In my experience, wedding days are literally brutal on gear, I feel u. Even though I'm still kinda new to the wedding scene compared to some big pros, the technical side of power management is something I've spent way too much time obsessing over... Basically, for you're R6, I highkey recommend sticking with the Canon LP-E6NH Lithium-Ion Battery for your primary work. Why? Because third-party ones - even the "good" ones - often dont support the full 12fps mechanical shutter or the green "H+" high-speed continuous mode once the capacity drops below like 60% or 7.2V. I've tried many, and while the Neewer LP-E6NH 2400mAh Replacement Battery is okay for backup, the R6 is SO picky about voltage. Honestly, its just not worth the risk of a communication error during the first dance. If you really wanna save some cash, the SmallRig LP-E6NH USB-C Rechargeable Camera Battery is actually pretty cool because it has that built-in port and 17.3Wh capacity. But seriously, the official one is the only one that feels 100% reliable for 12+ hour days. Also, for the power bank? I use the Anker 737 Power Bank (PowerCore 24K) and it works great! Just make sure your using a high-quality USB-C to USB-C cable. It wont charge the battery while you're actively shooting (unless the camera is off), but it provides external power delivery so their internal battery doesnt drain during the ceremony. It's a total lifesaver for long speeches! Anyway, hope that helps! Lmk if you need help with the PD specs. Cheers!

Seconding the recommendation above! I panicked at my first wedding so I got BM Premium LP-E6NH High Capacity Batteries, and they actually work great for way less money. Lesson learned: third-party is fine! lol

Saw this earlier but just now getting a chance to chime in. Everyone is pretty much right—OEM is best for the R6 speed, and grips are essential for long days. After owning mine for years tho, I've started using the SmallRig LP-E6NH USB-C Rechargeable Camera Battery as my backups. The built-in USB-C port is honestly a game changer because you can charge them in your bag with any cable without needing the bulky Canon cradle. Quick tips for the long haul:

• Keep your batteries in a pocket close to your body if it's a cold winter wedding; it helps the voltage stay stable.
• Grab a Nitecore UCN2 Pro Dual Slot USB Charger. It's way faster than the stock one and runs off USB, so you can top off in the car between the ceremony and reception. Dont overthink it too much, just make sure you have at least 4-5 total for a 10-hour day!

I totally agree with the point about the official batteries being the most reliable for those high speed modes, but after owning my R6 for over two years, I have found a couple other tricks that help for long wedding days. Honestly, managing five or six loose batteries gets old fast. Here is my setup for long-term power management:

• I highly recommend getting the Canon Battery Grip BG-R10. It lets u run two batteries at once and makes the camera way easier to hold for 8 plus hours. It really helps with the balance if ur using heavier RF glass too.
• If u want a solid backup, I have been using the SmallRig LP-E6NH USB-C Rechargeable Camera Battery. They are pretty cool because they have a built-in USB-C port. I can charge them in my car or from a laptop between locations without needing a bulky wall charger.
• For power banks, just make sure it supports PD (Power Delivery). I have used the Baseus 65W Power Bank 20000mAh and it works great for topping up the camera during the reception dinner. One thing to watch out for is that some cheaper third-party options dont communicate the battery health percentage correctly to the camera after about a year of use. I still trust the official Canon ones for the ceremony, but these alternatives are pretty solid for the less critical parts of the day.

Similar situation here - I went through a bit of a crisis during a brutal double-header last July. Honestly, the R6 is a beast, but man, it eats power when youre shooting high-speed mechanical shutter all day. I remember being halfway through the vows and seeing that red blinky light... literally my worst nightmare. I basically spent months experimenting with different power flows. I found that my current setup relies heavily on the official Canon cells because, tbh, some of the cheaper ones I grabbed online started swelling after a few months of heavy use. Not a vibe when youre trying to slide them out of the tray quickly!! Regarding the USB-C thing, I actually tried rigging a massive PD power bank to my belt and running a long cable up to the body. It worked for keeping the juice topped up, but honestly, I kept tripping over the wire or catching it on the brides dress lol. It was a total mess. Wait no, actually the biggest thing I learned was about heat management. When I used those off-brand batteries during a reception with heavy flash, the camera body got way hotter than when I stuck to the native ones. I think the internal resistance on the cheap cells is just higher or something?? Nowadays, I just keep a bunch of the brand-name ones in a pouch and swap them during the 'lulls' like dinner. It’s just more reliable for my peace of mind... peace

TIL! Thanks for sharing

Same setup here, love it

tbh I'm struggling with this exact same thing. I've been trying to figure out a solid power solution for my R6 for the last three months and I'm still basically lost. It's so stressful worrying about whether a cheaper battery is gonna mess with the high speed modes or just die out of nowhere because of some weird firmware block. I really wish there was a more straightforward answer to this compatibility mess because I'm just as stuck as you are.

Same here!