The following information has been directly quoted from TrakPower, all the thanks to them.
Talk to the experts
TrakPower comes from the same stable as FlightPower, technical and market leaders in LiPo for RC Flight. Each TrakPower product benefits from many years of experience in cell selection, cell matching and quality control in our own facility. As the actual manufacturer of the pack you buy, we are happy to provide first hand knowledge and expert technical support for the benefit of the customer and for the sport.
Lithium Polymer, The Facts...
Most importantly Lithium Polymer packs MUST be charged by a LiPo compatible charger, these use a CC-CV charging algorithm that limits the final voltage reached by the pack at full charge. NiCd/NiMH and all "delta peak" chargers rely on the battery to indicate peak voltage at full charge and are COMPLETELY UNACCEPTABLE for LiPo technology and WILL cause a fire.
LiPo technology has brought with it some extra terminology to indicate the way packs are configured. Generally LiPo packs are described as being, for example, a 2s1p pack. This means that there are two cells (2) in series (s) without additional row of cells in parallel (p). For TrakPower we have chosen to use the terminology 'Cell' to describe cells in series so that 2s1p or 2s2p = 2Cell LiPo. In both cases the final pack capacity is marked on the pack, hence we have chosen to use the term Cell to reduce unnecessary jargon entering RC Racing.
LiPo cells have a nominal voltage of 3.7V, maximum charged voltage of 4.2V and minimum voltage of 3V. These maximum and minimum voltages should be observed to avoid damage to the cells, for example in an RC car it is important to not discharge the pack lower than 3V per/cell (or 6V total for a 2s pack) otherwise irreparable damage will occur to the pack. Certain LiPo compatible speed controllers are available which will allow the driver to set a low voltage cut-off, which will reduce or cut the power when this low level is reached, this is highly recommended to set this cut-off to 3.2V per cell for extended pack life.
Drivers demand the best from their battery packs! With older technology this meant going to extraordinary lengths to get the most out of the individual NiCd & NiMH cells. This included employing capacity and IR ?matching? techniques. With LiPo technology we have used this principle since the first day our first LiPo packs rolled off the production line. Each TrakPower cell is tested at our factory for a full suite of electrical and mechanical properties. These cells are then logged by computer and grouped ready for pack construction. TrakPower and FlightPower packs are therefore termed Factory Matched LiPo products. Additional maintenance beyond voltage balancing is not required. Zapping LiPo is unacceptable as it will lead to damage without any beneficial effect and may cause explosion.
The Best Construction methods available
The TrakPower pack?s stunning looks are only the start, housed inside each robust gold hard case are the highest performance cells available which are connected together by wide-area ultrasonic tab-welding for ultra high-current low resistance and vibration proof joints. TrakPower-exclusive Gold-Plated terminals are used which remove the limitations of internal PCB constructions to help give the lowest IR ever recorded in a finished racing pack. 4.4 mOhm typical at the terminals (TP4900)! Connectors are 4mm Gold, 4mm Sermos, 4mm Corally compatible
Charging LiPo?s is one of the most talked about subjects in the sport, there are a few simple rules which will allow trouble free operation.
Lithium Polymer packs MUST be charged by a LiPo compatible charger.
LiPo?s are different to NiCd?s or NiMH?s in that they do not need to be cycled by a charger at all, unless the capacity needs to be measured. In fact LiPo technology prefers to be partially charged or top-up charged.
LiPo should not be charged below 5 degrees C, below -10 Degrees C, charging can ruin your pack
LiPo?s should not increase in temperature whilst charging, unlike NiCd or NiMH.
When you buy a new TrakPower pack it comes around 70% charged. The pack can be charged from new at the normal charge rates.
Normal charge rates for a LiPo pack are 1C (1 x Capacity in Amps) this will take around 1 hour, TrakPower packs are capable of being fast charged at up to 2C with a TrakPower V-Balancer or other certified balance charger.
Cell balancing is the process of leveling or equalising the individual cell voltages in a pack as an analogy to equalising the capacity charge state. TrakPower packs come balanced from new as part of the cell matching process. In use, this process is normally practiced whilst charging. Cell balancing helps maintain the performance and life of a LiPo pack by preventing a progressive drift in the charge state of the cells and ultimately exposing one or both cells to overcharge or undercharged states. Additionally balanced charging optimises the charged-in capacity. Some balancers including the TrakPower V-Balance have a charge-though safety feature that halts charging when balancing cannot prevent the overcharge or over-discharge of one or more cells.
For the LiPo pack to be compatible with a cell balancing system it must have connections to each individual cell in the pack, in the case of the TrakPower 4900 it has an extra balancing port (2mm female gold connector between the main terminals) In the case of larger series packs like the TrakPower 5400 3s Traxxas upgrade an extra connector on the pack is used for balancing.
There are two main types of Charger/Cell balancing system:
1. Standalone external cell balancer like the TrakPower V-Balancer which connects between a normal LiPo charger and LiPo pack.
2. Balancing charger, this charges the cells in the pack individually. To do this, it must have access to the individual cells in the pack, which is usually made by an extra connector on the pack.
TrakPower recommends cell balancing by using either of the above methods, it doesn?t take any longer to charge when balancing and it also adds an element of safety to the charging regime as each cell is being monitored in the pack.
TrakPower Lithium Polymer has a far greater energy potential than traditional battery technologies used in RC. The only performance enhancing practices recommended and authorized by TrakPower are as follows: Pre-race warming to 30-40 degrees Centigrade. Cell balancing (the practice of ensuring that each cell in the pack is equalised to identical charge voltage). While balancing is always good practice with LiPo Technology, in the absence of very cold temperatures 10 degrees C and below, most users will observe that warming is unnecessary because the pack will always be able to deliver more power than any other component in the drive train can draw from it.
Experience you can Trust?
We have used years of experience to develop our TrakPower products and make them the highest performance, highest quality LiPo battery packs available for racing. In the unlikely event that something does go wrong we have an experienced technical support team and a very comprehensive warranty system, see our support section for more details.