ThinkPad

This is from a sampling of aftermarket batteries for the "old body style" ThinkPads (T510, X230, etc.). This may or may not apply to newer ThinkPads using flat Li-Polymer cells.

In general, the performance of an aftermarket battery correlates with its cost. The cheapest aftermarket cells provide half the battery life of more expensive ones and degrade sooner.

Brand-agnostic observations

• Some batteries don't play well with charge thresholds. If not allowed to reach 100%, they lose track of the actual charge over the course of a few cycles. This usually manifests as suddenly dropping to nearly empty from 30% to 50%.
• If it advertises support for the **30 series, the battery will probably pass the boot-up verification on those models.
• Aftermarket labels make liberal use of Arial instead of Helvetica. Maybe I have an eye for typefaces, but this should be a dead giveaway that tends to slip under the radar.
• Good aftermarket batteries tend to be considerably heavier than low-quality ones.
• Low-quality aftermarket batteries tend to fit poorly in the slot.
• Boxes for aftermarket batteries, compared to originals, are missing the large sticker on the box with Lenovo part numbers, barcodes, and regulatory markings.

Kingsener

• Reasonable cost
• Genuine capacity, matches that of the original
• Heavy in the hand, slightly looser fit than original
• May sporadically register 0% on a Corebooted X230, but immediately returns to normal without shutting down
• Gradually loses track of charge with thresholds

Dr. Battery

• Most expensive
• Genuine capacity, matches that of the original
• Heavy in the hand and fits well
• Gradually loses track of charge with thresholds

DTK

• Relatively lower cost
• Genuine capacity, but less than that of the original
• Feels lighter than the original, but fits well
• Rubber feet fell off after less than a month
• Did not test charge thresholds for this brand

"Lenovo" with fake recycle symbol

• Reasonable cost
• The RECYCLE symbol uses a wider font and there is a typo in the text: "Use of enother battery may present a fire or explosion"
• However, capacity is genuine and matches that of the original
• Heavy in the hand and fits well
• Comes in a plain, unmarked cardboard box
• Works well with charge thresholds
• Rubber feet fell off after less than a month
• Can vary by actual manufacturer

Unbranded

• About half the price for half the battery life and a third the lifespan compared to a higher-quality battery
• Advertised 57 Wh, actual 48 Wh, compare to 63 Wh of genuine Lenovo
• Lighter and worse fit than original
• Rubber feet fell off within two weeks
• Loses track of charge within a few cycles if thresholds used
• Works fine for a few months, but capacity thereafter decreases noticeably beyond about 150 cycles
• May use scavenged cells: serial numbers on the cells inside are far apart, which would be uncharacteristic of a factory receiving and using fresh cells from a reputable manufacturer
• Can sporadically cause laptop to get stuck in suspend, requiring a hard restart
• Can vary by manufacturer

My use cases for these bottom-of-the-barrel batteries is getting beater ThinkPads up and running with some degree of mobility and getting rid of the void otherwise left if the battery is absent. Also fine for BIOS updates that demand a charged battery.