I replaced the aging battery on my MacBook Pro

I replaced the aging battery on my MacBook Pro

The battery on my seven-year-old MacBook Pro Retina from late 2013 (a.k.a. MacBookPro11,2) had begun to swell. This is caused by a chemical reaction that happens near the end of life for lithium-ion batteries. It’s no longer safe to use it in this state as the swelling battery can damage sensitive components, and it is more at risk of being punctured and burst into a high-intensity fire.

My MacBook has had a history of heat-problems and this has probably contributed to its battery death. I’ve got a small collection of old laptops, and it’s the hot ones that suffer from battery issues. It’s also a seven-year-old battery, and batteries don’t last forever. Whatever the cause, the swollen battery needed to be removed and replaced.

I originally planned to bring my MacBook in for service. The local repair shops wanted to charge almost ¼ the price of a new MacBook Air for the job, and didn’t have access to original batteries. Instead of paying the exorbitant service fee, I decided to attempt to remove and replace the battery myself.

A high-capacity battery can be dangerous; especially when it’s swollen or otherwise damaged. Don’t attempt to service it unless you know you can handle the fire-safety, ventilation, and personal protection requirements for defusing a small bomb. Inform the recycling center that your battery is damaged so they know to handle it with care.

I could see the battery right away after unscrewing the backplate. You only need to unscrew a couple of screws inside the laptop, and disconnect the battery cable. Then you can just lift the battery out of its slot. Well, things weren’t that easy. The battery was glued in place.

After researching on the web, I learned that the proper solution to get it out required pouring glue dissolver liquid into the battery compartment. I was hesitant to pour any liquid into my Mac. Instead, I opted for cutting through the glue with glue-cutting-wire. (Actually, I just used some dental floss.) It took some effort to get the dental floss in place between each of the battery cells and the aluminum chassis. Once the wire was in place, it was quite easy to cut loose the battery cells by wiggling the wire back and forth.

I didn’t replace the battery at this time, but screwed in the backplate, connected the MacBook to a power supply, and turned it on. I don’t actually need this computer to be portable any longer, and I’d like the option to keep using it without a battery. I’ve got other laptops, but I still want to have a system running macOS available. I thought I could still use it while it was connected to a power supply.

This is when I learned about another annoying design decision by Apple. macOS will undervolt the processor by 60–80 % when the battery is missing! It would turn on without a battery connected, but the performance tanked. The MacBook became unbearably slow. Every simple operation from clicking or opening a context menu to opening a Finder window or browser tab took what felt like ten times longer than usual. I even got the beach-ball of death for every couple of letters I typed into TextEdit.

I needed to replace the battery to get the Mac back in a working state. I initially wanted to replace it with an original battery, but ran into a few problems. Apple doesn’t want there to be any official replacement parts on the market. The only place you can get them is from an authorized repair shop; which isn’t allowed to sell them on to consumers. Anti-trust and right-to-repair issues aside, I came across a claim that made me change my mind regarding using an official replacement battery:

Lithium-ion batteries have a limited shelf-life. The chemicals in them deteriorate over time, even when they’re not in use. “Official batteries” tend to be manufactured in large quantities and then kept in storage for several years. Third-party batteries, on the other hand, get manufactured in smaller quantities depending on demand and are “fresher” at the time of sale.

After looking around for third-party options, I learned that no retailers that ship to my location had a compatible battery in stock. As far as I could tell, no European stores had it in stock at that time. This could be because of the COVID-19 pandemic, but the availability issue also did support the claim I’d read about third-party batteries being manufactured on-demand. Regardless, I had to wait two months to get a replacement battery! On the bright side, the replacement battery only cost ¼ of what it would have cost at an Apple Authorized repair shop.

Installing the new battery was way easier than taking out the old one. Pop open the backplate, slip in the new battery, and reconnect the battery connector. Easy-peasy, lithium-ion squeezy.

The replacement battery is a Cameron Sino-brand model CS-AM1494NB with an 8,4 ampere-hour (Ah) capacity. This is the same capacity as when the original battery was new. I find it interesting that the old battery still had a capacity of 6,4 aH after years of use. I wouldn’t expect to see swelling on a battery that seemed this, relatively speaking, healthy. My other older laptops have seen a higher degradation of capacity, but those batteries haven’t yet swollen.

However, I’ve noticed that the new battery lasts about five hours while the old one would typically last eight hours. So that’s eight hours at its end of life compared to six from a brand new one. Six hours is enough for my needs, but I’m not impressed by the performance of the new battery.

Update (2020-12-02): The battery capacity issue seems to have been caused by a calibration error in the battery controller. The battery would drop from 42 % to 7 % and remain there for a few hours. I failed to notice this and though it needed to be recharged. After I noticed the pattern, I just kept using the MacBook at 7 % charge until it powered off roughly three hours later. I then charged it back up to 100 %. After doing this once, the battery now reports the right charge level, and the battery life has increased to about eight hours.

Newer MacBook models received an update earlier this year to improve battery management. The updated battery manager is designed to improve battery lifespan by reducing its rate of chemically aging. The new feature would have been too little, too late for my aging battery. I hope to keep this Mac running for a few more years, and I’d be grateful if my Mac had received support for the new feature. It seems that Apple doesn’t expect MacBooks to last more than about seven years, although the model is supported in the latest version of macOS.

I can’t say for sure whether the reduced battery life is caused by the replacement battery. There are multiple factors at play, and I don’t have a way to identify the root cause without dedicating significant effort. I improved the efficiency of the cooling system when I replaced the battery. This could have contributed to an increased power demand as the computer hasn’t been thermally throttled. The battery replacement coincided with the release of macOS 11.0 Big Sur, which could also be the real culprit. My usage pattern may also have changed, although my Screen Time reports suggest this isn’t the case.

I’ve tried my darnedest to maintain the battery on this MacBook. One of the biggest challenges has been the bad thermal design. Batteries don’t like hot temperatures, and the MacBook runs way too hot for it. The Intel processor that’s in this machine is running too damned hot for its limited cooling system. I’ve learned a lot about battery management in recent years, mostly because of this computer. I’m kind of grateful for the learning opportunity it has offered, but I’m also frustrated with Apple.

I’ve worked around bugs in the system controller, repasted the cooling compound, turned off processor boost mode to keep it from overexerting the cooling system, and added some felt pad feet for better airflow. It shouldn’t be nessecary to put so much effort into prolonging the life of your laptop. It should have been designed to last. It’ll be interesting to see whether the new Apple-designed processor chips in the latest generation MacBooks will outperform the old Intel ones when it comes to thermal management.