Range expectations

Having lots of fun with my new build although I'm a little bit disappointed in the range. I took a trip of 14 miles total and my batteries were completely exhausted (11.6v).

I have X6 12v12a SLA running series to a 72v20a controller. I didn't/couldn't pedal much and kept the rpms high (efficient range on the 406). Not to many hills on this trip. Is something wrong?

Sounds par for the lead-acid course. 12ah SLAs are really 6-8ah under typical ebike amp demands.

Are they new SLA? Might take a few cycles to break them in.

Smoker said:

Having lots of fun with my new build although I'm a little bit disappointed in the range. I took a trip of 14 miles total and my batteries were completely exhausted (11.6v).

I have X6 12v12a SLA running series to a 72v20a controller. I didn't/couldn't pedal much and kept the rpms high (efficient range on the 406). Not to many hills on this trip. Is something wrong?

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got a watt meter? your SLAs have 864 watts total. but normal for an SLA under hard use is going to be arond 60%, 518 amps. thats before Peukert's effect kicks in. It depends on your speed and the bike, but i can see a 406 motor easily eating 400 watts in 14 miles at full speed. new batteries and Peukerts effect factored in, this may be about normal.

motor turning at most efficent RPM doesn't equate to getting most efficent mile per watt.

14 miles is not bad for a bike with xtracycle and 6 12ah batts. There was a guy who ran a 409 with 72 volts of 9ah sla's and got only 10 miles at 30mph at full throttle.

With that many sla's on board, you should be able to easily go over 20 miles with reduced speeds under 20 mph. If it can't then the 406 is an non-economy type motor.(amp eater)

OMG

Drop the lead, Lead Acid is dead for e-bike use NIMH or Lipo is where its at. there is no place for LA batts? I wouldnt even use an E-bike if it meant using Lead again, urgghh! Lipo is where its at!!

Knoxie

Small lead batteries such as 12ah batteries are good for semi-flat terrain areas. Knoxie lives in big hill areas. Thats why he doesn't like lead.

If I went from 42 volts to 72 volts of 12 ah batteries on my 408, this is what I would expect in range gains on semi-flat terrain. Its all about the lbs. Sure the current comes down when you raise the voltage. Keep the speed down and go forever.

42 volts = 31.5 lbs of lead
72 volts = 54.0 lbs of lead - 72% increase

42 volts = 15 miles at 20 mph
72 volts = 25 miles at 20 mph 72% increase

42 volts = 24 miles at 15 mph
72 volts = 41 miles at 15 mph 72% increase

I think your range issues are that:

1. the 406 is geared tall. You have the speed but at the expense of torque. I think a certain amount of torque helps with efficiency.

2. your bike is heavy-- especially with the extracycle on it

3. 32 mph is really fast. wind resistance is pretty significant at this speed. Basically anything over 25 mph (without fairing) is going to induce significant drag.

4. since all 6 batteries are in series, the peukert effect is, I believe, more pronounced-- even though your controller is "only" 20 amps

I too am using the 406 but on my 20" wheeled folder with about 500 watt hour batteries (milwaukee lithiums). My bike plus batteries weigh only 60 lbs and I have a top speed of 28 mph with 20 miles range at 20 mph. If i push it and do 28 mph all the time, range drops to maybe 12 ~ 14 miles.

Basically, you're using a turbo charged sports car motor for a GMC suburban.

...

To get the performance you want, I would change the motor to either a 5303 or 5304 and then add 2 more batteries (if you can fit them). You should configure the batteries for 48 volts and 24 amp hours. You should have a top speed above 30 mph and range above 20 miles or 50 miles range @ 20 mph. If you can't fit 2 more batteries, you might considering springing for 8 smaller (8 or 10 ah) batteries.

3. 32 mph is really fast. wind resistance is pretty significant at this speed. Basically anything over 25 mph (without fairing) is going to induce significant drag.

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Just to quantify this a bit further: my upright X5 bike requires twice as many amps to go 25mph as 20mph. On an upright, no-aero bike, even a 5mph reduction in speed can about double the range, no matter the batteries.

14 miles is pretty damn good for going 30 mph with my 12v12ahX4 pack i can only go about 8 miles at 26 mph and 13 miles at 20 mph.

Let's see, 72 volts on a 406 motor with a 26 inch wheel would have a top, no load, speed of around 43.3 mph. Yep, it would be pretty hard to pedal assist anywhere near that speed. :lol:

Why does everyone think it is hard to assist at higher speeds?
Throw a 52 tooth on the front and an 11 small on the rear and 120 rpm is over 43 mph.
There are much bigger rings available for the front a 52 is a standard large ring for a road bike.
And for a short sprint just about anyone should be able to hit 120 rpm and in a lot of cases much more.

The worst part is trying to get an upright to those speeds it is just so inefficient aerodynamically. sorry could not resist.

Geebee said:

Why does everyone think it is hard to assist at higher speeds?

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Because at high speeds on an upright bike, the act of pedaling saps more energy via aerodynamic drag than pedaling can provide.

xyster said:

Because at high speeds on an upright bike, the act of pedaling saps more energy via aerodynamic drag than pedaling can provide.

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Exactly.

That's why the "Road Racer" concept makes sense. On a slow uphill you get up off your seat and pedal assist the motor, but on a downhill or on a fast straight away the advantage of staying behind a fairing and letting the motor do it's thing far outweighs pedaling. I know on my non-pedal bike that when I sit upright my top speed is about 32 mph and in a tuck my top speed is about 38-40 mph. Aerodynamics is everything above 30 mph.