I have a like new bike and was wondering if it would be worth it to do a E-Bike Conversion. I live in the foothills of NC and am borderline disabled fighting neuropathy.
I was thinking along the lines of a 48-52 volt 20AH battery with a 1000 Watt rear hub motor. I notice a lot of the information is dated 5 to 7 years old. I weigh 270 lbs and would like a range of Aprox 60 miles.
What slopes do you deal with? Climbing hills will take a lot more power than riding on the flats, and more the higher the weight of the system, bike, and rider.
What speed do you want to go? Faster takes more power nonlinearly.
It's likely to take quite a large battery to go 60 miles. Commonly at 48v, going 20mph, on the flats with no wind, it would take around roughly half an Ah per mile, given no other unusual loading, or start/stop traffic, etc. That would be at least a 30Ah battery, with no hills at all. If you have hills, it could double that requirement easily, or more, to 50-60Ah or higher, which is a really big heavy battery. Even if you assume as little as half a pound per Ah, that's 30lbs of battery, or more...but it's more likely to be heavier than that, like 3/4pound per Ah or more, making it 45lbs+ . If it's only a 30Ah battery, at 48v that's 48 x 30 = 1440Wh. A 60Ah battery would then be 2880Wh. (Wh is better to use because it's more common to denote range / usage this way, in Wh/mile).
Some numbers (these only assume always riding uphill, which you won't be doing; you'll need to determine how many miles of uphills you have, vs on the flats, vs downhills, to actually determine battery size needed for range, and note that winds will increase power usage just as riding faster would, for the same reasons):
If we assume fairly steep slopes of 20%, and riding at as fast as the system will go up that slope, with 350lbs total weight (assuming a really big heavy battery and a large heavy DD hubmotor), it's going to take over 4kW of battery power (around 100A at 48v; a smaller controller won't even go up the hill in the simulator) to generate a bit more than 2kW of motor power just to go a bit more than 16mph, and it will melt a "1kW" hubmotor motor in less than a couple of minutes (will probably overheat the controller, too). This uses almost 300Wh/mile, which means 60 miles of this would take 60 x 300 = 18000Wh, which at 48v would be a 375Ah battery, and you would have to pull a trailer to carry that; it's not going to fit on a bicycle frame. So this isn't practical at all.
Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...
ebikes.ca
If yo'uve only got 10% slopes to deal with, then the same setup gets you a bit more than 23mph, only taking 3kW of battery power, only taking a 65A controller, overheating in just over 3 minutes, with only about 130Wh/mile battery usage that doubles the range.
Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...
ebikes.ca
If we take the system weight down with half the size of battery, call it 300lbs total rider/bike/system,and the controller down to 60A, you get about 23mph for only 3kW battery usage and 2kw motor power, overheating in 4 minutes, power usage dropping to 122wh/mile, range about 62 miles (if the motor didn't melt).
Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...
ebikes.ca
Dropping the slope to 5% power usage drops to over 2kw battery usage supplying oaver 1600w motor power, usage of almost 80wh/mile, range going up to almost 100miles with the 160Ah battery, speed going up to over 27mph.
Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...
ebikes.ca
All of the above assume full throttle all the time, too, so you will get better performance to varying degrees depending on the slope by using less than full throttle--but going too slow can end up heating the motor faster depending on conditions and motor / system setup.
A middrive that lets you shift gears depending on terrain/conditions to let the system stay closer to it's efficient zone will work in greatly varying conditions better than a hubmotor, for the same amount of power available, to keep a lighter system. It still takes a certain amount of motor power to do a task, so you can't get below however much it takes to do the job you need it to...but it may take less battery power because the system is more effiicient so your battery lasts longer.
You can use the simulator linked above to figure out the power required to do whatever job you have to have it do, and then you'll have a good guesstimate of the motor power required for that. Then that can be used to guesstimate battery power required, which along wiht the wh/mile guesstimate the simulator cna give you can be used to find out the batttery size and capabilities.
