We find batteries are a very overlooked part of maintenance and they are a very crucial part to going out and having fun. There are two common types of batteries that can be used in most R/C cars and they are NiMh (nickel metal hydride) or LiPo (Lithium polymer). Both battery types can benefit greatly by doing maintenance and taking care of them. On the NiMh batteries to cycle the battery (charge and discharge the battery multiple times) will ensure the battery cells are going to be matched and similar in voltage. On the LiPo batteries there are a couple more things to keep in mind to ensure you are taking care of them properly.  We always recommend to balance charge the battery to ensure all the cells are the same voltage when full charged (4.2v per cell) as well as if you are not going to run the battery for more then two week to put it into storage mode. Storage mode will either charge or discharge the battery to 3.7 – 3.8v per cell depending on the charger to keep the battery in a stable state to sit for prolonged periods of time. This procedure will ensure when the battery is sitting it will not puff or swell and not be left discharged when you want to reuse it as most chargers will have a safety feature built in to not allow a battery that is below 3.0v per cell to charge.