Using Dual Batteries in Your Traxxas 1/16-Scale Model
Traxxas 1/16–scale models only require one battery for operation, but the chassis features two battery compartments, allowing a second battery to be installed. Dual batteries may be connected in series for additional voltage and speed (using the #3063X Series Connector), or in parallel for increased capacity and run-time (using the #3064X Parallel Connector). In this article, we'll explain what "series" and "parallel" mean, and detail the benefits and effects of connecting batteries in series and in parallel.
Capacity and Voltage
The two essential characteristics of a battery are its voltage and its capacity. Capacity is measured in milliamp hours, and it's usually displayed as a big number on the battery's label: 1200mAh, 2400mAh, 5000mAh, etc. The higher the capacity, the more run time you'll get from the pack. Think of capacity as your vehicle's "gas tank." You can run longer with a 10-gallon tank than with a 5-gallon tank, and you can run longer with a 10,000mAh battery than you can with a 5000mAh battery.
Voltage is determined by the number of cells in the pack. For NiMh packs, 6 and 7 cell packs are the most common. Each cell produces 1.2 volts. A 6-cell pack is 7.2 volts (1.2 x 6 = 7.2), and a 7-cell pack is 8.4 volts (7 x 1.2 = 8.4). Traxxas Power Cell LiPo packs are either 2-cell or 3-cell. Each LiPo cell is rated for 3.7 volts, so a 2-Cell pack delivers 7.4 volts (2 X 3.7 = 7.4) and a 3-Cell pack provides 11.1 volts (3 X 3.7 = 11.1). The more voltage your pack has, the faster your motor will turn, and the faster your vehicle will go.
Now that you understand capacity and voltage, it's time to learn how we can increase each by using a Series Connector or Parallel Connector.
Parallel Connection = Increased Capacity = Longer Run-Time
The illustration above left shows two Traxxas 1200mAh Power Cell 7.2 volt batteries connected in parallel. Note that both positive battery leads (in red)attach to the positive terminal on the connector that leads to the speed control, and both negative battery leads (in black) attach to the connector's negative terminal. When assembled in parallel, the combined packs will still have an output of 7.2 volts, but their total capacity will be 2400mAh (1200mAh X 2 = 2400mAh). Your vehicle will not be any faster, but its run-time will nearly double. All Traxxas 1/16 models can be operated with dual batteries and the #3064X Parallel Connector.
Series Connection = Increased Voltage = Higher Speeds
The illustration above right shows two Traxxas 1200mAh Power Cell 7.2 volt batteries connected in series. Note that the negative (black) lead of the pack on the right is connected to the positive (red) lead of the pack on the right. When assembled in series, the voltage of the batteries is combined, but capacity is unchanged. In the example illustration, the combined packs will still have 1200mAh capacity, but their total voltage will be 14.4 volts (7.2 volts X 2 = 14.4 volts). Your run time will not increase, but your vehicle's speed will nearly double (as long as its speed control is rated to handle the extra voltage). Dual batteries connected in series using the #3063X Series Connector may ONLY be used in Traxxas' VXL brushless 1/16 models.
If your model is equipped with an XL-2.5 Speed Control and Titan 550 or 380 motor, DO NOT use dual batteries with the #3063X Series Connector. Dual Batteries may be used ONLY with the #3064X Parallel Connector.
If your model is equipped with a VXL-3m Speed Control and Velineon 380 motor, you may use dual batteries with the #3063X Series Connector or the #3064X Parallel Connector.
Using Packs Connected in Series and Parallel in Your Traxxas 1/16 Model
Traxxas offers the #3063X Series Connector for use in our 1/16 VXL models ONLY. The series connector is NOT for use in brushed 1/16 models because those models use the XL-2.5 speed control, which is rated for a maximum voltage of 8 cells (9.6 volts). Operating your 1/16 brushed model with two packs connected in series will overload the speed control and void its warranty. The VXL-3m speed control included in our 1/16 VXL models is rated for up to 14.4 volts (12 NiMH cells or 3S LiPo) and can be operated with two Power Cell 1200mAh NiMH packs connected in series. The #3064X Parallel Connector may be used in any of our 1/16 models, both brushed and brushless. Whether you choose to use a Parallel Connector for more run time, or a Series Connector for more speed, make sure you follow these guidelines:
• Install appropriate gearing.
Consult your vehicle's manual and follow the gearing recommendations for dual-battery operation. Your manual may include information about installing a larger pinion for high-speed operation. Use this gearing ONLY for high-speed running on hard, smooth surfaces. Avoid repetitive hard acceleration to prevent overstressing the motor, speed control, and batteries.
• Monitor temperature. When operating your model with two batteries, be careful to monitor the temperature of the speed control and motor to prevent overheating. Stop running your model and allow it to cool if the speed control's thermal overload protection activates or if the motor temperature exceeds 200° F.
• Additional weight affects handling. The extra weight of the second battery pack and connector will alter your vehicle's handling. On-road models actually handle better with dual batteries, as the extra weight improves traction and balance. Off-road models driven in rough conditions will benefit from stiffer springs, as the additional battery weight may cause the suspension to bottom out over harsh bumps and jump landings. Optional stiffer springs are shown in bold in the parts list included with your vehicle. Parts lists can also be found by visiting your model's page at Traxxas.com and clicking "Downloads."
If you have further questions about operating your model with dual batteries, call 888-TRAXXAS or email support@traxxas.com.
