LiPo 3S Battery 101: All About LiPo 3S Batteries
Lithium Polymer 3S batteries, also known as LiPo 3S batteries are lightweight and very powerful rechargeable lithium batteries. Lithium Polymer batteries feature electrolytes in the form of polymer gel with graphic anode and cathode in the form of a Lithium Cobalt Oxide (LiCoO2) or some similar material.
LiPo 3S batteries consist of 3 (three) LiPo cells connected in series, hence "3S". LiPo 3S batteries are commonly used in high-performance toys, drones, RC vehicles, and similar applications where high energy density is required, combined with high discharge currents.
Published: September 10, 2021.
LiPo 3S Battery - Features and Specifications
LiPo 3S batteries consist of 3 (three) rechargeable lithium polymer cells connected in series - so-called 3S1P configuration. Each individual cell features a nominal voltage of 3.7 volts (rarely 3.6 volts), a maximum charging voltage of 4.2 volts, and a cutoff voltage of 2.7 - 3.0 volts (may slightly differ among the brands).
Thus, the 3S LiPo battery features a nominal voltage of 11.1 volts (rarely 10.8 volts), a maximum charging voltage of 12.6 volts, and a cutoff voltage of around 9 volts.
The nominal capacity of the 3S LiPo batteries varies from several hundred mAh to 5-10+ Ah - small 3S LiPo batteries are often used in small helicopters, drones, electric RC gliders, and similar applications, while large 3S LiPo batteries power large RC trucks and other RC vehicles.
Discharge currents vary greatly and usually range from 25C to 120C+ currents.
For example, 100C 5000 mAh 3S LiPo battery is able to provide 500 Amps, which in theory is enough to crank the full-size cars.
Note: Lithium car battery jump starters are based on high drain lithium rechargeable batteries which are able to provide 50-100C+ currents.
Most popular LiPo 3S batteries feature discharge current in the 50-100C range. Such batteries can provide plenty of energy for RC applications like RC trucks, RC cars, RC planes, drones, and similar, but if required, they can also provide plenty of energy for shorter periods of time ensuring great acceleration, liftoff, and other required maneuvers.
The energy density of the 3S LiPo batteries varies from 120 to 250 Wh/kg, but it also depends on the discharge currents - LiPo batteries don't suffer from the capacity loss due to the increase in discharge current like lead-acid batteries do, but nonetheless, it is not the same to discharge the same battery at a rate of 1C or 100C.
Note: when the new 3S LiPo battery (or batteries) arrives, be sure to check the manual/Owner's Guide in order to get accustomed to your new battery - some battery models can be rather specific in terms of charging, discharging, storage, transport, etc.
One of the important features of the 3S and other LiPo batteries is that they feature two different cables/wires:
- discharging cables are thick and used ONLY for discharging. Depending on the intended use, battery size, average, and maximum discharge current, etc., 3S LiPo batteries usually come with Dean's T connector (T plug), XT30 plug, XT60 plug, EC5 plug, TR plug, etc.
Note: although it is good to avoid additional connections, if required, various adapters can help with mismatched plugs.
- charging cables are thinner and used for both charging and cell balancing. 3S LiPo batteries commonly use JST-XH(R) connectors and in combination with balance chargers, allow the user to both recharge the battery and to balance the individual cells, prolonging the operating lifetime of the battery.
When charging not just LiPo 3S batteries, but all LiPo batteries, never leave them unattended.
Although 3S LiPo batteries are capable of providing insanely strong currents, their charging currents should be kept in the 0.5-1.0C range or as recommended by the manufacturer.
Also, it is good practice to charge/discharge brand new 3S LiPo batteries few times at home, under controlled conditions by gradually increasing the Depth of Discharge (DoD%).
For example, charge/discharge the battery down to 25% DoD, then down to 50% DoD and then down to 75% DoD, after which the battery can be used freely.
Note: Some manufacturers claim that this is not required/necessary, but ...
Also, having a good fireproof and explosion-proof carry/storage LiPo battery bag can increase safety significantly.
Personally, even if You do have such bag(s), do not leave these batteries unattended when they are charging. These bags do increase safety, but Lithium Polymer batteries can burn/explode even without the oxygen present. And if the oxygen is present, fire can be really hot and spread further...
In the long run, it is good to have a high-quality balance LiPo battery charger that can increase safety and the LiPo's number of charging/discharging cycles which on average ranges from 100 to 500 cycles, sometimes even more.
Long Story Short: LiPo 3S batteries can provide enough power even for the most demanding applications, at least for a very short time.
Lithium Polymer batteries are not without issues, but when used, charged, stored, and transported properly they are safe to use.
But, never underestimate LiPo batteries, even when treated properly - better safe than sorry...