I use screw terminals found on deep discharge (marine) batteries for that purpose. I used to put the battery that was in use right aft of the CB trunk. That had the downside that it wasn't secured to the boat, but the cables from the motor reached it easily.
With a DS1 I have space in front of the seats. I attach one battery on each side to the seat front (with a strap, in a case). I purchased about 10' of really massive cable. (One or two sizes more up from the wires that come with the motor). I connected one end permanently to the motor cables. For the other end, I got the same kind of eyes as were on the motor cables.
The cable is long enough that it runs from the motor well, along the side of the cockpit (under the side deck - there is an open channel there in the older DS1s) all the way across the boat in front of the CB trunk. In other words, I can reach either battery and just connect it to the screw on terminals. When one battery is done, I move the cable to the other one.
I thought about a permanent installation and cutting the motor cables for a quick connect. I like being able to strip out the weight on days when I don't need the motor - currently I don't bring it more than about 1/5th of the time, although I may be too lazy to remove the batteries
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Even on trips where I know I will need the motor eventually, I usually do not bother to mount it until its actually needed. It tends to be a bit in the way in the back. Clamping it onto the transom at the motor well is quick and easy and I don't mind undoing and redoing a battery strap and two wingnuts. Normally, I use the motor when I'm becalmed, or before entering a channel with little or unreliable wind. Even when sailing solo, I don't need to bother with heaving to or whatever for the purpose, letting go the sheets and arresting the tiller is about it.
Conversely, once the motor has been mounted, I usually leave it up for the duration. The reason tends to be that the wind has come up and I'm busy sailing. And if I had to use the motor once, chances are, conditions will call for it again at some point during the same trip.
I'm rather fearless when docking under sail or tacking in narrow channels, but I'm also aware that I'm lucky that the local setup isn't that challenging. Calm periods and pockets of calm along a series of connected waterways as well as transiting certain channels and bridges tend to be my primary use case. Although, when it comes to a mid-afternoon calm on open water far from traffic, I "have a nap for that".