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basic explanation of electric bike workings and terms Help!!!!

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basic explanation of electric bike workings and terms Help!!!!

Old 02-22-16, 03:29 PM
  #1  
Outsidewave
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basic explanation of electric bike workings and terms Help!!!!

I am going to say straight out I know nothing about all this, But I am hell bent on converting my old gt Lts to electric. I decided that she is was great mtn bike for her day and deserves more that the $500 I was going to spend. so I have decided to go with a mid-drive 1000 watt motor the new baffling and a 48 or 52 volt battery . Now keeping in mind I am new to this I don't understand all the conversions etc. or how the controller works exactly. I have figure out it is possible to over heat some of the controls and motors so can some one explain what I need to understand interns of amps, volts and watts and how big or how high a rated c controller must be for certain motors

I do know that amps x volts = watts. but how does really work when applying it to the bike and the controller?

Why are some controllers better than others and the issue with lithium ion batteries if any? and last but not least is BAFANG the way to go what about cyclone?

So if you have say a motor rated at 3000 watts but are only using a 48 v battery and a controller of say 40 amps then you would be at 1920 watts . far less than the motor is rated.Is that right? Would this mean the motor would be sluggish ?
Does it take the full 3000 watts to make it perform well or would it be more like a safety factor to avoid burning up your motor?

Is burning up your motor more of a concern on hub motors or mid drives?

What is typically the weak link in the system motor, battery or controller?

I come from a 4 wheel drive back ground and we usually use the easiest part to replace as weak link in the system Ie it is easier to replace a u join on the drive shaft that to replace an axle in the field.

lastly I am 62 weigh like 250 and standup paddle surf so I am looking for a e bike that cannot say a 50 lb trailer and my F-- A-- and not burn up in the process
plus get me more exercise with destroying my knees, plus go off road. The road to the beach is mostly flat with some short but fairly steep hills maybe 100 - 200 feet of elevation gain at 6 % i am guesing.
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Old 02-22-16, 03:52 PM
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Look at endless sphere and/or ebikesca. to learn more than you ever want to know.
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Old 02-26-16, 06:07 PM
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If i read the beginning correctly, you have decided on a mid-drive BaFang BBSHD 1000W/48V system? If that is correct, it's plug and play. Bolt the thing on correctly. The controller is built in. Get a 48V battery (some say 52V is okay?) that matches or buy it as a matching kit.

I have persoanlly had an excellent experience with my BaFang BBS02 350W/36V mid-drive that I bought already installed on a MTB. It's a whole new world of enjoyment riding on and off road. The only thing I'd really like is about triple the range, but the battery and its' weight is the only limiting factor to resolve that.

Sorry, can't help you with any specific electrical engineering knowledge. Make the leap, you will not regret it!

Last edited by NoPhart; 02-28-16 at 05:52 PM. Reason: Typos
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Old 02-28-16, 12:10 AM
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If you have dynamo-powered bicycle lights, you already own an electric-powered bicycle! Consider: as you pump your legs up and down on the pedals, you make the wheels rotate. A small dynamo (generator) mounted on the rear wheel produces a tiny current of electricity that keeps your back safety lamp lit in the dark. Now suppose you could run this process backward. What if you removed the lamp and replaced it with a large battery. The battery would kick out a steady electric current, driving the dynamo in reverse so that it spun around like an electric motor. As the dynamo/motor turned, it would rotate the tire and make the bike go along without any help from your pedaling. Hey presto: an electric bike! It may sound a bit far-fetched, but this is more or less exactly how electric bikes work.
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Old 03-03-16, 07:06 PM
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One thing to keep in mind. All 48v batteries aren't even. Ask the manufacturer what is the top voltage and the cutoff voltage.

I had a Ping Battery Lipo4 that was called a 48v but charged up to 59v
This is comparable to the Luna Cycle 52v battery.

The 48v I bought from Calibike was reasonably priced but only goes up to 54v. I get around 2-3 miles less top speed then the Ping and it's more sluggish on hills.

Good luck.
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Old 03-03-16, 07:34 PM
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Originally Posted by tomzgreat
One thing to keep in mind. All 48v batteries aren't even. Ask the manufacturer what is the top voltage and the cutoff voltage.

I had a Ping Battery Lipo4 that was called a 48v but charged up to 59v
This is comparable to the Luna Cycle 52v battery.

The 48v I bought from Calibike was reasonably priced but only goes up to 54v. I get around 2-3 miles less top speed then the Ping and it's more sluggish on hills.

Good luck.
Yes...this "48V" notation is a bit of a misnomer and I think comes from the old car lead acid battery idea where 4 x 12V batteries were strung together to give "48V" (and those batteries weren't even 12V!).

The two most common chemistries for lithium packs we see these days are LiFePO4 and LiPo.
LiFePO4:
Nominal voltage per cell - 3.3
A "48V" pack is usually made up of 16 cells in series giving actual nominal voltage of (16 x 3.3) = 52.8V
These can usually be charged to about 3.6 volts/cell giving a "hot off the charger" voltage of (16 x 3.6) = 57.6V

LiPo:
Nominal voltage per cell - 3.7
A "48V" pack is usually made up of 13 cells in series giving actual nominal voltage of (13 x 3.7) = 48.1V
These can usually be charged to about 4.2 volts/cell giving a "hot off the charger" voltage of (13 x 4.2) = 54.6V

A "52V" pack is made up of 14 cells in series giving actual nominal voltage of (14 x 3.7) = 51.8V
and a "hot off the charger" voltage of (14 x 4.2) = 58.8V (closer to a 16s LiFePO4 pack)

Some may know more about the actual numbers but "48V" is really not 48 volts.
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Old 03-04-16, 07:15 AM
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Wattage of the motor is your basic measurement for power. Many ebikes are 350-500, and that gives you a good push. Voltage is the next consideration with 24, 36 and 48/52. Just like anything else theres more power in the higher numbers.

Next to consider is the amp hours of the battery. That will determine your range.

Have fun with your project.

-SP
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Old 03-04-16, 10:41 PM
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I like reading stuffs related to electric bikes and exploring new technology. Interesting post!
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Old 03-05-16, 06:47 PM
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Originally Posted by DonaldLozano
I like reading stuffs related to electric bikes and exploring new technology. Interesting post!
If you like reading this stuff, just wait until you ride one!
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Old 03-08-16, 02:42 PM
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Good questions but the answers get big. There are many variables, rider weight, health, terrain, bike type, size of electric system, etc. I will try to keep it simple.

Originally Posted by Outsidewave
I do know that amps x volts = watts. but how does really work when applying it to the bike and the controller? can some one explain what I need to understand interns of amps, volts and watts
You are halfway there, i would just rearrange your formula in order of general importance. Volts x Amps=Watts.

Volts = speed. 24v = 15mph, 36v = 20mph, 48v = 25mph. This is the average kit and average battery, on flat ground with the average 200lb new ebike rider, average old 26" mtb conversion, etc.

Amps= torque. Climbing and pulling power. Also called current. Amp draw is set by the controller. Most 48v kits come with a controller in the 20-30 max amp range. More amps = more heat. Too much heat and parts get fried.

Watts is just a number, a result of Amps and Volts. "Watts" is usually a label slapped on a motor by a vendor to sell it. How much it can handle depends on how much copper is inside and how fast it can shed heat. A name brand motor rated "750 Watts" can often handle 1500 watts+ for short bursts and not overheat.

So the rated wattage is helpful in general as a guideline, but it is more helpful to know the number of windings inside the motor. This will also determine the rpm of the motor. For a typical 200lb+ rider at 48v on an old mtb look for a lower rpm motor around 3-400 rpm for more torque to start from a stop, climb hills, etc.


Originally Posted by Outsidewave
So if you have say a motor rated at 3000 watts but are only using a 48 v battery and a controller of say 40 amps then you would be at 1920 watts . far less than the motor is rated.Is that right? Would this mean the motor would be sluggish ?
Does it take the full 3000 watts to make it perform well or would it be more like a safety factor to avoid burning up your motor?
Not sluggish. Sluggish means bad parts, hooked up wrong, weak battery. This is an efficiency question. For a typical 750 Watt geared hub motor max efficiency comes around 2/3 throttle, cruising speed around 18mph on the flats, with some pedaling, to get the least heat, most range from the battery, longest life from the system.

3000 watts is a really big direct drive (DD, no internal gears) motor that needs a 60 Volt+ system to get the most out of it. 40 amp+ controller and a big, expensive battery and will suck down a lot of juice for sustained speeds over 30mph that can be dangerous for a first-timer on an old beater in traffic. Yes it will run at 1200 watts but not to its full potential (speed) so why waste the money when a smaller motor would be fine. Better yet a geared motor for more torque at lower amp draw than DD.

Originally Posted by Outsidewave
Why are some controllers better than others and the issue with lithium ion batteries if any? and last but not least is BAFANG the way to go what about cyclone?
Bafang is a good name brand that has been around for a long time in ebike terms. Chinese brands come and go, look for a proven name that is affordable. As for cyclone try a search on endless sphere for user input they test everything over there.

Controller. Most ebike kits with a decent name have the controller matched to the system. At 48 Volts and 200lbs+ you'd want a 9 fet controller at 25 amps, and a 12 fet at 30 amps. Fets are terminals inside the controller that shed heat. If you go higher than 30 amps you really need to start looking at fet brands, custom controllers, etc = more money. A 25 Amp controller is fine for a first time build at 200 + lbs.

As for the battery.

First is Amp Hours, also called capacity = range. Average is 1.2 to 1.5 miles of range per Amp Hour without straining it. More range if you can pedal, less range with hills, etc. Cell quality and type have a lot to do with battery performance. Also the bigger the battery the easier it can handle short bursts at full throttle without overheating the cells inside = longer battery life.

Lithium Ion. "Lithium Ion" is a marketing term that doesn't mean much other than some type of lithium instead of lead. Lithium batteries are now cheap enough that "lead is dead" for ebikes.

Types of Lithium ebike batteries.
Lithium Nickel Cobalt Manganese (NCM) or Lithium Nickel Cobalt Aluminum (NCA) are the two current popular chemistries. NCA is the top of the line also more expensive. These are usually "18650" batteries which refers to the size, slightly larger than a AA cell. Light weight, high power, easy to use, last a long time, sold in many pack shapes and sizes also hard cases, relatively safe.
18650 cells are spot-welded together with metal strips wired to a circuit board (BMS) for protection. They are not user-serviceable without welding equipment and a lot of time/patience/small parts so it is important to buy a well-built pack with good cells (Samsung, Panasonic, etc) from a good vendor if you want it to last.

LiCo (Lithium Cobalt) is an older chemistry replaced by NCM/NCA. Cell makers are constantly upgrading chemistries to make batteries lighter, more powerful, safer.

LiFePo4 is an older lithium chemistry with less power than NCM/NCA, heavier, cost almost the same, more stable chemistry. They are roughly the size of c-cell batteries. They are more user-serviceable because the ends are screw connected, not welded. Also have a BMS wired in, usually come in plastic shrink wrap. They have largely been replaced in the mass market by NCM/NCA.

LiPo or LiPoly was swiped from the electric toy market, RC helicopters, etc. They are light, powerful, cheap, unstable. No BMS and you have to build your own pack with a rat's nest of wires. They have burned down houses from overcharging... also can burn from over discharging, or from being punctured in a crash. A hidden expense is you have to buy a bunch of monitoring equipment so they don't overcharge/overdischarge and burn. You have to babysit them while charging, store them in a fireproof place, etc. More for the track racing crowd, not for the new ebiker unless you already own toy planes with the knowledge and spare time to handle them.


Originally Posted by Outsidewave
I come from a 4 wheel drive back ground and we usually use the easiest part to replace as weak link in the system Ie it is easier to replace a u join on the drive shaft that to replace an axle in the field.
If you build an ebike you will know how to replace the parts, the physical replacement is easy. With a $15 digital volt meter (dvm) you can figure out which part is malfunctioning. With a good set of wire crimpers ($10) you can often repair a cheaper system by replacing cheap connectors with better quality ones from ebay or amazon, etc. Cheap connectors often fall apart so a dvm is a must. A dvm is also a good tool to keep an eye on the state of your battery.

Originally Posted by Outsidewave
What is typically the weak link in the system motor, battery or controller?
It is more about quality. The ebike pros say "don't cheap out on the battery." It is the heart of a system and the most expensive part to replace.

If you stick with a known motor or even a cheap kit from a seller with good feedback you should be fine. Especially through ebay or amazon if you need to exchange in 30 days. if it lasts 30 days it will probably last a couple years or more as long as you take care of it. You can always upgrade the motor or controller down the road, even from china. Eventually you will probably want more power. Learn how to build a wheel and you will save a lot on shipping. On all kit wheels you will need a spoke wrench, often right out of the box on the cheap kits. Or stick with mid-drive.

DIY ebikes are are mostly cheap old mountain bikes, with experimental chinese wiring and parts so that a chinese battery can push 200lbs+ down the road, up hills, etc. They are expensive for what you get, but cheaper than a car, don't need registration like a motorcycle, etc.

About every 6 months a new ebike technology makes it to the mass market. There is usually a 2-year run of the new stuff so new/old are always overlapping. Not all the new stuff is an improvement or well built. Look for what people have been using for a while, a bonus is the price comes down after a year when the next big thing hits the market. Right now you can get a good beefed up 48v kit with 11.6ah NCA pack for under $1000 shipped. Or a usable ebay/amazon kit + battery for $500 or less.

If you buy from china "you are the quality control" especially on the battery, costs too much to ship it back and forth, language barrier, shipping delays, etc. If you can stick to a us vendor you might get some warranty service. On cheap ebay/amazon kits you can at least get a refund if it doesn't work. hope this helps
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Old 03-08-16, 06:40 PM
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Great primer slo; would have taken me about three hours to type if I knew that much; you must be a technical writer with the spelling and grammar excellence.
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Old 03-09-16, 12:15 PM
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Thanks 2old but i think i said more than outsidewave asked about, probably too much theory.
He has a hi-end mtb and i talked about old beaters.
He asked about mid-drives and i talked about hub motors.
He's looking to spend $1k and i went on about a $500 kit + battery.
$1000 for a first kit + battery is a big investment and you really want to get it right the first time. It is possible if you understand what you're looking at, maybe harder with a mid-drive b/c of the higher price for a good one.
A lot of guys on here are better than i am with the short answer i hope they can help out the OP with his questions. If he ever comes back lol
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Old 03-09-16, 03:19 PM
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slo, still excellent info for all; couple of his questions
1) Some controllers are better than others because they have superior fet's (look up - has to do with the amps they can distribute).
2) Mid-drive best choice for steep hills and off road; less chance of failure since you can use gears to control rpm and keep it in most efficient range.
3) Most electric motors are most efficient at 80-90% max, but can run fairly well at less speed.
4) 1000w add on system means BBSHD, Cyclone, lectric cycles, lightning rods kit, tangent motors, AFT or others. BBSHD most user friendly.
5) IMO, most important consideration is battery --- can recommend only Luna Cycles or EM3EV and only conditionally.
6) Read all threads on whatever system you select to discover tricks and pitfalls.
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Old 03-10-16, 10:14 AM
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Care to elaborate on #5 ? I am looking for a small 25R pack, any other choices out there?
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Old 03-10-16, 11:43 AM
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slo, Luna is the best that I've found, and since they're in the US, shipping is cheaper. The fact that no DIY company that I know of offers a warranty speaks volumes (TO ME). The OEM's like Haibike can offer a two year warranty on vehicles that will be used off road and BionX offers a three year warranty on their batteries (I think). Crap shoot with all of the DIY AFAICT.
Wouldn't even consider an ebay or "ali (baba or express)" battery.
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Old 03-13-16, 12:50 AM
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Very good info. Just wanted to add a few more things.

A 3000W Cyclone run at around 2000 watts is crazy powerful. That's over 2.5 horsepower PLUS using your bike's gears. Here's a great thread about the Cyclone Luna Cycle sells.

https://endless-sphere.com/forums/viewtopic.php?f=28&t=69867&start=325

One user got up to 35 mph at 44.4V (12 cell lipo), so the volts vs speed is probably more of a hub motor thing. For mid drives, wattage more closely tells your top speed, since wattage is a measure of power.

That Cyclone motor can handle up to 4800 watts, so it will not break a sweat at stock power levels. Fried motors are probably more of a concern on hub motors since they only have one fixed gear ratio. At low speeds, they can draw tremendous amounts of current, only limited by your controller. If hills are a concern, a mid drive is the way to go since it can use your bike's gears.

One thing about the Cyclone is that there is little installation support for it (Luna Cycle does not support it). You must be handy to install it.

Also, amp hours doesn't really tell the whole story about range since we all use different battery voltages. One amp hour at 48V has the same amount of energy as two amp hours at 24V. Watt hours is what we should go by.

As far as the weakest part. That would probably be your bicycle chain. But of the parts you listed, the controller would probably be the 1st to go, but if you're running stock power levels, you shouldn't have many issues. Often people modify their controllers to pass more current, and that can cause them to burn out. Then you can have an excuse to get a Lyen controller.

LYEN Controllers

Issues with lithium-ion batteries: I would stay away from Lipo batteries as they are potentially very dangerous to charge. If your charger malfunctions, you could end up with a huge fire. I just bought a new battery for my bike and it is based on 18650 cells. It's the 20Ah 52V pack from Luna Cycle. It's a very safe battery. It is also lighter than an equivalent LiFePO4. The 25r can output 20 amps per cell, and since that pack has 8 cells in parallel, it has no trouble sending 40 amps to the controller. It is, however, limited by the battery management system (50A continuous and 80A burst).

52v Samsung INR18650-25r 20ah HIGH POWER - Luna Cycle

Originally Posted by slo
Good questions but the answers get big. There are many variables, rider weight, health, terrain, bike type, size of electric system, etc. I will try to keep it simple.


You are halfway there, i would just rearrange your formula in order of general importance. Volts x Amps=Watts.

Volts = speed. 24v = 15mph, 36v = 20mph, 48v = 25mph. This is the average kit and average battery, on flat ground with the average 200lb new ebike rider, average old 26" mtb conversion, etc.

Amps= torque. Climbing and pulling power. Also called current. Amp draw is set by the controller. Most 48v kits come with a controller in the 20-30 max amp range. More amps = more heat. Too much heat and parts get fried.

Watts is just a number, a result of Amps and Volts. "Watts" is usually a label slapped on a motor by a vendor to sell it. How much it can handle depends on how much copper is inside and how fast it can shed heat. A name brand motor rated "750 Watts" can often handle 1500 watts+ for short bursts and not overheat.

So the rated wattage is helpful in general as a guideline, but it is more helpful to know the number of windings inside the motor. This will also determine the rpm of the motor. For a typical 200lb+ rider at 48v on an old mtb look for a lower rpm motor around 3-400 rpm for more torque to start from a stop, climb hills, etc.




Not sluggish. Sluggish means bad parts, hooked up wrong, weak battery. This is an efficiency question. For a typical 750 Watt geared hub motor max efficiency comes around 2/3 throttle, cruising speed around 18mph on the flats, with some pedaling, to get the least heat, most range from the battery, longest life from the system.

3000 watts is a really big direct drive (DD, no internal gears) motor that needs a 60 Volt+ system to get the most out of it. 40 amp+ controller and a big, expensive battery and will suck down a lot of juice for sustained speeds over 30mph that can be dangerous for a first-timer on an old beater in traffic. Yes it will run at 1200 watts but not to its full potential (speed) so why waste the money when a smaller motor would be fine. Better yet a geared motor for more torque at lower amp draw than DD.


Bafang is a good name brand that has been around for a long time in ebike terms. Chinese brands come and go, look for a proven name that is affordable. As for cyclone try a search on endless sphere for user input they test everything over there.

Controller. Most ebike kits with a decent name have the controller matched to the system. At 48 Volts and 200lbs+ you'd want a 9 fet controller at 25 amps, and a 12 fet at 30 amps. Fets are terminals inside the controller that shed heat. If you go higher than 30 amps you really need to start looking at fet brands, custom controllers, etc = more money. A 25 Amp controller is fine for a first time build at 200 + lbs.

As for the battery.

First is Amp Hours, also called capacity = range. Average is 1.2 to 1.5 miles of range per Amp Hour without straining it. More range if you can pedal, less range with hills, etc. Cell quality and type have a lot to do with battery performance. Also the bigger the battery the easier it can handle short bursts at full throttle without overheating the cells inside = longer battery life.

Lithium Ion. "Lithium Ion" is a marketing term that doesn't mean much other than some type of lithium instead of lead. Lithium batteries are now cheap enough that "lead is dead" for ebikes.

Types of Lithium ebike batteries.
Lithium Nickel Cobalt Manganese (NCM) or Lithium Nickel Cobalt Aluminum (NCA) are the two current popular chemistries. NCA is the top of the line also more expensive. These are usually "18650" batteries which refers to the size, slightly larger than a AA cell. Light weight, high power, easy to use, last a long time, sold in many pack shapes and sizes also hard cases, relatively safe.
18650 cells are spot-welded together with metal strips wired to a circuit board (BMS) for protection. They are not user-serviceable without welding equipment and a lot of time/patience/small parts so it is important to buy a well-built pack with good cells (Samsung, Panasonic, etc) from a good vendor if you want it to last.

LiCo (Lithium Cobalt) is an older chemistry replaced by NCM/NCA. Cell makers are constantly upgrading chemistries to make batteries lighter, more powerful, safer.

LiFePo4 is an older lithium chemistry with less power than NCM/NCA, heavier, cost almost the same, more stable chemistry. They are roughly the size of c-cell batteries. They are more user-serviceable because the ends are screw connected, not welded. Also have a BMS wired in, usually come in plastic shrink wrap. They have largely been replaced in the mass market by NCM/NCA.

LiPo or LiPoly was swiped from the electric toy market, RC helicopters, etc. They are light, powerful, cheap, unstable. No BMS and you have to build your own pack with a rat's nest of wires. They have burned down houses from overcharging... also can burn from over discharging, or from being punctured in a crash. A hidden expense is you have to buy a bunch of monitoring equipment so they don't overcharge/overdischarge and burn. You have to babysit them while charging, store them in a fireproof place, etc. More for the track racing crowd, not for the new ebiker unless you already own toy planes with the knowledge and spare time to handle them.




If you build an ebike you will know how to replace the parts, the physical replacement is easy. With a $15 digital volt meter (dvm) you can figure out which part is malfunctioning. With a good set of wire crimpers ($10) you can often repair a cheaper system by replacing cheap connectors with better quality ones from ebay or amazon, etc. Cheap connectors often fall apart so a dvm is a must. A dvm is also a good tool to keep an eye on the state of your battery.



It is more about quality. The ebike pros say "don't cheap out on the battery." It is the heart of a system and the most expensive part to replace.

If you stick with a known motor or even a cheap kit from a seller with good feedback you should be fine. Especially through ebay or amazon if you need to exchange in 30 days. if it lasts 30 days it will probably last a couple years or more as long as you take care of it. You can always upgrade the motor or controller down the road, even from china. Eventually you will probably want more power. Learn how to build a wheel and you will save a lot on shipping. On all kit wheels you will need a spoke wrench, often right out of the box on the cheap kits. Or stick with mid-drive.

DIY ebikes are are mostly cheap old mountain bikes, with experimental chinese wiring and parts so that a chinese battery can push 200lbs+ down the road, up hills, etc. They are expensive for what you get, but cheaper than a car, don't need registration like a motorcycle, etc.

About every 6 months a new ebike technology makes it to the mass market. There is usually a 2-year run of the new stuff so new/old are always overlapping. Not all the new stuff is an improvement or well built. Look for what people have been using for a while, a bonus is the price comes down after a year when the next big thing hits the market. Right now you can get a good beefed up 48v kit with 11.6ah NCA pack for under $1000 shipped. Or a usable ebay/amazon kit + battery for $500 or less.

If you buy from china "you are the quality control" especially on the battery, costs too much to ship it back and forth, language barrier, shipping delays, etc. If you can stick to a us vendor you might get some warranty service. On cheap ebay/amazon kits you can at least get a refund if it doesn't work. hope this helps

Last edited by Robocam; 03-13-16 at 01:04 AM.
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