Intermittent Power Loss?

safe

safe

1 GW
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Dec 22, 2006
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This is an interesting problem...

Starting with my previous ride and getting worse today I've noticed that my electric bikes power is starting to become irregular. Sometimes when I roll on the power it goes through the powerband normally. Other times it will start to "power up" and then just flatten out and remain low. It seems that when I shift and try to rapidly crack open the throttle that it's more likely to occur than if I very slowly and gradually roll on the throttle from down low, but so far that's just my guess, it's hard to figure exactly at this point.

The batteries are fine, I've made certain of that by completely recharging them and testing the voltage and everything and they are fine.

So it has to be one of these three:

:arrow: 1. Motor (it only has 350 miles on it, so that's unlikely)

:arrow: 2. Controller (a very good possibility, it's an unmodified controller)

:arrow: 3. Throttle (I've already broken two of these, but they tend to get stuck in full throttle when they short out, so this is a new symptom)

Given the symptoms already described, what experiences have people had before? Give me a probability factor for each option or give me another idea if you have one...
 
I could also be a bad connection in the high current wires. Look around for melted spots. Othewise you might need to crack open the controller.
If you can manage to hang a voltmeter across the motor and watch it while riding (this can be hazardous), you could see if the motor is getting full power. A 36v light bulb across the motor might work too.
 
I used 16 guage wire and now I'm wondering if it would have been better if I used a thicker guage. The wires have DEFINITELY been warm (but not hot) to the touch after a hard ride. The wiring harness is rather intricate and completely taped from end to end, so it would be a major hassle to try to look into it.

Do controllers fail very often?

Or is a stock controller most likey to be okay?

The throttles that they sell for scooters are complete crap and if I were to guess what the problem is I'd guess it was the throttle. I've already had to replace two of them.
 
cheap Chinese controller fail often.
The wires usually only fail at the connection points.
16ga is too small. Go for 10ga or heavier to minimize losses.
I've not had any problems with the throttles I've used, but they might be higher quality ones.
 
fechter said:
cheap Chinese controllers fail often.
Click to expand...

But do the symptoms sound like a controller failure?

What usually happens when a controller goes bad?

The controller is a Model CT-660B9:

101205.gif


I've got another one to try which is better quality (I think) and is brand new... (YK42-3) Yi-Yun Brand:
101202.gif
 
Maybe--to rule out the harness and its terminations:

fechter's idea of a 36V bulb---and I suggest TWO of them: one across each end of the harness---at the controller, and at the motor.

And any differential in brightness also shows out the voltage drop across the harness length too.

fwiw (i dunno!)


r.
 
It's so much easier when things either work or don't work. When things work, but they do so in a manner that is inconsistant it's tricky. If there is a problem with the wiring then I might simply want to redo the entire wiring harness because I really shouldn't have used 16 gauge in the first place. I can convince myself it's a performance improvement (1% maybe) and it would ease my mind about the wires getting warm. That's NEVER a good sign!

The controller might still be failing too... (or the cheap throttle)

It also might be a good time to test those "Deans Connectors".

Hmmmmm....
 
When controllers fail, they usually expode a FET and get stuck on full throttle (I hate it when that happens) - or go completely dead. Smoke optional.

But there's a hundred ways to blow up a controller and I've only found about half of them so far.

Changing the wire is a no-brainer. Can't hurt, but may not solve the problem.

I hate intermittant failures too. It's somehow more satifying to have bits of exploded components to make a problem obvious.
 
:arrow: "A properly wired electric vehicle should NEVER have wires that get warm under ANY circumstance."

If that statement is correct then that's reason enough to redo the wiring and test out those "Deans Connectors" which I will need to use later in the next project anyway. (it's good practice and a decent upgrade)

It's very likely that the failure is with the connector that I know little about as far as it's internal capabilities. I bought it because it had six prongs and was rated as 16 gauge wire, but you never know how well built they are underneath the plastic of the connector. It's very possible that it's that one link in the system that is weakest and the rest of the wiring is okay. But that's enough to drag everything else down.... :(
 
After further inspection I do in fact have 10 gauge wires in the majority of my electrical harness.

HOWEVER :evil:

The crummy connector I bought has 16 gauge wires and they run about 3" out from each side of the connecter. I bought that connector before ever going to the Voltage Forum and so at the time I knew basically nothing. (it's this 3" wire segment that gets hot, the rest stays cool)

If I were to make a motorcycle comparision the bike seems to behave like the "gas filter" is clogged. If you use the throttle sparingly (and keep the amps low) then it works fine. But if you try to use the full current limit then it shorts out and loses power. Seems like right now I've got a machine that has a current limit of 40 amps, but in practice I can maybe use 30 amps. (wow, I got a "Boost Control" without even knowing it! :lol: )

So the answer is to cut out the old connector (and it's 16 gauge wires) and switch to the Deans Connector.

The correct answer (it seems) is that the wiring went bad.. (fechter gets a "gold star")

So I'll add to my original list:

:arrow: 4. Wiring (Check for shorts)
 
It was finally warm enough today to go out and test out my new wiring harness. No change. So I take the motor apart to check the brushes. They are fine. So then I try a different controller.

:arrow: Bingo!

It was the controller... (the weakest link it would seem)
 
Lessss said:
What in the controller? The Capacitor?
Click to expand...

I have no idea. All I did was swap out the old and put in the new and all of a sudden the power was back to normal. Someone like Fechter could probably take it apart and fix it, but I'll just buy replacements. So far I've burned up two throttles and one controller and I'm only up to 350 miles on the bike... (I wonder if the controller actually destroyed my throttles?)
 
Having already been through the cycle of constantly replacing lesser quality components on my projects, I tend to more readily accept investing in the greater initial cost of the good stuff. In the long run, I usually end up better off. Its things like the Transmagnetics motor/controller I had posted about a while back and you (safe) had posted about its greater cost. I can be a frugal man but I've learned sometimes spending more up front can save me a lot in the long run.

There can be many different factors when deciding on components and everyone's needs and drive for adventure are different. Greater costs doesn't always mean better dependability either as I'm sure we all already know.
 
101202.gif


The new one just looks of better quality to begin with. The other one was really cheap looking and I actually spray painted it to make it match my new color scheme and that might have added to it's quiick demise. (the problems began after the paint job) Maybe it trapped too much heat? Probably.

The new aluminum colored controller is fine without paint and since everything is all nicely packaged I hope to just run it and forget about it.

This time I'll solder in some "Deans Connectors" so the controller can be removed easily. If there is another problem I can swap out the controller in no time. At $25 apiece they aren't worth bothering with too much. (as long as they are a quick replacement)

With Lithium cells costing $5 apiece the controller is worth only 5 cells...
 
I'd like to see the insides also.
Heck, take apart the new one too. You might find something cool like an adjustable current limit.
 
fechter said:
I'd like to see the insides also.
Click to expand...

It's been spray painted. You won't be able to tell where there is a problem. When I did that (spray painted it) I was sort of thinking "well here goes nothing" and I'd have to guess it was heat buildup that caused some partial failure. Since it never completely "burned out" the problem is likely invisible.

The garage right now is 40 degrees and the day before yesterday it was just above freezing. Temperatures are going back down again and will be down for at least another week. We got ONE nice day (55 degrees) and so that's why I went out there and went for a ride. When it warms up I might fiddle with it, but I'll need to get the thing opened first and it doesn't "want" to open. So I'd have to wrestle with it for a while. (freezing cold tempts are no fun to work in)
 
fechter wrote:
I'd like to see the insides also.
Click to expand...


It's been spray painted.
Click to expand...

No wonder it busted, you sprayed paint in it!

Let us know how it goes with the new controller.
Where did you buy it?
I see TNC scooters is selling that model for $40 and electricscooterparts.com for about $60.
I might pick one up with an order for new tubes and tires my scooter requires.
 
xyster said:
I see TNC scooters is selling that model for $40.
Click to expand...

That one is the 36 Volt @ 40 Amp version which is only $25. (YK42-3)

But I also bought the 48 Volt @ 100 Amp version at the same time for $40. (YK42-4)

So I have both types... (and I'm sure I'll buy more later :wink: )

Spray paint was a bad idea, but it did work for about 50 miles before it must have over heated. I know when it happened too, it was a long hill climb at low rpms and the bike was already hot from about a half hours ride. No big deal though, I just replaced it and it's fine and now I've got the "Deans Connectors" and new wiring, so the whole thing got an upgrade.... (in this weather it's not like I'm "missing out" on any good riding days)

I did the whole bike paint job at the end of a long stretch of riding every day and I knew winter was coming and didn't want to be trying to paint in the cold. So now the paint is getting nice and hard and I won't have to worry about it next year.

Also, I don't want to be spending too much time on the "old bike" because there will be two more being built that will be much more "outrageous" than this one was with more power, lighter batteries and better aerodynamics.

So hopefully this bike is now "done" for good...
 
<<< WOW >>>

:arrow: What a difference a new controller makes!

I think from day one on my original controller it was not very good and it seemed to always lack low end torque. (like there was none at all) With this new controller all of a sudden I've got low end torque like I've never known existed before and the thing can now climb hills with ease that once used to make the bike struggle. Not only that, but the low end torque is SOOOOO much better that now I can use my tall "transaxle" gear (the 22 tooth verses the 14 tooth) and I'm hitting speeds of 38 mph with ease just in my neighborhood. And what's even better is the one "monster hill" that I could barely get up before I can now climb it easily with my tall 22 tooth gear! (and first gear)

:idea: This kind of makes me "rethink" everything because the power I'm getting now is what I "should" have gotten all along. So my personal experiences about the motor "powerband" were DEFINITELY distorted by a malfunctioning controller.

This means I'll be able to tack on about 10 mph to most of the places I ride already, so it's like practically having a new bike. The new wiring might also be helping too, the resistance is sure to be much lower.

The snow is melting and this week the tempertures will be in the 50's so I'll actually get some real riding in... I can't wait! :D
 
Good news! That explains plenty! Now u get to waste some amps LOL
U never checked it with a DVM? D'oh Shame on U LOL.
U call yerself an enggenner?
 
Matt Gruber said:
Good news! That explains plenty! Now u get to waste some amps LOL
Click to expand...

:arrow: The first controller was "supposed" to have a current limit of 40 amps, but I suspect that all along it was LESS than the specified amount.. probably around 25 amps or so. The reason I think this is that the top end hasn't changed much if at all. Ihere's no "extra" power in the top end and one wouldn't expect there to be because that area is bound by the physics of the motor.

:arrow: This new controller seems to allow a full 40 amps with no problem. It might be a good idea to get an amp meter so that I can verify what I'm getting. My next projects will have all that stuff.

The "lesson learned" is that you can't rely on the quality of the controller if it's a really cheap chinese one. Having never owner a better quality controller before I would have no "baseline" to compare it to.

:arrow: I've noticed another thing.... heat! For the first time my motor actually gets warmed up and I can see it being an issue which it never was before.

So the whole time I was riding on what was probably a 25 amp controller... (but the darn thing was listed as 40 amps) And the "defect" seems to have gotten progressively worse with time, so that now it's like a 10 amp controller.
 
The "lesson learned" is that you can't rely on the quality of the controller if it's a really cheap chinese one. Having never owner a better quality controller before I would have no "baseline" to compare it to.
Click to expand...

Not just Chinese controllers, the "40 amp" 4qd brushed controller from the UK I put on my scooter was noticeably weaker than the stock 30-amp chinese unit. I replaced it with the 80-amp model which was much, much stronger (I never measured current either).
Unfortunately, that 80 amp controller was defective and died right away. I received a refund and am back to the stock 36 volt, 30 amp unit, overvolting it to 48 volts.
In this case, even overvolted by 33% the cheap stock chinese controller has proven far more reliable than the 4x as expensive controller from the UK.
 
xyster said:
The "lesson learned" is that you can't rely on the quality of the controller if it's a really cheap chinese one. Having never owner a better quality controller before I would have no "baseline" to compare it to.
Click to expand...

Not just Chinese controllers, the "40 amp" 4qd brushed controller from the UK I put on my scooter was noticeably weaker than the stock 30-amp chinese unit. I replaced it with the 80-amp model which was much, much stronger (I never measured current either).
Unfortunately, that 80 amp controller was defective and died right away. I received a refund and am back to the stock 36 volt, 30 amp unit, overvolting it to 48 volts.
In this case, even overvolted by 33% the cheap stock chinese controller has proven far more reliable than the 4x as expensive controller from the UK.
Click to expand...


what controller do you use then? cheapo Chinese controllers in the UK seem to be a bit overpriced compared to the US

Andrew
 
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