BOSCH GBA18V80-2PK 18V CORE18V® Lithium-Ion 8 Ah High Power Battery, 2-Pack

Bought a few of these. 8ah is the sweet spot, IMO. Not too big or heavy but plenty of power and use. I would imagine 12ah would be too cumbersome to carry around but has a better run time than 4ah, obviously. Great for more constant use tools like angle grinder, sanders, saws, etc. Still using a standard charger so takes 2-3 hours to charge a dead one.

I usually only keep 4 AH on hand but my vacuum and reciprocating saw run them out quick. These are a must have for high demand tools. Got them on sale for a really good price. Little hefty in a drill or impact however.

I didn't even realize what my tools were capable of doing until I started using these batteries. They're excellent for the oscillating tool. The upgrade was definitely worth the money. The batteries last a long time and have a lot more power

I purchased 2 of these last year to expand my collection for shop tools. I liked them so much, i bought another 2. The bigger capacity than some of my other batteries lasted much longer and delivered better performance for drilling, running timber and deck screws, and all my other tasks. I assemble large amounts of beekeeping equipment and need long lasting power to get it all done.

Bosch is top tier! All Bosch products are first class! The 18volt Bosch system is super powerful! I have too many Bosch tools to count! I bought these for the vacuum cleaner to add to the run time! Love Bosch tools!