Bike running slower.

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hguido1
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Joined: 09/16/2009
Points: 216

When I did the shunt mod and the 60v upgrade the xb-600 was reaching 30 mph on the stock speedometer pretty quickly. I know the speedometer is off because I installed a bike speedometer and it is really about 25mph not 30mph. Now after a few weeks of riding the speedometer takes much longer to get to 30 mph than before and most of the time it only reads about 28mph when not fully charged. My bike speedometer is also reading a little lower around 23.5 or 24mph. Can something have changed in the controller with the shunt mod or maybe the batteries are already going south. Just seems not to have as much pickup as it did, top speed is close to the same just taking alot longer to get there.

Also the terrain is not the issue since I am riding the same routes I always have. Weight of me and the bike is also the same.

Any idea guys?

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eeraser
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Joined: 02/23/2009
Points: 24
Re: Bike running slower.

I also noticed that after a few months, I felt my top speed was not as high when it was new. Over the summer, I had to replace all of the batteries and I felt that the top speed was higher, closer to when it was new. Jump ahead 3 months later and I feel my top speed has again began to decline. I wonder if the controller is wearing out the batteries faster than usual?

Has anybody upgraded the controllers and gotten better results with top speed and extended performance?

sixpax2k9
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Joined: 03/25/2009
Points: 285
Re: Bike running slower.

I also have to say that the acceleration and top speed of my bike have dropped as well. I even have completely re-wired the battery pack with 10 gauge wire. Next project is to replace ALL the wiring to the battery pack/controller/ and motor. The only thing I can think of would be that MAYBE to capacitors in the controller start to lose holding capacity when you run them at 60V+. If I recall they are only rated about 63V, although the ~68V you get from a fully charged pack wont fry them, perhaps it affects them. Perhaps I will order some new mosfets and caps and see if that changes anything....

Other than the caps and mosfets in the controller I cant think of anything else that would cause this... maybe something in the motor breaking in??? I doubt very seriously that it is the batteries as I have tried 5 brand new batteries with the same result.

__________________

Dave ; Tennessee
XB-600.

hguido1
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Joined: 09/16/2009
Points: 216
Re: Bike running slower.

We put a additional shunt into the controller to fool it as to how much current it is sending correct? Is it possible there is another circuit in the controller that limits the current to protect itself afer seeing the increased amount of current for a set amount of time? RC Timing circuit maybe? Is it possible that more resistance has developed in the shunt? I have no idea, I am just throwing ideas out there.

I now know I am not crazy. Thanks Guys.

sixpax2k9
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Joined: 03/25/2009
Points: 285
Re: Bike running slower.

I very highly doubt that a controller board at this level would be self correcting. Only high end electronics have such capabilities. MY best guess would be the capacitors or something with the motor or wiring. Or even just the batteries not holding/discharging as good as brand new ones.

__________________

Dave ; Tennessee
XB-600.

hguido1
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Joined: 09/16/2009
Points: 216
Re: Bike running slower.

You mean to tell me that this $100 controller isn't self correcting. LOL. You are right that makes more sense.

mf70
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Joined: 12/01/2006
Points: 712
Re: Bike running slower.

Try testing the individual batteries in your pack under load. It sure sounds like a sagging battery caused by unbalanced charging.

Depending on how you've added the fifth battery, you are asking to get the pack out of balance.

To test under load, I would open up the battery pack so all terminals are exposed for testing, and replace the controller/motor system with a nichrome wire of about 3 Ohms in a water bath.

captainslug
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Joined: 11/02/2008
Points: 177
Re: Bike running slower.

Make sure your tires are properly inflated. They can easily affect both your range and speed if they're not fully inflated.

sixpax2k9
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Joined: 03/25/2009
Points: 285
Re: Bike running slower.

mf70 wrote:

Try testing the individual batteries in your pack under load. It sure sounds like a sagging battery caused by unbalanced charging.

Depending on how you've added the fifth battery, you are asking to get the pack out of balance.

To test under load, I would open up the battery pack so all terminals are exposed for testing, and replace the controller/motor system with a nichrome wire of about 3 Ohms in a water bath.

That sounds fine in theory, however, after installing 5 brand new batteries each individually charged beforehand I still saw the same performance as beforehand. I dont know about anyone else, but the nichrome wire trick.... Well I am not sure how to do that or even what it would tell me.

captainslug wrote:

Make sure your tires are properly inflated. They can easily affect both your range and speed if they're not fully inflated.

Yes, I suggested that as well. It helped increase my performance closer to normal.

I still think it has something to do with going to 60V or higher with the stock controller. I really think that the caps and fets do get somewhat "damaged" by the higher voltages and lose effectiveness. I do not recall having a problem with the stock controller shunt modded performance decreasing before I went to 60V. It seemed to run fines and stayed the same for a few months until I went to 60V.

Guess if I take the trouble to order and install the higher Voltage fets and caps I will have to let you all know if there is a difference.

__________________

Dave ; Tennessee
XB-600.

mf70
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Joined: 12/01/2006
Points: 712
Re: Bike running slower.

I dont know about anyone else, but the nichrome wire trick.... Well I am not sure how to do that or even what it would tell me.

You need to measure the battery voltages individually, under load, and with a discharged pack. Batteries without load can seem almost fully charged. The stock controller won't let you put a load on a locked wheel for more than a few seconds, so you need to substitute a resistive load without using the controller. I've discussed the "nichrome trick" in another post, but it's pretty simple; anything with about three ohms resistance will pull about 15A @ 50V. Whatever it is will also get hot, so you'll need to cool it. I used jumper cables with the clamps holding the nichrome and the other end changed to my Anderson PowerPole pack connection, just beyond the BrainDrain's shnut.

marylandbob
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Joined: 06/22/2009
Points: 524
Re: Bike running slower.

Maybe your batteries are NOT getting fully charged? Try charging them separately, then test again. (A 5 battery string should measure around 72 volts immediately after full charge, or about 14 volts per "12 volt" battery, at or below 80 degrees F. temperature.) Check individual battery voltages, near the completion of charging, and be sure all cables/connectors are clean and tight. (If you were to carefully TOUCH the terminal connectors, right after a "Full speed" run, they should NOT be hot or very warm.-Be careful of electrical shock hazard!)-Bob

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Robert M. Curry

hguido1
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Joined: 09/16/2009
Points: 216
Re: Bike running slower.

I charged my batteries this morning and I had 67.2 volts after charging with 5 batteries. 13.44 per battery. I also checked voltage with all 6 batteries and it was 80.6 volts. I think the batteries are pretty balanced but they normally charge to 13.9 volts per battery. Just last week that was the voltage per battery. It was colder here today than it has been all year, could that have affected the charge voltage?

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