This handy adapter allows you to easily wire an internal battery into the external battery port of any Ninebot ES model scooter. As described in our Ninebot Modular Battery Mount post, the cylindrical internal batteries are cheaper than the official pod shaped external batteries even though they have the same capacity. They are therefore a great option for an external battery (modular or otherwise) on a budget.
 
Our early testing suggested that internal batteries couldn't be wired into the official external battery port so we simply wired our modular external batteries in parallel with the internal one. As many have pointed out, this was questionably safe due to the large voltage difference between the two batteries. Our latest tests have proven that it is in fact possible to wire an internal battery through the external battery port. The official external battery port is connected to the internal battery through 2 N channel MOSFETS allowing the speed controller to regulate the power flowing from the external battery into the internal battery. Despite this, the speed controller firmware only balances out the two batteries when they are charging. For a modular battery setup, it is therefore necessary to wire a charging plug (barrel connector) in parallel with the power leads of the external battery and plug it into the charging port of the scooter when a new battery is swapped in. The fresh external battery then begins to slowly and safely balance out its voltage with the internal one. If you plan to use a modular battery configuration, please select "yes" for the modular charge plug option so we can install it onto your adaptor. 
 
For installation steps, see our Thingiverse post
 
Modular Charge Plug (+$5)
We'll include an 8mm charge plug to allow modular batteries to safely balance with the internal battery.
 
Pre-Assembled (+$10)
We'll pre-assemble and test your external battery adapter as well as solder on an official charge and data connector that we've salvaged from a broken speed controller. 
 
Important: 
-This is a kit that requires some soldering. Please purchase the pre-assembled version if you aren't comfortable with your soldering skills.
-You will still need to purchase/salvage a charge/data connector to connect to your external battery, Alternatively, you could replace the connector with a 4 pin JSTXH or purchase the pre-assembled version which has it included.