First ever e-bike build - touring in mind

Hello, I'm planning an e-bike build and would appreciate advice since I'm new to e-bikes.

I'm converting my steel road bike to an e-bike with the desire of extending my long distance cycling range. So I want to supplement constant peddling up to 6-8 hours of biking time in a day. Without a battery I can consistently do about 22 km/h for 5 hours for 110 km range, without too much difficulty; with the e-bike I'd like to have an average speed more like 30-35 km/h, and I figure it should make it easier to bike longer, so hopefully 180km+ range.

I'm pretty certain of what I want for most of the components, but I'm uncertain about the battery.

Battery:
-option 1: em3ev 50V 18.6Ah triangle battery (937Wh) https://em3ev.com/shop/50v-14s6p-small-triangle-pack/
-option 2: em3ev 50V 27.9 Ah triangle battery (1406 Wh) https://em3ev.com/shop/50v-14s9p-large-triangle-pack/
-option 3: 2x bmsbattery 48V 12.5Ah bottle pack (600Wh each=1200 Wh) https://bmsbattery.com/ebike-battery/817-48v116ah-case-08-bottle-panasonic-battery-pack-battery.html

Motor: Q128C 500W 201rpm 36V version for ideal rpm combined with 48/50V battery https://bmsbattery.com/ebike-kit/768-q128c-135mm-500w-rear-driving-ebike-hub-motor-ebike-kit.html#/213-rpm-201/42-voltage-36v
Controller: S12S 500W Sine Wave https://bmsbattery.com/ebike-kit/552-s12s-500w-torque-simulation-sine-wave-controller-ebike-kit.html

The em3ev batteries seem good, but a little pricey, although the 18.6 Ah is reasonably affordable and probably has enough watt hours, at 937. The 27.9Ah em3ev battery might be overkill for capacity, considering that I plan to do a fair amount of pedaling, but I am not sure how that will turn out in reality.

The bmsbattery is much more affordable per Wh ($201 per 48V12.5Ah that I linked), but I am unsure if it is good quality. I'm confused by the fact that other batteries with similar specs have widely varying prices on that site, e.g. a higher price for what seems to me a worse battery: $281 for a 48V10Ah (https://bmsbattery.com/ebike-battery/784-48v116ah-case-08-bottle-panasonic-battery-pack-battery.html); another 48V10Ah battery that is only $201 (https://bmsbattery.com/ebike-battery/786-48v116ah-case-08-bottle-panasonic-battery-pack-battery.html); and a different 48V12.5Ah battery that costs $218, but again I see no difference in specs compared to my "option 3", yet different price (https://bmsbattery.com/ebike-battery/813-36v145ah-bottle-09-panasonic-battery-charger-battery.html)
^that inconsistency makes me not trust those batteries, but maybe I just don't understand some subtle differences...

I'd be glad to hear what anybody thinks about these batteries and build in terms of my goals for the e-bike.

Thanks

Battery cells are available in many chemistries, with a large choice of quality and specs. So the size of a battery does not reflect its value. Batteries from reputable brands, selected specifically for your power and capacity requirements, are always a better investment. Batteries are well documented on ES.

Glad to see another tourer and realistic distances and speeds.

My last tour (no e-assist) on average, I was on the bike from 8am - 4pm with 5.5 hours moving time at 23km/h (14.2mi/h)

What kind Wh/km do you expect your motor to consume when pedaling at 35km/h (22mi/h)?

Presuming 10Wh/km (16Wh/mi), 1400Wh should deliver 140km (87mi) in only 4 hours.

To go 180km with 1400Wh, your efficiency would need to be around 7.8Wh/km.

Touring with a credit card, or camping gear?

With camping gear, I needed a big cargo bike, and 1500-2000 watt hours of battery. ( like 48v 40 amp hours for 2000wh) I got about 25 watt hours per mile, but I was not pedaling hard at all. That got me and all that weight to travel 15 mph. I also needed a very big motor for the mountains, or short but quite steep hills, with all that weight. I was about 400 pounds total. Me, bike, gear, batteries.

A fit person should be able to go a long ways on 1000wh, but you might still have to plan on some charging during the day to extend range more. Long lunch break, like 3 hours, where you can plug in.

Long day trips are another matter, if you can get your wh/mi into the 15-20 wh/mi ballpark, then a 48v 20 ah battery gets you into 60 mile range. FWIW, my personal ass endurance is about 60 miles, 80 is just too long in the saddle for me. I want off at about 5 hours or so.

TheRammer said:

What kind Wh/km do you expect your motor to consume when pedaling at 35km/h (22mi/h)?

Presuming 10Wh/km (16Wh/mi), 1400Wh should deliver 140km (87mi) in only 4 hours.

To go 180km with 1400Wh, your efficiency would need to be around 7.8Wh/km.

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I think 10Wh/km should be doable, using e-bikes simulator for some reference. It seems like with those numbers, 1400Wh would be a good bet for my aims.

dogman dan said:

Touring with a credit card, or camping gear?

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Probably credit for the most part, from hostel to hostel. By the time I do some with gear maybe I'll be ready for an upgrade. From what you say sounds like 1000Wh might be stingy unless I can count on charging breaks.

Thanks for the comments!

shugasam said:

I think 10Wh/km should be doable, using e-bikes simulator for some reference. It seems like with those numbers, 1400Wh would be a good bet for my aims.

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I think that's a little optimistic. The motor makes it easy to get sucked into more complacent pedaling than you realize. But even if you avoid that, 1400 wh doesn't give you the 180 km range you are hoping for. You need closer to a 2000 watt hour capacity for that - especially if you want any capacity to spare - nice to have for headwinds and long uphill climbs.

Dogman Dan's setup was heavier and went fewer miles. But you are going faster, and that will cost you. In the end, I think you'll find your power needs are pretty similar.

It would help if I converted my data to metric. But 10wh/km is not outrageously low. It can be done, especially by lower drag fully recumbent bikes.

It makes a huge difference what the terrain and weather will be, as well as whether you carry camping gear or not. But lets just say the total load is a more reasonable 300 pounds, the bike, rider, motor, battery, and any other gear. ( I had to carry a full 15 pounds of water on my tour rides in desert)

At that weight, canceling out the weight of the motor and battery alone will take at least 100 watts. So your own full output could be needed just to compensate for the weight of the motor system.

At 300 pounds, a typical 32kph speed will take about 500-600w of power. So your 1400 wh battery will last only two hours at that speed. Your 100-150w effort will mean seeing about 500w on a watt meter as you ride.

You will definitely need a watt meter on the bike, at least a very crude display that shows the draw, to learn how to pedal enough, and work the throttle or the PAS settings for max efficiency.

Your best strategy might be to run only 100w of assist on the flat, saving the real power for hills and headwinds. Just tickle the motor enough to make it ride like the weight is not there till the hill.

If you run the motor fast at all times, like 36 kph/20 mph, then you will find one ah of 48v takes you about 2 to 2.5 km, at 300 pounds/136 kilos. At 180 kilos, same rate but at more like 24 kph.

dogman dan said:

It would help if I converted my data to metric. But 10wh/km is not outrageously low. It can be done, especially by lower drag fully recumbent bikes.

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I agree. It doesn't seem impossible, just unlikely. I suspect it could be done on a regular bike, but I don't think so at the speeds desired.
Here's an ES member's data on a fairly large "cargo" recumbent. He gets just a tad worse than 10 wh/km at the 35 km/hr that the OP is looking for. But it is a recumbent and then there's the whole headwind/terrain issue.

But heck, if the OP is willing to go on pedal power alone if he runs out of juice, then no big deal.

https://endless-sphere.com/forums/viewtopic.php?f=3&t=78828#p1164765

My situation is similar to yours in that I built with q128c in 700c wheel on a hybrid with the aim of slight augmentation of leg power (200-500W) for daily 30 km of commuting. Having logged over 100k km on a regular bike, I describe myself as fit cyclist.

If it helps, I can sustain average speed of 25 kph (with inner city riding, frequent stops, hilly terrain) and my 48V 11.5 Ah battery (BMSB, Panasonic cells) will get me about 60-80 km range if I'm miserly.

Edit: the ebike weighs 20 kg, I'm 78 kg and I mostly carry about 5 kg of gear in panniers.

For the strong cyclist, 35 kph on level ground should be sustainable for hours with 200W max motor power. The important thing imo is to limit the motor to 5A at 48V for 250W max but have 10A override for hills etc. For 5h riding at 4A (200W), you would need 20Ah, which is quite heavy.

Choosing the highest power density cells will reduce weight. EM3EV's 50V 14s7p 23.5Ah LG-MJ1 high energy pack is 5.7Kg - not that bad. You could ask them to custom build it to 14s6p (approx 20Ah) to get it under 5Kg, but you might want the extra range.

10 wh/km ( 15wh/mi) IS outrageously low for 400 pounds. Especially if the extra 150 pounds you are lugging are going up steeper hills.

Its plausible for 250 pounds for sure (113 kilo), rider only 160 pounds, bike with huge battery 70, cargo less than 20 pounds. I just couldn't tour that light, starting with my weight, the rocky mountains, and 20 pounds of water to survive. But I did prove that 25wh/mi is doable for 400 pounds, at 15 mph. If you are young and tough, 10 kilos for tent and bed is possible, making a 250 pound load out possible for a lighter rider than me.

Just got back from a weekend trip - glad to have more reading here!

dogman dan said:

But lets just say the total load is a more reasonable 300 pounds, the bike, rider, motor, battery, and any other gear.
...
Your best strategy might be to run only 100w of assist on the flat, saving the real power for hills and headwinds.

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dogman dan said:

Its plausible for 250 pounds for sure (113 kilo), rider only 160 pounds, bike with huge battery 70, cargo less than 20 pounds.

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In terms of weight, the 250 might be doable, let's see: rider=160 lbs + bike=30 lbs + battery/motor etc=~25 lbs (3kg motor+7kg battery+extra bits) + gear=~50 lbs ... TOTAL=265 lbs; pretty close.

I'm definitely intending to use the motor primarily as pedal assist, and 100W should be fine. Running some numbers on ebikes simulator it seems like 30km/hr is a more reasonable speed if I want to maintain range: that appears to get me to my desired range at 0% grade even with under 1000Wh, but obviously the ride will not equate to 0% grade. If I sub in my biggest battery option, it might be enough. Of course I have to remember that I won't be using the full battery capacity.

wturber said:

I agree. It doesn't seem impossible, just unlikely. I suspect it could be done on a regular bike, but I don't think so at the speeds desired.

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I think my speed is more flexible for me than the range is, so as long as the time required to go full range doesn't get too high (i.e. less than 8 hours, that would take a substantial butt break in the middle I'm sure), I can sacrifice the speed.

wturber said:

But heck, if the OP is willing to go on pedal power alone if he runs out of juice, then no big deal.

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it'll be just like normal except plus 30 lbs :?

molybdenum said:

My situation is similar to yours in that I built with q128c in 700c wheel on a hybrid with the aim of slight augmentation of leg power (200-500W)...

If it helps, I can sustain average speed of 25 kph (with inner city riding, frequent stops, hilly terrain) and my 48V 11.5 Ah battery (BMSB, Panasonic cells) will get me about 60-80 km range if I'm miserly. ...

...The important thing imo is to limit the motor to 5A at 48V for 250W max but have 10A override for hills etc. For 5h riding at 4A (200W), you would need 20Ah, which is quite heavy.

Choosing the highest power density cells will reduce weight. EM3EV's 50V 14s7p 23.5Ah LG-MJ1 high energy pack is 5.7Kg - not that bad. You could ask them to custom build it to 14s6p (approx 20Ah) to get it under 5Kg, but you might want the extra range.

Click to expand...

Thanks for the info and advice. Nice to hear of a similar setup.

shugasam said:

wturber said:

I agree. It doesn't seem impossible, just unlikely. I suspect it could be done on a regular bike, but I don't think so at the speeds desired.

Click to expand...

I think my speed is more flexible for me than the range is, so as long as the time required to go full range doesn't get too high (i.e. less than 8 hours, that would take a substantial butt break in the middle I'm sure), I can sacrifice the speed.

Click to expand...

Yeah - if you are willing to slow down a bit, you can extend your range substantially.

I went for a 40 mile ride this afternoon with the idea in mind to take it easy and use minimal battery power. I tried to cruise at 20 mph (32 kph) or slower unless going downhill. I stayed out of the throttle for the most part and used PAS settings 1 & 2 for level and downhill and only used PAS 3 for uphills. I always pedaled with moderate effort - probably 15 mph with no motor. Heart rate typically between 120 and 130 bpm. With 20 mph as my target, my average moving speed ended up being 17.5 mph (25 kph) due to slowing for some folks on multi-use paths, some uphills where I went slowly, and the slow down and start up for lights and stop signs. I ran my 12v 30 watt headlight for the entire trip.

I ended up going 39.65 miles (64 km) and used 13.594 AH of battery at an average of about 39 volts. So that's about 530 watt hours. And that works out to 13.37 watt hours per mile or about 8.8 watt hours per km. That's still about 1500 watt hours to go 180 km, but then I did waste some juice on the last few uphill miles right before I got home. (I was running late because I had a flat and had to change the tube in the dark. )

One thing that took me a bit of time to understand, just how much difference even a 4kph decrease in speed makes, once you are at or under 30 kph.

I took to riding 18 mph on my longer rides, wanting for sure 30 mile range with no worries at all over hills, wind changes, etc. It really was unbelievable how much farther I got at 18 mph vs 20.

Its the aero more than the weight. I do ride upright, so the aero is the worst. But even tucked, it will astound you how much just a slightly slower ride makes the difference.

Fully loaded at 400 pounds of me and camping gear, and 1500wh battery, 15 mph was the ticket for a camp trip. 60 mile range (96km), if I just kept my wh/mi average on the cycle analyst display at or below 25wh/mi. Next town 60 miles, next water 60 miles, next plug 60 miles. I had to carry enough water for 24 hours in the desert in case of problems, and had to make that range. BTW, I had to keep my pedal wattage very low, because of an illness. 50-75w personal pedaling wattage is my max. Can't sprint up a hill at all, it will take me out for the day, if not week. You will do much better of course.

The other thing to know, if you ride it right, rolling hills cost you nothing. Coast enough down and use that savings on the next hill. But into enough wind, coasting starts to fail, so I mean in reasonable weather, you get very close to same as flat. Just resist the temptation to increase speed with the motor on the downhill, to shorten the saddle time.

My ass tended to give out at about 5 hours, with 6 my real maximum. Depends on the road too, but always bad here on the safe side of the stripe.

Fortunately, at 15 mph, 60 miles is only 4 hours. plus whatever stopping to pee, or eat or what not. So generally just about right, 5 hours then you had to stop at the first available place to plug in and charge some more. Getting back on for 20 more miles later was tough though. my personal best distance in a day was 80 miles.