It is not possible to have an electric bike without a battery. The batteries that are used on electric bikes are lithium ion rechargeable batteries that are relatively small, energy dense, and somewhat expensive. It is important to know that all electric bike batteries are a Class 9 hazardous material and therefore cannot be shipped by common carrier (FedEx, UPS, USPS, DHL) without the services of a licensed hazardous materials shipper. It is a $75,000 fine if one is caught shipping a lithium ion battery. Also, handle these batteries carefully as a damaged battery may lead to a fire during charging. Is it dangerous installing this battery? No, it is safe but be careful you do not drop the battery. These batteries can weigh over nine pounds and can be easily dropped while installing. Never assume a dropped battery is not damaged because the case is not cracked. Inside the battery are a number of cells that are bonded together and a battery that has been dropped may cause one of these cells to break free. On the assembly floor of one of the largest electric car manufacturer in the world has a policy that if a battery cell is dropped it is immediately marked for recycling and not used in the pack that will go on the car. All lithium ion batteries of the size used on an electric bikes must be treated with care.
There are many choices to buy a battery online. We purchase hundreds of batteries so we work directly with the manufacturer. But where do you go to purchase a single battery? There are five most common portals to purchase an electric bike battery. These are: Amazon, Alixpress, and eBay. Please note that when you buy a battery from Amazon or eBay that will come from the same source as purchased from AliXpress. Sellers on eBay and Amazon drop ship batteries from the Asian battery manufacturers. Drop shipping means the seller never even sees the battery he just sold to you because he has it shipped directly from the seller on AliXpress to your front door.
I have always found purchasing items from AliXpress safer and more reliable than from Amazon and eBay. When purchasing from AliXpress only buy from companies that participate in the Buyer Protection program. Sellers on AliBabba and AliXpress have a lot to lose if they in any way are caught in fraud. We have purchased 1000's of batteries from the same companies that sell on AliXpress and AliBaba and have never been taken advantage. Some are concerned about giving their credit card number to an overseas company. Our company credit card has been used many times in overseas purchases and have never lost a single dime. On the other hand, we have had our card number (both personal and company) stolen a number of times here in the US.
If it were possible we would buy all of our motors, batteries, bikes, and components from American manufacturers. However, there is no one building electric bike batteries in the US and even if they were the battery cells they require comes from overseas. Even the battery cases are built overseas. If, one decided to set up a manufacturing plant for the purpose of building electric bike batteries from lithium cells produced here in the US and put in cases also built here in the US, the cost of an electric bike battery would more than triple. It would not make sense building a product that is already on the market and sells 1/3 of the selling price of a domestically produced product.
There are a few resellers of electric bike batteries here in the US. These resellers purchase the batteries in lots of 20-50 and then sell them to buyers in the US. Typically, they have their own website and do not sell on eBay or Amazon. Remember, purchasing a battery is a one way proposition as they cannot be returned. If possible, always purchase your battery from a local source. For most people that is not possible as there is no one within driving distance that is selling electric bike batteries.
Electric bike batteries are typically 36v, 48v, and 52v. The battery pictured above is a typical downtube battery and can be a 36v, 48v, or a 52v battery. If your motor is 500 watts or below, you would use a 36v battery. If your motor is above 500 watts then you will use a 48v or 52v battery. Please note: If you are using a Bafang BBSHD 1000 watt motor then your battery will have to have a 30amp BMS card. This is important as anything less the 30Amps can damage the motor controller. The Bafang BBS02b 750 watt motor runs fine on a 48v battery with a 25a BMS card.
When we talk about watt hours we are using a general metric to arrive at range, or how far can you ride on a single charge. Range is determined by many factors but if all these factors are the same then we use watt hours as the formula. Watt hours are calculated my multiplying the watts of a battery by the amps of the battery. For example a 48v 13Amp battery will provide 624 watt hours. A 52v 17.5Amp battery will provide 910 watt hours. It is one way to calculate range but in the end it all about riding conditions, not the watt hours. Riding conditions, (wind, hills, weight of the bike, weight of the rider, size of the tires, air pressure in the tires, type of bike, use of throttle, power contribution of the rider, age of battery, quality of cells), will always be the final arbitrator of range.
This is a downtube battery. It is the most common of all electric bike batteries. It is easy to install (sometimes), sits low in the frame, and has a hard shell case for protecting the battery cells. Typically, this battery can be installed using the existing water bottle inserts. However, if these inserts do not fall in proper line with the mounting plate connection points then additional work will be required. Sometimes one can alter the mounting plate while other times one will need to install new inserts in the frame. The installation of inserts should only be undertaken by a skilled bicycle mechanic.
This is a battery made by Unit Power Pak and is our favorite battery. The downtube battery can only be used on bikes with a large triangle whereas the side release battery can fit in tight spaces. A downtube battery needs to go forward and up in order to remove from the bike. That movement requires a fair bit of space. A side release battery releases in a side swing motion. Therefore, the side load battery is the battery of choice when working on full suspension bikes or bikes with small frames. Because this battery only weighs less than six pounds it is perfect for carbon framed bikes or when we need to mount a battery on top of the top tube.
This battery is a 52v 20Ah triangle battery and it is very heavy. We rarely use this battery due to its weight. This battery uses large, heavy duty Zip ties and velcro straps to attach to the bike frame. We do not like to use this battery because it tends to swing while riding the bike. While it can be secured to the point that it is stationary but then it cannot be removed for shipping. Some will build their own cases in which too install this battery thus eliminating the problem of swing. Out of 1000 of the electric bikes we have built we have only used this battery one time.
A battery like this can solve a lot of problems when working with a bike where there is no place to put the battery. These rack batteries can pack a lot of power due to their size. However, they are not very popular. For one thing, it puts a lot of weight up high behind the rider. Also, people do not like that fact they have to swing their leg over the battery rack in order to mount the bike.
A block battery can be made to just about any size within reason. You can find a 72v 50Ah block battery online for around a $1,000. The downside of the block battery is somehow finding a way to attach it to the bike. Also, there is no hard plastic case to protect the battery. On occasion we use small block batteries on road bakes. We take the battery and place it in a large behind the saddle tool bag and fill it with cushioning material to protect the battery.
Bottle batteries are typically 36v batteries with limited amps which gives reduced range. Some people do not like the looks of the larger downtube batteries and prefer the sleek appearance of the bottle battery. It is possible to fit the battery into tight spaces because it is a side release battery. IF you have a 500 watt motor then this battery might be right for you. Remember, it may be smaller and look cleaner on your bike but you will be giving up a fair amount of range.
This is an example of the downtube battery install. This battery is the typical 48v 13 top load battery. It is important when you use this type of battery to remember it will need room to slide forward about an inch and then upwards about a half an inch in order to install and remove for charging. Many, who are ordering a battery for their bike will measure the triangle area of the frame and then order a battery that will fit the triangle. Nope...that is not the way it works. There must be enough room for it to slide forward and up in addition to have room for the size of the battery.
We have mounted batteries on the top tube of a number f bikes. It is not our first choice but sometimes there is no alternative. When mounting on the top tube I highly recommend using the smaller, lighter, side release battery. To install a battery on the top tube you will have to drill and insert Rivnuts. When possible, we use three Rivnuts. It is very difficult to install a battery on top of the top tube and should only be attempted by an experienced bike mechanic.
On some full suspension bikes the best (if not only) place to mount a battery is on the bottom of the downtube. Most full suspension bikes do not have any way of attaching a rear rack which eliminates the use of a rack battery. Usually, there is no room on the downtube and mounting the battery on the top tube is best to be avoided whenever possible. Note: If you are going to mount the battery on the bottom of the downtube make sure the front tire does not come into contact with the battery when the fron suspension is compressed.
This is a Dahon folding bike being prepped for conversion. We always use the side load battery for small collapsing bikes. When attaching the battery cable to the motor remember to do it in such a manner that will allow the bike to fold. We take the battery cable and attach it to the existing cables on the bike (shift or brake). By using the existing cables as our guide we know the bike will fold once the battery is installed.
This well machined product is made by Terra Cycle (T-cycle.com) and is invaluable for installing a battery on a recumbent. It is an expensive item but it is very well made and worth the cost. There is no downtube on a recumbent bike and nearly every square inch is already accounted for and there space is limited. This product creates space for the battery and if you are converting a recumbent then I recommend you include the Terra Cycle battery base in your budget.
This was a custom build we did for a very nice gentleman. He was over 6' 9' and needed a very tall bike. Battery placement was going to be a problem as the frame was round tubes made of steel. The only place we felt we good get a secure fit for the battery was on the seat tube. This can only be done on bikes that have a very long seat tube. When we were finished installing the battery we were pleased with the result.
This is the Bafang DPC965 five button display. It also comes in a three button model which is the newer and better version. This is simple to install. It comes with three very small screws and locknuts. It is very easy to drop either the screw or the locknut during installation. If dropped they are very hard to find so think about laying down a towel to catch the dropped part.
This is the Bafang thumb throttle. While this throttle is sufficient there is a heavy duty throttle on the market that is much better in both design and function. If you use the stock throttle pictured above it is absolutely essential it is placed in a position where it cannot come into contact with any part of the bike!!! The lever on the throttle can get stuck on the brake lever attachment bolt if mounted to near the brake lever. This can cause an open throttle situation. Make sure nothing can come into contact with the throttle lever.
This is what the heavy duty throttle looks like. It deploys to the side as opposed to the up and down of the stock throttle. It uses larger gauge wire and its design allows it to fit against the display control far better than the the stock throttle. Hands down this is a fa better throttle than the two and it only costs around $20. Note: We always mount the throttle on the left side along with the display control. The reason for this is there is much more room as the right side is being used by the rear shifter.
We do not use twist throttles on any of the electric bikes we build. The quality is extremely poor. A good twist throttle would cost more to make than people would be willing to pay. Thus, every twist throttle we have ever seen has been of below standard of what one would expect. One can buy a set of twist throttles for less than $20 and it is simply impossible to build an electric bike twist throttle for $20. Whereas the heavy duty thumb throttle will be trouble free for years.
These brake levers are for front and back brakes and each has a motor cutoff switch. When the brake lever is pulled a mechanical sensor tells the motor to shut off. Seems simple...and of course it is not. Brakes have different lever pull or what is known as "throw." If your Bafang lever is short pull and your brake system is long pull then the brakes will be mushy. Decide for yourself but our solution is to use the Bafang brake lever that controls the brake on the front wheel and leave the original brake lever that controls the rear brake. Because the distance between the front brake lever and the front brake is very short, even a short pull lever with a long pull brake system will work. However, because the distance between the rear brake lever and the rear brake is very long, a short pull lever will not work with a short pull brake system.
This little sensor is used as a motor cut off switch for those who have hydraulic brakes. First, the small black sensor is to be glued near the brake lever. Then, a small magnet is glued or Ziptied to the brake lever. When the lever is pulled the magnet moves away from the sensor shutting off the motor. Our confidence in this product is very low as the magnet or the sensor often falls off while riding. Also, some hydraulic brake systems are shaped in such a way there is no practical way to attach both magnet and sensor in such a fashion that they would functioned. What to do? You can convert the front wheel to a mechanical disc brake, or you can order a hydraulic brake system with a built in motor cutoff.
I have been ask many times why I tell others how to do this themselves. The thinking is that if I help people convert their own bikes I would be undermining my own business. Perhaps, but on the other hand there are many out there who will take up the challenge of converting their own bikes with or without my assistance so I might as well help when and where I can.
I think the most people underestimate what it takes to convert a standard bike to electric. First priority must be safety. In this case I mean safety of the one doing the work of conversion. There are a hundred different ways to injure oneself when working on a bike. For example, using power tools, lifting heavy objects, working around sharp chainrings, using high torque tools, breaking free crank bolts, (crank arms, bottom brackets), and other tasks that can cause serious injury. Bottom bracket removal, for example, is a task that has a high potential for injury if the right tool is not used. If one is not mechanically inclined it is highly recommended you proceed with caution. Perhaps take your bike frame to your local bike shop and have their mechanics remove the crank arms and the bottom bracket. If your budget is a bit squeezed then ask a friend who is mechanically inclined to give advice and direct you in the process.
After the safety of the person building the electric bike comes the safety of the end product. Stand back and take account; This bike can travel in excess of 28MPH and if poorly constructed something might fail. Take a look at your tires, are they new and are they of such quality they can withstand sustained high speeds? It is my view that all electric bikes should use electric bike rated tires. A electric bike rated tire has thicker wall and added puncture protection. It is worth the added cost for the level of safety they will provide. Also, take a good long look at the brakes on your bike. Are you brakes sufficient for slowing and stopping an electric bike traveling at 28MPH? A good set of rim brakes that have new brake pads and are properly aligned will be sufficient. If you have disc brakes make sure the brake pads are new and that the rotor is not worn out.
Lastly, take your wrenches, screwdrivers, torx and hex drivers and check every nut and bolt on the bike! Check the cables, cable housing, chain, cassette, pedals, stem bolts, headset, spokes, and insure the wheels are in perfect true. Now...it is ready to enjoy.