You just can't simply use any random power cable and expect the same results as compared to what you get from direct from the manufacturer. No two power twines or power bricks are the same and results do vary, as electric current flows also vary based on the power cabling and the power brick, which are essential to not only the proper operation of your PC, but also to allow for the proper charge of the internal battery.
If you have issues keeping a charge to your battery and it's not the battery, it's likely you need to replace your power cables and power brick, but to effectively replace your old one, you need to have the serial number and any additional applicable information to be able to go online and purchase a replacement.
Sure, knockoff versions sell on Amazon and eBay inexpensively, but those products, when used incorrectly, can lead to power surges and corruption of your hard drives and even further damage to your computer. It also isn't worth voiding out the factory warranty on your computer just because you want to buy cheaper power supplies. Improper charging can damage the battery, leading to leakages and explosions - not to mention having to purchase another battery on top of that.
The lifespan of your computer's battery depends on how often you use the computer. With normal usage, the battery will continuously wear down after a year or two. With less activity, they can last 3 to 4 years. As mentioned before, should the battery drain down faster than usual, it can be that 1) the power cord and power brick are failing, 2) there was an improper charge of the battery, leading to damage or 3) the battery is failing and needs replaced. Sometimes, none of those scenarios are the case and it may be an issue with the internal power jack of your computer. Replacing this crucial power unit will require disassembly of your computer and should be performed at an authorized repair center. We do offer this service in Central and Southern Illinois and we can perform the service in-house within two days or we can come to you. We will invoice for the parts needed.
Make sure you do your research before buying your next power cable and power brick - or any power supplies, for that matter.