Ebike Batteries in Perspective

George S.

Well-Known Member
Ebike Batteries in Perspective

Five years ago, when I was going to buy my first ebike, the battery was a limiting factor. Basically, a 36 volt and 8 Amp Hour battery retailed for $700 or so. We now see mostly 48v batteries, even in the low end stuff, and 12 AH is pretty standard. In the replacement market or on Ebay, a 48v/12AH battery is maybe $300 to $500.The battery for a Rad Mini, with that configuration, runs $400 right now. Summing up, the batteries cost half as much and hold twice as much power.

Looking back 5 years, $400 is arguably a good deal for an ebike. How long should a pack last? True cost is more than upfront cost. Consider the life of a battery pack. A few vendors are using the Samsung 35e cells. There are maybe 50 cells in a pack, the standard 18650 cell. Vendors increasingly use Samsung, Panasonic, and LG, the big names. For $400, what might you expect from the pack?

3d-2N5rXL0Mvtl0Y2zSvHxvyICLWEjihM3dcnVeeoGFV-36JMbP3MMOzEG08H9zV3PZwdZ6A1h2eiY7weWSRSHzTEKK4YmBXSlpHvxRhzxzAnkIxzrmywj_6huPyZwuT12tON51M


This is a cycle life curve, but given in terms of the capacity of the battery. Every time you charge and discharge, the battery holds a bit less. An industry standard is the cycles to get to 80% of original capacity. The cell is rated for 3400 mAh for the first few cycles. It drops a bit to 3000 mAh within the first 150 cycles, and slowly droops to 2700 mAh, after 500 cycles. If there are 4 parallel sets in a 48v battery, you get 4x the 3400 mAh to start. That is 13.6 Amp hours, times the 48v, for 650 watt hours. But after 500 cycles the capacity is down to 518 watt hours. It’s good to start with more capacity than you need.

If you could get 500 cycles out of a 400 dollar battery, the cost ‘per ride’ would be something like 80 cents a ride. If you were commuting to work, 5 days a week, the cost over a year would be around $200. If you charged to 90% and kept the battery from going to 0%, you might double the cycle life. But after 500 cycles, you might just want to new battery or a new bike or whatever.

If they simply set the battery capacity to 90% of the total capacity, and set the charger to this rating, the cycle life would be very high, pushing 1000 cycles. But there would be less capacity over time, and 90% is less capacity to begin. You can see where making a bigger battery, but charging less, is a trade-off. Battery pack prices are low enough that most people won’t chase a few cents a day.

One of the surprises in ebike battery packs is how quickly the higher capacity cells peaked out. A few years ago, the Sanyo GA was a super cell, with a lot of capacity. Today the Samsung 35e has only marginally better capacity, and both the GA and SE seem to lose capacity fairly quickly. Old cells, like the Samsung 22P, continue to find favor.

If someone is on a budget, they should follow Micah Toll and Jehu Garcia. There are ways to get a basic ebike battery for $100, but it requires some research, maybe patience.

The net effect of cheap batteries is that people can also put a cheaper battery in a small motorcycle type vehicle. That may require 2 or 3 kWh of power, but it’s not going to cost much more than the small ebike battery of 5 years ago. That makes the motorcycle or scooter more of a focus. Toll bought a small CSC motorcycle for around $2800. It supposedly goes 45 mph, a true city commuter speed. Be interesting to see how it works out, since anything under $3,000 is an ebike kind of price.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Top speed is worthless to me, unless it's capable of doing that for at least an hour. I don't think we have the battery tech. to go fast. Not for long anyway.
 

Ken M

Well-Known Member
It was my understanding that the lower energy density LiFo batteries could hit 2000 charges before 80% degraded but maybe that was some early marketing hype. While I'm a big advocate of ebikes for transportation, I think the industry is not being totally upfront about the cost of batteries and how they impact the total cost of ownership of an ebike. If the battery costs me more than a $1 per recharge my 36 mile commute then my savings vs driving isn't as good as I thought it was. That's more than I had calculated for everything - amortizing the cost of the bike, bike service/maintenance, recharge energy costs, any special clothing needed, etc. Obviously it's hard to put a value on the physical and mental health benefits of riding a bike vs. driving a car to work in traffic everyday but I was hoping I was saving at least $.20/mile and maybe that is not the case.

This might be a great study for someone to conduct without any of the hype or misinformation that usually comes with such an assessment.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
For your "true cost" calculations, I'm thinking figuring 2000 cycles on a battery is WAY optimistic. Even half of that would be very kind. One of the bigger issues regarding your calculations is how new this technology really is. I'm not sure it's been around long enough to provide a solid basis for the numbers you need - especially considering the distance of the ride you need.

Though somebody may achieve results that make what you want to do practical, the next 9 guys may not! For instance, ambient temps are going to have a lot to do with it. Somebody that never has to ride in temps below 50 degrees, or higher than 90 degree might do much better on a project like this than somebody based in Chicago or Detroit for instance. My thoughts anyway. -Al
 

JoePah

Well-Known Member
Ebike Batteries in Perspective

Five years ago, when I was going to buy my first ebike, the battery was a limiting factor. Basically, a 36 volt and 8 Amp Hour battery retailed for $700 or so. We now see mostly 48v batteries, even in the low end stuff, and 12 AH is pretty standard. In the replacement market or on Ebay, a 48v/12AH battery is maybe $300 to $500.The battery for a Rad Mini, with that configuration, runs $400 right now. Summing up, the batteries cost half as much and hold twice as much power.

Looking back 5 years, $400 is arguably a good deal for an ebike. How long should a pack last? True cost is more than upfront cost. Consider the life of a battery pack. A few vendors are using the Samsung 35e cells. There are maybe 50 cells in a pack, the standard 18650 cell. Vendors increasingly use Samsung, Panasonic, and LG, the big names. For $400, what might you expect from the pack?

3d-2N5rXL0Mvtl0Y2zSvHxvyICLWEjihM3dcnVeeoGFV-36JMbP3MMOzEG08H9zV3PZwdZ6A1h2eiY7weWSRSHzTEKK4YmBXSlpHvxRhzxzAnkIxzrmywj_6huPyZwuT12tON51M


This is a cycle life curve, but given in terms of the capacity of the battery. Every time you charge and discharge, the battery holds a bit less. An industry standard is the cycles to get to 80% of original capacity. The cell is rated for 3400 mAh for the first few cycles. It drops a bit to 3000 mAh within the first 150 cycles, and slowly droops to 2700 mAh, after 500 cycles. If there are 4 parallel sets in a 48v battery, you get 4x the 3400 mAh to start. That is 13.6 Amp hours, times the 48v, for 650 watt hours. But after 500 cycles the capacity is down to 518 watt hours. It’s good to start with more capacity than you need.

If you could get 500 cycles out of a 400 dollar battery, the cost ‘per ride’ would be something like 80 cents a ride. If you were commuting to work, 5 days a week, the cost over a year would be around $200. If you charged to 90% and kept the battery from going to 0%, you might double the cycle life. But after 500 cycles, you might just want to new battery or a new bike or whatever.

If they simply set the battery capacity to 90% of the total capacity, and set the charger to this rating, the cycle life would be very high, pushing 1000 cycles. But there would be less capacity over time, and 90% is less capacity to begin. You can see where making a bigger battery, but charging less, is a trade-off. Battery pack prices are low enough that most people won’t chase a few cents a day.

One of the surprises in ebike battery packs is how quickly the higher capacity cells peaked out. A few years ago, the Sanyo GA was a super cell, with a lot of capacity. Today the Samsung 35e has only marginally better capacity, and both the GA and SE seem to lose capacity fairly quickly. Old cells, like the Samsung 22P, continue to find favor.

If someone is on a budget, they should follow Micah Toll and Jehu Garcia. There are ways to get a basic ebike battery for $100, but it requires some research, maybe patience.

The net effect of cheap batteries is that people can also put a cheaper battery in a small motorcycle type vehicle. That may require 2 or 3 kWh of power, but it’s not going to cost much more than the small ebike battery of 5 years ago. That makes the motorcycle or scooter more of a focus. Toll bought a small CSC motorcycle for around $2800. It supposedly goes 45 mph, a true city commuter speed. Be interesting to see how it works out, since anything under $3,000 is an ebike kind of price.

So many people fall in love with low prices from China. Except when something goes wrong, not unusual, the customer is holding the bag. Micah May have found a scooter that is reliable long term.. time will tell

Running a large capacity battery down is not really an issue. The battery in your example can run down 50% and still provide 20 miles. That will take a few years, 4 0r 5 years. Not bad imo

If a cheap ride is wanted just buy a factory bike from Sondors. There is a huge aftermarket business to replace and upgrade the bikes. He’s sold over 20,000 ebikes since 2015
 

Thomas Jaszewski

Well-Known Member
Jehu is a hustle. M surprised you of all people find him an expert. Long on talk, short on providing truly useful information. Building is not something this forum is big on, and I find that a relief. Fewer bombs on eBikes.
 

indianajo

Well-Known Member
I bought a 17.5 AH battery which cuts my number of charge cycles and increases my range. $620 from a reputable e-cycle parts shop, luna. fewer charge cycles may increase the life of the battery, too. I've been running the second charge for 10 weeks now, not using power much in town.
Luna wanted $70 for a two voltage (100% and 80%) 2.5 A charger. That would take 7.5 hours to charge 0 to 17.5 AH. Nuisance on a long trip.
So built a dual voltage LiIon 14s (stack of cells) charger out of parts in my inventory of amplifier projects. see schematic below. Charges to 100%, 54.6 v and also to 90%, 53, by means of a selector switch. 4A ouput. Although the transformer would source 6 A, the battery is limited to 5 A charge, and I didn't have room in the case for a heat sink for a 3rd power transistor. It large, about the size of a loaf of bread. I don't design switcher supplies here, and i couldn't figure how to modify the surplus 58.4 2 A chargers left over from the LiFePo4 garbage batteries I bought.
the green LED lights up as it is nearing full charge. I mounted it where I could see it through a hole in the top of the case.
 

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Thomas Jaszewski

Well-Known Member
Wow you charge from zero? And always @ near maximum BMS rate of charge? I opted for a spare battery, then two... obsessive compulsive with an inane fear of no backup battery.
 

indianajo

Well-Known Member
well, no, the first time I charged the battery it was at 47 v from the dealer. That was using a $22 2 amp charger from E-bay, fixed voltage 100%. The second charge I ran it down to 44 v. I'm going to try to wait until 42 v next time which is 10% then charge to 90%.
the charger is designed to limit current to a shorted battery, in case that happens, without blowing a fuse. ccs will sink only 4 A. If more than that comes in a PTCR 4 A "fuse" will blow until the AC input is shut off. Those reset automatically without disassembly.
One of my desires for electric assist is to get me to concerts 30 miles away without more than 6 hours on the saddle. I don't imagine bouncers will let me carry a spare battery into a concert venue, there are usually metal detectors. If I leave a spare battery in the pannier on the bike in the the parking lot it would be likely be stolen.
 
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