The importance of Battery Mounting
Any ebike builder will tell you that the hardest part of ebike design is…where to place the battery pack? Most builders understand that the battery belongs in the frame triangle, for balance, for looks, and for practicality. Most bicycle triangles have convenient bottle holder mounts drilled in the downtube, which is the ideal place to mount a hard-case battery pack.
New technology in battery cells make it all possible
The 18650-format batteries have gotten more energy-dense and affordable in the last few years. Luna Cycle turned the ebike industry upside down by offering quality ebike packs with name-brand quality cells at never-before seen affordable prices. Now it is possible to have as much as 17-Ah in a hard-case pack that will fit into most bicycle frame triangles at a reasonable price.
A few years back, the best cells available were LiFePO4 chemistry, or crappy sealed-lead-acid packs (SLA), which you could never get away with when mounting into a triangle, because of their bulkiness.
As of this writing (October 2016) Our favorite cell is the Panasonic GA (pictured above) which puts out an amazing 3500-mAh of range, and enough power to run a high performance ebike such as the BBSHD 1000W.
If you are looking for maximum performance and bleeding-edge power-density (fits in a small space), you want a cell that is made up of these high-quality Panasonic cells. No 18650 on the market has a better energy density, especially at its high performance level.
All of the best 18650 battery cells (like the Panasonic GA) are made by factories in Korea and Japan, and no 18650 that China makes can compare in performance, reliability, or safety. However, China has proven it can make good looking clones…so please, be sure you trust who you buy your packs from.
Picking the right battery pack
Although Japan and Korea make the best battery cells, China is making the best variety of hard-cases.
The Amercian company Luna Cycles (located in southern California) is doing the best job of bringing the two together, by offering the Shark battery pack and the new Jumbo Shark (pictured above), and they fill them with quality authentic Samsung or Panasonic cells.
The smallest size of these cases is the original Shark 52V 14-Ah, which is the way to go if you have a tight space. 52V 14-Ah Shark packs (which provide 700 watt hours) should give you a pretty damn good range (20-60 miles depending on riding style).
If you have an extra inch or so of space in your frame, you could choose a 48V 17.5-Ah Jumbo Shark (which has 840 watt hours), and has an amazing amount of power-density to fit into a bolt-on triangle pack hard-case.
Picking the right full suspension frame
For most frames, mounting a downtube hard-case battery (whether it is a shark, jumbo shark, dolphin, killer whale, or a bottle style) is pretty easy. However, mounting it in a full suspension frame can be tricky.
The biggest consideration is, size matters! The larger the frame, the better your chances. It’s a good idea to show up at the bike store with the hard case of your choice in-hand, if you are buying the frame brand new.
The shark hard case is the smallest today, but if you have another inch or so to spare, you can get the newer 48V / 17.5-Ah Jumbo Shark which gives you 840 watt-hours, and that means even more range.
The fattest hard-case battery pack right now is the Luna Killer Whale pack. It is our number-one choice for the Electra Townie (hardtail) street commuter, with its huge frame triangle…
What happens if the Shark Does Not Fit?
Sometimes it is necessary to modify the bracket, or even the bike, to get a shark to fit in a full suspension bike. And sometimes even then?…if it will not fit, you could get stuck with a less than ideal solution.
Look at this link for tricks, to get that shark to fit.
If worse comes to worst, it’s time to get drastic. If possible, maybe use a backpack battery (read article)
Mount a hard case above the top tube (ugly, but it works…like my girlfriend in school)
Mount your battery pack on a rear rack (poor handling, but it works….don’t judge me)
The Ultimate Solution…Custom Pack (a Luna Love Story)
By now everyone knows Luna Cycle does everything with a lot of passion and love (and energy) …This is the story of our first Luna-branded bike the Luna Ludicrious, and we encourage everyone out there to put as much passion and love into their bike builds as possible.
The Luna Ludicrous went from a concept, to an orphan with no battery pack, to an ugly orphan with an attitude, to a beautiful swan…..all based on triangle battery pack selections.
We decided that we had to build a custom 18650 triangle pack, as the ultimate solution (for the big dogs on the porch!)
Read our article on DIY pack building….on what is possible from even a home builder…
So we decided to turn the problem into a opportunity and outfit the bike with one of our 50-amp off the shelf batteries (11.5ah PF Pack) and fit the bike with our new extreme power 2500 watt BBSHD on the ebike).
We got the bike build done, and announced the bike, (lets be honest), it was pretty ugly. Luna loves big battery packs (just like everyone else) and 11.5-Ah / 52V is OK for our competitors, but we are selling to people who know the difference. (600 watt hours is fairly small on a high power bike that can gobble up watt hours like sunflower seeds)
Damn….. this bike needs some more love, more power and most importantly more watt hours. Here is how it looks with the PF 11.5ah battery rectangle pack.
This bike is awesome, and it would be great just like this if we are not Luna and wanted to show off all the cool tools we just bought, and the abilities we have.
SO!…we went to town on this bike and first built our own plastic hard case and calculated the maximum 18650’s we could put into the given space, and as you can see from the drawing above, we can fit as many as 130 of them in this case, utilizing every cubic inch of open space in that triangle….
Wow!!!! You can see the results below. Now our first complete production ebike can compete with the best ebikes on the market at an unheard-of low price….something we can proud to have our butt on top of.
So, using the ability to make a custom cases and battery to fit perfectly into that space, the result is the 2500W Luna Ludicrous, which can fit up to 23-Ah at 52V into its triangle for a beastly 1200 watt hours in an amazing package.
1200 watt hours is larger than almost any other commercial ebike, and we still kept it very light (the Ludicrous weighs 65 pounds with this giant battery), and slick looking.
Luna put lots of love into this bike and it came out awesome…and we encourage all ebike builders (even the new ones) to put as much love as you can into making your bike awesome.