We have attempted to install a Super Shark battery in a bike frame that is barely too small many times. The battery will actually fit in the space available in the triangle (see picture below) but there is no room to slide it on and off of its mount. Since the mount cradle requires that you mount it to the water bottle mounts first and then slide on the battery, there is no way to mount the battery. That is, there was no way before Grin Technologies invented the Bottle Bob and Triple Bob. Now it is easy if you don't mind a semi-permanent battery mount where you just leave the battery on the frame all the time. Hey its better than the alternative!
To mount the Triple Bob in the smallest space possible on a frame that has no room to take the battery on and off once it is mounted, first attach the battery mount to the Triple Bob. Then attach the battery to its mount and lock it in place. Then position the battery in the frame and lock it down with hose clamps through the Triple Bob. We do this all the time to install batteries in frames that are a tight fit with no room to take the battery off once mounted. We used to do it with zip ties and holes drilled into the battery mount but Triple Bob's are so much better.
As an alternative, you can also do this with Bottle Bob's. They are a tiny bit shorter and we have on occasion even filed them down a few millimeters in especially tight frames.
Another technique for installing a downtube battery if it won't fit in the triangle like on a lot of full suspension bikes, is to mount it on the bottom of the downtube. Place it as far down toward the mid-drive motor or bottom bracket as possible considering other clearance factors and lock it down with a Triple Bob and hose clamps. If you have a suspension fork, let all the air out of it so you can completely collapse it and check that the tire will not hit the battery if the suspension bottoms out. If it bottoms out going off a jump or hitting a rock or curb it could damage the battery. That said, I have had a few people mount it there anyway and either lock out the fork, or add air pressure and promise to never go off a jump. 😯
For more info on Triple Bob's check out this article.
Let me qualify that. We have tried the Triple Bob from Grin Technologies with all of the Reention shark-type cases we use and most of the Hailong shark cases and it dramatically improves the strength and rigidity of the mount every time. We are now recommending them with all of our downtube batteries. While they improve every mount, they are most important on Jumbo Sharks and Mega Sharks. These weigh from 9 to 12 lbs and are taller so there is more side to side leverage pulling on the mount. With a Triple Bob, the battery is on there rock solid and doesn't move.
For even more flexibility in mount location and dramatically added strength, the Triple Bob also comes with recesses for hose clamps. It even includes 2 different sizes of high-quality stainless steel hose clamps. They even include some flat shrink tube to dress up the hose clamps for a clean professional look that also protects the frame. You can put up to 3 hose clamps on each Triple Bob. Two is enough by themselves or one for extra strength if you are also using the water bottle mounts.
There is one other cool feature I should mention. At one end of the Triple Bob is a chamfered, counter-sunk, bolt hole like the other ones but this one takes a flathead screw, also included. This can go under a part of the battery mount that is flat such as the part on some batteries that holds a controller or the part where the power connectors are located.
Then position the battery in the frame and lock it down with hose clamps through the Triple Bob. We do this all the time to install batteries in frames that are a tight fit with no room to take the battery off once mounted. We used to do it with zip ties and holes drilled into the battery mount but Triple Bob's are so much better. For more info on mounting batteries in a small triangle or full suspension bikes see this article.