Balancing Li-Po battery packs

When talking about balancing Li-Po battery packs, we’re not talking about finding their correct Centre of Gravity! Instead, the balance refers to the voltage of each cell in a pack relative to the other cells.

LiPo Battery balancingBalancing is required however on any RC LiPo battery pack that has more than one cell since the charger can’t identify from different cells and know if one might be overcharged even though the total voltage of the pack indicates otherwise. For example let’s look at a 2200mah 3s 11.1v 30c lipo pack (three LiPo cells hooked in series or 3S). A two cell is equal to 7.4v lipo pack, a three cell is eqaul to 11.1 volt pack - and so on.

How long it takes to balance charge is going to depend on how deeply you discharge it. The GT Power A6 is a 50 watt charger, on 4S the max rate it will charge is roughly 3.3 amps at the beginning with a completely discharged pack, and go down to 3.0 amps as it approaches full. As any of these CC/CV chargers reach the end of the charge the voltage drops to a constant level and the amperage is reduced as it tops off the cells, and usually balances them at this time as well. The following we mainy talk about the 5000mah lipo battery balanced.

Let’s say you had completely discharged 5000mah 14.8v lipo, charging at an average of 3 amps, this is roughly a 6/10C charge. That charge rate would take 1 hour and 40 minutes just to replace the 5000mah, but, will take slightly longer as the charge rate slows at the end, and the cells are balanced. Assuming it’s a good pack, 1 hour and 50-55 minute would be a good estimate. The reality is, you don’t ever want to be putting 5000mah back in, rather 4000mah. That would mean you aren’t discharging more than 80% out of the pack. That would drop your charge time for that pack down to 1 hour and 20 min in theory, but more like 1 hour 30-35 min after the CV phase and balance finishes.

On the other end of the spectrum is if there is one cell in the pack that is not reaching full charge when the pack is charged and then gets discharged below 3.0 volts under load even though the 3 cell battery pack is indicating a voltage of 9 volts or higher.

Balancing ensures all cells are always within about 0.01-0.03 volts per cell so over charging or discharging of one or more cells won’t ruin your battery pack, or worse become a safety issue from overcharging a cell.

You don’t have to balance your RC LiPo battery pack each time you charge it. Most will agree every 10th to 20th time is fine with a healthy battery pack. The problem is knowing if your pack is healthy, cells in older packs may become unstable? As far as I am concerned, if you have a good balancer or balancing charger, use it at every charge, or at least at every 2nd charge. That might be overkill, but if it prevents a damaged battery or fire just once… well, you decide.

Balancing Li-Po battery packs should be done regularly and you should get in to the habit of checking the balance often. A poorly balanced pack will give poor performance, and in the worst case scenario will be damaged beyond repair over time. It’s also important to understand that lithium polymer battery packs vary greatly in quality between brands, and it stands to reason that a better quality pack will probably balance better and stay balanced longer than a cheaper, lower quality one. Mentioned Lipo battery brands, here we can talk about Gens Ace lipo battery, they are the famous brand manufacturer in the world, choose Gens ace for you car, it is the right choice.

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