When fired point blank, plastic BBs can hurt as much as rubber bullets, however most people engaging in military simulations with airsoft guns wear thick military garb. Additionally, precautions are taken to protect the neck, face, and eyes. Many people chose to wear a balaclava around their face and neck and edison battery ANSI approved eye protect is a must. The only place that plastic BBs can really cause damage is to your eyes.
There are several types of battery in use at the present time and each must be treated differently. There are Nickel-Cadmium (Ni-Cad), Nickel-Metal Hydride (NiMH) and Lithium-ion. Ni-Cad is old technology and hence only found in ancient handsets, so I will not be covering them in this article. NiMH batteries perform much better than Ni-Cad, typically giving 30% more talk time, but Lithium are thinner and give even higher performance. I will be concentrating on lithium facts-ion as it is the most used modern mobile phone battery to date. Check which type of battery your phone has before following any of the following.
The last thing to start tinkering on is the rate of fire. The biggest thing that will determine your ROF is the battery voltage and the amount Milliampere-Hour rating (mAH). Some of the best batteries for increasing ROF are the LiPoly batteries (Lithium Polymer) but you should not use these types on out of the box guns. When preparing to use the Lipoly battery you need to make your internal components are reinforced and upgraded where they need to be.
But that means that laptops need to have bigger batteries and bigger batteries mean bigger size. Laptops won't be portable and convenient to carry in this case. That's the reason why laptops have compact batteries that gives it a sleek look. But these batteries don't lithium bettery stock have good battery-life.
In terms of charging these powerful cells, when specifically used in an LED flashlight, special chargers are available all over the internet. Most will handle a 18650 battery as well as a variety of other Li-ion sizes.
For jobs where the batteries are required to be light weight as well as being reusable, then lithium batteries are ideal. But if a battery is needed to be very reliable or to remain unused for a long time then they might not be the right batteries for it.