Controller/Electronics options

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Re: Controller/Electronics options

Postby Burgerman » 17 May 2018, 20:30

But thats 10Ah per kilometer. Thats 16Ah per mile?

:cussing

Most are getting 45 miles or 65 kilometers from 90Ah. Eg expresso in new york. Or 100 miles from 150Ah like snaker.

They are then getting around 1 mile per 2Ah worst case, and 1.5 miles per Ah best case.

Now thats on a run. Electric motors on a chair draw the least current when travelling in straight lines on flat ground. Turns, take 10x more. Ramps, hills, can take a lot more too. But thats an extreme rate of power use! Teslas new 3 car, does more distance per Ah than you do! Something must be very wrong!

If you were on lead, you would have got just 2.5 km. Or 1.4 miles... :oops:
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Re: Controller/Electronics options

Postby sin85 » 17 May 2018, 20:47

I have 140Ah and 9.3mph motor and cc 100km range on a run .
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Re: Controller/Electronics options

Postby hotwheels_75 » 17 May 2018, 23:00

I’m not sure what’s up then. That’s what I was expecting, similar to what you guys have gotten and why I was surprised when it dropped so soon. It could be that my guesstimate is way off. It was very little straight line driving, a 100 trips up and down my driveway, and dozens of laps around my back yard and around my pond with a couple trips around walking trails.

I put two km on this morning on a smooth trail, after a fresh recharge. I’m clocking my distance much more accurately and will watch my battery a lot closer this time.

I should be able to plug a cell checker to a balance lead and wire that to a Dsub connector and use that to plug into my charging cable and check my battery occasionally? Would that work?
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Re: Controller/Electronics options

Postby Burgerman » 18 May 2018, 00:37

yep!
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Re: Controller/Electronics options

Postby Burgerman » 18 May 2018, 00:48

Housework, sweeping up, turning left right, grass, gardens, slopes, hills, all use easily 10x more power than driving in straight lines, so its possible to do what you said you did.

Turning left, at zero speed, uses 100A per motor to turn. Every time you do it.
Driving at max speed uses maybe 10A or 15A or so.
Driving up a hill, anything up to 100A or greater..
Grass? Doubles everything.
Solid tyres, add a few amps.
Tired less efficient motors, maybe adds 10% wasted energy
Nose heavy chair, eats power on turns.
I can kill a set of lead batteries leaf blowing the crap off my drive and garden. In say 1 hour. And get roll back and no power3 or 4 times over!
Same chair will go 3 hours at 6 mph non stop and do 18 miles. In a straight line. But not if I waste a load of power getting ready in a morning around the house. That halves it.
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Re: Controller/Electronics options

Postby hotwheels_75 » 18 May 2018, 18:46

Burgerman wrote:Housework, sweeping up, turning left right, grass, gardens, slopes, hills, all use easily 10x more power than driving in straight lines, so its possible to do what you said you did.

Turning left, at zero speed, uses 100A per motor to turn. Every time you do it.
Driving at max speed uses maybe 10A or 15A or so.
Driving up a hill, anything up to 100A or greater..
Grass? Doubles everything.
Solid tyres, add a few amps.
Tired less efficient motors, maybe adds 10% wasted energy
Nose heavy chair, eats power on turns.
I can kill a set of lead batteries leaf blowing the crap off my drive and garden. In say 1 hour. And get roll back and no power3 or 4 times over!
Same chair will go 3 hours at 6 mph non stop and do 18 miles. In a straight line. But not if I waste a load of power getting ready in a morning around the house. That halves it.


Well in that case, it’s definitely possible then. My chair is still a bit nose heavy and the front suspension I find really makes the front casters grip the ground, so it’s hard to spin them around at times depending on the surface I’m driving on. So far rollback hasn’t been a big issue, with the lifepo4 and setting rollback temp to 70°.

I’m currently using lawn tractor tires on the hegar wheels and the black scooter tires in the front.

I’d like to get out on some sidewalks and test range that way. Unfortunately I’m in the country with no sidewalks.but I’ll get it figured out eventually!

Do you think the R-Net 120 would be a big improvement over the Pilot+ 100 amp?
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Re: Controller/Electronics options

Postby Burgerman » 18 May 2018, 19:39

It will give you a 20% increase in very low speed torque, ie turning etc or curb climbing. If you need it.

But 100 extra settings.
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Re: Controller/Electronics options

Postby snaker » 19 May 2018, 03:04

@hotwheels_75: Can you fit a camera and record your off-road in a couple of km? I am really tempted to see the way you drain 10Ah/1km :worship :worship :worship

A 4-digit voltmeter is easy but good and safe enough, fit it before your next 'draining test'.
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Re: Controller/Electronics options

Postby hotwheels_75 » 19 May 2018, 14:14

snaker wrote:@hotwheels_75: Can you fit a camera and record your off-road in a couple of km? I am really tempted to see the way you drain 10Ah/1km :worship :worship :worship

A 4-digit voltmeter is easy but good and safe enough, fit it before your next 'draining test'.


I was actually thinking of doing that! It doesn’t seem that extreme to me. But this chair was never efficient even when new 16 years ago. Built like a tank and heavy. It gets a very mixed bag of reviews. http://www.usatechguide.org/itemreview.php?itemid=353

Some also claiming only 5 - 6 miles per charge on lead. Others claiming 25 mile range... :roll: those might be from Mark E. himself. :D

I’ll see what I can do for a video.
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Re: Controller/Electronics options

Postby Burgerman » 19 May 2018, 15:55

Best way to find out is to fit a hobby type watt meter. Set it to measure Ah and Ah used. And do a couple of measured miles at 3mph on a runway type surface. Then do it at 6mph. And see how many Ah or mah its using per mile like that. It will show you its best possible range ability.

Then turn left/right a few times, and watch how much it wastes!
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Re: Controller/Electronics options

Postby Burgerman » 19 May 2018, 15:59

Heres a link. I use one fitted with andersons to see how many Amps,Ah, watt hours, etc each chair takes. Under various conditions.

https://hobbyking.com/en_us/turnigy-180 ... tore=en_us

With lithium having no capacity diminishing peukert, it easily lets you see straight line range accurately by just testing say 1km. Although in hill testing, or rapid acc/dec testing you actually get more range than this shows as it ignores any reverse currents by regeneration that occur.
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Re: Controller/Electronics options

Postby hotwheels_75 » 19 May 2018, 18:46

I assume you plug it inline between the battery and the power module?
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Re: Controller/Electronics options

Postby Burgerman » 19 May 2018, 19:31

Yep. Or between charger and chair to watch the charger or bench supply, and see what it does and how much it puts back. Or hobby packs in flight. Etc.
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Re: Controller/Electronics options

Postby hotwheels_75 » 19 May 2018, 19:58

Ok! Sounds useful!

Would this be capable enough? Looks like an identical design, just 30Amps less, but I can get it in 2 days instead of 2 to 6 weeks.

https://www.amazon.ca/RENOGY-High-Preci ... B00PSQPSWQ
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Re: Controller/Electronics options

Postby Burgerman » 19 May 2018, 21:31

Hopefully.
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Re: Controller/Electronics options

Postby hotwheels_75 » 20 May 2018, 21:46

snaker wrote:@hotwheels_75: Can you fit a camera and record your off-road in a couple of km? I am really tempted to see the way you drain 10Ah/1km :worship :worship :worship

A 4-digit voltmeter is easy but good and safe enough, fit it before your next 'draining test'.


Here’s a video of one of my favourite spots. Not the greatest quality, I didn’t realize my GoPro Settings had reset. I sped up most of it. Sound quality was awful, so I added some cheesy music. :dance This trip is probably right around 2km. There’s lots of gradual inclines, it’s hard to see in the video. It’s pretty easy going though.

I have another video of around my yard but I haven’t uploaded it yet.
I’ll get better video when I get my settings sorted, and a better mount for the camera.

https://youtu.be/Wdr76PzkTzs
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Re: Controller/Electronics options

Postby snaker » 21 May 2018, 01:48

Yes, that kind of surface eats a lot power. But it's only about 2-3Ah/1km in my case.

In the video, was it a nature park? There are some nature parks in my province, deep green as tropical jungles, cool all day a year and plenty of fresh air to breath. But they are fairly far from my house, my powerchair does not have enough power and speed to go there :thumbdown:
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Re: Controller/Electronics options

Postby hotwheels_75 » 21 May 2018, 02:38

Yes it’s a public park. Used to be a town water reservoir, but it’s been out of use for decades. The town converted it to a public park and walking trail. It’s about 20km from my home so I have to drive there in my van.

There’s another one a bit closer, an actual wildlife marsh, but still need a drive there. I’m going to video that one too. They’re both maintained, so the paths are always in pretty good shape.

Where do you live?
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Re: Controller/Electronics options

Postby snaker » 21 May 2018, 09:49

Now I am free in the radius of 50km, 20km seems a modest distance to me :mrgreen:

I am in Vietnam. Maybe I use wrong words "nature park", I meant protected jungles to reserve the environment for plant, trees, animals etc ... They are all 100-200km far, out of my reach :fencing

I just had a nice ride along a sea side. The road was not good, this surface ate about 1.5Ah/1km.
https://youtu.be/FpMiLJZnN3A
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Re: Controller/Electronics options

Postby hotwheels_75 » 25 May 2018, 02:10

Awesome! The road I live on not safe for wheelchair travel. So if I want to go somewhere I have to go in my van 1st. The park in my video is not really a nature reserve, although there is 1 of those that I go to. I've made a video that one that I will post
https://youtu.be/hhlh-C4nr-4


I definitely have a power consumption problem! After fully recharging I mostly only drove on the hardpacked dirt trails, nothing too aggressive, no full speed or big hillclimbing. I checked my pack level yesterday with the PL8 PC software and I was still at 26.2 V approximately. I had gone approximately 8 km on the trails. I went for a haircut today and was only on paved sidewalks for a couple hundred feet. I went around my yard a little bit and spent the rest of the day in the house and noticed my green bars were dropping. It dropped to the orange bars just moving around my room so I stuck it on the charger to see and it was down to 24 V. I didn't even get 10 km this time.

I started charging 3 hours ago using a preset espresso just posted in another thread, I bumped the charge amps up to 25 and it appears to be about 90% done.

My battery amp hour metre and analyser is in the mail, so I hope to have some data to look at soon. I have a set of identical motors on different gearboxes, I wonder if installing those motors on my gearboxes would make any difference?
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Re: Controller/Electronics options

Postby shirley_hkg » 25 May 2018, 02:38

Chair eats a lot of power to steer / maneuver , if it is nose-heavy . Check it out .

90Ah for 10km worry me a lot , that your entire system won't last long . :fencing
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Re: Controller/Electronics options

Postby expresso » 25 May 2018, 02:43

i get at least 30 miles from 90ah which i did today 646 with lift and tilt and about 10 mph
Quickie 636 - 230ah LifePo4
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Re: Controller/Electronics options

Postby hotwheels_75 » 30 May 2018, 18:17

I got my amp hour meter and analyzer. Going to be a few days before I can test it. I’m getting a few things modified so I can move the seat back one more notch and make it less nose heavy. I don’t have high hopes that alone will magically triple or quadruple my range like expresso and others get, but I’m determined to figure out the problem.

I don’t know if this is normal, but my seat tilting module draws power even when everything is shut off and not in use. I connected my amp hour metre and there was a 0.05 amp draw and between 0.7 and one watt. I narrowed it down to the tilt module.

Very small, but I’m looking under every stone to see where my power is going.

I suspect it’s a combination of very inefficient motors and gearboxes on a very heavy chair, along with the way the suspension works.… Causing a lot of friction and effort to make the chair moved in every direction
.
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Re: Controller/Electronics options

Postby Burgerman » 30 May 2018, 19:22

Yep... And terrain, use. Maybe inneficient old motors. And 8mph eats double the power on every turn and at every speed compared to 4mph. Everything is a compromise. Inc Ah to lb weight of chair.
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Re: Controller/Electronics options

Postby hotwheels_75 » 31 May 2018, 17:58

Question: if a chair came in a 6mph and 8mph version. How do manufacturers normally get that speed difference? Is it different gear ratios? Or different motors? Or a mix depending on the chair/manufacturer?
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Re: Controller/Electronics options

Postby Burgerman » 31 May 2018, 19:18

Gear ratios. And very occasionally and incorrectly in programming, leaving 25% free torque and 25% free range on the table for no good reason.
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Re: Controller/Electronics options

Postby hotwheels_75 » 31 May 2018, 21:47

That’s what I assumed. Although with the blast 650 which is the 6.25mph version of my chair, they used 2 pole motors and a 70amp controller :| I assume it’s a different gear ratio too. Trying to come up with options to improve my range and maintain decent performance...without scrapping the whole thing. :problem:
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Re: Controller/Electronics options

Postby Burgerman » 31 May 2018, 22:24

There are usually these options:

4mph HD with 4 pole. For high torque bariatric use.
4mph 2 pole because its cheap slow gives adequate torque.
6mph 2 pole because its cheap! And useless...
6mph 4 pole because it works properly, and can make use of a bigger amp controller.
8mph 4 pole - same as above, but less torque and control, high drain, more speed, otherwise the same as above. OK on flat ground, and are skinny...
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Re: Controller/Electronics options

Postby sin85 » 01 Jun 2018, 01:07

Burgerman wrote:There are usually these options:

4mph HD with 4 pole. For high torque bariatric use.
4mph 2 pole because its cheap slow gives adequate torque.
6mph 2 pole because its cheap! And useless...
6mph 4 pole because it works properly, and can make use of a bigger amp controller.
8mph 4 pole - same as above, but less torque and control, high drain, more speed, otherwise the same as above. OK on flat ground, and are skinny...


a question from the ignorant (me):
if you have the same controller(rnet 120 single channel) and a 10km version uses a motor that develops maximum torque @3000 rpm but controller is limited @150A 30 sec burst and;
15 km version motor develops maximum torque @4000 rpm but controller has 180A 30sec burst (and it can be upped to 210 A burst) would that solve the torque issue?
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Re: Controller/Electronics options

Postby Burgerman » 01 Jun 2018, 01:57

All DC motors develop max torque at stall. So theres something wrong with your figures.

And the motor impedance tells us exactly how many stall amps each will take. Expect it to be around 300/400. Dont try it it will burn or break something. In use it never sees this as the controller limits it. The torque is directly proportional to motor Amps. Which is greatest at stall, This High natural stall amp, falls away as the motor speed increases. Until at max free running speed, its about 5 Amps, and in a theoretical motor with no friction would be zero. At half RPM (half volts) free running, this is again 0A.
With a controller this is limited to x Amps, at both stall, and at up to a specific speed under load. So torque is determined by controller amps. Motor impedance then determines efficiency, and the point where max controller limited Amps drops away due to motor RPM.

In your case you will need to know that allowing the motor to pull 210A wont break something or wont burn something. Theres a reason they limited it. But yes provided the motor has low enough impedance it will increase drive motor torque.
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