How best to carry extra semi-integrated battery packs?

[shelvacu]

I have a RadRunner 3+ with the large basket mounted on the back.

I would appreciate a longer range than I am currently getting and it would be great to carry along 1 or 2 extra battery packs that I could swap in. I know I could just throw a battery in a bag but I was hoping there might be a more secure option.

[John Rose]

A. Is the space under the rear rack wide and deep enough to put two of the batteries under it? Make a sling out of nylon webbing for them to sit on.

B. If you put two of them in pannier bags it would lower the centre of gravity.

C. If you're going far enough to burn through three batteries, you'll probably want to take a break. Then consider something a bit more theft-proof, like a lockable hard-shell box or steel cage.

[inoxa]

Wow you will probably need that break.  My butt gets soar on the long rides.   

Securing will be your issue.  You best option is to take the batteries when you dismount.  But they are heavy.  If it is just for the ride to and from home then not an issue.

[Naranja_CT5+]

To me riding my e-bike is like building a rocket. Any additional weight is not a good thing. But I respect that others have different needs.

The expensive way is to attach a hard case like a Pelican on top of the rear rack. Or see if a 3 inch PVC pipe will fit underneath the rear rack. Put an end cap on one end  and use a long removable shackle padlock on the other end.

[John Rose]

... Or see if a 3 inch PVC pipe will fit underneath the rear rack. ...

My first thought about that idea was to make a cone-shaped cap for the front, have a flat rear end cap with a few inches of fake fuse (twine) sticking out of it, paint it all red, and (finally) stick on an "ACME" label.