Why is my iphone battery jumping levels!?!?

The battery is starting to fail.

This happens for all rechargeable batteries, and WILL happen after 5-7 years of continuous use no matter what you do. It's a limitation of today's battery technology -- not just Apple's but every manufacturer's.

A battery can fail before that 5-7 yr, based on how you keep charging/discharging your phone/device. For example, if you always let your phone discharge and die (if it always turns off at <4% or 0% charge)... this is a surefire way to damage the battery.

Apple recommends to (and I've found it's true if you) always start recharging when the phone is down to between 10%-20% charge. If you always let it get below 10%, that is damaging the battery a little each time.

Also, don't charge the battery if it's way above 20%. For example, if you always start charging it when it's over 60%, this can affect the total capacity. This is true for all modern batteries -- they all have a very slight "memory effect" that was so common with the older NiCd technology.

Bottom line -- if this is already happening, put the phone through many full charge-discharge cycles. This means charge it fully (to 100%) and leave it connected for at least 1/2 hour after it already has hit 100%. Then use it (until it gets to 30% or 40%). Then charge it again to 100%. Repeat this over and over -- for say 50 or 100 days.

You will see the battery will get better -- but it depends on how much it was originally damaged. If it was damaged too much already, you might not be able to get it working fully.

I had this happen with an older iPhone, and now it works fine (it charges fine to 100%, discharges fine to 10%) - though I now always charge it around 20-30%. It's been going strong for 2 years since I saw your type of problem. It's an old phone and working fine.

Though it does discharge faster now than when new -- this happens with ALL phones/batteries. For example, when new it went for about 30 hours without charging, now it'll go for about 15-20 hours. But that's after many many years of great use. This also is normal for all batteries (reduced total capacity after many discharge-cycles).