New replacement MacBook Pro battery discharging erratically

Hello,

I've just installed a replacement battery (bought from iFixit) for my mid-2012 MacBook Pro 13inch Unibody.

The battery charges up to 84% then jumps to 100%. On disconnecting power lead battery holds 100% for a minute then jumps back down to 84%.

I've done an SMC reset. No difference.

coconutBattery shows the jump in current charge from 5712mAh (fully charged) to 4784mAh (tried uploading images but get a resolution error).

Is this a dud battery. Do I need a replacement from iFixit?

thanks

Mark

January 23, 2015

I'll accept @mayer's answer. After several days testing my MacBookPro *seems* to be performing normally. The replacement battery seems to be ok. However I do have some reservations.

So to recap I reinstalled OSX Mavericks using latest combo update. Did SMC and PRAM reset then did two discharge-recharge cycles. I'm now getting 5-6 hours from a full battery with low-medium use. Time remaining and estimated time to full is generally ok - at least there aren't any big jumps from say 50% to 100% or crashes from 50% to zero.

I'm still getting the impression though that OSX doesn't have a perfect handle on how much charge is on the battery and neither is coconutBattery. Occasionally the machine won't reboot after being down to ~30% charge but I'm not sure whether this is because of heavy apps that OSX is trying to reload after previous shutdown. Sleep seems ok and isn;t drastically draining battery.

As a rule of thumb how much charge can I expect to see lost during periods of x-amount of sleep (say overnight) or from shutdown to reboot (say overnight)?

As a further query the design capacity value from coconutBattery jumps from ~85% to ~96% between and during periods of recharge. Is this normal?

thanks all

Mark