How Long Should You Charge a 7.2V Battery?

Recharge times depends on the battery chemistry

If They Are NiCad or NiMH Batteries

Nickel-cadmium (NiCad) and nickel-metal hydride (NiMH) 7.2-volt batteries can be charged over 14 to16 hours, with a current equivalent to 0.1 times the battery's amp/hour capacity. Charging in less than an hour is also possible, using a charging current equivalent to the battery's full amp/hour capacity.

If They Are LiPo Batteries

Lithium-ion polymer (LiPo) batteries contain multiple 3.6-volt cells in a sealed casing that states the number of cells. Charge LiPo batteries only in LiPo chargers set to the voltage and number of cells in your battery, following the manufacturer's guidelines. Overcharged cells may burst into flames. According to the Air Line Pilots Association, recently charged LiPo batteries have self-ignited, even when not in use.

Bottom Line

Both quick and slow charging are possible. Choose the method appropriate to your battery chemistry and charger capabilities. LiPo batteries require precise recharging, whereas there is greater room for error with NiCad and NiMH batteries.

References

• Electropaedia: Battery Chargers and Charging Methods
• RC Car Tips: RC Car Batteries
• Air Line Pilots Association: Responding to In Flight Passenger Electronic Equipment Fires
• Hobby Services: Lithium Polymer Battery Safety and Handling Instructions