## Range calculator

pengyou   1 kW

Posts: 325
Joined: Oct 27 2007 10:38am
Location: Beijing

### Range calculator

I found a post that did this - maybe it was a link to another page - but I cannot find it now. I would like to know what size battery I will need to power an escooter with 48V 500 watt motor with 16" wheels to do 50 miles (still leaving a 20% reserve on the battery) at about 20 mph. Land is mostly flat. Does anyone have the link?

Chalo   100 GW

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Joined: Apr 29 2009 11:29pm
Location: Austin, Texas

### Re: Range calculator

Rough estimate? If you're normal sized, on an e-bike it will take about 500W to the ground, say 600-700W electrical, to maintain 20mph. So 2.5 hours of that will take 1.5 to 1.75 kWh of battery power. Round up for the draggy tires and heavy scooter. Figure 2kWh.

You really want to spend two and a half hours on a scooter between opportunities to recharge?
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pengyou   1 kW

Posts: 325
Joined: Oct 27 2007 10:38am
Location: Beijing

### Re: Range calculator

Chalo wrote:
Mar 18 2018 2:26am

You really want to spend two and a half hours on a scooter between opportunities to recharge?
Thanks! I travel a bit more than an hour to get to a certain place and the same amount of time to return. I am not sure I will be able to recharge in the middle. That is ideal. So, if I assume 2kw, a 50 amp 48v battery would give me a large margin for error.

Chalo   100 GW

Posts: 7289
Joined: Apr 29 2009 11:29pm
Location: Austin, Texas

### Re: Range calculator

pengyou wrote:
Mar 18 2018 2:53am
So, if I assume 2kw, a 50 amp 48v battery would give me a large margin for error.
It should be fine. You can fault check with this speed and power calculator:.

http://www.kreuzotter.de/english/espeed.htm

But it is focused on bicycles so you may have to make some guesses.
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dogman dan   100 GW

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Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

### Re: Range calculator

I would agree, at 20 mph, about 30-40 ah. My answer based on a crapton of 30-80 mile rides.

20 ah will get you 30 miles at 20mph, To have a huge reserve left at 50 miles, more like 40 ah of 48v.

This type of ride is why one of my custom bikes was designed first and foremost, to carry two 48v 20 ah batteries. To have enough to do 80 miles at 15 mph.

Ride with a watt meter, and know what wh/mile average you need to hit your range. Then adjust your speed as needed out on the road to hit that number, whatever the weather or terrain.

So say you have about 2000 wh, 48v 40 ah. 80% of that would be 1600 wh. You would need to get 32wh /mi average to go 50 miles. 20 mph should be more like 20-25 wh/mi, but depending on the weight of the bike, ( 30 pounds of battery for starters) and the terrain, and the pedaling effort you can do for all 50 miles, 32 wh/mi by the end of the day is very plausible.

This is why I don't give you a promise you can do 50 miles on 30 ah, even if its possible. Unless you ride it slower, which increases the % of the total watts you get from your legs, per mile. Most of us at 20 mph, only produce about 20% of the energy used with our legs. most of us can't put out a 150w effort for 50 miles. Bike racers put out 200- 300w for 150 miles!!!

Anyway, slowing to 18 mph vs 20 mph, will make an astonishing distance possible from 30 ah. When I needed to make it to a town 60 miles away, I'd slow to 15-18 mph. Then maybe, if I did well, I could speed up the last 10 miles.

The tool you need is a cycle analyst, it will read out your average wh/mi. Then if you see 25 wh/mi at mile 40, you can rip it in full speed the last 10 miles.

markz   100 GW

Posts: 6191
Joined: Jan 09 2014 11:38pm

### Re: Range calculator

I am constantly doing range calculations with my total distance known from measurements on Google Maps (plan to buy a cycle comoputer) on a 48V system with a 25wh/km estimate as I'm a smidge heavier then finding out the battery capacity (Ah). My pack is 13S8P so I can deduce from that. Not like bench top measuring each cell, it seems to be right. Perhaps toothpicks may only use 20wh/km.

parajared   10 kW

Posts: 812
Joined: Apr 16 2012 11:33pm
Location: Northern Arizona

### Re: Range calculator

10 watt-hours per mile: you and the bike are working in tandem, you and the bike are equally contributing.
20 watt-hours per mile: you are hauling a load, in a hilly environment, or in loose soil.. or you aren't doing much work.
40-70 watt-hours per mile: usually the wh/mi rating you see when you are clipping along at 30+ mph or so. E-scooter, no peddling

John and Cecil   1 kW

Posts: 473
Joined: Mar 14 2018 7:26pm

### Re: Range calculator

It depends how much you will be pedaling and how much you weigh. We seem to expend about 20wh per mile at 20mph doing 1/4 the work with pedaling pushing 270lbs total weight with 3" wide tires.

filtvet   1 mW

Posts: 10
Joined: Mar 13 2017 4:45am

### Re: Range calculator

Dunno about miles, but I tested 2 levels on my bbs02. 5 wh/km on the lowest level (max 150w), and 7 wh/km on level 2 (max 300w). This was on a semi-hilled route with 3 km climb in it.

I also see if I use the throttle, it really drains the battery, so it should be avoided for touring. My dream is to be able to go 120 km with 2 17.5ah batteries. Seems possible.

parajared   10 kW

Posts: 812
Joined: Apr 16 2012 11:33pm
Location: Northern Arizona

### Re: Range calculator

I also see if I use the throttle, it really drains the battery, so it should be avoided for touring. My dream is to be able to go 120 km with 2 17.5ah batteries. Seems possible.
When I did my 207 mile bike ride I would pack 12s 20 ah (880 watt hours) in order to have plenty of head-room, then knock out about 50 miles at a time.

I rode the Grand Canyon this weekend for instance (Tusayan to Yaki to Hermit) and I was glad I didn't just bring my usual 10ah 12s pack. I consumed 12ah on my 37 mile trip which was more than expected.

When I did my first cross-country trip: 185 miles I packed 30ah which seemed overkill when I started but the combination of camping gear and lots of battery weighed me down and I had to stop more frequently than expected (every 40-50 miles).

I really liked having solar panels and on my 251 mile solar cross-country trip I found 10ah 12s more than adequate for unlimited riding.

filtvet   1 mW

Posts: 10
Joined: Mar 13 2017 4:45am

### Re: Range calculator

Great video.

I think the problem now is my lower back. I have pain after about 60 km - so maybe a small walk after every 50 km will help.

dogman dan   100 GW

Posts: 34413
Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

### Re: Range calculator

For a lot of people, its the ass or the back that wears out first, once you have a decent size battery. Like 20 ah or more.

For me the type of bike really matters, I have crushed disks from construction work 30 years ago.

Those nice pedal forward cruisers, or recumbent bikes, I last about 5 miles. What I need, is to stand on the pedals using my legs to support 80% of my weight, like a real cyclist does. But I still need an upright body too, no tucking on a road bike now for me. That stance also makes saddle choices less cruicial, but I do like a good spring seat, narrow as I can get them.

So figure out what it is you need to be more comfortable, just a mis fit saddle height can cause back pain eventually, on a fit healthy person.

You might need a longtail, or full suspension bike if your back issue is as bad as mine. On a 5 hour ride, yes, get off and walk, or lie down, or something once every hour.

parajared   10 kW

Posts: 812
Joined: Apr 16 2012 11:33pm
Location: Northern Arizona

### Re: Range calculator

filtvet wrote:
May 01 2018 11:53pm
Great video.

I think the problem now is my lower back. I have pain after about 60 km - so maybe a small walk after every 50 km will help.
Slipped disc for me. Recumbent trike ended up being my solution. I got a screaming deal on ebay for a display model trike KMX Typhoon at \$700.

For a brand new one it seems you are looking at \$1100
http://www.utahtrikes.com/PROD-11617629.html