If you have decided to get a triangle-shaped battery pack for your ebike, this article is about where to find the different sizes, so…whether you have a small frame triangle space, or a large one…here are the options available to builders as of November of 2015. The header pic is courtesy of Rafe at Calibike.
Why choose a Triangle pack?
Even if you’re not an engineer, most people can immediately appreciate how a builder deciding to move the weight of the battery pack to the center of the bicycle will make it handle better, plus, most slender “cargo rack” battery packs don’t have a huge amount of range.
If you bought an ebike a few years ago, the stock battery will be getting a little old right about now. When its time to replace the worn stock battery pack, choosing a central triangle battery will make the bike ride a lot better, and…it might give you the option of dramatically increasing the range.
When its time to get a new battery, you might even have the option of raising the voltage (depending on the controller) from the common 36V up to 48V or 52V, with no danger to the rest of the system.
Last year, there were not as many choices when it came to the cells that are inside the battery packs. The ebike industry had recently changed over to almost all of them using the very safe 18650-format cells (cylindrical, 18mm diameter, 65mm long), which are the type of cells found in cordless tools. Due to a variety of factors, this last summer there was a boom in variety of high-capacity and high-current cells. This meant that ebikers no longer had to use a huge and heavy battery pack to get high-performance, or longer range.
If you live where the terrain is relatively flat, you would probably be satisfied with an affordable 36V system, but…our experience and frequent polling indicates that anyone who falls in love with ebiking here in the USA, they will typically want a little more power on their second ebike. This usually means moving up to a 48V system, and recently we researched and wrote about the trend of using a 52V system, and the benefits of doing that.
Many years ago, the only option to get high performance was to go to a very high voltage system. Frame space on a bicycle will always be at a premium, so…using more cells to get higher voltages often meant having short range. Now, there are many high-current cell options. The new ability to choose high voltage or high current opens up an entirely new world of ebike system design and component selection.
There will always be a place for 60V-100V systems in the hot rod world, but most ebikers have ended up being happy with 1200W as an affordable and reliable daily commuter. Higher voltage components are less efficient, so they produce more waste-heat, so where’s the sweet-spot? I am on a kick to promote 52V ebike batteries and power systems (14 cells in series/14S), and here’s why…
If you are getting our recommended 1200W from 36V, then you’d be drawing about 33-amps (and its the amps that cause most of the heat in an electrical power system). But, if you bump up the voltage in your system to 52V, then you can get the very satisfying 1200W from only 23-amps! A low amp-draw means a cooler running battery, controller, and motor. Also…you will actually get more range from the same battery.
Well…what if we decide on getting a second ebike, but we want to really cut loose and build a fun weekend hot rod? If we still limit ourselves to using efficient and cooler-running components that operate on a 52V /14S system, there are affordable and available components that can run 50A, so 52V X 50A = 2600 watts of power!
List of Triangle Battery Sizes
In the picture below, the bike is a cheap Walmart Genesis V2100 frame, and because of the rear shock absorber being mounted inside the triangle, the space for a triangle pack is very limited. If you count the cells in the pic, there are 100, but that case doesn’t have a Battery Management System (BMS) crammed into it yet, so the final configuration will actually have to be made from a few less cells than what the pic shows.
If you take a set number of cells, they can be configured into series groups and parallel groups. The Series groups control how many volts that pack will put out, and…the individual cell-capacity times the number of cells in the parallel groups determines the amount of Amp-hours (Ah) that a pack will have.
The cell-type that the pack manufacturer has chosen has a dramatic effect on the current-output capability of the pack, and also the amount of Amp-hours of range (so, two packs with the exact same number of cells can have widely different amounts of range and amps they can safely produce)
The volts times the Amp-hours equals the “Watt hours” of a pack, which is a measure of power density. For example, a 48V pack times 15-Ah = 720-Wh
The BMS’s are all about the same size (typically a flat green circuit board), so…it is the number of cells that determines the physical size of the pack. For that reason I am listing these selections in order of physical size.
I was able to find triangle packs with cell-counts of 78, 84, 91, 104, 112, 117, 126, 128, and 140, and here’s a breakdown:
48V = 78, 91, 104, 117
52V = 84, 91, 112, 126
60V = 128
75V = 147
Let’s move on to the list!…
78 cells, Ballarat Electric bikes
Sam is located in Australia (west of Melbourne), and he ships to all of Oz, New Zealand, and the EU. He has custom ordered triangle packs for customers in many sizes and configurations, but…every summer he tries to keep some of his most popular 48V/12-Ah size on the shelf (December, Jan, Feb, March is the “summer” in Australia).
Depending on the cell type chosen, this size can be had in 48V with 12-Ah, 15-Ah, or 20-Ah, and Sam only uses Panasonic and Samsung cells.
84 cells, em3ev.com
25R cell___14.7-Ah___40A (60A peak)
His 84-cell pack is very small, and depending on the cell type, it can still provide 16.5-Ah or range, or a 40A continuous/60A peak performance. You will have to use a 52V / 14S system to get the benefits of this pack, but…once you try out 52V, I don’t think you’ll want to go back to anything less.
91 cells, Calibike
Calibike has been retailing triangle packs for a couple of years now, and I haven’t heard anything bad about them yet, so initial reports are good. If anyone reading this has a Calibike triangle pack, please post about it to endless-sphere, so the ebike community can collect more information about your experience with them.
I did some math, and it “looks like” they are using a 2200-mAh cell. They are rating this pack at 20A continuous and 35A peak. So, 20A from a 7P string is 2.8V per cell.
91 cells, Luna Cycle
In the interests of full disclosure, electricbike.com is owned by Eric, the same person who owns Luna Cycle LLC.
A while back, Eric was looking at the battery options for his longtail cargo fat-bike. As the owner of electricbike.com, he has travelled to China in person, and he attends the Interbike industry conventions. Since he is constantly in contact with industry leaders and the information they have, he was surprised that battery pack retailers were not upgrading their packs to the newest cells as quickly as he knew they could.
As of the summer of 2015, a very small and “fittable” pack could be made that uses cells which provide decent range, and also…an insane amount of amps.
Someday, there will be even more choices than this, but…if 91 cells was going to be Luna’s small pack, Eric decided to stuff it with the absolute newest “Beast” cell..the HG2, from LG-Chem in South Korea. It puts out the same 20A per cell as the hot rod Samsung 25R, but it has 3000-mAh of capacity…meaning 20% more range.
If you are using a BMS that does not restrict the output amps, a cell that is capable of putting out 20A, times 7 cells in parallel (7P) = 140A. One hundred…and forty…freakin..amps. This means if you are only pulling 70A from this pack, it will barely get warm.
Speaking of high amps, Eric’s BMS has a temp probe and over-temp protection on every pack.
104 cells, Luna Cycle
In the pack above, Eric chose the absolute best performing cell available. But what if you could be happy with a little less performance, and also wanted to pay a little less to help with your budget? After evaluating many different options, Eric chose the Samsung 26F cell as his “best value” option.
Although this pack is “only” 48V, it has eight cells per parallel group (8P). The 26F cell is rated to safely provide 5A continuous, so eight of them will produce 40A continuous and roughly 60A as a temporary peak.
All of Luna Cycles’ battery packs come with a voltage read-out. The 5 bars in the pic above shows that this battery is fully charged, and the 54.2V read-out indicates that this is a 48V / 13S pack.
112 cells, Luna
This pack uses that same Samsung 26F cell in the pack above, so it also uses the 8P configuration to provide 40A continuous with 60A peaks.
However, this pack adds a few more cells for those buyers who have enough frame room to keep the 52V systems we are promoting. This is the most affordable option for the 52V X 50A systems I discussed at the beginning of this article.
BUT WAIT…There’s more!
112 cells, Luna
If your frame has room for a 112-cell triangle pack…and 40A/60A just isn’t going to satisfy your itch? Eric made sure that his 112-cell triangle pack will have a Samsung 25R cell option. At 20A per cell, and 8 cells per parallel group? That’s 160A
117 cells, Calibike
They list 20-Ah from 9P = 2200-mAh per cell
They are rating this pack at 30A continuous, 50A peak. Also, at 30A for 9P, that would be 3.3A per cell.
126 cells, em3ev
Here is the performance quote from his website:
- We recommend controllers of up to 40A are used with the 29E equipped packs. With 25Ah capacity, 40A discharge is only 1.6C. For the 22P Pack, these can also be used with a 40A controller, but both the 22P and 29E packs are more comfortable operating at slightly lower discharge rates. If long term continuous discharge rate is close to or exceeding 40A, the high power 20R or 25R cells should be considered. With a 20R or 25R pack, the BMS is the limiting factor. The 20R and 25R cells deliver High Current effortlessly, with little voltage sag and also tends to maintain a higher voltage at the end of the discharge, with a flatter discharge curve.
- BMS Protection Current >100A.
126 cells, Hallomotor
I haven’t found any info yet about Hallomotor, except that they sell ebike kits and batteries. They are claiming that they are using the Panasonic NCR18650PF 2900-mAh cell, which is well-regarded and rated for 10A.
For performance, they are rating this pack at 78A continuous, and 130A peak.
128 cells, Kinaye Motorsports
I have been tracking kinaye from the time they first started selling components to the high performance ebike market. Barent, their owner, is a frequent poster on the endless-sphere.com discussion forum, and Kinaye is based in Belleview, Washington. His 60V triangle pack has a 6-week lead time, and uses the well-regarded Samsung 29E cell. He rates this pack for 50A continuous, and 80A peak.
140 cells, Calibike
I will keep an eye out for any info on Calibike battery packs. They appear to have sold many rectangle packs, and are now offering several sizes of triangle-packs.
147 cells, ebikessf.com
Ilia from ebikessf in San Francisco has been a respected and reliable vendor of electric bike components for over a decade.
He only has one triangle pack option. The Samsung 20R cell has slightly less capacity than the famous 25R, but it also provides 22A per cell, so…8 cells in parallel (8P) would be 176A
The first triangle bag I can recall ever seeing was the Falcon-EV bag (which are still available). Even if you had a common rectangle shaped battery, it helped hide the battery and the wiring for a less-cluttered look, plus keeping the power-system weight centered (of course).
As soon as em3ev.com began selling triangle packs, they immediately also offered a triangle bag. But now, there are many choices.
If you decide to use an available triangle bag instead of building a hard-case…I strongly recommend you add padding and some thin side-panels. I have seen reinforcement panels made from polycarbonate, 1/4-inch plywood, lexan, and whatever else was cheaply available from a local supplier (no sheet-metal, though…it conducts electricity in case of a short that resulted from a crash or chafing).
Most of the triangle bags available use wide velcro strips to attach them to the frame. Luna Cycles also has a bag with reinforced edge panels and holes with metal eyelets to allow the builder to use zip-ties, which is an option that works surprisingly well.
Written by Ron/spinningmagnets, November 2015