Turn off the bot by plugging in the charge jack:

Making your Viper battery connections is straightforward, but there are some things you need to pay attention to.
  1. Plug in the charge jack cable to the connector you installed on the bottom of the bot. This does two things:
    • It shuts off the bot. Plugging in the cable cuts the power to the bot.
    • It allows the battery to be charged while inside the bot, without removing the battery.  This can be a huge convenience when at an event, but only if you use a lipoly battery.


TIP: Use the charge jack to disable your bot after a match, instead of using a power switch. No need for both. SAFETY TIP: This Power Jack is wired so that rechargeable batteries can be charged through it. Because both positive and negative battery leads are in this Power Jack switch, do not use a solid metal rod in place of a lost Power Plug! Use only a “3.5mm Mono Headphone Jack” or you will cause a short circuit. SAFETY TIP: Never attempt to recharge a standard (non-rechargable) 9V battery using the charge jack. The charge jack is only meant to charge rechargeable Lithium Polymer batteries. 9V batteries must be removed and replaced when they run down.
Charge jack Cable for Fingertech Viper
Viper Chassis bottom showing the charge jack inserted for charging the lithium polymer battery.

Understanding the JST Battery Connector:

  1. If you have elected to use a Lithium Polymer battery, your battery comes with two connectors:  a balance connector and a JST Battery connector.  The balance connector is used for a special kind of charging to make sure all of the cells are in balance.  You will plug into, and generally use the JST connector on your Viper.
JST-RCY connector, Red, Male-female pair with red and black wires
JST RCY Connector Image Credit, Wikipedia:
  • JST’s have a polarity. The male and female connectors have a key that tries to ensure the connectors are plugged in correctly with the correct polarity.
  • Gently align the connector sides and slide them together.
JST-RCY connector, Red, Male-female pair front view showing polarity
It is VERY IMPORTANT not to force your Viper battery connection, for two reasons:
  1. You may have the connector upside down and forcing it will damage the connector.
  2. One of the pins may be bent and forcing it will damage the connector pins. You can see a bent pin in the picture on the right side.
  3. This is easily fixed. Using a small screwdriver or other tool, gently bend the pin back in line. If you can get it in the general position, the connector will self-align when you push the sides together.
  4. Take your time. When it’s right, the connectors will push together.
  5. You will have to use some force to get the connector to completely engage once it’s in the right position, but the initial step of sliding the connectors together should be smooth and easy.
JST connector showing offcenter pin which will cause problems when plugging in

Connecting the Viper battery, 9V:

  1. If you are using a 9V battery, use the supplied wire harness to connect to the terminals on the battery.
  2. Plug the opposite end, with the JST connector, into the JST connector coming from the switch/charge jack.


SAFETY TIP: Remember that 9V batteries are not rechargable. Don’t attempt to recharge the battery using the charge jack.

Single JST to 9V battery adapter
Galaxy 3s LiPoly battery

Connecting the Viper battery, Lipoly:

  1. Simply connect the JST connector on the Lipoly to the JST connector on the charge jack, paying attention to the connector orientation as described above.
Connecting the Galaxy Lithium Polymer battery to the Viper

Charging your Viper Lipoly battery:

  1. Nothing could be easier! Just plug the charging cable into the bottom of the bot.
  2. Plug the opposite end of the charging cable, with the JST connector, into the JST connector coming from charger. Pay attention to the connector orientation as described on this page.
  3. Operate the battery charger as though you were charging the battery directly.
  4. See the picture for details.


SAFETY TIP: Remember that 9V batteries are not rechargeable. Don’t attempt to recharge a 9v battery using the charge jack.

Connecting the Viper Combat Robot through the charge jack





© 2021 Fingertech Robotics, Inc.

Modifications © 2021 ItGresa Robotics, ItGresa Consulting Group, Inc.  All Rights Reserved.