How To Add a Second Battery to the Super73 Z1

Super73 Z1 Dual Batteries
Super73 Z1 with two batteries

The Super73 Z1 is a fun little electric motorbike, but the range from its 36 V 11.6 Ah battery does leave something to be desired. Luckily, it’s fairly easy to add a second battery to the Z1 to double its range. This step-by-step article will walk you through the process of adding dual battery capabilities and includes a supply list.

The Z1 is the perfect bike to learn how electric bikes work since all the electrical components are easy to access. The battery and controller are located beneath the seat, and it has the perfect frame for attaching a second battery using its built-in bottle cage bosses.

There’s no need to cut or splice wires, so there’s no need for any kind of electrical expertise, but by the time you finish the installation you’ll know a lot more about how electric bikes work.

What You’ll Need

Before you do anything you need to make sure you buy the right battery. You’ll need to choose a 36 volt lithium-ion battery. A 48 volt battery will not work or any battery that is 36 volts will not work. Both batteries need to be of the same voltage. Amp hours can be different however.

I chose a 36 V 13 Ah battery for my Z1’s second battery, (see supply list above) and purchased it on Amazon. I’d recommend choosing a battery with an Anderson connection already attached because the Z1 uses Anderson connectors. I’m assuming most people doing this installation are complete novices, as I was. Might as well keep it as simple as possible!

DISCLAIMER: Adding a second battery will likely void your bike’s warranty. Also, there’s always a risk of damaging the bike or its electrical system when modifying it. You assume all responsibility.

Step 1: Remove seat from frame

There are only 4 screws holding the seat to the Z1’s frame. Two screws are located in the back and two in the front. Remove these.

Step 2: Disconnect motor and display wire

First make sure that the bike isn’t powered on!! You’ll need to detach the wires leading to the motor and the display (throttle) in order to lift the seat from the frame.

Unscrew and pull apart the motor wire at the back of the bike and pull apart the display wire that leads to the throttle/battery indicator of the handlebars.

You’ll also need to cut some zip ties for the motor wire in order to lift the seat. I’d recommend using a side cutter to reduce the chance of damaging the wires, but I was able to do it with a pair of scissors. You just need to be super careful.

Step 3: Lift the seat out of the frame

You’ll need to tilt the seat some to lift the seat out of the frame due to the motor wire. Just tilt it so that you can easily remove the seat.

Step 4: Remove the seat from the plastic case

Battery and controller of the Z1
Battery and controller of the Z1

Flip the seat over to expose the bottom. There are 7 screws holding the seat to the plastic case. They are located around the edges of the seat. DO NOT remove the 4 inner screws. These are what holds the controller in place. We don’t need to do anything with the controller.

Once the screws are removed lift the case off.

Step 5: Expose the battery wires

Battery wires showing Anderson connector
Battery wires showing Anderson connector

Once you have removed the seat from the plastic case you’ll see the battery (in blue) and the controller (silver) of the bike. There should be wires laying along the side of the case.

The wire has two ends, a red and black one. These are called Anderson connectors. They connect the battery to the controller.

We’ll be coming back to this step in a minute.

Step 6: Attach the second battery to the frame

Battery plate
Battery plate attached to the Z1’s frame

The battery should have a plate that can attach to the frame of the bike using its bottle cage bosses. We’ll need to screw it onto the frame.

Make sure that the wires are pointing upwards so that we’ll be able to connect the second battery’s wires to the bike’s wiring.

The battery will have to be installed upside down, but it should still be securely connected once it’s locked into position.

Once you have the backplate installed, attach the battery to the plate by sliding it on and then use the key to lock it into position (assuming the battery you have chosen is similar to the one used in this example.)

Step 7: Plug in the second battery

Second battery installed
Second battery showing wires

Disconnect the bike’s battery by pulling apart the Anderson connector wires in the case.

We can now test whether we have connected the second battery properly by turning on the bike by its display. You should see the battery indicator lights light up.

Second battery connected
Second battery plate connected to the Z1

Step 8: Connect both batteries using a parallel battery connector wire

By using a parallel connection (see in supply list) we won’t have to plug and unplug the wires to switch batteries. Before connecting both batteries, fully charge both so that their voltage is the same. Both batteries must be 36 volts otherwise the battery with the higher voltage will discharge into the battery with a lower voltage at a high rate which can damage the cells of the battery, or even cause a fire. This is why both batteries need to be of the same voltage.

Both batteries will need to be charged independently. Make sure to unplug the parallel connector when charging. The connection to the second battery will be accessible and exposed for easy disconnecting. See the second image below. Before reconnecting the batteries ensure that they are of the same voltage. Don’t connect a dead battery to a fully charged one. Try to keep them both at the same charge level.

Now that the batteries are connected in parallel the controller will draw power from the two batteries.

Parallel connection wire to second battery is exposed, so it can be disconnected when charging the batteries.

Conclusion

So far, the bike has been working just fine with this set up. The Z1 is an ideal ebike to learn from because it’s so easy to work on. The frame also makes it easy to add a second battery. I’ve learned a lot about ebike batteries and did a lot of research before attempting this. Just be aware that there is always a risk when working with electrical components, but I didn’t experience any problems.





I now have an ebike with pretty much double the range which is great, because I had always cut my rides short for fear of running out of juice. Now I can have twice the fun!

4 COMMENTS

  1. hi! loved your write-up so much I had to sign up to leave a comment!
    I saw your IG post and was excited to perform this mod myself too.
    I have just ordered the necessary battery and cable, have you gotten your cable yet?
    couple of things I wonder. since the factory battery has a different capacity with the new QZF , would it result imbalance while charging? in theory, when this parallel cable is connected it should charge all the battery connected.

    love your articles and IG page!

    • Thanks! I’ve updated the article with the parallel connector and some info about voltage concerns and capacity. So far, it’s worked out fine for me, but you want to make sure that both batteries are at the same voltage before connecting them to each other. I’m looking into other options too, such as adding a switch to select which battery I want to use. That way the batteries wouldn’t have to be connected to each other at all.

  2. Just came across this post and was wondering how this has been preforming? I have a Z1 with a second stock battery and would like to do this. Would I not be able to charge both batteries simultaneously?