Introduction: New Life for an Old Ebike - New Battery, Ignition, Lights, Charging Port, and a Trailer!!!
Have you looked at the newest e-bikes available? Just in the past five or six years things have changed drastically. Both motors and batteries have gotten lighter yet more powerful, not to mention more affordable. Major bike companies such as Giant and Trek are buying into e-bikes and are producing some really slick designs... but at between $3,000 and $12,000 that whole affordable thing goes right out the window. About six years ago I built an electric bike to use as a commuter to go from home to work. I posted the build to instructables about one year ago. The bike has served me extremely well and I have put 5,000 miles on it and the batteries running it. But, alas, those batteries have seen better days. Being reclaimed from the start, they did not have as much capacity as they once did in the Ford C-max they had called home. Now, after so many miles they have finally given up the ghost and I needed to find an affordable, higher capacity battery system. I was lucky enough to come across a guy in Boston who was selling 10ah, 48V Sanyo batteries with NCR18650GA cells for $165 each. I figured I could get two of these, wire them in parallel to each other and have a 20ah battery with amazing cells for $340. That was cheaper than actually buying the 18650 cells and putting them together myself (at the time they were selling for $5 each and I would have needed 78 of them... do the math on that!!).
But why stop at new batteries only? Why not add some headlights, an ignition, a charging port, and even a trailer? I thought that it would be fun to share with you my alterations to my bike and hopefully inspire you to give one, two, or a few of them a go. Let's talk batteries first!
Step 1: Removing the Old Batteries
As I mentioned earlier, the older batteries I had in this bike were taken from a Ford C-max that had met an early end. I wired these up to form a 13S-2P pack with a BMS. They really did a great job over the years but their range was pretty short. By the time I decided it was time to change them out I was only getting 9 miles out of full charge. So, out they came. I was careful to remove them so that they were still 100% useful in some capacity. In fact I plan on building an electric go cart for my kids (and me of course) over this winter using the batteries. There wasn't much to taking them out and you can see the fully removed system in the second picture.
Step 2: Starting From Scratch...ish
Now that I had the battery box taken off the back and the central box empty of any additional cells I had a nice "clean" slate to work with. The remaining parts located in my central box were the motor controller, shunt, and the connections for the battery, computer, controller, and motor. Now I needed to find a way to store and protect my new batteries. Sadly they didn't fit into the central box, which I anticipated, and I wasn't too keen on building a new central box to fit the batteries. I decided that I could once again have them attached to the back rack... but what box was I going to use?
Step 3: Don't Be Such a Tool... Box. - Building the Battery Box From an Old Toolbox
I've had this old Craftsman toolbox kicking around my shop for years. For quite a while it was empty and then one of my kids commandeered it and put piles of random tools (and wrappers, army men, etc...) in it. I figured that the box was long, watertight, had a lot of air between the layers for insulation, and was sleek enough for my purposes. Plus, it was taking up space in my shop :)
The batteries fit in the box nicely oriented with the tall side up. It would be tight, but I probably could have fit a third battery (30ah!!!). I'd need to properly insulate and protect the batteries though, so it's nice to have some room for some foam. Next step is to run some big honking wires from the battery box to the central box.
Step 4: Waste Not, Want Not - Using an Old Dryer Plug for the Battery Wiring
I think you can tell that I like repurposing things. So, in the spirit of "waste not want not" let's use a power cord from a deceased dryer. Benefits of using this cord are as follows; the outer casing is insanely robust, the wire is AWG 10 and really nice copper, it was taking up space in the shop, and there are four wires, perfect for our application. My batteries have both a fused power side and a non-fused charging side. I will need a positive and negative for each task... so four wires! I cut off the plug head, leaving some length for reusing that in the future of course, then got to task figuring out which wires would go where. The wire housing will need to pass through the toolbox so I drilled a tight fitting hole for the wire in the toolbox. I planned on wiring my two batteries in parallel to each other (more on that later) so all I needed was one xt60 female lead for charging and one xt60 female lead for a power feed. I soldered these to the two wires for each specific task and then sealed them up. At this point it isn't a bad idea to check how things are working out so far and making sure you can run everything up to the central box on the bike. I didn't solder any connections on the end of the big wire going into the central box since it had to pass through a hole already drilled in the central box. I planned on soldering the pieces once I passed this through the box and the battery box was attached to the back rack.
Step 5: Attaching the Toolbox / Battery Box to the Bike
I had already had a back rack on the bike for the previous battery box so this was pretty easy for me to put together. The rack was just a cheap one that came with the motor and controller when I bought them (see the link to my previous posting on this bike on the first page of this ible). The rack has a piece of plywood on it as a base and three holes drilled in it for bolts to pass through to firmly attach the box to the plywood. I used some hand knobs to tighten the bolts down through the plywood base (the knobs are really just nuts surrounded by plastic now since the knurled part has busted off, but they work fine for this purpose). To make sure the batteries don't jump around in the box at all and have a cushioned ride I used an old piece of foam and cut out a nice fitted slot for each battery to ride in and then fit this into the battery box. Snug as a 20ah bug! Now we just need to make the connections to the controller and motor.
Step 6: Wiring the Batteries From Battery Box to Central Housing
As I mentioned earlier, I wired the two batteries in parallel to each other. I made a couple of "Y" connectors to do this so that the positive ends of the charging side meet with each other and the negative ends do the same coming out to a single male xt60 connector. You do the same thing for the power side of the battery with the other "Y" adapter. The main cord has to then pass through the central housing from the battery box. This is one big, thick wire, so it is plenty rigid to pass between the bike frame and is completely protected from the environment. The charging wires coming through had another male xt60 soldered to it. The power wires had a bit of a different route. The negative wire had to run to one end of my shunt which has the ammeter connected to it. Another negative wire runs from the other end of the shunt and then the positive wire from the power line and the negative wire from the shunt connect to another male xt60 connector. This then runs to the motor controller. But what if you don't want anybody to just jump on your bike, hit the power switch and go? Well... you'll have to wire up a keyed ignition of course!
Step 7: Putting in an Ignition and Charging Port!
This is pretty straight forward, so I won't go into crazy detail. I ordered up a switch that could handle at least 30 amps at 54v. I ended up getting a two-way switch just in case I decide to add some parts to the bike that I want to run without the key in the "on" position. I ran a 10AWG power lead from the switch and connected it along with the negative wire from the shunt to a male xt60 connector. I then ran the power lead from the battery to the switch. I also had to run a power lead from my computer to the ignition switch. I ended up connecting this to the battery side so that the computer stays on all the time so that I can easily check the voltage of the battery if I am not using the bike for a while without using the key. I am thinking I might change this to the controller side so that I have to use the key to turn it on, but I don't know yet if I really want to. I don't think the computer is pulling much juice from the battery (.04 amps from my readings).
I also made a charging port to easily charge the bike. The charging wires from the battery run to this charging port. I used these two files from Thingiverse to print them on my printer.
https://www.thingiverse.com/thing:2230705 Cap for charger port
https://www.thingiverse.com/thing:3113398 xt60 mount
I mounted the charging port below the ignition on the outside of the central box. Now only if I had some lights to see where I was going...
Step 8: Adding Headlights
I definitely did not break the bank here. I purchased these headlights for $20. They are not amazing, but they definitely work well enough for riding safely at night without blinding oncoming traffic. I attached the switch to the handlebar and ran the wires into the central box keeping them tightly connected to the other wires running into the box with wire wrap and zip ties. These wires were connected to a 48v lead that came from my motor controller. The lights will only turn on when the key is turned to the on position and the switch is turned to on for the lights since the controller isn't energized until the ignition is turned on. As for mounting the lights, I put them right in the center of my handlebars and positioned them so that they would shine about 20' ahead of the bike while not blinding oncoming traffic. Nobody has flashed me so far so I can assume that they are positioned well.
Step 9: Add a Trailer!
So, this has been on my "to do" list since I first built the bike but since the bike's range started to dip off over the past couple of years I decided to put a trailer on hold. Now that I have some significant range and power I decided to build a simple trailer for the bike. This was a freebie I found on the side of the road nine years ago. We used it with our kids for a few years until the nylon on it started to decay beyond repair. I removed all of the nylon and fittings leaving a bare trailer and it sat in the shed until just now! To make the trailer I used a piece of 1/2" plywood as the base, attached a couple of 2x4s to the front and back to hold a big plastic bin to cart things around in. I mounted the mounting plate for the trailer hitch onto my bike using the two mounting holes for the back racks. This all really depends on your bike and the type of trailer you end up finding. I have been able to load 50 pounds into the trailer and pull it for ten miles (up to 25 mph) with no problem at all. I am certain I could pull 100 pounds if needed but obviously I would lose a fair amount of my range.
So that's it! A new battery, ignition, charging port, lights, and a trailer for my six year old ebike build. I love driving this thing around and I have a blast using the trailer to run out to the grocery store or pick up something at a friends house. Also, now with the new batteries the bike has a lost a lot of weight so it is easy to put on a bike rack. I hope that this gives you some inspiration to either build an electric bike or build something for one you already own. Happy trails!
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