Battery Information

There are 2 main groupings of batteries we allow in the club.  NIMH/NICAD battery packs and LIPO/LION battery packs.

Below, we'll break down what's allowed in the club, followed by information about each grouping that will (hopefully) help you make a decision on what works best for you!

 

NIMH/NICAD

Allowed in the club: 6-7 cell NIMH/NICAD packs.

Pros: Inexpensive, easy to charge/store, resilient to damage, safer due to less chance of a failure due to mishandling

Cons: Power from battery is "peaky" - you feel the most power from the battery at 100% charge - below that feels like it's a little less powerful, provides slightly less runtime, provides slightly less peak and overall power

 

NIMH (nickel–metal hydride) is the latest type of individual c-cell style battery pack.  These generally come in either "stick" configurations, "hump packs", or "side-by-side" configuration.  Cells are a standard size and you must make sure your vehicle has the room and ability to handle 7 cells if you want to use them.  7 cells provide additional power/runtime.  Each cell contains a certain voltage and they are all added together to get the total volts.  Each cell is 1.2 volts, so you'll see that a 6 cell pack is 7.2 volt pack, while a 7 cell is a 8.4 volt pack.  The volts are indicative of the amount of power (if the vehicle can handle it, the 8.4 volts will make the vehicle slightly faster than the 7.2 volts).  These are much better than the packs from the original days of R/C and generally come in sizes averaging around 5000mAh.  mAh (milliamp hours) is a measurement of the length of time the battery can last.  While it is dependent on the vehicle, motor, how it's driven, etc, you can use these to compare.  For example, a 4500mAh battery will last longer than a 3300mAh but less time than a 5500mAh.  We would recommend no less than a 3300mAh battery for indoors and probably a 5000mAh or greater for Fair racing.  Best way to tell if it will work is to practice on the Fair track once it's built and make sure you can make 8 minutes of racing.

NICAD (nickel-cadmium) is the older version of c-cell style battery packs.  These generally aren't available for 1/10th size vehicles any more and would not be recommended.  Get a NIMH pack instead.

 

LIPO/LION

Allowed in the club: 2s (cell) HARD-CASED packs (soft-cell packs allowed for 1/14 and smaller vehicles where it's nearly impossible to find hard-cased packs)

Required Equipment: LIPO safe battery bag or case, LIPO compatible charger, LIPO compatible speed control (all of this explained below)

Pros: Relatively inexpensive (cheap brands can be found on Amazon), great power, non-peaky - you get max power from start to end of the battery charge, provides max amount of runtime, relatively stable

Cons: Mishandling or abuse can cause the battery to swell and eventually burst (see note below on handling requirements), needs slightly more equipment to use (see LIPO equipment below)

LIPO (lithium-polymer) is the latest type of battery packs available.  They do not use traditional cells that look like every-day batteries, but instead each cell looks like a soft pouch of chemicals.  Each cell in a LIPO pack is 3.7 volts.  Packs are generally referred to by their "series" cell count (2s, 3s, 4s).  This tells you how much total voltage (2s = 7.4v, 3s = 11.1, 4s = 14.8).  Mainly when referring to a battery, we use this slang (2s, 3s).  However, unlike a NIMH/NICAD, LIPOs are much more likely to be wired both in series and parallel.  In that case, you may see the "2s" battery says "2s2p" somewhere on it.  That means there are actually 4 total cells, 2 in series and 2 extra in parallel with those first 2.  Parallel actually increases runtime as it increases the mAh (milliamp hours) of the battery.  So a 4000mAh 7.4v 2s2p pack has 4 cells, each with 3.7v and 2000mAh rating.

Handling LIPOs - Because of the power and chemical make-up of LIPO batteries, they require extra care to ensure they are used safely.  When LIPO packs are "overdrained" or "overcharged", they can start to "swell".  The soft LIPO cells will puff up.  A slight puffing due to use is normal, but if they are starting to split the hard case, or suddenly become significantly swollen, this could be an indicator of a failing pack.  If the LIPO swells too much and bursts OR is damaged and opens, the chemicals inside will react to the air and start shooting a very hot flame.  This is a RARE occurrence.  Usually a pack will just swell, or maybe even slightly smoke, but never get to the full failure.

In order to prevent your LIPO from failing in this way the following precautions should be made:

  1. Never leave a LIPO unattended when charging.  Always be in the near vicinity to check on it to ensure everything is working properly.  
  2. Always charge or store a LIPO in a LIPO safe bag or case.  These are very easy and relatively cheap to obtain.  If you're not actively racing, the battery should be in there (storage at home, transporting the battery, when you're not using it at club or elsewhere).  These bags/cases will prevent the LIPO flame from escaping just in case there's a sudden failure.  
  3. Use a proper charger with a balance plug or balance capability!  As long as it's a LIPO safe charge, you're using the LIPO setting, and you have the balancer plugged in (newer traxxas and spectrum balancers are built into the battery plug), everything should be fine.  The balancer ensures each cell within the battery pack are charged evenly.  Without a balancer, the charger only detects the total charge and could accidentally overcharge once cell if they are out of balance (e.g. one cell could be reading 3.3v and the other could be reading 3.7, the charger would think it's at 3.5v and potentially overcharge the cell reading 3.7v
  4. Ensure your vehicle's electronic speed control is LIPO capable and set in LIPO mode.  LIPO mode ensures that the speed control is reading the voltage of the battery continually and if it detects a drop below a certain value (as the power in the cell is used up), it will automatically cut the car off to prevent "over discharging".
  5. Treat LIPOs or ANY battery with care.  All battery types can fail if fully mistreated and cause an issue.  Never poke, drill, throw, punch, stab, or do anything else in an attempt to damage a battery pack.  Even NIMH batteries will explode if mishandled to an extreme