MacBook Pro Battery Drains while Plugged into External Monitor and RAID

That computer is a battery-CAPABLE device. It is not optimized as a battery-operated device.

Your computer performs best when connected to AC power. It can use the full output of the Power Adapter AND when doing especially challenging work will also freely "borrow" power from the battery. In some cases, even with the power adapter connected, the charged state may even decline during stressful work.

When used only on battery, your computer has no extra cushion of power, and will perform more slowly. However, for ordinary non-stressful tasks this may not be objectionable (possibly not even noticeable.)

In general, you should ALWAYS connect AC power when it is possible to do so, and only run on batteries (which will be somewhat slower) when no AC sources are at hand. There are three micro-controllers cooperating on battery and charging issues, and your Mac will NEVER over-charge.

Peripherals consume power, often at "Desktop Computer" levels. Some displays supply some power over USB-C, but generally not enough to cover heavy use or a lot of peripherals.

Plug in the Apple Power Adapter!

Hello brennen50,

Welcome to Apple Support Communities!

If we understand your post correctly, your MacBook Pro battery drains within 3 hours when you have your LaCie and LG plugged in at the same time. We're happy to help!

Have a look at this article for help when the battery drains quickly: If your Mac battery runs out of charge quickly

Also, have a look at this article which provides help for the battery as well: Get help with your Mac notebook battery

You can also perform an SMC reset to see if that helps: How to reset the SMC of your Mac

We also recommend starting in safe mode. Sometimes just starting in this mode and then restarting can resolve issues like this: How to use safe mode on your Mac

You can also create another user on your Mac and test to see if you experience the same issue: Set up users, guests, and groups on Mac

Let us know if you have any questions.

Thank you for using Apple Support Communities.

Take care!