I thought some of you may find this useful.
I needed a battery holder to try my new tri-p7 and didn't want to wait for the delivery of a turboferret holder. I grapped some items from my shed and made a tri 18650 holder that I can attach to the bicycle using a pump holder next to the water bottle. It turned to be that good, simple and cheap that I won't order any other. It is a 22mm plastic pipe with two copper cups at both ends. One is fixed (with a spring for the negative pole) and the other can be removed to get the batteries in and out. The cup stays in place nicely and tied and it is easy to remove too. Very much self explanatory:
I needed a battery holder to try my new tri-p7 and didn't want to wait for the delivery of a turboferret holder. I grapped some items from my shed and made a tri 18650 holder that I can attach to the bicycle using a pump holder next to the water bottle. It turned to be that good, simple and cheap that I won't order any other. It is a 22mm plastic pipe with two copper cups at both ends. One is fixed (with a spring for the negative pole) and the other can be removed to get the batteries in and out. The cup stays in place nicely and tied and it is easy to remove too. Very much self explanatory: