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FAQS | BALANCEPRO HD LIPO PRODUCTS (FORMERLY SKYVOLT)
Please decipher the following description of a BalancePro HD pack rating. In particular (15C / 90%) & 15C, 11C/140 degrees. Thanks.
The old ratings method was seen as something like your first example; 15C / 90% It meant that at a 15C discharge rate (or 15 times the pack capacity C) you would still get 90% of the stated capacity. This older rating scheme focused on the capacity left in a pack at a high discharge rate and turned out not be be a critical factor in maintaining cycle life or longevity of the pack. In those days, most vendors (including FMA) had not documented the effects of temperature, cell balance, and discharge rate on the Lithium pack life span.
Today, the new rating scheme looks like this; Ratings: 15C , 11C/140°F , Cell Rating Spec
The first number, 15C, is the maximum discharge current that the cell will handle without puffing, catching on fire, or generally destroying itself.
The second numbers, 11C/140°F, means that the cell can truly be continuously discharged at 11C without loss of cycle life because it remains at or below 140°F. In a multiple cell pack, the inner cells will be about 10°F hotter or 150°F which is ok. The Rule-Of-Thumb is that this second set of numbers is about 70% of the highest C discharge rating without puffing. There are exceptions to this rule but it works for most manufacturers cells.
The last "Cell Rating Spec" is a hyperlink to the information in chart form that plots all the data taken during the cell qualification testing. As FMA is about to release many new cells from multiple manufacturers, the Cell Rating Spec will provide a consistent and more appropriate method for rating the discharge capabilities of Lithium cells.
Which balancing line is better for me; Cellpro or BalancePro HD?
It is better to understand what you want and be confident of your choices before ordering. The size of your plane often determines which line is best for you but there are also other factors to consider.
Although we used to think that the BalancePro HD to Cellpro Adapter (SVCPA1) would work at 10amps on the Cellpro packs, Engineering has recently reported that the maximum current level should not exceed 5amps or the white Cellpro node connector pins will get warm.
There are pros and cons to each choice of using either two 3-cell packs or one 6-cell pack. If you intend to fly smaller planes using a 3-cell pack, then the flexibility of combining two smaller packs is best but it adds the complexity of wiring the two packs in series to the ESC. If you only intend on flying a glow conversion, the simplicity of a single pack is best. A single 6-cell pack only requires one DPM (Discharge Protection Module) but also forces you to use the BalancePro HD line. The BalancePro HD 6s charger can charge up to a 3C or 10amp rate. The two 3-cell packs allow you to use the Cellpro line which does not require the use of a DPM.
Buying two Cellpro 4s chargers so that you can recharge both packs at the same time helps to negate some of the advantage of the BalancePro HD 10-amp charge rate and 6s capabilities. The Cellpro charger has a 3amp rate limit or you can use a BalancePro HD charger with the adapter for a 5amp rate limit.
The Cellpro line and charger is the most simple for 2s - 4s applications. It is literally plug-n-play and walk away. When you jump to 5s and 6s applications for glow conversions, the BalancePro HD line has its advantages for keeping a single pack and a higher charge rate up to 10amps. Both cell balancing lines provide the ultimate protection for safe Lithium charging.
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