Coonyard (2-Pack) 9.6V 1000mAh NI-CD Rechargeable Battery Pack Replacement for HuanQi 781 728 RC 1:24 M1A2 Toy Tank, RC Car, RC Battle Tank, RC Boat Model Toys Household Appliances

I wanted a lightweight and compact battery for my model rocket launch control. Model rocket igniters are designed to draw a large current from a 6- 12V source, quickly heating the bridgewire to ignite the propellant. The traditional source is a car battery; however, driving onto the launch field is not always practical, and lead-acid batteries are bulky and heavy to carry. Ni-Cd batteries can put out high currents for their size, with less decrease in voltage under load than other battery types. I tested several Ni-Cd batteries, and this was the best. Estes igniters have a resistance of 0.7 ohms. To test these batteries, I measured the resistance of a length of 24 AWG bell wire, calculated the resistance in ohms per foot, then cut the approximate length to 0.8 ohms. I measured the resistance and trimmed the wire until it measured 0.7 ohms. I connected the ends of the wire to the battery leads and measured the voltage drop across them. 7.1 V / 0.7 ohms = 10.14 A 10.14 A x 7.1 V = 72.0 W dissipated as heat.

Keeps the toys going