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Uncontroller

4K views 21 replies 7 participants last post by  Braindead 
#1 · (Edited)
This is my third attempt to do a posting, never seem to know how to post anything but here goes . . .
Are there any affordable controllers for a DC motor and what rating of motor do I need to propel a 3/4 ton pickup to 60 kph with a 1500 kg load on board (Max practical GVW in Imperial measure would be around 10,000 lbs). My idea of an "affordable" controller would be around $200 - 400.
If more than one (identical) motor is run off the same controller, does it have to handle twice the load or is there a trick to get around that?
I am thinking I may have to design my own controller to get something that does not require a degree in rocket surgery to just hook it up.
I have a question about transmissions. I remember some of the locals having automatics with clutches (clutchomatic was the term I heard), other than being somewhat expensive are they practical for an EV?
Also I have questions about regen. Has anyone ever made a setup with alternative propulsion systems in an EV?
I remember reading about a teacher or professor a long time ago who had a Pinto that he drove into a parking lot, shut the engine off, then drove away.
Uphill.
He had fitted the Pinto with a flywheel under the car that was spun while decelerating. Not that I want a potential shrapnel spreader and gyroscope under my butt, however what if the regen also wound some kind of clockspring or rubber band, as well as charging batteries. That way my truck would have an easier time accelerating up a hill with a heavy load from a full stop, possibly utilizing the front axle of a 4X4 and the electric on the rear axle.
 
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#2 ·
hate to break this to you but: it ain't gonna happen the way this is written.

Figure perhaps at least $10,000 for the assorted bits, even scrounging about in super miser mode.

10000 MGWV means really big stuff which also means expensive and complicated. It may not be rocket science.

Start small do a lot of research then go do this.
 
#3 ·
I am starting small. I am building a "trailer tugger" and an ebike for a bit of practical experience. But I think I have the answer to the controller issue. I have a theoretical design ready to be built. Plus I have a bunch of floor sweeper drive transaxles to practice with. I have just fitted one with a treadmill motor, should be interesting to see what three times the power and about five times the RPM is going to do. The drive axle is very robust, so I actually do not expect it to break.
I was just wondering what correlation the controller's pulse frequency has to the motor's output? Is higher frequency better, or is there an optimum and is if there is an optimum, is it the same for all motors and voltages?
Thanks for responding.
 
#4 ·
something in the 10khz range seems to work. no big efficiency loss till you get extreme. There is an optimal but you have to find it experimentally.

too low and you lose current resolution, higher peaks, might let out the smoke. (pack voltage/impedance and motor inductance are major factors)

too high and you get into switching losses, or the switches just cant handle it (worse for igbt vs mosfets).
 
#5 ·
I will look online for a graph or chart showing the voltage output of a controller.
What about the alternative propulsion, or "augmented acceleration" idea? I know it has to have merit, especially in a case such as mine where I need to move a relatively heavy mass from a dead stop many times in a day. I wonder what the energy efficiency of a spring is? Or, it just occurred to me that maybe a pneumatic system would work. It would be somewhat ironic if the answer to my question was an air pump, since an infernal combustion engine is basically an air pump.
Also I had been thinking about using multiple motors inline and switching off motors when less power is required, possibly even using a clutch between to reduce parasitic drag when not in use. Or, for that matter, a small motor with a flywheel and clutch that spools up before use that is only engaged at initial acceleration from a standing stop. I will try to implement that on my trailer tugger. Throw in a treadmill motor with it's flywheel attached.
I know that some of these are way "out there" on the feasibility scale, but that is how I have always been able to do what I was told cannot be done. By trying unique ideas instead of dismissing them arbitrarily.
Besides, trying stuff that was not intended to be done the way you are doing it is usually lots of fun.
Besides, I use safety equipment and we have full medical in Canada, what could possibly go wrong? ; )
 
#6 ·
but that is how I have always been able to do what I was told cannot be done.
some will tell you they appreciate your enthusiasm, I will tell you I don't give a rat crap. Except when I try to explain why it wont work you will be closed minded to the explanations, and accuse me of being closed minded in kind, so this is a big red flag. This isn't about an electric car conversion but how awesome you are in your own mind.

What about the alternative propulsion, or "augmented acceleration" idea?
it sucks, not worth my time anyway, long story, comes down to physics and energy density, and budget and experience and knowledge and resources and time. You don't fully understand it so you are defaulting to an optimistic mode where it is magically going to work, though you haven't defined what "works" means. I define "works" as offering a meaningful efficiency improvement over existing solutions FWIW (within time/budget constraints of course).

If you can design a controller, and clearly identify the losses in an existing system, and make improvements, there might be hope for you. But as long as you are throwing scrap at tornadoes and hoping a 747 will pop out, I can't talk to you.
 
#7 ·
At a minimum you will need about 1 horsepower for every 100 lb. (the early Bugs where about 1 horsepower for 60 lb. but expected to hit 110 kph slowly, while you are only asking for 60 kph.) The motor and the controller are both less than 100% efficient, so you need about 1 kW for each horsepower (at 100% efficiency it is 746 watts per horsepower.) Look around for controllers than can dish out 100 kW. Look around for a battery pack that can dish out 100 kW.

You don't build an EV to save money. The upfront cost is high and if you do well it might save you money over the service life of your conversion.
 
#8 ·
dcb, as far as the technical aspects, you are probably right. I am just being myself, hence the screen name I chose.
I enjoy screw-ups and successes almost equally. Success for the obvious reason, failures for the experience and the knowledge gained.
I learned to cook by trying anything and everything. I can now cook pretty good, there were a few "less than stellar" meals along the way, to be honest. I am a disabled single parent that makes a living by removing old equipment and re purposing almost anything that otherwise has no value. I have a good deal on hospital bed batteries that are only two years old and have to be removed from service regardless of the condition, they are 6.5" x 7" x 5" SLA batteries, and I get them DIRT cheap. So far only one has had any issues. I have measured and they will fit between and on the outside of the frame rails easily, and still under the sheetmetal of the bodywork. for the last year I have been saving up materials for the builds. Other than the batteries I get most of it free, or get paid to take it away almost as often. I am using mostly obsolete, unwanted, and broken equipment (obviously I REPAIR the broken equipment before I use it), so I work with what I have on hand, and make do. Like using a paint shaker to make "crushed" glass for the sand blaster, I use a modified double ended paint shaker as a ground tamper, converted a ride-on floor sweeper into a snowplow/tractor, and used high-end hospital beds to make equipment lifts.
IF my idea for a controller works, fantastic, and yes I am exceedingly optimistic on that front. I don't expect it to be easy, though, one particular part is going to be a daunting challenge to make.
If I was doing this to save money, then I WOULD be delusional, I understand the financial implications VERY well.
And, perhaps I look at life a bit differently than most. I think that is what individualism is all about. I am building the vehicles for the experience, because it is educational, and interesting, and I get to converse with interesting people such as yourself and the other members of this site, and the other sites that I am a member of.
I do not want to waste anyone's time, I just ask for answers if they are available. I like to test the status quo, i guess, take nothing for granted.
 
#9 ·
EVfun, and piotrsko, thanks for the input. I was going about this all wrong, but I have to work with what I have. I am putting the pickup on the back burner until the proof of concept small scale vehicles are finished first. At least they will cost almost nothing. Instead of the truck, I have a frame that will make a pretty decent Honda Odyssey type dune buggy, and that will be my third build. Slightly larger than the first two (ebike and trailer tugger), and should be loads of fun.
 
#10 ·
I have a good deal on hospital bed batteries that are only two years old and have to be removed from service regardless of the condition, they are 6.5" x 7" x 5" SLA batteries, and I get them DIRT cheap.
Lead batteries are nice to start with. They are cheap, simple, and safe.
They work fine for "proof of concept", but when you want to go more than 15 or 20 miles they suck!
 
#12 ·
Well, in my experience anyone saying they got 40 plus miles per charge from their lead acid packs were either full of shit or drove like they were in a golf cart. I built a very good lead acid build of 96 volts of 6 volt golf cart batteries with a very good controller and motor and a very good rolling resistence. The car at best would get 25 miles at 55mph max and that max was crawling into my driveway. I quadruple checked everything and quadrupled it all again and again to see if anything was out of whack.

The reason I decided to do an electric car was because all those builds shown over on EVALBUM stating that they could do 60 miles per charge using lead acid was no brainer. I said, shit, I can do that and I did. I was gassed at doing this because I only had 22 miles each way into work on a flat road pretty much all the way there and back. What a perfect way to travel. So I built my car. I was so disappointed that it was all bull shit on the range. I finally realized that those ranges being posted were calculations and not real world and I did build my electric car to go car speeds. Had I wanted to go golf cart speeds I would have built a golf cart. I did not build a car to drive like a golf cart.

Sorry but Lead is for starting your gas car or powering your golf cart. Nothing else.

Go with lithium. Hands down. LiFePO4 or others will do.

Pete :)

PS. I would not trade my electric for gas but I sure would not go with lead acid again. Not for any reason.
 
#14 ·
LOL. I drive electric cars every day. I commute to work and back but the car is not LEAD ACID.

The other problem with lead is the dangerous overweight of the vehicle that has been put on the road. Cars were designed with a max allowable SAFE weight. Lead will take that well over that SAFE limit.

The other issue is they just don't have the life expectancy of Lithium.

I don't buy the BS about Lead Acid Batteries and many others don't either. This is from experience.

By the way. I know of plenty of other Lead Acid Builds that don't get good mileage either. Putting around is fine. If that is all you need then by all means go lead if you must. I'd still go Lithium because of life issues.

The other is Lead as is discharges in a linear way so when get to half it will take more to continue the same rate of driving and eventually it will just not have the ooomph to go and you MUST stop. Usualy within 25 miles or less.

Show me your 40 mile @ 55mph EV Build.
 
#17 ·
Yeah, I suspected that was the case with batteries. That puts a different spin on things, really. I guess I will know more after some tests with the tugger and ebike. The lead batteries were the reason I was going with a truck in the first place, for their load carrying capacity. That, and about 70-80% of the driving I do is in my trucks. Fortunately I have a very short distance to cover in the truck, longest trip is about 10 miles or less. And that is only two or three times per week at the end of the day, other than that the rest is every day, stop and go between 100 feet to a half mile from one stop to the next, then the three mile drive back to my yard. Total time from departure to return is from 45 minutes to 1-1/2 hours.
I figured that is the perfect situation for an EV. Now I am thinking maybe I will return to my original idea of just a helper motor hooked up to the front axle from a 4x4 on my current pickup. Just use it for the rush hour drive three days a week when it takes up to a half hour to go one mile. I was thinking I could just shut the engine off and use a small motor to move ahead because it is often slower than walking. If it is small enough, maybe I don't even need a controller.
 
#18 ·
For your needs and if you don't mind the upkeep with the lead acid batteries AND if you can find a source for reasonably priced Lead Acid then your situation may be just fine for Lead Acid. Personally after my experiences with Lead, I'd go with lithium and would purchase battery packs from wrecked electric cars. They are cheaper. If you decide to go with the Leaf Modules be sure to get them from the newest you can. Don't bother with the ones from 2011 or 2012. Prefered 2014 - 16. If you are building a power wall then the early ones will be fine or a short distance runner.

Building my very first Lead Acid build was a great experience. It just sucked that the batteries just don't have what others were claiming. Had I only had a 10 mile commute round trip then my Build would have been quite useful. But it was not good for the 45 mile commute.

Go out and price out batteries before you make a decision. Price out Leaf Modules and Price out Lead Acid batteries. Out here in California Lead Batteries have gone through the roof in priceing. Just through the roof. Consumers are being horribly ripped off. Even cheap starter batteries for your car are outragiously priced.


Go price out batteries and let us know what they cost. Then price out for a 144 volt pack.

I'd still go with a straight Electric Truck vs trying to do the electric assist. How big of a Truck do you require? Remember, Trucks have a frame that you can put batteries in between below the bed of the truck. Built a tilt bed so you have access to the packs and put the packs forward of the rear axle.


 
#19 ·
I am getting the batteries for $5 each. Not a LOT of money, but it is manageable. I cannot see using anything else for my needs. Even if I only had a 20 mile range, I would be OK. I had always planned to use the space under the box and cab for battery storage. In the past I would use that space for subwoofer cabinets.
 
#21 ·
Originally I was planning to use my old 89 Ranger extended cab because it was fairly light, had absolutely no squeaks, rattles, shakes, vibrations, etc. It rode like it had just been built. Other than the transmission that acted like it had Alzheimer's. Then it was stolen, so I decided to focus on something larger, I currently have a 78 Mustang II 5.0 auto notchback (might be already sold), 93 Ranger 2.3 four cyl. with 5-speed standard cab, a 99 F150 extended cab short box with 4.2 auto, a 92 F150 300 six 5-speed standard cab long box, and a 95 F250 extended cab long box 460 auto with blown head gasket. My choice among these would lean heavily towards the 99 F150. It runs quite well (does need a starter) but it is a PAIN to service the ICE, because it sits under the windshield. and it is a prairie truck that has 400,000 km on it, so it has the lowest resale value as well.
What the execs at Ford were thinking when they designed these trucks, I just don't understand. "lets go from the 300 six, the best gas engine ever factory installed in a truck, and put in a new basically untested V6 and ram it waaaay back under the windshield, and while we are at it, lets put in a poorly designed spark plug"
I would like to meet the moral reprobate that came up with that line, and the sack of hammers that agreed with him.
 
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