I want to share a product I found that perfectly compliments a Brake Buddy system if power supply is a consideration for you. I have a Brake Buddy Classic and my toad is a Minicooper Countryman (3250 lbs) and power was definitely a problem.
The 12v accessory supply in the Mini is only 8 amps, but my BB requires 15--not to mention that I do not want to drain the Mini's battery on a long trip, so I went to Harbor Freight and for less that $50 I purchased a 12v Jump Starter And Power Supply (12 Volt Power Supply and Jump-Start
All I can say is, this system really does the job for me! The Power Supply has a detachable 110v charging cord and it charges fully in about 8 hours (or less). There is a convenient 12v plug on the side, and it runs my Brake Buddy all day on long trips with plenty of charge to spare.
If you're looking for a reasonably priced power solution for a 12v braking system, you probably won't go wrong with this one. If there isn't a Harbor Freight near home, you can order almost anything online.
I'm sure there are better power supplies out there, but I'm not looking any further.
Harbor Freight's 12v Jump Starter And Power Supply is my Brake Buddy buddy