If you are thinking of building, buying, or servicing ANY electric vehicle, please read this safety tutorial completely before you begin. I have been working on electric vehicles for many years now and I have made some mistakes that I hope you can avoid by following some safety steps I have laid out for you.
Whenever you approach an electric vehicle the very first thing to do is MAKE SURE IT IS OFF! As we know electric vehicles make very little noise, and are dead silent at a stop. It is too easy for someone to walk by and bump the throttle, or like many who just twist the throttle on purpose. We are accustomed to hearing an idling engine so much that everyone will just assume the vehicle is completely off, when in actuality it’s 100% ready to drive. Be sure to test with a multi-meter that the vehicle power is off, so you know the connections are safe to touch.
put on your protective gear, Technically you should have long rubber insulated approved lineman’s gloves on, with leather gloves over them. for most hobbyist like me, I prefer using thin rubber gloves covered by leather “Mechanix” gloves. Make sure there are no holes in the finger tips or thumb area where stray power could zap you. Wear a snug fitting pair of safety glasses, this is more important then you may realize. If you accidentally have a large short occur, sparks and molten metal, sometimes accompanied with battery parts will come flying at your face, you will be happy you wore glasses!
Wearing the high protective hand wear is only necessary when disconnecting or re-connecting high power electrical systems, once the system is disconnected, and checked, then you can continue to work without the gloves.
Disconnect the battery, this can be done by many methods, but mainly two are most practiced. Find the negative terminal of the battery and remove it, be sure to tie the wire away so it cannot spring back and re-connect unexpectedly. The second method is to remove the main fuse, or in some cases flip the circuit breaker.
Insulate your wrenches and ratchets! your tools make a great conductor, I learned this lesson the hard way by accidentally dropping an 8mm wrench on my bike and having it short on 72 volts positive to negative. There was an explosion and not much left of the wrench, the batteries were also severely damaged. There are some very simple methods of modifying your tools to prevent a short from occurring.
buy some liquid tool handle cover, this is available at most auto parts stores. This allows you dip ratchets, wrenches, pliers, or whatever you want into a liquid rubber that dries to a solid durable insulating handle. Another solution is to purchase various sizes of wire heat shrink and use this to insulate your tool handle’s.
I just recently found these composite covered ratchets, You can find these at any Harbor Freight store or buy them from their website. The ratchets have a very fine tooth feel, similar to very expensive snap-on ratchets. These are great because is you accidentally bump the ratchet into the chassis of your EV it will not short out, preventing any arcing from happening, there very affordable $16 for 1/4 and 3/8 drive. The inside of the ratchet is steel making it very strong as well.
Trust me, it is worth your time and money to make some simple battery wrenches, this is what happened to my wrench after it shorted on a 72 volt system, I was lucky the motorcycle was not completely destroyed and I was not hurt.
Do not reach into a “mystery spot” on an electric vehicle, this is epically dangerous because if you get electrocuted you will most likely not be able to pull your hand out. Be sure that whenever you are working on an electric vehicle that you know very well what you are touching and what is around you.
Whenever testing any components that requires the power to be on, you should jack the vehicle up so the drive wheel(s) is off the ground and the vehicle is stable. Another option it to remove the drive chain, shaft, or belt. to render the vehicle from moving. This will prevent any accidental throttle activations from becoming a complete disaster. This should be taken in to consideration when programing your speed controller, because it must be powered up to communicate to the computer.