Note: Don’t try this at home unless you know what you are doing. There is always a chance of serious injury or death when working with electricity. Always get the proper training before attempting anything like this. This is not a manual, just a high level overview of the process.
At the end of August 2018 I purchased a 2010 Zero S Motorcycle, a fully electric motorcycle, off an auction site for $1800 CAD. It was advertised with the following warning “The battery & charging system is unserviceable. This vehicle requires expensive repairs.” and only had 800 km on it.
Looking online, it seemed like a common issue with these early bikes was the BMS could kill the battery if the bike wasn’t kept plugged in. Some people seemed to have success replacing the battery so I took a gamble to see if I could as well.
First thing I tried was charging the battery, and all I got was an error pattern on the charger. The dashboard was dead, no response to the key being turned. If only it was that easy…
Pulled the battery out, pretty much completely dead. Supposed to be around 56V, measured output was around 4V. Disassembled the battery and recycled it when my city had a Household Hazardous Waste collection day.
The new battery (Nissan Leaf Modules)
Pretty much all the heavy lifting for the design of a replacement battery was already done from some people on electricmotorcycleforum.com, I’ve listed the threads below.
I used 7 2015 Nissan Leaf modules purchased from Ebay Canada. I connected the modules with 5/16 threaded rod. Decided on using Copper Flat Bar with dimensions 0.125 inch x 1.250 inch x 2.0 inch from Metal Supermarkets, drilled through with a 6mm bit.
To cover and protect the battery connectors I designed a cover in TinkerCAD and 3d printed them. Printing using TPU allows the plastic to be flexible enough to slide over top the copper. It has a hole in the side to allow a BMS quick connector to attach to the terminal connector (from Digikey).
I also printed covers for the center terminals, these use the 45 degree terminal connectors from Digikey (can be seen in the BMS photo later).
When I connected the BMS the first time, the BMS gave a pattern that wasn’t in the Zero manual, 5 quick beeps followed by 3 longer beeps. First attempt at wiring the BMS I did was wrong. The second attempt had some of the BMS wires not working, and after some troubleshooting it was the inline fuses. Soldered some new ones, working great, link for fuse at Digikey down below. Shrink wrapped it for protection.
Crimped new main cables (4 awg), the new negative cable needed a special Anderson connector lug so it could attach to the main power disconnect. Found it on Amazon, linked below. Amazon also had the other parts; lugs, crimping tool, and cable sleeving.
Connected up the BMS and got the ready beep pattern.
Putting the battery back into the frame was a pain, used ratchet straps to lift and hold it in place. The battery needs to be lifted and shifted towards the back wheel to get past the frame, then shifted forward again. Next time I’ll get a car lift, the ratchets were finicky.
And finally, a video of it working:
7 Nissan Leaf Modules: ~$980
Parts + Tools: ~$250
4 x The Hillman Group 5/16–18 Zinc-Plated Steel Standard (SAE) Fully Coarse Threaded Rod — 11012
The Hillman Group 5/16-18 Zinc-Plated Steel Standard (SAE) Fully Coarse Threaded Rod - 11012 |…
Shop The Hillman Group 5/16-18 Zinc-Plated Steel Standard (SAE) Fully Coarse Threaded Rod at Lowe's Canada. Find our…
8 x Hillman 5/16-in-18 Galvanized Standard (SAE) Hex Nut
Hillman 5/16-in-18 Galvanized Standard (SAE) Hex Nut | Lowe's Canada
Shop The Hillman Group Hillman 5/16-in-18 Galvanized Standard (SAE) Hex Nut at Lowe's Canada. Find our selection of…
BMS Wire Fuse
0453004.MR Littelfuse Inc. | Circuit Protection | DigiKey
Order Littelfuse Inc. 0453004.MR (F3339CT-ND) at DigiKey. Check stock and pricing, view product specifications, and…
8 x Terminal Connector (Flat)
7 x Terminal Connector (45 Degree Angle)
TPU Plastic for printing
Main Battery Cables Parts
SB120 Large Gauge Anderson Connectors 4 Gauge
PET Expandable Braided Sleeving (Red/Black and Black)
Lug Crimping Tool
Marine Grade Electrical Heavy Duty Tinned Copper Lugs (4-Gauge, Size 1/4 Screw, 25-Pack)
MG Chemicals Lithium Grease