Making your own tec pack?

Torpedillo

New Member
Nov 4, 2020
29
11
Spain
Finally managed to assemble a battery pack, hopefully will find time to test it this weekend :) It is a bit on the longer side, but 378WAh, same as TEC.

I've used rosenberger connectors both as the outputs and inputs to the pack in hopes of using bike's charger... but seems it won't work that way. When connected to the battery, charger starts to blink red; when the charger is first connected to the bike and starts charging it (and there is a usual click after a couple of seconds) -> and then I quickly switch it to charge the pack, its lights just go out (and do no come back even if I start to charge the bike itself). Wonder if it is actually charging at the point.

Did anyone experiment with using the "native" charger for custom packs? I think Booz uses it, so should be possible in theory... doubtful that they have the same access to data protocols as in TEC though

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Hi I think your idea is fantastic. Could you please post a link to the materials? I'd like to do something similar.
Thanks in advance
 

sdcoffeeroaster

Active member
Jul 22, 2018
563
209
San Diego, CA
I think it will look okay, esp if you would install black colored padding (this one looks gray?). On the other hand, these holes will fill up with dirt...

You can also try transparent anti-gravel tape I guess. The one I use is also self-adherent, so easy to install and protects quite decently. The only thing is, it is not matte, so creates a bit of gloss - but barely noticeable.

On my end I decided to rebuild the battery, to make it 24 cm is length, so that it will fit to standard bottle cage container not hitting the tube. Still in progress, will post here once completed
Thanks. Here is my other option. I plan to make an SLA (PC/ABS printed part) of a 93mm OD 6" long bottle to fit my present battery with a lid. It should fit this cage and then I could have the option of easily using a water bottle if I wanted. Overall I think what I have now is close to 3 lbs with everything.

 

Torpedillo

New Member
Nov 4, 2020
29
11
Spain
Hi guys. I'm planning maybe to connect directly the second battery to the engine with a Y cable. Anybody knows the name of the connector I attach ?. I have open the left cover to check itp

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themoon

Member
Sep 12, 2020
96
16
Ukraine
Re-assembled the battery to reduce it's weight and dimensions. Now it only 1.15kg, so can be held by magnetic fidlock system for quick release - very convenient. Mounting and dismounting it now takes just a couple of seconds.

The configuration is 10s2p, 3500 mah LG cells. First charge and ride gave 25 km on trail road (no ascending), with 60% eco, 30% trail, 10% boost - all on high settings.

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sdcoffeeroaster

Active member
Jul 22, 2018
563
209
San Diego, CA
Re-assembled the battery to reduce it's weight and dimensions. Now it only 1.15kg, so can be held by magnetic fidlock system for quick release - very convenient. Mounting and dismounting it now takes just a couple of seconds.

The configuration is 10s2p, 3500 mah LG cells. First charge and ride gave 25 km on trail road (no ascending), with 60% eco, 30% trail, 10% boost - all on high settings.

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Nice. I thought your pac was 378 wH (5000 mah 20170) not 250wH (3500 mah 18650). What does the actual battery pack look like and can you include a picture? I think you said custom because the hoverboard batteries sizes need at least an 86mm ID for the smallest one like I have to fit given how the batteries are stacked up. How about some details on that Zefal bottle since I don't see one that looks like that anywhere. Good job and the weight seems reasonable.

I think mine is about 1.36 kg total with the bracket mounted under the case at on the cage mounts, battery (1000g) and the case/cable. It's possible my new one will be somewhat lighter and I hope to get the SLA (solid model print using PC/ABS) this Friday along with the new cage to hold it. I'm going pretty thin on the wall thickness to make the awkward battery size fit but it's only 93mm OD. It may be too weak so we'll have to see.

Oh what BMS did you use? Rectangular or did you find a round one? I did see a round one suitable for water bottle sizes on AliExpress but didn't order it. I have never welded up a custom battery but know a person there that could do that. I would have to design a round/long plastic structure to hold the batteries. I used to design using SolidWorks but don't have access but have been using Autodesk Fusion 360 which is free and can export SLA files. My current 250wH hoverboard battery is smaller than the typical Chinese ones I've bought online but it's diagonal dimension still drives the need for an oversize 93mm water bottle size unfortunately.
 
Last edited:

themoon

Member
Sep 12, 2020
96
16
Ukraine
The build is indeed a custom one, as it was the case with previous pack. To allow for a smaller ID you place a cell in the middle, then surround it by additional 6 batteries - like in a shape of flower. This way, resulting diameter for 7 batteries will be roughly 3 * diameter of single cell. So in case of 217000's it was smth like 6.5cm; for current build it is even less: approx 6 cm. For that, any tool box with the given specs will fit: 6.5mm ID, approx 22-24cm in length. You have to be mindful though that some of the bottles (like the one I used) have "extenders" -> when these are fitted, they decrease its resulting ID by a bit.

Theoretically, even 20 21700 batteries could have been packed to the Zefal bottle I used (that's Z BOX L, btw), but then there would be too little space for BMS and connectors would be external, which I did not want. If you take a look at my previous build, it had an additional tube attached to it, making the resulting length 27cm - too much actually. And then ofc the weight... given that it mounts to the bottle cage, additional 500 grams play a big role for extreme riding. Hence using lighter and more compact 18650's. Resulting 7A vs 10A does not make that huge of a difference to me, my routes are up to around 40-50km anyway.

Cannot show you the picture of the assembled cells, cause battery is now sealed and opening it might damage the wiring; in that sense, it is not really serviceable.

My idea of using this form factor for the battery was that it should be:

1). Easily transportable (total weight with a nylon pouch and mounting system is 1315g; cables are detachable, so easy to stow away as well)
2). Very quick to mount/dismount (thanks to Fidlock Base + Uni mount that's 1-2 seconds)

Oh, and btw, I considered another mounting option - Ibera cage. It rotates 30 degrees to either left or right and can be adjusted to different diameter of the bottles. However, as it is metallic, using it will scratch the plastic on the Zefal bottle eventually, and mounting is not a quick as with the Fidlock system. For larger frame sizes, probably you could go away with using other, "conventional" cages, but mine is M, and putting the battery there was being a little awkward, not to mention that not a lot of space was left for connectors.

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themoon

Member
Sep 12, 2020
96
16
Ukraine
just to confirm here - the two large holes on the opposite sides of cage plate mount, are they reserved for tec pack and not used otherwise? Should they be just left unscrewed?
 

Torpedillo

New Member
Nov 4, 2020
29
11
Spain
Hi, If you refer to this holes (see the attached photo) are to fix the internal battery, I removed them to see what where they doing, and the internal battery moved down.

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Torpedillo

New Member
Nov 4, 2020
29
11
Spain
Yeahh, this is the internal part of the back screw that supports the internal battery. Just remove one if you are curious , is very simmilar to a wheel axis
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themoon

Member
Sep 12, 2020
96
16
Ukraine
Quite strange that they are screwed only from the bottom then if in fact it can be screwed from the cage mount plate as well... But apparently that's enough also
 

sdcoffeeroaster

Active member
Jul 22, 2018
563
209
San Diego, CA
Hi, If you refer to this holes (see the attached photo) are to fix the internal battery, I removed them to see what where they doing, and the internal battery moved down.

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Yes and I can tell you that once you slide the internal battery out it's a real chore to get everything back in the way you thought it was. I did a complete frame swap on my carbon bike. The decals cracked all over and Focus did warrantee that but not the labor so I did the frame swap myself. I put the battery back in at least 10 times before I was satisfied with the cable routing and main wiring harness. I'm hoping once the native battery fails I can either buy a replacement or find someone locally to attempt a complete rebuild. It's the real reason I built my DIY TEC pack, extending the life of the native pack.

My last ride my high end hoverboard pack only went 17 miles and 1100 feet of climbing. I was pushing very hard but only used ECO. When I charged it I monitored the gross amount of energy to charge and it was down from the previous high of 256 wH by 100 wH so the pack quit early this ride. I wish I had measured the voltage before the charge but the final is 40.2 volts so the pack has a full charge. I don't normally run it down until it quits but only go around 15 miles on it or less before I switch over to the native pack. I charge at 2A so a pretty slow charge too. I need to run it down again to see what's up with it.

I wish there was a way to figure out the data lines on the Rosenburger plugs. I think two of them must send voltage levels to the Shimano computer so that the display will show the level of charge on the TEC pack and not the native pack. Maybe the other two tell the computer to use the TEC pack voltage to update the display. They could be short together to do that or ??? It's the missing part to make these DIY packs predictable and not suddenly just quit on a hill which is what normally happens if you don't switch over early.
 

Torpedillo

New Member
Nov 4, 2020
29
11
Spain
Yes and I can tell you that once you slide the internal battery out it's a real chore to get everything back in the way you thought it was. I did a complete frame swap on my carbon bike. The decals cracked all over and Focus did warrantee that but not the labor so I did the frame swap myself. I put the battery back in at least 10 times before I was satisfied with the cable routing and main wiring harness. I'm hoping once the native battery fails I can either buy a replacement or find someone locally to attempt a complete rebuild. It's the real reason I built my DIY TEC pack, extending the life of the native pack.

My last ride my high end hoverboard pack only went 17 miles and 1100 feet of climbing. I was pushing very hard but only used ECO. When I charged it I monitored the gross amount of energy to charge and it was down from the previous high of 256 wH by 100 wH so the pack quit early this ride. I wish I had measured the voltage before the charge but the final is 40.2 volts so the pack has a full charge. I don't normally run it down until it quits but only go around 15 miles on it or less before I switch over to the native pack. I charge at 2A so a pretty slow charge too. I need to run it down again to see what's up with it.

I wish there was a way to figure out the data lines on the Rosenburger plugs. I think two of them must send voltage levels to the Shimano computer so that the display will show the level of charge on the TEC pack and not the native pack. Maybe the other two tell the computer to use the TEC pack voltage to update the display. They could be short together to do that or ??? It's the missing part to make these DIY packs predictable and not suddenly just quit on a hill which is what normally happens if you don't switch over early.
Hi, you're totally true about the main battery mess. I almost have the same problem but I was lucky. About the Rosenberg, I work in a high tech machinery factory and I'm asking the electrical engineers about it. Let's see if I have some questions. Also I'm thinking about to take an eBike training course, but the actual situation of COVID doesn't me allow to travel too much in Spain. I already bought a battery
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and I think I'm going to dismonunt the internal Rosenberg to weld directly a XT60 connector with it comes with the battery.
Lets hope he can get more information abou thte rosenberg connector
 

valex_1974

Member
Nov 13, 2020
10
7
Rome
hi guys, but i don't understand.... themoon when you connect with the rosenberg cable your extender to the frame charge port you use the exender for charge the first battery inside?
this connection work in ride mode?
Thank you very much :)
 

sdcoffeeroaster

Active member
Jul 22, 2018
563
209
San Diego, CA
hi guys, but i don't understand.... themoon when you connect with the rosenberg cable your extender to the frame charge port you use the exender for charge the first battery inside?
this connection work in ride mode?
Thank you very much :)
When you plug a 36v battery into the charge port of the bike with a Rosenberger plug the bike turns on instantly and runs on the external battery only. It "knows" that the DIY tec pack is NOT the charger (probably because the data line are not being used for that). The display continues to read the native battery charge and if it's full or whatever, that doesn't change.

Once you run down the external battery the bike just quits running with an error code (forget what that is but I think it's 13) that means your DIY tec pack is out. At that point you just disconnect the DIY tec pack and hit the start button on the bike to run off of the native battery. I don't know of a way to get the display to register the voltage in the DIY tec pack like it does with Focus TEC pack and that has to do with how the TEC pack uses those data lines which are not connected to anything in the DIY tec pack.
 

sdcoffeeroaster

Active member
Jul 22, 2018
563
209
San Diego, CA
I ordered a few of these PET containers for my battery along with a rounded top. The shipping costs way more than the bottle, lol, so I order 5 of them. I think my hoverboard battery will fit and I'm using my new oversize water bottle cage. I do have someone making an SLA (plastic printed) bottle but I'm not sure they can squeeze in my project right now.


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valex_1974

Member
Nov 13, 2020
10
7
Rome
When you plug a 36v battery into the charge port of the bike with a Rosenberger plug the bike turns on instantly and runs on the external battery only. It "knows" that the DIY tec pack is NOT the charger (probably because the data line are not being used for that). The display continues to read the native battery charge and if it's full or whatever, that doesn't change.

Once you run down the external battery the bike just quits running with an error code (forget what that is but I think it's 13) that means your DIY tec pack is out. At that point you just disconnect the DIY tec pack and hit the start button on the bike to run off of the native battery. I don't know of a way to get the display to register the voltage in the DIY tec pack like it does with Focus TEC pack and that has to do with how the TEC pack uses those data lines which are not connected to anything in the DIY tec pack.
Tank you very much!!! Very kind!
You connect only cable black and Red on the rosenberg connector? Rigth?
 

Torpedillo

New Member
Nov 4, 2020
29
11
Spain
Not a Rosenberger of course so you have some rewiring to do.
Yes, of course. I'm asking my purchase department colleagues for the rosenberg connector in Spain, so if I find it at a reasonable price I will buy through them (I'll post it here if there are other here interested then I can send to them. 60/70 € for a connector it's too much. I prefer to open the internal rosenberg and weld a new cable with a XT60 connector.
 

sdcoffeeroaster

Active member
Jul 22, 2018
563
209
San Diego, CA
My latest DIY pack proto is here. Already there are changes to be made and this red material is not the final black PETG SLA material I will use. There are two mounting positions for this cage and the lower one is very close to the shock. I posted a version of both of them. I think a larger radius at the bottom will help but I need to enlarge both the OD and ID because the battery is still snug. Wish I had the right angle Rosenberger now too. But I will move the plug more to the edge of the bottle to help with the routing of this straight plug. I'm after something that looks more like a water bottle and less like an ebike battery, lol. With this oversize cage I still have the option of taking a water bottle instead of the battery and a water laden backpack for shorter rides. Next version is probably a week and I am getting some black PET bottles (off the shelf) with twist tops and 89mm ID that cost only aoubt $1.10 each on Wednesday. They will probably be thinner wall. Right now I'm 0.125" and the next version will go to 0.100" to buy me some additional battery clearance.

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Torpedillo

New Member
Nov 4, 2020
29
11
Spain
My latest DIY pack proto is here. Already there are changes to be made and this red material is not the final black PETG SLA material I will use. There are two mounting positions for this cage and the lower one is very close to the shock. I posted a version of both of them. I think a larger radius at the bottom will help but I need to enlarge both the OD and ID because the battery is still snug. Wish I had the right angle Rosenberger now too. But I will move the plug more to the edge of the bottle to help with the routing of this straight plug. I'm after something that looks more like a water bottle and less like an ebike battery, lol. With this oversize cage I still have the option of taking a water bottle instead of the battery and a water laden backpack for shorter rides. Next version is probably a week and I am getting some black PET bottles (off the shelf) with twist tops and 89mm ID that cost only aoubt $1.10 each on Wednesday. They will probably be thinner wall. Right now I'm 0.125" and the next version will go to 0.100" to buy me some additional battery clearance.

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Getty , your approach is awesome. Are you from Europe or USA? To know the best place to buy the brosenberger if I don't find it in a local dealer
 

Torpedillo

New Member
Nov 4, 2020
29
11
Spain
Hi,where did you find this cable?

do you think it fits in the xt60?
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I'm in the USA. I bought mine from Germany and they do have the right angle one too. Powerbutler Adapterkabel für Brose 36V Akkus (Rosenberger Magnetstecker)
Thanks a lot , i think for my configuration will fit perfectly. And it's a very good price
 

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