UPDATE (9-29-15): Turns out that the Case-08 battery case design isn't nearly as bad as I had originally posted...
After weeks of BMSBattery refusing to talk to me at all about my problems or my desire to return my Case-08 battery (due to the issues mentioned in the original post, below), I finally filed a dispute with PayPal to try to force some action. It was at that point that BMSBattery actually started communicating with me, and after a few emails, they pointed out that there were 3 small rubber pieces that came with the kit that can be used to adapt the flat plastic mounting bracket onto a round down tube. (I've attached a photo of this piece.)
I tried re-installing the pack with these rubber pieces included, and the final assembly was reasonably stiff and seems robust enough to use. I'm still a tad wary of the plastic construction of the mounting bracket, but I was able to get the screws pretty darn tight, and the rubber pieces seem to spread out the clamping load pretty well.
**I did make sure to add some Loctite onto the screw threads in case the screws might want to back out/loosen in response to vibration during riding.**
In my own defense, I think it was a stretch to expect someone to realize exactly what these particularly rubber pieces were intended for -- especially given that literally zero instructions were included with the kit, nor were there any instructions available online. So I had assumed that these pieces were for clamping something to the handlebars. And absent ANY customer support, what should have been a quick fix of a simple misunderstanding ballooned into a huge issue.
So this new info mostly nullifies my complaints in points #1 and #2 below (in my original post).
However, point #3 is still a problem for my bike, especially since I noticed that mounting the pack backward/upside-down (i.e., with the wires pointing up towards the handlebars), means that there are 2 potential water infiltration spots up on the front/top of the pack where I think water could get install the pack or controller. One of these spots is where the wires exit the controller, which should be pretty easy to caulk. But the other spot is at a joint between the battery case and the controller, which could also be caulked, but would have to be re-caulked anytime you need to remove the battery from the bike, or if direct sunlight degrades the caulk over time. I'm currently waiting to hear back from BMSBattery on this point, as the guy I was talking to (Suga) is currently out on vacation.
But, other than that point #3 issue, I'm feeling cautiously hopeful that this kit might actually work ok after all. Long-term quality and longevity will certainly take time to assess tho. And I'll come back and post more if I have any further updates. (I also attached a photo showing the various components that came with the battery to fill out the kit, except for the motor.)
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ORIGINAL POST:
I’m generally a fan of battery packs that are designed to mount to the down tube on a bike frame using the water bottle holder bosses, and I recently ordered such a pack from BMSBattery.com. It’s referred to as the “Case-08” pack.
Specifically, I got the 36V 14.5Ah version with Panasonic cells and an integrated 18A controller for $379+shipping. https://bmsbattery.com/ebike-battery/773-36v145ah-case-08-bottle-panasonic-battery-pack-battery.html But the tech specs are kinda out-of-scope for this review, as this review pertains entirely to the design of the pack's case and mounting bracket. Bottom line, I just wanted to post this to warn people away from this particular product.
The battery case’s design has 3 key flaws, all in the mounting bracket:
1. The mounting bracket, which bolts onto the frame, is made of a pretty flimsy plastic.
Every other frame-mounted pack that I’ve come across previously is either made of metal or is made with a combination of metal and plastic, where the metal provides most of the strength to the part.
2. The shape of the mounting bracket is almost entirely flat. This results in 2 serious problems:
-This means that when mounting the flat bracket onto a round down tube, the only points of contact are a few square millimeters on the tops of the bosses. This results in a pack that is very unsteady and can rock back and forth so much that there’s no way that the plastic mounting bracket will last long before cracking. (This is my personal/professional assessment as a mechanical engineer.) It also means that a (relative) ton of bending stress will go through the mounting bolts and directly into the bosses as the 8lb pack rocks and vibrates back and forth while riding the bike.
I’ve had 3 similar packs in the past, and none of them have had flat mounting brackets. They’ve either been C-channels, where points of contact are made on the sides of the down tube, or they’ve had rounded undersides that contour to the down tube (like BMSBattery’s “Bottle-09” pack, which is well-designed IMO).
-The flat design also means that the bracket inherently has very little bending strength (aka “flexural strength”), which contributes even further to how much the pack can sway side-to-side and increases the likelihood that the mounting bracket will eventually fail.
3. The location of the mounting holes and slots in the mounting bracket are positioned too far “forward” on the pack (6 inches, such that I couldn’t even install the pack on my bike in the correct orientation* (i.e., such that the pack would have to be lifted up and forward to be taken off of the mounting bracket). The “rear” of the pack (the side with the wires) hits the seat tube and prevents the mounting holes from lining up with the water bottle holder bosses in the frame. This is despite my frame triangle being quite spacious, and the water bottle bosses being in a typical position along the down tube (this statement is simply based on what I’m used to seeing on other bike frames). Plus, I have had 2 different packs mounted in the same frame previously without any clearance issues.
The only way to get it to physically fit in the frame would have been to install in “upside down”, such that gravity would slide the pack out of its mounting bracket if it wasn’t properly locked in place.
I've uploaded a video of me VERY lightly wiggling the pack with my fingers and showing how un-sturdy the mounting bracket is: [EDIT: I've deleted the video from Youtube since it showed the battery pack WITHOUT the rubber adapter pieces installed that I later learned help to stabilize the pack on the frame]
And I've attached a few photos as well.
(On a side note, it's really too bad that the "Case-08" case is so poorly designed, cuz it looked like this kit was gonna be pretty slick overall. It comes with a handlebar-mounted LCD screen that serves kinda like a Cycle Analyst, displaying speed, watts, distance, etc., and also allows you to select from 5 different (programmable(?)) speeds. And all of the handlebar connections (LCD display, throttle, brakes) are made with color-coded, water-tight connectors splitting off from a single wiring harness. And all of the motor-to-controller phase and sensor connections are made in one compact, round, water-tight 9-pin connector. (Probably not suited for higher power setups, but this kit's controller was limited to just 18A.)
BMSBattery also sells a pack called "Bottle-09" which is much better designed and actually mounts securely to the frame. It uses a mounting bracket that is mostly plastic but also includes an aluminum piece for structural strength.)
After weeks of BMSBattery refusing to talk to me at all about my problems or my desire to return my Case-08 battery (due to the issues mentioned in the original post, below), I finally filed a dispute with PayPal to try to force some action. It was at that point that BMSBattery actually started communicating with me, and after a few emails, they pointed out that there were 3 small rubber pieces that came with the kit that can be used to adapt the flat plastic mounting bracket onto a round down tube. (I've attached a photo of this piece.)
I tried re-installing the pack with these rubber pieces included, and the final assembly was reasonably stiff and seems robust enough to use. I'm still a tad wary of the plastic construction of the mounting bracket, but I was able to get the screws pretty darn tight, and the rubber pieces seem to spread out the clamping load pretty well.
**I did make sure to add some Loctite onto the screw threads in case the screws might want to back out/loosen in response to vibration during riding.**
In my own defense, I think it was a stretch to expect someone to realize exactly what these particularly rubber pieces were intended for -- especially given that literally zero instructions were included with the kit, nor were there any instructions available online. So I had assumed that these pieces were for clamping something to the handlebars. And absent ANY customer support, what should have been a quick fix of a simple misunderstanding ballooned into a huge issue.
So this new info mostly nullifies my complaints in points #1 and #2 below (in my original post).
However, point #3 is still a problem for my bike, especially since I noticed that mounting the pack backward/upside-down (i.e., with the wires pointing up towards the handlebars), means that there are 2 potential water infiltration spots up on the front/top of the pack where I think water could get install the pack or controller. One of these spots is where the wires exit the controller, which should be pretty easy to caulk. But the other spot is at a joint between the battery case and the controller, which could also be caulked, but would have to be re-caulked anytime you need to remove the battery from the bike, or if direct sunlight degrades the caulk over time. I'm currently waiting to hear back from BMSBattery on this point, as the guy I was talking to (Suga) is currently out on vacation.
But, other than that point #3 issue, I'm feeling cautiously hopeful that this kit might actually work ok after all. Long-term quality and longevity will certainly take time to assess tho. And I'll come back and post more if I have any further updates. (I also attached a photo showing the various components that came with the battery to fill out the kit, except for the motor.)
--------------------------------------------------------------------
ORIGINAL POST:
I’m generally a fan of battery packs that are designed to mount to the down tube on a bike frame using the water bottle holder bosses, and I recently ordered such a pack from BMSBattery.com. It’s referred to as the “Case-08” pack.
Specifically, I got the 36V 14.5Ah version with Panasonic cells and an integrated 18A controller for $379+shipping. https://bmsbattery.com/ebike-battery/773-36v145ah-case-08-bottle-panasonic-battery-pack-battery.html But the tech specs are kinda out-of-scope for this review, as this review pertains entirely to the design of the pack's case and mounting bracket. Bottom line, I just wanted to post this to warn people away from this particular product.
The battery case’s design has 3 key flaws, all in the mounting bracket:
1. The mounting bracket, which bolts onto the frame, is made of a pretty flimsy plastic.
Every other frame-mounted pack that I’ve come across previously is either made of metal or is made with a combination of metal and plastic, where the metal provides most of the strength to the part.
2. The shape of the mounting bracket is almost entirely flat. This results in 2 serious problems:
-This means that when mounting the flat bracket onto a round down tube, the only points of contact are a few square millimeters on the tops of the bosses. This results in a pack that is very unsteady and can rock back and forth so much that there’s no way that the plastic mounting bracket will last long before cracking. (This is my personal/professional assessment as a mechanical engineer.) It also means that a (relative) ton of bending stress will go through the mounting bolts and directly into the bosses as the 8lb pack rocks and vibrates back and forth while riding the bike.
I’ve had 3 similar packs in the past, and none of them have had flat mounting brackets. They’ve either been C-channels, where points of contact are made on the sides of the down tube, or they’ve had rounded undersides that contour to the down tube (like BMSBattery’s “Bottle-09” pack, which is well-designed IMO).
-The flat design also means that the bracket inherently has very little bending strength (aka “flexural strength”), which contributes even further to how much the pack can sway side-to-side and increases the likelihood that the mounting bracket will eventually fail.
3. The location of the mounting holes and slots in the mounting bracket are positioned too far “forward” on the pack (6 inches, such that I couldn’t even install the pack on my bike in the correct orientation* (i.e., such that the pack would have to be lifted up and forward to be taken off of the mounting bracket). The “rear” of the pack (the side with the wires) hits the seat tube and prevents the mounting holes from lining up with the water bottle holder bosses in the frame. This is despite my frame triangle being quite spacious, and the water bottle bosses being in a typical position along the down tube (this statement is simply based on what I’m used to seeing on other bike frames). Plus, I have had 2 different packs mounted in the same frame previously without any clearance issues.
The only way to get it to physically fit in the frame would have been to install in “upside down”, such that gravity would slide the pack out of its mounting bracket if it wasn’t properly locked in place.
I've uploaded a video of me VERY lightly wiggling the pack with my fingers and showing how un-sturdy the mounting bracket is: [EDIT: I've deleted the video from Youtube since it showed the battery pack WITHOUT the rubber adapter pieces installed that I later learned help to stabilize the pack on the frame]
And I've attached a few photos as well.
(On a side note, it's really too bad that the "Case-08" case is so poorly designed, cuz it looked like this kit was gonna be pretty slick overall. It comes with a handlebar-mounted LCD screen that serves kinda like a Cycle Analyst, displaying speed, watts, distance, etc., and also allows you to select from 5 different (programmable(?)) speeds. And all of the handlebar connections (LCD display, throttle, brakes) are made with color-coded, water-tight connectors splitting off from a single wiring harness. And all of the motor-to-controller phase and sensor connections are made in one compact, round, water-tight 9-pin connector. (Probably not suited for higher power setups, but this kit's controller was limited to just 18A.)
BMSBattery also sells a pack called "Bottle-09" which is much better designed and actually mounts securely to the frame. It uses a mounting bracket that is mostly plastic but also includes an aluminum piece for structural strength.)