We frequently receive questions about why we have chosen the unique, upright, mid frame battery location for our UNIMOKE instead of keeping the frame "empty" and putting the battery on top of the frame or on the rear rack like you would find it for example on the Super 73 bike and others.
This short blog post will explain the reasons and thoughts behind this particular battery position!
So why did we put the battery in the center of the bike?
The battery of an e-bike is not only the most expensive part of your e-bike, it is also the heaviest part of your bike and most of all, it is is considered a "dangerous good" when you try to ship it via courier or airfreight.
So, in short, e-bike batteries are:
Therefore, quite a little bit of thinking should go into on where to place this expensive and sensitive package when designing an e-bike and the rules are simple:
1.) Mount it low and in the center of the bike
As e-bike batteries are heavy and bikes are sensitive to weight distribution (also and especially when parked with a side stand...), the battery should go somewhere REALLY close to the natural center of gravity of your bike. This is why rack mounted batteries are less than optimal, as are batteries mounted on top of your frame.
Also, a well positioned battery will not affect the driving behaviour of you bike at high speeds.
2.) Mount it well protected and accident-proof
The question is not IF your bike will fall over or be involved in a crash, it is just the question WHEN this will happen. So if someone (or you...) tips your bike over when parked or if you have an accident, the battery should not be able to hit the ground or any hard object.
So we decided to not only keep the battery low and central, but to actually mount it in a special protective chromoly sheet metal steel cage that also stiffens the frame considerably!
Our battery mounting structure actually protects the flanges of the battery and reduces the chance of the battery hitting something hard in case of an accident by over 90 %.
3.) Keep it secure form the elements
Electric bike batteries should NEVER be exposed to intense heat or direct sun radiation over a prolonged period of time. Also, your battery should not be exposed to constant rain or snow when parked.
Our mounting position (vertically under the seat...) reduces the exposure to elements to an absolute minimum and keeps your battery dry and cool most of the time! Also, the central battery "tunnel" greatly reinforces the frame in a vertical direction.
4.) Mount the battery close to the engine and controller!
Even 250 W rated engines take a good sip out the battery during acceleration and the stronger versions of our UNIMOKE with up to 1000 W can very well reach 25-30 Ampere peaks of current running from the battery through the controller to the engine!
Keeping all those components as close as possible greatly reduces cable lengths, unwanted electromagnetic radiation and resistance in the cables.
So, as you see, our mounting position has strictly been chosen in a "form follows function" approach and this position offers many benefits:
Also, this position gave us full freedom in regards to seat design and cargo options!
We hope, this short article helped you to understand our design choices and the reasoning behind our solutions better!