I have a MacBook pro 2010, A1286, 15.4in what battery do I get to replace

Fair to excellent 'examples' of third-party batteries exist online.

NewerTech has been a good product available through OWC.

• MacBook Pro Battery Replacement Kits from OWC

https://eshop.macsales.com/shop/laptop-batteries/macbook-pro

Site shows several 2010 ones, be sure to accurately choose if ordering.

Newer Technology NuPower®

MacBook Pro 15-inch Unibody

Mid 2009 & Mid 2010 models. .

• Mfr P/N: BAP15MBU85N

• OWC SKU: NWTBAP15MBU85N

Up to 16% more capacity than factory stock battery

1 Year Newer Technology Limited Warranty (before S/H: $90.)

This one says it will work with MB/Pro 15" Unibody 2009-2010

https://eshop.macsales.com/item/NewerTech/BAP15MBU85N/

They also have a Calibration regime to put the Mac and new battery

through & check the internal power gauge to report accurate storage.

Notes: "When installing a new battery in your laptop, OWC recommends

you properly calibrate the power management system. See our article

on How to Calibrate a Mac Laptop's Power System."

Includes:

• (1) Battery
• (1) Installation Instructions
• (1) Phillips Screwdriver
• (1) Tri-lobe Screwdriver (for MacBookPro6,2)
• (1) Pentalobe P6 screwdriver (for MacBookPro5,3 and MacBookPro5,4)
• (1) How to Calibrate a Mac Laptop's Power System Online Guide

(If needed, see their upgrade replacement parts RAM, drives + specs)

Other resellers also offer DIY items. You may call OWC; ask before

ordering, for info about instructions on DIY battery replacement.

[Not sure if they could send you email of instructions sheet.]

For these older MacBook Pros, they have a panel with screws that

hold the battery in place. Newer ones have combined parts & glue.

On my mid 2012 MacBook Pro 13-inch, I upgraded RAM, checked battery;

and know I could replace it. Saw stock HDD had been upgraded to SSD.

(On other Mac portables: memory chips, disk/drives, & batteries replaced.)

The tech specs Apple provides for this model tells us that it is a 77.5-watt-hour lithium-polymer battery.

This model MBP is on the obsolete list and any repairs and support will have to be found from a third party. It's time to do some homework about getting a battery replacement service or an aftermarket battery to replace yourself.