Potential problem with throttle on an R-20

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ElectroLex
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Potential problem with throttle on an R-20

Hello forum. I'm all of a sudden having a reduction in the top speed of my R-20. As of now, the top speed that the speedometer reads (the speedometer accuracy problem is not relevant) on flat surfaces is 28 MPH, down from 35+ that the speedometer showed on flat runs prior to now.

In my thinking, this is either a problem with the batteries, the controller, or the throttle (or "accelerator" on the wiring diagram). Since I'm getting much better range with this reduced top-end speed problem, I'm inferring that this is not a problem with diminished battery capacity. My suspicion is that the throttle assembly is not working on the high end of the switch. I tested the leads yesterday with my multimeter and found that the 5 V line in registered 4.96 V. No problem there. However, when the throttle was fully turned to the highest position, the line out registered only 4.16 V .

Does this mean that the throttle is indeed the problem? Has anyone taken apart the assembly to try to fix it? I am hoping to not have to deal with EVTA on this issue.

Thanks in advance,
ElectroLex
Raleigh, NC

ElectroLex
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Re: Potential problem with throttle on an R-20

To follow up, after a charge at my office yesterday, I'm having the "lurch forward and won't go" problem now. I can get the scooter to lurch again after a reset or flipping the breaker, but I can't get more than half a second of acceleration out of the thing before it has no response and I have to reset it again.
No smells coming from the controller.

Any advice? Who thinks I should start the purchasing process for a Kelly controller?

--
EVTA R-20 with Kelly Controller - 2,500 km (odometer)
XM-3500li with 3,500 km and Fechter/Goodrum BMS

Scotty
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Re: Potential problem with throttle on an R-20

I don't know about the throttle voltage, but it sounds suspiciously like a controller problem.

When I started riding my Z-20, there were times when the bike would start to move and then just quit. Most of the time, recycling the throttle (going back to 0 and starting again) would get the bike going, sometimes I would turn the ignition off and back on and it would go. It didn't happen very often but did make me hesitant when entering traffic.

Then one day after about 4 miles on the first 90 degree day of the year, I was accelerating and the motor just quit after hitting about 20mph. I stopped, tried turning the ignition off and on, and waited to make sure the controller wasn't overheated, but all I could get was a little lurch and then nothing. After a number of attempts it wouldn't even lurch anymore. There was no smell from the controller, and even after I opened it (which Andy scolded me for) it did not appear to be burnt out.

After about 3 months of frustration with EVT, I finally got what Andy called a "4th" generation controller, installed it, and it has been working since. However, we have had a cool spring and are just now hitting the 90 degree mark again in Chicago. I've been hesitant to ride any distance in these temperatures.

I did purchase a KEB72601 replacement that I have not installed yet. I sent several email to Andy months ago trying to get a pre-wired Kelly and have never gotten a reply. But after emailing Kelly directly, I had my new controller 3 days later.

There is no question the Kelly is a better controller that should serve for the life of the bike, but I'm not really looking forward to figuring out the wiring. Kelly included a prewired "J2" cable that helps greatly, but is not plug and play.

So, it is possible you have lost a couple of MOSFETs in your controller and it is still working but at a reduced output. It is also still possible it could be batteries. One disadvantage of charging batteries in series is if batteries reach full charge at different rates, it is possible for one or two to get overcharge and damaged, which could then pull the whole pack voltage down.

I had added battery balancers to my bike and they are now standard on the 30 models. From what I read they seemed to be worth the roughly $180 I paid for them if they actually end up increasing pack life 2-3 times. The disadvantage I have found, is they are contantly balancing the batteries, so they are always pulling a small amount of power. If the bike sits without the charger for more than a few days, the pack will not be fully charged. They need to be disconnected for storage. Some people have also wired their bikes so they can use 5 separate 12 volt chagers, one for each battery. That also eliminates the imbalance problem.

Hope that helps.

Scott...

astar
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Re: Potential problem with throttle on an R-20

I would also suspect a controller problem. I had similar lurching behavior with the original EVTA controller. The Kelly controller does not have that problem. My throttle was returning 4.4 volts at full throttle, so your's may be a little on the low side, but I don't think it's your fundamental problem.

ZEV 7100 Alpine
Fort Collins, CO

ElectroLex
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Re: Potential problem with throttle on an R-20

Thanks for the replies, guys. I've ordered EVTA's customized Kelly controller kit with the expectation that a) it'll be easy to install and b) I will never need to replace another damn controller on the thing. The current [failed] controller is a "4th generation" one, and is the second replacement. Both of the previous replacements were acquired under warranty.

I'm going to get a new throttle, too, just to be sure. In doing the math, the reduction in the accelerator voltage is roughly proportional to the reduction in top-end speed. Just out of curiosity, does anyone know if the Kelly KEB72601 has an adjustment to be able to "tune in" the throttle's voltage range?

Maybe I'll make a tangent posting, but based on many postings in this forum, I've been pondering the likelihood of the OEM controllers' failures being the result of slightly high voltage (i.e. after a fresh charge of the batteries or during warmer conditions) damaging the FETs or other solid state components in the controllers? Maybe it's a little excess current that's caused some of the failures? Either way, how many of these controllers would be saved by a "dampener" circuit (I'm not an electrical engineer, so I'm not sure of the proper terminology)?

--
EVTA R-20 with Kelly Controller - 2,500 km (odometer)
XM-3500li with 3,500 km and Fechter/Goodrum BMS

Scotty
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Re: Potential problem with throttle on an R-20

Looking at the Kelly Controller manual, I don't see an adjustment for the voltage range. The manual shows a 0-5v range for the throttle. However, the controller does provide a 5v supply input. So, if the throttle is a variable resistor, the top end of the range is normally shorted. In other words, full throttle is the equivalent of putting the 5v supply directly into the throttle input.

The controller is programable using software that can be downloaded from their web site, so I wouldn't rule out being able to control the throttle voltage range.

As far as a "dampener", I'm thinking you are saying exactly what the Kelly controller does that the OEM does not, that is protect itself. If the controller detects an over current or over temperature condition, it will reduce output or shut itself off to prevent controller damage.

Scott...

antiscab
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Re: Potential problem with throttle on an R-20

Looking at the Kelly Controller manual, I don't see an adjustment for the voltage range. The manual shows a 0-5v range for the throttle. However, the controller does provide a 5v supply input. So, if the throttle is a variable resistor, the top end of the range is normally shorted.

Hi Scott,

in the configuration software, you can change the "0" lower voltage limit and the "full" upper voltage limit for the throttle.
they dont label it in volts, they label it as percentage.
for lower limit you can choose between 0, 10%, 20%, 30%, and upper you can choose between 80%, 90%, 100%.

you can use eitehr a variable resistor, or a hall effect device.
If you have the option, *always* use the hall effect device. They are more reliable and last *forever* (failure mode on a hall effect is not working, failure mode on a resistive throttle is dead spots of full throttle)

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

Iccarus
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Re: Potential problem with throttle on an R-20

Electrolex, Hi I just installed a kelly keb72601 in my xm3500li. It was fairly easy. If you have any questions post them here and maybe I can help. I live in Lindenhurst so we're In the same general area. You'll love the kelly controller and you should hook up the regen braking. You can set it to work through the throttle as is but I recommend getting a 0-5v thumb throttle and using that to get full variable regen. I'll post the link to some other info on regen.
http://visforvoltage.org/forum/6520-activating-regen-braking
If you look at the other thread that says kelly controller much smoother I left some info on installation. I could have done a better job. I might install one in a friends scooter. If I do I'll take some pictures and describe the process better. Hope this helps.
PS I know it's frustrating but the quiet electric ride is pretty cool you have to admit

2008 XM3500li Mods/Kelly KBL12251/84v 28cell 40AH pack/ Variable regen brake trigger on left brake handle/Givi/Cycle Analyst/Homemade BMS

KMX Typhoon Home build (recumbent pedelec) with two Astro Brushless 3220motors/twin castle Phoenix ICEHV 160/ Cycl

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