Making your own tec pack?

[sdcoffeeroaster]

If i am understanding right, you dont even need a Rosenberger connector. You can solder on two wires under the Rosenberger plug in the Focus harness and bring them out where you want. Then just plug your extended battery on.
If i right the System recognizes the range extender an drains it first. I see no reason why this will not work. I am planning to build a 10s5p Extension with Samsung 35e . Maybe a switch like on the tec pack is needed addionally. Greetz

Yes I guess that's right but I still plan to use the Rosenberger plug since I found a source that will sell them in Germany and have ordered 5 of them. The price of 20 euros plus 16% VAT is not too bad but shipping was a bit high which is why I order 5 and they are slowly making their way to the US. I just don't want to mess with the wiring or put any extra access holes in the frame or side covers. I suppose there are ways to do that without damaging things but I just think it's cleaner with the Rosenberger plug if it can be purchased. I see now that Luna Cycles in the US has discontinued ordering that connector so it's fortunate I found a source, Powerbutler in Germany, willing to sell and ship them to the US.

 

[Daslevin]

Yes I guess that's right but I still plan to use the Rosenberger plug since I found a source that will sell them in Germany and have ordered 5 of them. The price of 20 euros plus 16% VAT is not too bad but shipping was a bit high which is why I order 5 and they are slowly making their way to the US. I just don't want to mess with the wiring or put any extra access holes in the frame or side covers. I suppose there are ways to do that without damaging things but I just think it's cleaner with the Rosenberger plug if it can be purchased. I see now that Luna Cycles in the US has discontinued ordering that connector so it's fortunate I found a source, Powerbutler in Germany, willing to sell and ship them to the US.

I am looking forward to see your setup running.

 

[sdcoffeeroaster]

I am looking forward to see your setup running.

Yes me too. Tracking shows it's still in Germany a week after shipping but it went from DHL to USPS so I expect I won't get an update until it's in the states. I just hope it's not on some slow boat, lol. I paid 40 euros for shipping 5 cables, lol!

I'll post updates when it's all here.

 

[BlushingCrow]

Also following along here. Only found one place in the UK for a potential November supply for the TEC pack and they are only taking prepaid orders up front.

Think I'm going to follow you guys with a DIY approach. I kinda like the idea of a smaller battery or two that I can just throw in the backpack.

Contemplating building my own pack... not sure how much I trust the ebay stuff is new branded rather than recycled cells. So I guess you guys are the guinea pigs!

 

[Daslevin]

I purchase my stuff in Germany from linergy. I dont ever buy stuff from ali. In my opinion you need at least 10s3p to handle the amps. Greetz

 

[sdcoffeeroaster]

I purchase my stuff in Germany from linergy. I dont ever buy stuff from ali. In my opinion you need at least 10s3p to handle the amps. Greetz

Yes we'll see how the DIY pack goes. There are examples of bottle range extenders of the 250 wH variety out there that have a similar number of batteries, 10s2p but obviously more capacity, 3500 mAh VS 2200 mAh. These packs are used in hoverboards all the time and the BMS they use is designed for higher current draw along with the batteries being the deep draw variety. They are NOT using the so called 8-9000 FAKE mAh hour batteries out of China that can't even keep up with a normal 2200 mAh 18650 battery. It remains to be seen how much range they will add and battery performance over time. Jaanos, another user here, built one and it seems to be working for him and like him I am not endorsing this but will report on mine.

Once I get mine built (Rosenberger plugs here this week) I'll be using it 2-3 times a week on all my rides and plan to monitor it's temperature during use as well as range and elevation, etc. Prices on these 158wH packs seems to vary a lot from $34. up to $70. so there may in fact be some quality issues with the one I'm using. I bought it on ebay not AliExpress and while I've had to resort to AliExpress once for an upgraded Novatec hub which worked out well, I don't normally buy things there. First time buying from Germany and that has proved to be much tougher than buying from anywhere else outside the US...shipping cost, etc. It's just the way global trade has been set up. I found it a lot easier to buy from GB for instance when I bought some Gorilla brake pads.

 

[BlushingCrow]

Yes we'll see how the DIY pack goes. There are examples of bottle range extenders of the 250 wH variety out there that have a similar number of batteries, 10s2p but obviously more capacity, 3500 mAh VS 2200 mAh. These packs are used in hoverboards all the time and the BMS they use is designed for higher current draw along with the batteries being the deep draw variety. They are NOT using the so called 8-9000 FAKE mAh hour batteries out of China that can't even keep up with a normal 2200 mAh 18650 battery. It remains to be seen how much range they will add and battery performance over time. Jaanos, another user here, built one and it seems to be working for him and like him I am not endorsing this but will report on mine.

Once I get mine built (Rosenberger plugs here this week) I'll be using it 2-3 times a week on all my rides and plan to monitor it's temperature during use as well as range and elevation, etc. Prices on these 158wH packs seems to vary a lot from $34. up to $70. so there may in fact be some quality issues with the one I'm using. I bought it on ebay not AliExpress and while I've had to resort to AliExpress once for an upgraded Novatec hub which worked out well, I don't normally buy things there. First time buying from Germany and that has proved to be much tougher than buying from anywhere else outside the US...shipping cost, etc. It's just the way global trade has been set up. I found it a lot easier to buy from GB for instance when I bought some Gorilla brake pads.

Yeah I did look at linergy but they seem incredibly expensive for battery packs but I didn't see any translate option for the site and refuse to install google translate for tinfoil hat reasons. So I am probably going DIY or ebay battery pack as well.

 

[sdcoffeeroaster]

Ok I received my Rosenberger plugs. Not 90 deg and didn't realize that but they will work. Once all hooked up plugging in the external battery turns on the display and it shows 5 bars. To turn the bike off you must disconnect the battery. Then restart normally to use the native battery. Not using any data lines so they are left open. Seems to behave as expected so I'll try it out in the morning to see how long it lasts and will report back. Here are a few pictures of what I've done so far. I think if I take the cost per connector into account I have about $110. invested with the charger. Total additional weight is 2 lbs. Hoping for 10+ miles and 1000 feet of climbing and that it doesn't get hot in the pack. I'll check that often and plan to instrument with a thermocouple one day if it even gets warm.

 

[BlushingCrow]

Ok I received my Rosenberger plugs. Not 90 deg and didn't realize that but they will work. Once all hooked up plugging in the external battery turns on the display and it shows 5 bars. To turn the bike off you must disconnect the battery. Then restart normally to use the native battery. Not using any data lines so they are left open. Seems to behave as expected so I'll try it out in the morning to see how long it lasts and will report back. Here are a few pictures of what I've done so far. I think if I take the cost per connector into account I have about $110. invested with the charger. Total additional weight is 2 lbs. Hoping for 10+ miles and 1000 feet of climbing and that it doesn't get hot in the pack. I'll check that often and plan to instrument with a thermocouple one day if it even gets warm.

View attachment 38885

That is looking awesome and, yeah, the non right angle probably works better in this scenario. I think we also have the exact same model bike as well.

 

[RCDallas]

I'd like some clever person to see if the internal battery with, I assume 18650 batteries, can be upgraded to the newer higher capacity 21700 batteries

I was looking into this a while back and unfortunately the layout of the cells and location of the bolts securing the battery to the frame is not conducive to using the larger cells. That's not to say it can't be done but would require some modifications to the frame I think.

 

[sdcoffeeroaster]

That is looking awesome and, yeah, the non right angle probably works better in this scenario. I think we also have the exact same model bike as well.

I rode today with the pack. The display reads 5 bars when the pack is plugged in but this is only the SOC of the main battery and will not change nor will it give you a warned when it's low. Good news the bike had no difference in torque and the battery did not get hot. The bad news is that when you buy a pack for $34. that everyone else is selling for $60. you get what you pay for. At 5.5 miles and 425 feet of climbing it abruptly ran out of juice on a steep uphill, lol. I don't think I pushed it very hard and used mostly eco and trail modes set to medium.

Upon returning home I charged it and monitored the w-hr it needed to fully charge. It did not want to charge to 42 volts which is where it started and it only took 67 W-hr to charge it up not even taking into account the efficiency of the charger (80%???). So this appears to be a 54 wH pack not 158 wH. Not sure if my numbers are right here but I have measured my regular battery during charging and with 1-2 bars left it consumes 300 w-hr or more. I know they don't run down to zero and in the case of the this pack and BMS it will run down to 26 volts. I'm not sure how low the regular battery goes when depleted. Anyone know? I finished my ride adding another 13.62 miles and 1609 feet of climbing using about 3 bars. It was not hot but it was very muggy and I had to work pretty hard today so using more trail mode than I normally do. This just seems like a weak battery pack to me and maybe the $60. variety will work better.

 

[Gspot]

You are old enough to know "you get what you pay for". Looks good though.
Nothing ventured nothing gained. Going to try to build a better one? Get a TEC
and have no worries.

 

[sdcoffeeroaster]

You are old enough to know "you get what you pay for". Looks good though.
Nothing ventured nothing gained. Going to try to build a better one? Get a TEC
and have no worries.

Yes I knew it was a $34. gamble, lol. Now I have to look around for something better. I don't mind paying $60. but not for the same thing. They all come from China, they all look the same and they all claim to have the same specs. Probably the only way to get a good battery is to build one yourself using the LG MJ1 3500 ma battery like Focus uses. At about $4. that's only $80. for 20 plus the BMS, welder and supplies to build. Then there's the expertise to necessary to not have them blow up in your face, lol. I sent a message to the seller of this battery but doubt I'll get much back. Since the pack itself weighs 950 g and if you deduct 50-100g for BMS/wiring/wrap you end up with 42.5-45g per cell, not unreasonable so they are probably legit cells of some sort.

Oh I charged the bike and with 2 bars left it took 245 W-hr on my ride today. That sounds pretty reasonable with 2 bars left. I just hit 2 bars so that' 60% of the 378 wh capacity. It's pretty obvious that this pack is not giving me 158 wH or I should have seen closer to 10 miles given the easier climbing I did with the extended pack.

Do you know if you can plug a TEC pack in AFTER you've depleted the main battery? My extended pack quit on a very steep uphill fire road today where I need to boost so it was very abrupt without warning. It would be better to be able to use it in reserve when you run out on a very long ride.

 

[Daslevin]

Hi, i found these bottle. You can configure it after your demands and it dont look ugly. Maybe i go with these. Neue Ankunft Mini Flasche eBike Batterie 36V 10,5 Ah 9Ah 7Ah für Bafang Motor | eBay

 

[sdcoffeeroaster]

Hi, i found these bottle. You can configure it after your demands and it dont look ugly. Maybe i go with these. Neue Ankunft Mini Flasche eBike Batterie 36V 10,5 Ah 9Ah 7Ah für Bafang Motor | eBay

Nice product. I don't see a Rosenberger cable available so you might have to make your own adapter. Not a solution for those of us in the USA but might be a good option Europeans.

 

[Gspot]

Yes I would use it as an emergency/lifeline. No you cannot run the internal flat. I usually start with the
TEC. Did a three hour BOOST ride today I guess you could remove it after it dies but I just leave it.
Should have brought my new pack. Will have to see how it is carrying the weight on my back.

 

[sdcoffeeroaster]

Yes I would use it as an emergency/lifeline. No you cannot run the internal flat. I usually start with the
TEC. Did a three hour BOOST ride today I guess you could remove it after it dies but I just leave it.
Should have brought my new pack. Will have to see how it is carrying the weight on my back.

So what if you ran the internal down to the last bar and then plugged in the TEC pac. Does that work? Are you saying that if the internal is totally dead, plugging in the TEC pack doesn't work? Maybe that justmeans you must have some small amount of power available from the TEC pack to start up the external.

 

[Gspot]

Pretty sure that is what I have heard. Haven't actually done it. Try not to run any battery flat.
But yes I believe you must have some power internal to use the TEC.

Maybe that justmeans you must have some small amount of power available from the TEC pack to start up the external.

I think you mean internal to start the TEC.

 

[sdcoffeeroaster]

Pretty sure that is what I have heard. Haven't actually done it. Try not to run any battery flat.
But yes I believe you must have some power internal to use the TEC.

I think you mean internal to start the TEC.

Thanks yes that's what I meant.

 

[sdcoffeeroaster]

You are old enough to know "you get what you pay for". Looks good though.
Nothing ventured nothing gained. Going to try to build a better one? Get a TEC
and have no worries.

So here we go again, lol. I think the ebay company is going to replace the pack. As long as I don't have to ship the old one back I'm OK with that. In the mean time I've been looking around, (shudder) Aliexpress. I found a pack that uses the Panasonic ncr 18650B which is not Chinese but is made in Korea. It's also rated at 7.0 A because of the 3500 mah Panasonic cells. It's inexpensive too at about $40. with shipping. The concern is that these cells are only rated at 5 A continuous instead of 10A like the std LG cells.

But I got to thinking that there are two strings of 10 cells each so each string can go to 5A or 10A total max. At a 10A burn rate our native battery would be exhausted in about an hour. So that's pretty hard riding boost all the time I imagine. My rides last 2 hrs or more and I've only once run the battery down all the way. The downside if you draw too much (5A or more from the cell) is that it will overheat on you which is why the 10A cells are better. More margin. My pack was not even warm after it's short 5.5 mile ride today.

I also found another one that is 6A for about the same price and it says it's rated at 10A. I am inclined to try that one rated for 7A since that is about 252 wH overall and should be good for 20 miles. Same size as what I have now too.

 

[Gspot]

Try the 7A. I was looking back through the topic at the German diagram? The Focus system is unique.
The TEC plugs into the same port as the charger. This is different than the twincore. So does the TEC
flow through the internal? How does the internal differentiate between the TEC and the charger? Guess
I should go to engineering school.

 

[sdcoffeeroaster]

Try the 7A. I was looking back through the topic at the German diagram? The Focus system is unique.
The TEC plugs into the same port as the charger. This is different than the twincore. So does the TEC
flow through the internal? How does the internal differentiate between the TEC and the charger? Guess
I should go to engineering school.

Make sure it's electrical engineering. I'm a retired mechanical engineer and while it helps, having an electrical degree might be better. Battery technology is a specialty too so even an EE might need to do a lot of research and there just isn't much info out there. I do think there are diodes in play when you plug in a battery rather than the charger. That Rosenberger plug has some data lines that might tell the bike it's on a charger rather than a battery (all data lines open). And since we're not using those data lines (don't know how) the bike really doesn't know the state of charge of the battery. I did think it would be looking at voltage and as it goes down just used up the bars like the normal battery but it didn't. It stayed at 5 bars the whole time until it quit. I'm assuming the display properly reads the TEC pack SOC. I know the TEC pack also has it's own small charge indicator so that might not be true.

 

[sdcoffeeroaster]

After looking around at videos showing batteries like mine with leaky and old cells used to fill half of the pack I think I might be willing to spend a lot more on a good pack. Check out the hover board pack at fullbatery.com. Yes it’s expensive but 248 why and high end cells and made in the USA and safe. $119.

 

[Tooks]

I’ve been following this with interest, as I also have 2 home brew e-bikes running TSDZ2 mid-drive motors.

I use 2 x 5s 5000 mAh RC Lipo batteries connected in series to make a 36-42v pack, they use XT-60 connectors as well and a Y lead. I use those as my experience with the cheap 18650 cells is that capacity is never anywhere near what they say. The RC batteries use pouch cells, and brands like Turnigy or Zippy always meet their capacity and have minimum 20c discharge capabilities. You can pick up quality batteries for about £40/$50 each, so about $100 the pair or maybe even less.

Using a pair of those on one of my conversions, I get a 5Ah battery and about 10 miles of range. The packs are quite small, so it’s no trouble to carry two more and get another 10 miles etc. I think they’d work well on your Focus, I’d use them myself but I’ve already got a TEC Pack.

 

[sdcoffeeroaster]

I’ve been following this with interest, as I also have 2 home brew e-bikes running TSDZ2 mid-drive motors.

I use 2 x 5s 5000 mAh RC Lipo batteries connected in series to make a 36-42v pack, they use XT-60 connectors as well and a Y lead.

The 5000 mAh versions go for about $62. here in the states. I can get that battery from fullbattery for $129., made in the USA, using high quality batteries and 249 wh which should give me an extended range of at least 20 miles based on what I get out of the std pack. I guess you get what you pay for, lol. The vendor of this $34. pack is sending out a replacement for free and I don't have to send this one back. I plan to cut it open today to see if it really using all 20 cells or if 10 are weak cells and 10 are dead and not even wired up like the one I saw on youtube. It acts that way and only seems to have 1/3 of it's rated capacity. Just so many scams from China these days and this in NOT the first time I've been suckered, lol. Bought a doorbell camera on Facebook that turned out to be just a very cheap doorbell and would have cost more to send it back to China than it was worth and then probably not getting a refund. Classic bait and switch. Buyer beware so I don't think I'll buy another battery from China again.

 

[sdcoffeeroaster]

I tried my range extender again today and rode 10.5 mile and 1366 feet of climbing!!! So what happened, lol? Once it cools off (temp is 103F) I'll charge it and see what it takes this time. Warmer today and I didn't use boost. It quit last time on boost on a very steep uphill. I did 3X in climbing and 2X in miles today and this is really about what I expected. I just don't understand unless using and charging the pack a few times improved it? Anybody have a thought. I'll update this post later with what it took to charge. I'm guessing closer to 158 wh this time.

 

[Daslevin]

Yeah the cells may improve capacity after charging it a few times. Nice to hear. Looks like your system work fine. I had broke my ellbow last week so my projekt have to wait... ?

 

[sdcoffeeroaster]

Yeah the cells may improve capacity after charging it a few times. Nice to hear. Looks like your system work fine. I had broke my ellbow last week so my projekt have to wait... ?

Sorry to hear that. I've had some bone breaking crashes too. Collar bone/2 ribs/should blade all in one crash and then frozen shoulder. Later I landed on my elbow, no pads that day, and it still hurts and lumpy...maybe bursa swelling not sure. It comes and goes.

So I found this in an article about li ion batteries that supports that maybe using boost really hard up a steep slope is what made it quit so early the first time:

Power tools and medical devices drawing high current tend to push the battery voltage to an early cut-off prematurely. This is especially apparent at cold temperatures and in cells with high internal resistance. These batteries may still have ample capacity left after the cutoff; discharging them with a battery analyzer at a moderate load will often give a residual capacity of 30 percent.

 

[sdcoffeeroaster]

Now that I've got some reasonable mileage out of that cheap battery (with another free one on the way from that vendor) I decided to buy the one from Fullbattery for $129. It uses the Sanyo 18650GA cells made in Japan. It is assembled in the USA and should give me 15-20 miles. The goal is to not run it down to zero (shortens life) and also not run the main battery so hard so that it lasts a long time. I don't think the cheap Chinese batteries will be reliable enough or have enough range so I decided to buy quality and stop guessing. Buying a Chinese battery claiming to have 3500 mah batteries while only costing $25.-40. has got to be a scam. 20 very high quality batteries should almost cost $100. alone so the $20-40. price tag tells me these are scams. Too easy for them to hide what is inside the pack with the shrink wrap.

This 2 lb packs overall price has gone up a bit from $110. to about $212 because the new battery is $147. with shipping and tax, but well worth it compared to a heavy TEC pack at $650.

2nd ride today netted 10.6 miles and 1335 feet of climbing. So I think the Chinese pack could be used safely for 9 miles then swap it out before it quits on a hill. Better not to run it flat every time but at $34. not a big deal. I noticed my bag is slightly rubbing the external reservoir on the DVO shock. My bracket brought it just a bit too close I guess. I could either move the assembly up a bit or just go back to the Fox shock which wasn't all that bad. I could then move my battery even lower giving me a lower cg. I'll probably do the later when I get the bigger battery and build up an entirely new pack.

I was able to lower the battery a couple of inches with the Fox shock. Now we'll see if I tell any differnce between that and DVO or if I miss the DVO. I never could get it to use full travel with my weight.

 

[sdcoffeeroaster]

I just received the Chinese made replacement battery and will test it out tomorrow. My 3rd ride with the first battery confirmed that if you've run the battery down a bit and then used boost for too long it will cut out very early. I was at the end of a very steep section of switchbacks when I did this and the battery quit working at 7.5 miles and only 550 feet of climbing. I'll see if the replacement does the same. I am still waiting to hear back from the USA made 7A version of this battery pack using the 18650GA Sanyo battery. They have not shipped it yet and also have not even sent any update other than the automated order acceptance. So for now it appears I can at least get 10 miles out of my battery pack and at least 1000 feet of climbing if I avoid anything but a momentary use of boost. It's possible that some of the more powerful inexpensive ones I saw at aliexpress might work much better but I'm just reluctant to to be a sucker again and risk another $40.!

I do have one or two of those Rosenberger straight cables available for $40. with shipping (my cost only), US only, if anyone is interested in building a pack for themselves for their Focus.