First Step to a Faster E-bike?

[REZN8R]

Hello,
Pardon my ignorance, but I just got into E-bikes and need help. I purchased a Crystalyte "Go-Hub" kit modified to 48V from Largo Scooters. The install was easy and everything works but... I was really hoping I could cruise around 20 mph unassisted and 25 or so while pedalling. I had my first comute to work today (22 mi one-way) and was kinda dissapointed with the speed. Without pedalling it would manage 12-14 mph, while pedalling I could only manage 18-19 mph. It's better then a regular mountain bike, but not by a lot. For some background, I am quite heavy (225 lbs) and the 4 SLA 12ah batteries are in the 45 lb range, but even if I lift the hub motor off of the ground and apply full throttle it tops out at around 19 mph. What gives? I guess my question is, what's the first step in a faster E-bike? More voltage, better controller, bigger motor? Does the throttle have anything to do with it? Thanks for any help!

 

[TylerDurden]

Hi.

In a nutshell, more volts will get you higher speed, but there are always some tradeoffs and related issues....

More volts = more batteries & possibly modding your controller to handle more Volts and Amps.
Better batteries (not lead) are lighter and don't have the voltage sag like lead does.... more $$$ tho.
More power (Volts and Amps) can overheat your motor, so due dilligence should be exercised.

Lotsa people here can help you find a solution that suits your interest & budget.

 

[csmarr]

The performance seems a bit weak for the kit you have. Check the voltage on the individual batteries and at the controller. You may not have good connections at the batteries. What kind of bike do you have? What are your tire and wheel size? Have you cheed for a dragging brake or other problem with the bike?

 

[REZN8R]

The bike is a cheap Wal-Mart mountain bike with 26" rims and Bontrager street tires. The brakes don't drag, the hub motor wheel spins fairly easily with no real resistance (sort of like a fan clutch on a car). This is interesting though, I just measured the batteries. A single battery is at 19.1 volts, and the output to the controller is 77 volts. That seems a little excessive for a "48" volt pack even at full charge doesn't it? The ID on one of the batteries is 'BL19L1', I can't find that model online. If they were 19 volt batteries and the kit was operating at 76 volts, wouldn't it be much faster? Or is there some sort of controller protection circuitry in action slowing everything down?

 

[TylerDurden]

I need to see pictures of this stuff...

:?

 

[EMF]

The bike is a cheap Wal-Mart mountain bike with 26" rims and Bontrager street tires. The brakes don't drag, the hub motor wheel spins fairly easily with no real resistance (sort of like a fan clutch on a car). This is interesting though, I just measured the batteries. A single battery is at 19.1 volts, and the output to the controller is 77 volts. That seems a little excessive for a "48" volt pack even at full charge doesn't it? The ID on one of the batteries is 'BL19L1', I can't find that model online. If they were 19 volt batteries and the kit was operating at 76 volts, wouldn't it be much faster? Or is there some sort of controller protection circuitry in action slowing everything down?

There is no way those voltages are correct, they both are off 50% it seems to me reading high. SLA is not going to put out 77 volts with 4 batteries, even in series. I think you have a bad battery or connection and you are not getting even 48 volts - and also a bad meter. Is the battery brand name BB? They use BPL model number, which is similar to what you see on the one and maybe the battery you read has a damaged lettering. You ought to check your car battery with your volt meter and see if the meter reads 14 volts or less. Then if it does, check each of your ebike batteries again.

Largo Scooters is a good place to buy a simple to assemble kit and the owner is very nice, I have emailed with him before as I considered getting one of his kits when I first started to investigate ebikes. If the batteries are making good connection to the controller and also they are fully charged, I think that bike ought to go up to 22-23 mph - at least 20 with a level surface without pedalling. Even if you are heavy on a level surface, this is not so important. He sells a special controller, it's very small, but it's rated at 20 amps, but I seriously doubt it would function at 77 volts so this is another clue that the voltages you are reading are not correct. Also, AFAIK, there is no speed limiter on it and the kits used to come with a Crystalyte 409. It looks like now they use a 408, but this motor ought to be fine too.

 

[OpAmp]

22 miles one way? Must be a misprint. That motor will do about 20-23mph with any Crystalyte controller on 12ah sla's at 48 volts. Where are you getting your speed-readings? Make sure that the wire between the batteries and controller are well soldered/connected.
You’re battery voltage readings are not correct no matter where you are getting your readings from, and there is no sla battery sold (that I know of) that will read 19 Volts. Maybe you have a junk worthy meter? :lol:

Don't be disappointed. You have a god old 408 motor that obviously works. Unfortunately there are some bugs that need to be worked out.

I bough the go-hub motor from Largo Scooters about 5 years ago, and until recently I upgraded the Crystalyte 408 motor (that it came with) to a 5303 motor. At 48 Volts (4 SLA batteries) my 408 kicked ass, and the 5303 has incredible speed.

 

[fechter]

Your meter must be off.

Check the little battery inside the meter. I've seen reports of whacky voltage readings when the meter battery got low.

 

[Drunkskunk]

If it's a Radio Shack meter, they are infamous for high readings as the internal battery dies.

Test it. Check a AA out of your TV remote or something. if it doesn't read 1.5 (for a disposable) then you're meter is dieing.

As for the motor, you should be breaking 20 without pedaling, So there seems to be something wrong with the batteries of a connection someplace. The motor has 1 moving part, and usualy it either works or it doesn't. who did you get the kit through, and have any pics of your setup?

 

[REZN8R]

Thanks for the replies guys. I checked the meter against a car battery and it read 12.8 volts, so I though it was accurate. It may be of on higher voltages. I have an analog meter I can use to recheck later. I'm getting the MPH numbers from a computer with the sensor on the front wheel. The computer was on my first mountain bike and seemed to be accurate. It's still calibrated to the same tire dimensions. It also feels accurate during the ride (22 mi one-way, no misprint ). All of the battery connections look good, I disconnected one battery and ran at 36 volts and it was indeed slower. Is it possible to over-tighten the hub motor bolts, or somehow install it so there is to much rolling resistance in the shaft bearings?

 

[REZN8R]

Ok, I just checked against the analog meter and the total output voltage is a much more reasonable 50v. I replaced the battery in my cheap meter and it still read 57. I was asking about the throttle because I received a thumb throttle that was labelled 36v. Would that make any difference?

 

[Drunkskunk]

Ok, I just checked against the analog meter and the total output voltage is a much more reasonable 50v. I replaced the battery in my cheap meter and it still read 57. I was asking about the throttle because I received a thumb throttle that was labelled 36v. Would that make any difference?

Those numbers sound a lot better. The car battery should read 12.66 volts if it's in good condition, with the car switched off. 12.6 and 12.7 are signs its that its bad, so it gives a tight window to judge accuracy. another source to use is your computer. its output is either 12V exactly, or 5v exactly.
Just a few things to help evaluate your meters.

As for the throttle, it shouldn't matter unless its one of the throttles with the lights on it. Thats said, its possible its just a bad throttle and not letting you give it full power.

 

[EMF]

I'm getting the MPH numbers from a computer with the sensor on the front wheel. The computer was on my first mountain bike and seemed to be accurate. It's still calibrated to the same tire dimensions. It also feels accurate during the ride (22 mi one-way, no misprint ). All of the battery connections look good, I disconnected one battery and ran at 36 volts and it was indeed slower. Is it possible to over-tighten the hub motor bolts, or somehow install it so there is to much rolling resistance in the shaft bearings?

I doubt there is a problem with rolling resistance as you have only 20 amps to play with. If the bike was being held back mechanically this much, you would have noticed the controller cutting out and also, you would never have made it 22 miles on those batteries. On the contrary, the bike must have very little rolling resistance and you must live in Illinois or some such flat area. I think you went so far, because you went so slow, not fighting as much wind resistance which makes me think your speedometer is correct. Now, I also suspect there is a problem with that throttle. Time to contact Largo Scooters for a replacement!

 

[REZN8R]

I live in Washington State, but my commute is generally flat, mostly on a paved bike trail (very little stop and go). I was also pedalling most of the time, because it was the maiden voyage and I didn't want to run out of juice half way to work. As for the throttle, it is the lighted kind but I was told it was used for both 36v and 48 volt systems :? . I don't know if Largos will replace it since it does technically work, but if I buy a replacement on my own it should only be $20-30 I would imagine. Thanks for the insight!

 

[EMF]

I live in Washington State, but my commute is generally flat, mostly on a paved bike trail (very little stop and go). I was also pedalling most of the time, because it was the maiden voyage and I didn't want to run out of juice half way to work. As for the throttle, it is the lighted kind but I was told it was used for both 36v and 48 volt systems :? . I don't know if Largos will replace it since it does technically work, but if I buy a replacement on my own it should only be $20-30 I would imagine. Thanks for the insight!

I think he would replace it. At least he seemed like a good guy when I emailed him a couple times. Just explain to him what is happening. He may have some ideas as well as to what may be the problem, since he sells these.

 

[REZN8R]

Chalk this one up to stupidity. I started thinking about the throttle and wondered "I wonder if I mounted it wrong or something...." So I turned off the power and gave it full thrttle to check the range of motion. Guess what, the paddle on the thumb throttle was hitting the bolt that keeps the grip shifter in place. So it would only go to about 3/4 throttle. I rotated the throttle upward to get a full range of motion and now it screams. I actually averaged 21 mph in to work! On the bright side, the insight from this forum led me to find the mistake instead of living with a dissapointing bike. Thanks to all who helped out!

 

[lazarus2405]

the paddle on the thumb throttle was hitting the bolt that keeps the grip shifter in place.

I've done the opposite: I mounted my half twist throttle so that it blocked the paddle of one of my shifters :lol: It was quite frustrating, not being able to use my gears.

 

[TylerDurden]

I turned off the power and gave it full thrttle to check the range of motion. Guess what, the paddle on the thumb throttle was hitting the bolt that keeps the grip shifter in place. So it would only go to about 3/4 throttle. I rotated the throttle upward to get a full range of motion and now it screams.

Kudos...

You can now edit your first post to direct nooBs to your last post. I think it qualifies as the first step.

 

[lazarus2405]

I think it qualifies as the first step.

You mean after recharging the battery? :wink: