The goal of this ible is to show you how to fix the most common problem with small electric scooters. The most common issue is related to the battery, followed by the charger, meaning these are often available for anywhere from 50$ to free.
What is more, in fixing this, we can easily make it 50% more powerful with stock hardware (changing nothing else) and 100% more powerful with a full rebuild. I do not have the parts for a rebuild yet, so for now this will focus on the easier and simpler upgrade modification.
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*extra note* I designed this as a 2 batteries in series; I would recommend doubling that to 2 in parallel x 2 in series for longer rides. The 15 amps drawn continuously for approximately 10 minutes made the plastic around my battery terminals go soft and they shifted. However, I don't consider this to be dangerous per say, the battery was in good shape chemically, it's just the plastic that was not doing so well at this point.
Step 1: Material
The standard equipment needed will be
- Your scavenged scooter, or new for as little as 170$ (see below)
- Batteries and appropriate connector and charger (see below)
- Anderson Connectors
- 12 gauge wire (14 if you must, but try not to skimp, you will lose power).
- Wire strippers / snips / pliers
- Screw drivers (probably number 2 Phillips, but look at what your scooter has)
- Replacement nuts and bolts if yours are all rusted as mine were
- A soldering torch
- A helmet
First and foremost, you will need an electric scooter. There are three "main" popular models (and them some derivatives of those). The Razor E100, E200, and E300. There is also a less popular E90. All but the E90 are modded the exact same way. If you happen to have an E90 (the less common of the bunch), keep the voltage to half of everything specified here (so a single 18v battery instead of 2 in series).
The second major thing that can vary quite a bit is your power source. You can replace it with more cheap-ish lead acid batteries (not much of an upgrade as you will still be using a 24v system with the same issues as the original). The next option is using lithium batteries, and this is where it can get a little tricky. There are many options, and you can build a pack from scratch, but that can be an large undertaking, requiring quite a bit of learning. The easiest lithium option is to buy a ready-made pack (can be hard to pick the right one, lots of confusing options), or make your own from safe and reliable power tool batteries as I show in my other ible https://www.instructables.com/id/Using-Ryobi-Power...l
I will actually be using a custom pack long term, but for the ible I will stick with the Ryobi pack, as it is much easier to test with such a flexible option.
Step 2: Back to School: Why Does This Mod Even Work?
When building electric vehicles (or working with motors in general), there are three related ratings. Watts is the total amount of power (either as torque or speed). Voltage determines the speed, and amps the amount of force with which the motor turns (torque).
- Total power, or Watts (W) = voltage x amps.
- Each motor and motor controller is capable of a certain amount of total power (W).
- Each motor is capable of a certain amount of amps (theoretically voltage too, but inconsequentially in this case).
- Each controller is capable of a certain amount of volts, and controls the amount of current (amps) that flows to the motor.
Now it so happens that the way in which controllers a built accounts for a bit of extra headroom. So a 24v controller can usually handle a 36v lithium battery. The issue that can come from this is the low voltage cutoff would be set too low. This is where having a battery with a built-in BMS (battery monitoring system) is important, and guess what! Our Powertool batteries have that!
This means that our 36V scooter won't be able to pull anything heavier than it did before (no change in amps), but if it was able to reach top speed before, now it should go 1.5x faster!
Step 3: Removing the Old Battery
The first step is to remove the battery. To do this, you need to remove the base plate, which is held in by a few nuts and bolts. Once this is done, you can simply snip the battery out. Only cut one wire at a time, and make sure the freshly cut wires don't touch your snips while you cut the next one, or you may just weld them in place if there was enough of a charge left (or at least make a few sparks).
If you are using a custom pack and the appropriate charger, you may also want to remove the old plug as it is a harder to use style and we are moving on to all Anderson connectors. Do make sure you label everything as you are cutting it.
If you are using power tool batteries, the batteries will likely not fit in the base (and would be a pain to take in and out), so you will most likely have them in a bag or a caddy of some sort, which means you need to run wires to power everything down there. You can either make a new hole for running your power cables, or you can remove the old charging connector and re-use the slot to feed your battery power in there.
Step 4: Get Our Wiring Ready
We now need to add Anderson connectors where the batteries used to be plugged in. I am choosing to have a very short run with Anderson powerpoles staying down in the base, and my batteries will have a very long cable running down to the "inlet".
The wiring can best be seen in the video instead of a bunch of pictures, but essentially, the link between the batteries and the fuse have to be changed. The picture does have notes to help you through the steps.
The red wire from the battery is still going to go directly to the new battery. The black wire from the controller is going to be re-routed to the fuse, and from the fuse, we go back to the battery. In my case, the easiest way to re-route through the fuse was to have the fuse wire and "-" (black) wire that goes into the controller directly soldered together. This left me with 2 lose wires that I had cut that now needed to be re-finished with the anderson connectors.
For safety reasons, I am also adding Anderson powerpoles near the battery, so the cord between the battery and the base will just act as a quick release extension. This way, if the cable ever gets snagged, there is less risk of damage.
For more on how to do the wiring, you can see my two ibles for more details, or go with your own battery option.
Step 5: Close It Back Up and Enjoy
That's it! Close it back up, connect that 36v battery pack we built in my other ible, strap on your helmet, and enjoy!
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Make it Move Contest 2016