bought a transducer, so we'll be basing it on pressure. I'd still like to be very aggressive with it, make it a brake-in-a-straight-line car. The stock non-power brakes are very weak and flimsy, so if we can get most of our braking done with the motor then it'll save me from having to do a minivan/LeBaron brake swap on it. I should finish getting all of the suspension bolted back on to it tomorrow and we'll drive it around tomorrow or Thursday.

Everybody grab your brooms, it's shenanigans!

Re: "Racing" the Duff Beer Electric Car

Just got it working, immediately took it out and did burnouts in front of the shop:

https://youtu.be/5fo1rVRPxbE

This feels 100x better than the old setup. Tomorrow we'll wire up some brake lights and take it out on the highway. Jay told us that it had to go 70 MPH, and it feels like it will hit that easily. I think I can actually pass someone at Barber.

Everybody grab your brooms, it's shenanigans!

Re: "Racing" the Duff Beer Electric Car

kakarot1232001 wrote:

what kind of motor you putting into that thing? naps are always good smile

HPEVS AC-51, Curtis 1239 controller, 144v nominal. (sold as a rather expensive package) It's shockingly lite versus the forklift that came out of it. The entire system weighs less than the original GE EV-1C controller. A big advantage with the 1239 is isolation between HV and LV circuitry.

kakarot1232001 wrote:

go full Lemons, scavenge alternators from pick and pulls. rewire them as motors. have fun smile

Lexus RX400h AWD rear motor-generator. 70hp and really makes the 2.5ton beast move. Alas, I've not found any, and no one has tinkered with driving it. If Yasa would like to sponsor us, I'd LOVE to have a pair (or two) of those things. (they hold the electric car speed record)

Bayley wrote:

Please be careful with those Lithium pouch cells from the Volt pack.

I found a spec sheet from LG (who makes them) before all that information disappeared from the web. They are a hybrid chemistry: LMO-NMC (google it) 3.2-4.1v is the "butter zone". They'll last for years in that range. 3.0v is the point where physical damage begins. 4.2v is the point where gassing begins. They are not prone to thermal runaway. (unlike Tesla - LiCo, the worst in the history of LiPo technology) I don't know how much they will sag at the bottom end. The testing in the above video were with an 130v pack that dropped to 127v at full (500A) load. And it's programmed to only allow full load for ~20s. (when either McDaniels brother is in the car, I'm flipping a hidden switch to reduce it even further. Roger said he liked it better like that!)

On the subject of regenerative brakes... I'm not going to set it up with a Tesla style "one pedal" mode. Zero throttle is neutral. We're accustomed to that, as the original DC forklift didn't have any regen at all. I would much rather draw zero amps coasting along than burn 50A keeping the motor spinning. And this motor is a lot more powerful, and efficient. It take a few dozen amps to get the car moving. The old system needed 50A to get it's attention. It took 100A to hold 45mph from T8-11 at CMP. As long as the pressure transducer works (it currently doesn't), the first ~10% of actual braking (manual brakes - you really have to stand on them) linearly progresses to 50% regen. I'll tweak that up or down as necessary. [the way it will be setup tomorrow is 30% regen with the brake lights. Once I actually reattach them.]

Duff Beer Civic (#128) -- 2014 Sebring - Class B (#1 of 7), 2016 Barber - Class B
1981 Jet Electrica 007 [Plymouth Horizon TC3] (#128) -- Mk.1 - Index of Effluency Eco (IOEe) @ 2016 Lemons South Fall, Mk.2 - Judges' Choice @ 2017 'Shine Country Classic, Mk.3 - Index of Effluency @ 2017 Southern Discomfort

Re: "Racing" the Duff Beer Electric Car

rmcdaniels wrote:

Just got it working, immediately took it out and did burnouts in front of the shop:

Roger I think your definition of "burnout" must be different than the rest of us.

Captain
Team Super Westerfield Bros.
#411
'93 Acura Integra

Re: "Racing" the Duff Beer Electric Car

We do sad EV car burnouts, any wheelspin counts.

Ricky could turn up the power and shorten the torque delivery ramp, but we're trying to take it easy on our 36YO VW Rabbit transmission. He's also trying to program it to give us maximum range and to prevent overheating anything, so power suffers.

Everybody grab your brooms, it's shenanigans!

Re: "Racing" the Duff Beer Electric Car

VKZ24 wrote:
rmcdaniels wrote:

Just got it working, immediately took it out and did burnouts in front of the shop:

Roger I think your definition of "burnout" must be different than the rest of us.

He meant in the Lucas sense of the word.

Re: "Racing" the Duff Beer Electric Car

VKZ24 wrote:

Roger I think your definition of "burnout" must be different than the rest of us.

Those tires cost $35 EACH. I'm not about to smoke 'em. *grin* That it can do that, at all, is impressive. The original system had trouble doing that on wet grass.

Duff Beer Civic (#128) -- 2014 Sebring - Class B (#1 of 7), 2016 Barber - Class B
1981 Jet Electrica 007 [Plymouth Horizon TC3] (#128) -- Mk.1 - Index of Effluency Eco (IOEe) @ 2016 Lemons South Fall, Mk.2 - Judges' Choice @ 2017 'Shine Country Classic, Mk.3 - Index of Effluency @ 2017 Southern Discomfort

Re: "Racing" the Duff Beer Electric Car

The old system would make smoke if you accelerated hard; it was just coming out of the motor.

Everybody grab your brooms, it's shenanigans!

Re: "Racing" the Duff Beer Electric Car

Passing a Food Lion truck at 72 MPH:

https://youtu.be/YHw5mp9tTdw

The CMP version of the electric race car wouldn't even have considered this.

The handling is also vastly improved without the extra 800 pounds of batteries back behind the rear axle.

I drove it around for 22 miles today before the batteries dropped to 3.3-3.2. I'm thinking that 8-lap stints at normal car speeds is doable.

Everybody grab your brooms, it's shenanigans!

Re: "Racing" the Duff Beer Electric Car

It is done, or close enough to it. I'm in Portland for the week at some meetings and will fly in on Saturday morning. Hopefully the rest of the team will already be there dominating.

100 laps is our target for the weekend.

Everybody grab your brooms, it's shenanigans!

Re: "Racing" the Duff Beer Electric Car

If you want to catch up and have dinner one night while you are in Portland let me know. I'm working on a project in Hillsboro.

Re: "Racing" the Duff Beer Electric Car

That would be fun. I'm in Tigard. I've got team building events (corporate annual sales meeting) every night except for Friday; does Friday work for you?

Everybody grab your brooms, it's shenanigans!

Re: "Racing" the Duff Beer Electric Car

My hat is off to you. This race really does have something for everyone; I'm glad to see someone pushing the envelope and literally doubling their vMax (can anyone else say they've done that in Lemons?) but man, this is more work than I'd ever want to put in to run 8 laps at a time. Did going fast just get too predictable for you guys?

OMG Racing '94 Benz S500 #140: https://www.facebook.com/pages/OMG-Raci … 2774944199
Judges Choice and Regional Award winner! Chuckwalla '12, Buttonwillow '13, BFE GP '15, Miller '14 & '15, Sonoma '13,'14,'15. Inde '16,17.Finisher of the inaugural Lemons Rally, in the black Jag.... and IOE in the Super Snipe back in '12...look for the #820 Audi back on a track near you in 2017!!

Re: "Racing" the Duff Beer Electric Car

rmcdaniels wrote:

That would be fun. I'm in Tigard. I've got team building events (corporate annual sales meeting) every night except for Friday; does Friday work for you?

Friday should work fine. Drop me a note directly and we can coordinate. trackgeeks at gmail.

Re: "Racing" the Duff Beer Electric Car

Type44 wrote:

and literally doubling their vMax (can anyone else say they've done that in Lemons?)

Just wait to see the new and improved '48 Plymouth...and it is a lot of work.

Re: "Racing" the Duff Beer Electric Car

Type44 wrote:

Did going fast just get too predictable for you guys?

Kind of, after winning B we got kicked to A and didn't want to go. The car was really just a joke, but after we actually ran it at CMP, we fell in love with the challenge.

It's still in the science experiment stage. We figure we'll need to turn 300 laps at CMP or Barber in order to actually be racing, so we're working out how to do that. This weekend we want to be the second slowest car on track and turn over 100 laps.

We really need a third battery pack for power and distance reasons, but we'll have to build a new battery box before we do that. So for now our stints will be short and slow, but not as short or as slow as they were at CMP.

Everybody grab your brooms, it's shenanigans!

Re: "Racing" the Duff Beer Electric Car

jfbeam wrote:
kakarot1232001 wrote:

go full Lemons, scavenge alternators from pick and pulls. rewire them as motors. have fun smile

Lexus RX400h AWD rear motor-generator. 70hp and really makes the 2.5ton beast move. Alas, I've not found any, and no one has tinkered with driving it. If Yasa would like to sponsor us, I'd LOVE to have a pair (or two) of those things. (they hold the electric car speed record)

I just checked and copart has quite a few of the RX400 hybrids available right now with salvage titles and listed as a pure sale.

Team FPO (For Parts Only)

Re: "Racing" the Duff Beer Electric Car

rmcdaniels wrote:
Type44 wrote:

Did going fast just get too predictable for you guys?

Kind of, after winning B we got kicked to A and didn't want to go. The car was really just a joke...

A horrible, expensive joke. If someone wants to bankroll a few 10's of thousands for state-of-the-art batteries, this thing would be a monster. (or an unstoppable fire in a wall if they're Tesla batteries) CALB and Voltronix make batteries that are ~5x as powerful, but 3x the cost. And we need A LOT OF THEM. Charging them during a race is unrealistic. At CMP this becomes "impossible" -- the power situation at CMP is iffy enough to use an angle grinder, getting a Tesla supercharger worth of power simply isn't possible. (Barber, however, has 50A RV plugs all over the place. And two actual EV chargers.)

Duff Beer Civic (#128) -- 2014 Sebring - Class B (#1 of 7), 2016 Barber - Class B
1981 Jet Electrica 007 [Plymouth Horizon TC3] (#128) -- Mk.1 - Index of Effluency Eco (IOEe) @ 2016 Lemons South Fall, Mk.2 - Judges' Choice @ 2017 'Shine Country Classic, Mk.3 - Index of Effluency @ 2017 Southern Discomfort

71 (edited by rmcdaniels 2017-02-07 04:47 PM)

Re: "Racing" the Duff Beer Electric Car

The car ran well. It's much faster now, we can actually race it.

Stints are still short, but over twice as long as last time. We need more batteries. I'll build a new battery box before CMP that will hold another battery pack. I want to be able to do 30-minute stints by next race.

Most of our chargers failed immediately. We were only able to charge one battery at a time. That severely limited our time on track. More/better chargers and better pre-race charger testing is necessary before CMP. I'm on the road for work now, but as soon as I return I'll order another Volt battery assembly and build more battery packs.

All things considered, it was a qualified success. We proved that the car can be run on track at race speeds. Now we just need to figure out how to keep it out there.

Everybody grab your brooms, it's shenanigans!

Re: "Racing" the Duff Beer Electric Car

Sorry about blowing you off Chris. With the ice storm on Friday they let us go early so I got on an earlier flight to get to Barber.


I got some work done on cell  monitoring. Much thanks to Craig from Terminally Confused for making a circuit board to let me use $2 cell monitor boards. Here's a video of one in action:

https://youtu.be/HEl3-F_K2KQ

I'm also working on batteries and charging. I want to turn some laps at CMP.

Everybody grab your brooms, it's shenanigans!

Re: "Racing" the Duff Beer Electric Car

No problem. Totally understand.

How do you do cell balancing when charging? Do you use a bunch of single cell chargers or do you have a balancer and charge the whole pack at once?

Re: "Racing" the Duff Beer Electric Car

TrackGeeks_Chris wrote:

How do you do cell balancing...

Poorly. With RC car chargers. That blow up. A lot. (The "A9" is an 8 cell charger they call a 12S charger. Yes, it has ports for 12, but it is completely an afterthought.)

In an ideal world, we'd use the fancy technology LG built for the things. However, they don't tell anyone anything about those custom ASICs. And I don't have an actual running Chevy Volt to spy on. (and that's not so easy either as that stuff is in the battery module.) Tesla, of course, uses commonly available, publicly documented TI chips. The Nissan Leaf BMS has been reverse engineered, and I have one, but it can only watch 96 cells. We're about to have 108 cells per pack.

Duff Beer Civic (#128) -- 2014 Sebring - Class B (#1 of 7), 2016 Barber - Class B
1981 Jet Electrica 007 [Plymouth Horizon TC3] (#128) -- Mk.1 - Index of Effluency Eco (IOEe) @ 2016 Lemons South Fall, Mk.2 - Judges' Choice @ 2017 'Shine Country Classic, Mk.3 - Index of Effluency @ 2017 Southern Discomfort

Re: "Racing" the Duff Beer Electric Car

We use RC chargers with an integrated cell balancer. We don't balance them on the way down, but the cell monitors are an attempt to give us a warning if one cell is discharging faster than the others. In our limited practice at Barber, they tended to discharge evenly.

The A9 charger is actually an offshoot of a commercial agricultural sprayer drone charger designed for a specific 12s battery pack. The commercial version comes in a Pelican case and is nicely integrated with a big DC power supply, but is not programmable and only charges to 4.2v. You connect it and hit the big button and wait until the charging light goes out. We are charging to 4.1 and probably don't want to exceed 4.15, so I like the programmable RC chargers better. They are also cheaper. I have no idea why they put the 12s functionality in a consumer/hobbyist-grade charger; pretty much everywhere they use 12s batteries in the RC world they are wired up as 6s packs.

Single cell chargers would be impractical; we'd need hundreds of them.

Also, anything that requires a big-ass wiring harness is impractical; we have to swap out battery packs pretty frequently. Of course we could build something in to the battery pack, but then we'd need a lot of them, so it would have to be something cheap. Before this is over I expect to have 9-12 battery packs.

I've ordered a whole-pack charger (a small one that will do one 48v battery module for testing) and cheap balancer board, but the balancer board will probably blow up in actual use. Ricky tried one at Barber and it blew up, but a lot of stuff blew up at Barber. The other limitation of the cheap balancer board is that we can't use it as it was designed to be used; we pull too much power during operation, so we'd have to just use it during charging.

RC chargers are a problem. Looking at the failure mode of the chargers and discounting the one or two that my poor QC process probably damaged when I was building power and balancing connector harnesses for them, I'm guessing (guessing because I haven't done differential equations since high school and am probably not going to do any more real soon) that we have an inrush current problem with the output filtering capacitors when we connect the battery packs. It's rarely seen in the RC world (although I have found references to it in some drone forums) because the batteries/wires in the RC world can't supply enough current to blow too much stuff up. We have huge batteries (compared to RC batteries) and big wires, so we can blow up stuff pretty well. I'm experimenting with a pre-charge harness for the battery charge connection now and will do a lot more experimentation and testing before CMP.

Barber was a success in one aspect, we made the car fast, but I ran out of time after prepping the car to do proper QC on the charging solution, and that hurt us. Charging and batteries are my first priority for CMP.

Everybody grab your brooms, it's shenanigans!