Making your own tec pack?

[Torpedillo]

as far as I know lithium batteries are quite susceptible to shock... so unless I'm very sure that this thing can hold at least 1.3 kg of dynamic weight, I would be quite cautious - this thing might snap. And the point of boa in Fidlock system is that it can easily be snapped of because of used magnets. IMO boa in itself does not seem like a better option to a bottle cage then... I'd suggest using this: Fine Tune Bottle Cage Fully Adjustable. I have one, seems quite nice

Hi , thanks for the info, it seems very interesting this device. I will take a look

 

[sdcoffeeroaster]

as far as I know lithium batteries are quite susceptible to shock... so unless I'm very sure that this thing can hold at least 1.3 kg of dynamic weight, I would be quite cautious - this thing might snap. And the point of boa in Fidlock system is that it can easily be snapped of because of used magnets. IMO boa in itself does not seem like a better option to a bottle cage then... I'd suggest using this: Fine Tune Bottle Cage Fully Adjustable. I have one, seems quite nice

Wow and that is not very expensive either.

I just read that a battery rebuilder said that the Focus BMS goes dead if you disconnect it from it's battery and will not work again even with a fresh pack plugged in. Sounds very strange doesn't it? I'm not sure how this can be and there must be some initiation procedure to wake it up that is not proprietary. That person wanted to get his pack rebuilt but could not because of this. Maybe there is a way to figure out which line is seeing power and "fake it". If I learn battery welding, etc well I might want to rebuild my battery at some point in the future since this person also said that Focus was not supporting him in trying to get a new battery here in the USA.

 

[themoon]

You mean internal battery, right? Just wondering: if say you just remove the internal battery and connect diy pack, will it work? In this case, you can actually make custom battery in place of internal one when it is completely dead. For TEC you have to have some charge in internal I guess, but how about diy...

 

[sdcoffeeroaster]

You mean internal battery, right? Just wondering: if say you just remove the internal battery and connect diy pack, will it work? In this case, you can actually make custom battery in place of internal one when it is completely dead. For TEC you have to have some charge in internal I guess, but how about diy...

Yes it's the internal battery BMS. I don't know if any of it will work with just the external pack connected. Once you remove the internal pack what will the display function at all with the external connected and on. Good questions. If the internal is dead you would not want to lug it around anymore, lol. I suppose you could make a new internal battery but the interface with those 4 data lines and getting all of that to work with the display is the challenge. I imagine if I ever had a totally dead native battery I would figure something out somehow to avoid just throwing away the bike, lol.

 

[savas]

As far as i know you need the original bms.In the german forum there was one report that it works as well only with the extender TEC pack-the original one , without the internal battery.So you need a original Bms shimano or focus one.

 

[themoon]

So then when the internal battery dies, you can just throw it away and ride with the TEC pack, having the same weight it total... And ugly looks

Wonder if it is possible to repack TEC with the new batteries though.

 

[sdcoffeeroaster]

As far as i know you need the original bms.In the german forum there was one report that it works as well only with the extender TEC pack-the original one , without the internal battery.So you need a original Bms shimano or focus one.

But if you take the internal batteries out and leave the BMS you have to unplug and it's said that is what locks it up. So I'm not sure how that would work. Or do you just rip out the batteries from the internal pack and leave the BMS plugged in but not powered up? Lots of questions and few information in the public domain on this.

 

[themoon]

If somebody can take the internal battery out (as as whole, with BMS board) and then connect DIY pack this will clear things up a bit. But I guess then the display won't boot - it displays status of internal battery, and afaik you have to have some charge in it for TEC to work; so maybe the same for our diy packs

 

[Torpedillo]

I found this guy in a forum that was playing with BMZ bms and battery, but nobody gave him more information. Maybe he could "iluminate" us about this issue.

Looking for Replacement BMS's for Varta and BMZ batteries

Hi Folks: I recently acquired two non-functioning e-bike batteries to see if I could revive them. After some testing and partial disassembly I discovered that the cells in both batteries were in good shape and all balanced, but the BMSs in both batteries were not working. Since these are...

endless-sphere.com

 

[sdcoffeeroaster]

I'm currently researching the build for my lightweight emergency pack. It will only be a 10s1p (10 cells) weighing 1 1/4 lbs, range of 8-15 miles depending on battery used (125 to 180 wH). Since there are no parallel cells it will limited by the maximum current rating of the cell and of course whatever BMS I pick, matched to that rating. You get what you pay for so 18650 or 21700 batteries are most costly at 10A and above ratings. The Shimano motor is 250 watts (continuous) which would imply just under 8 amps but the ultimate limit is the Shimano controller which might be 15-20A, I don't know. Use of this pack might be limited to ECO mode only to "limp" home once the native battery is out. I'm looking at 10A batteries but some are rated as high 20-45A. You get what you pay for.

My current 250 wH pack uses 10A batteries so it can put out 20A max. The native Focus pack can put out 30A max but might be limited by it's controller to avoid overheating the pack. I'll be building a test pack from some used 2200 mah batteries soon...not powerful enough to be practical but good enough to evaluate the size, construction methods and do some eco riding with it. It could be either 5A or 10A rated batteries, hard to tell with these Chinese "no-name" batteries but I'm guessing 5A.

I heard from a major range extender manufacturer this week that they will soon be releasing a 250 and 378 wH version for the Focus. Good news.

 

[themoon]

For using only 10 cells I'd consider the ones below. According to test, they actually provide the same current as 20 lg's I use in my pack, and I had no problems running the pack in boost mode with extreme loads.

Each one weights 70g though

 

[sdcoffeeroaster]

For using only 10 cells I'd consider the ones below. According to test, they actually provide the same current as 20 lg's I use in my pack, and I had no problems running the pack in boost mode with extreme loads.

Each one weights 70g though

View attachment 54362

What was the cost and what is the current rating. I found Tesla batteries, new, model 3 5000mah for $100. for 30. Are this higher than 15A rating? Looks like 5C so 25A and only about $4. each. Where did you buy them? Lots of them on Aliexpress but only the 4000mah ones on Banggood.

 

[themoon]

To be honest, from time to time I also get the idea to build the pack from 10 21700. Just for the fun of it, below is how it would compare to my current one. Quite cute, I think

Regarding the test, I did not make it myself, but here is the excerpt from some YouTube video where a reviewer compared it with Samsung. And also the guy who soldered and assembled my pack said that these liito kalas are pretty rad.

 

[sdcoffeeroaster]

To be honest, from time to time I also get the idea to build the pack from 10 21700. Just for the fun of it, below is how it would compare to my current one. Quite cute, I think

Regarding the test, I did not make it myself, but here is the excerpt from some YouTube video where a reviewer compared it with Samsung. And also the guy who soldered and assembled my pack said that these liito kalas are pretty rad.

View attachment 54367

View attachment 54368

View attachment 54369

View attachment 54370

View attachment 54371

View attachment 54372

View attachment 54373

The LiitoKala ones appear to be 5C and 5000 mah so that's 25A. Teslas 21700 are 15A. My pack will be two rows of 3 on the bottom, 2 rows of 2 on the top with the BMS on the bottom, nice and small even with the 21700. I can get 30 tesla cells for $100. I'm more inclined to avoid the LiitoKala right now based on variable reviews I've seen. Probably just fine but would have to order thru AliExpress and the Tesla cells are right up in LA 100 miles from me. Once I get all my supplies I'll build a 78 wH version as practice with the cells I currently have and if it comes out OK I'll order some 21700's probably enough for 3 packs.

 

[sdcoffeeroaster]

Latest update on my 10 cell range extender. I finally built one of these and settled on some 20A LG 3000 mah cells. With only one string of cells to carry the load I think it's important to pick a cell that will not overheat and allow me to at least use trail mode. A 5A cell is marginal and I've found the Tesla 21700 cells are a bit too large to make a pack to fit the enclosure I've found (water bottle cage compatible). I had some weak Chinese cells from an old pack to build a proto of this for sizing purposes. I used the BMS from that pack and tested all the cells first (found one with 300 mohms internal resistance that I did not use). These cells are at best 1800 mah.

I charged the pack, fire extinguisher in hand, and it only took about 62 wH (should be 78 wH). This is my first pack build and I admit I need to think a lot more about assembly, order, routing, etc. 11 lines from the BMS are a lot to contend with for a such a small pack. And I need more practice shrinking large pvc sizes. This runty little pack is pretty ugly, lol. I bought a small welder and lots of supplies and I admit doing this for just one pack is NOT cost effective. It's more a hobby for a bored retired engineer so that's how I justify the cost. Welding was OK but my little welder can only do up to 0.15mm thickness nickel strips. So I had to add another layer of 0.1mm to handle the current.

I tested it by going up around the block and measuring the temperature every loop. This loop has an 18% climb at the corner and is all cement or asphalt. My weak pack still had about 18% left after 7 miles and 900 feet of climbing. It never got above 95 deg F and I used ECO for all of the loops except one where I tried trail mode. The 20A rated LG cells should be a lot better and allow me to use trail mode with more confidence. Remember this is an option for when you use a bit more from the native pack on a ride and it's dead. This way you don't have to struggle home and you're not lugging around too much extra weight. The total weight of the pack, pouch and Rosenberger plug is slightly less than 1 1/2 lbs and it fits a standard water bottle cage without screaming out "I am an ebike" lol.

 

[sdcoffeeroaster]

I had a major setback on my new 10s1p 108 wH pack this week. I bought some Lg hg2 batteries that are supposed to be "100% authentic and A1" 3000 mah. I later learned that this LG battery is often faked. Well I now have 10 fakes that cost me $3.40 each from a VAPE shop in Ontario CA. They all test out at 2610-2699 mah and might be the LG he2 model which is often substituted to save a $1. per cell. They look good and you can't tell without testing that they are fake.

Vape shops do not give refunds even when they commit fraud. I should have known the price was too good to be true. I now have NCR18650GA batteries on order ($5.10 each) from the company that made my 250 wH pack. I know these will be 10A, 3500 mah and designed to take deep discharge and used in many ebikes and cars. This dealer is also reliable. NEVER buy batteries from a VAPE shop, lol.

 

[sdcoffeeroaster]

I finally built my 125wH tec pack using 10 3400-3500 mah 10A rated batteries. The pack itself weighs 1lb 4 oz. I rode the bike today with the entire ride in ECO mode set to medium. I still had some power left in the battery at the end, voltage was about 34v when it recovered. I rode for 13.5 mile and 1503 feet of climbing in 1hr 39 min. The pac barely got warm. Not a hard ride but not an easy one either in ECO. I'm pretty happy with this light weigh emergency pack. I'm charging it now and will provide pics soon. I used the older wheels up enclosure this time but will now prep the smaller water bottle size for the this pac. This is my 2nd battery pack and hopefully my last for a long time. They are a real pain to build.

I've gone for a few rides with this new lighter pack. I've used it as a backup just in case my ride was longer than anticipated and also as my 1st battery to power the bike. In the later case I got about 11.3 miles and 1500 feet of climbing using mostly ECO but some trail mode. It did get warmer with the use of more trail mode but not hot. Probably only 110 deg F. It's lightweight and very convenient. It still have the 250 wH pack now in a bottle that just barely fits this adjustable cage and I've also gone on longer rides using just that. It's twice as heavy though but both packs reduce the number of charges to the main pack a lot. My main battery is still giving me a 40 mile range prediction in ECO set to medium so maybe it will last 5-10 years total. I'll probably have to replace the motor first, 5000 miles on the bike now.

 

[themoon]

I've also made a new version of a pack, but moved in a bit different direction - is has basically the same capacity as internal battery (20 * 5000 MAh 21700 cells).

Had to be really precise with dimensions this time, and in the end even shaved 1-2 mm from the bottom to clear the shock.

This baby now weights ~ 1900 grams, almost the same as the TEC pack... Just in my opinion not that ugly and more compact.

Nevermind the red electric tape on top, will replace it with some plug for a charging port later.

 

[sdcoffeeroaster]

I've also made a new version of a pack, but moved in a bit different direction - is has basically the same capacity as internal battery (20 * 5000 MAh 21700 cells).

Had to be really precise with dimensions this time, and in the end even shaved 1-2 mm from the bottom to clear the shock.

This baby now weights ~ 1900 grams, almost the same as the TEC pack... Just in my opinion not that ugly and more compact.

Nevermind the red electric tape on top, will replace it with some plug for a charging port later.

View attachment 59456

View attachment 59457

View attachment 59458

Cool. I assume the battery is custom to get it to fit inside that bottle. Too bad there isn't a compact cylindrical 10s2p battery available in that shape. The std hoverboard 10s2p batteries are all too wide for a smaller diameter water bottle size. I guess I could stack two of my 10s1p packs but running them in parallel can present some balance issues with uneven discharge and the inability to wire them up correctly. I thought about using those 21700 too but the volume was a bit large but I might still do one out of boredom, lol. My 250 wH bottle solution that barely fits my water bottle cage is a bit too wide and bulky looking and it might also interfere with my DVO shock when I get it. A 180wH version using the 21700 might work better. I have the tools now so might as well pick up some 21700's. With their 40%+ increased volume you really don't gain anything over using the 18650's. Someday they'll be improved battery chemistry and electrodes that might give us more capacity without the increased volume.

Did you buy the Testla cells or get those on AliExpress?

 

[themoon]

These are Liitokala cells, so yes, aliexpress basically. And I agree about the volume - however nothing else will fit in that shape with higher capacity...you either have to make something ugly like TEC or a smaller battery. I have limited space in my backpack, so carrying only one relatively compact battery was a must

 

[sdcoffeeroaster]

These are Liitokala cells, so yes, aliexpress basically. And I agree about the volume - however nothing else will fit in that shape with higher capacity...you either have to make something ugly like TEC or a smaller battery. I have limited space in my backpack, so carrying only one relatively compact battery was a must

One of the limitations of my design with 6 cells on the bottom and 4 on top, 3 wide by 2 length wise on bottom is that the width if using the 21700 Tesla cells will be at least 63 mm (3 diameters), a bit too wide for my pac bag. Currently I'm at about 54mm which fits with some space. The length will go from 1300mm to about 1400mm with the Tesla cells but I think I can fit that. Since my pack is about 2 diameters tall plus the BMS that puts that dimension at about 36+10mm now and with the Tesla 21700 cells about 42+10 mm so the Tesla pac would fit on the height.

After thinking about this I came up with a new configuration that can reduce that width by 3-4mm, nesting the cells along the width so they are less than 3 diameters. The pic is a mock up using the smaller 18650 cells. It also eliminates the difficult welding of cells end to end and I have just one 10gage wire joining the two 5 cell modules. I just ordered 10 of the 5000maH Testla Panasonic cells on ebay for $42. to build this new 180 wH pack. The hope is that I can squeeze it into the existing bag. I'm not so concerned about the increase weight. I'm getting 11-13 miles out of my 125 wH pack so this new one should be 16-19 miles. I've been able to run this 125 wH 10s1p pack on mostly ECO and more and more Trail mode now with full power and not too much heating, maybe 105 deg F at the most, pretty good for an enclosed pack and a 1-1.5 hr run time. The Tesla cells are 15A rated while the ones I'm currently using are 10A. So this existing water bottle carrier will allow fitment all 3 packs but the 250 wH pack is a pretty bulky looking bottle and I have some mods in mind to help it clear the DVO shock I have on order. But the 180 wH pack should be more than enough for my needs. I might even sell my 250 wH pack one day.

 

[themoon]

When I've done some calculations, it seemed that you can very easily make a small bottle with 10x teslas, which will clear basically any shock you want to use... why not go this route?

 

[sdcoffeeroaster]

When I've done some calculations, it seemed that you can very easily make a small bottle with 10x teslas, which will clear basically any shock you want to use... why not go this route?

That's basically what this will be but will fit that "tool bag" I'm using that fits a bottle cage. I don't want to go any taller than 2X length of the battery. The width of the BMS, unless you find a balancing round one, is a factor at about 55mm. Most std bottles I've come across are at best 64 mm id and will accept my 18650 pack but not the 21700 unless I try for a taller bottle and go with the 3X length. The bms still can mess up the overall size on a 10s1p pack. What configuration were you considering for the 21700 10s1p pack?

I can't seem to find that ZEFAL bottle you use in the US. Where did you buy it and what's the ID?

 

[themoon]

That's Zefal Z Box. As for the configuration, I think 5 in each row would fit without issues. Maybe 6 + 4... But actually it might be better just to measure and print the bottle yourself

 

[sdcoffeeroaster]

That's Zefal Z Box. As for the configuration, I think 5 in each row would fit without issues. Maybe 6 + 4... But actually it might be better just to measure and print the bottle yourself

The shorter version of this is about the same as my Profile Design tool bottle. While the two over 3 layout 2X fits with the bms in the 18650 size I don't think the 21700 would fit once you add the 10mm thick bms. My 2-1-2 layout 2X has a bit more room and may even fit the shorter bottle in the 21700 config. What are you Zefal dimensions, id and length. I found your larger one here: Zefal Z-Box L Black Large 643187014592 | eBay

I should get the 21700 Friday and will build up the pack this weekend. My 125 wH pack is really working out well for me. Today I rode a harder, longer ride for me, 2300 feet and 24 miles and used more trail and boost than normal so I was down to one red bar on the native pack so I just did the last couple of miles on the extender. But usually I just use the extender for the first 12 miles or so and then do the balance on the native pack since my rides are tending to be shorter lately (having a lot of saddle discomfort issues...sucks being 72!) at around the 15-16 mile range.

 

[themoon]

I actually used the large bottle as well. It has an extender, which you can just remove, to make it smaller, just for the size of 10 teslas. ID is about 70mm. Just checked, 6 + 4 configuration should fit without problems. On top, where there are 4, it should be enough space for bms as well

 

[sdcoffeeroaster]

I actually used the large bottle as well. It has an extender, which you can just remove, to make it smaller, just for the size of 10 teslas. ID is about 70mm. Just checked, 6 + 4 configuration should fit without problems. On top, where there are 4, it should be enough space for bms as well

View attachment 60070

View attachment 60071

View attachment 60072

 

[sdcoffeeroaster]

Looks like a few detents to get in the way in that bottle but maybe the photo is deceiving? The Profile Design bottle I have right now is 74mm od and only 66m id. Lots of room for the 18650 cells in my new configuration. It only has one external detent (for grabbing I assume) and fits perfectly in a normal water bottle cage.

I am tempted to buy a 3d printer of my own. I'm currently getting a friend to run my parts designed on Autocad Fusion.

 

[sdcoffeeroaster]

I just got the larger Zefal and it's exactly the same ID as the Profile Design. There is a slight internal lip on the first cap thread that could be trimmed on both of them if necessary. My 21700's are late so I'll post an addition to this message once they arrive to see how they fit either of these bottles.

Just received my Tesla 5000 mah hr batteries and testing them now which will take a couple of days. I just realized that with the BMS my config of 5 and 5 will not fit unless I can find a round BMS with balance. The configuration I plan to use will just barely fit the Zefal and Profile Design bottles not including the bms. It might be OK in some other configuration that is slimmer down one end for the BMS like the 6+4 maybe. The bottle is 66mm with the lip not 70mm. Cutting the lip might get it to 69mm. The 6x4 config is tight. The 4 cells would have to sandwich the bms between two cells on top and two on the bottom to barely fit. This is becoming a very tricky pack to build for sure.

I also see how you fitted a 250 wH pack into the longer Zefel bottle (7+7+6, like you told me, lol...had to trim the lip). I'm probably going to do one after I do the Tesla pack and will sell my entire 250 wH pack. It has about 12 rides or so on it and I'll sell the FullBattery pack, the soft bag, bracket, capacity gage and Rosenburger plug for it all ready to bolt up. Someone would just need to buy a $10-12. charger for it. I'm guessing around $150. for all it plus shipping when I get ready to sell. I am currently drowning in range extender packs, lol. I have 3 including the very weak Chinese one I built to test things out and the Tesla makes four. This is what happens when mechanical engineers retire too early, lol.

 

[sdcoffeeroaster]

OK here's my "final" pack, a potential 180 wH pack made from Model 3 Tesla batteries. They were a good price but as they sat on the shelf for the past year and they seem to be a bit low on output. A 5000 mah 21700 will usually test out at 4900 mah. These came in at 4700-4800 mah. When I initially charged this pack it took about 174 wH, not an absolute test and we'll see how it performs when I try it out on Monday. After I put Kapton tape and shrink tubing on my battery assembly (6+4 modules joined together) the pack still fit the bottle after I trimmed the lip but will not come out easily, so no final picture. But I did join the two sub-assemblies with the Kapton tape and pvc overall shrink tubing. want to try to force it out now since I can charge it place and it's just some of the lip still holding it in. I have foam on the top and bottom too. My 3 packs are 125 wh (0.173 wH/g), 180 (0.195 wH/g) and 250 wH (0.193 wH/g). This pack was a real pain to build and I think I'm done with building packs. Time to ride!

I rode with the Tesla pack today and went 17.1 miles and 1425 feet of climbing. It might have disconnected from a rough road and the way I have it clamped adds to the overall weight of the plug that could cause a momentum disconnect. I'll have to pay attention next ride but I was mostly ECO with maybe 15% Trail and 1% Boost. The battery didn't even get warm. I like these smaller packs a lot since they really keep me in ECO a lot more and I get a much better workout...and Trail/Boost are only a click away if needed.