Noob Questions

Hey everyone, so I feel like I've done as much research as I can on this forum and the google in general but I'm still bugging out on something I feel should be fairly simple.

I would like to connect a bunch of 18650 Li-ion 4200 mAh Ultrafire batteries 12S4P. That should amount to 48V and 16.8 Ah. I found a nifty BMS module, controller, charger and 48V 1000W motor.
My questions:
1) How the hell do I connect all of the above?
2) Do I need a seperate BMS module for each string of batteries? i.e., I should have 4 individual BMS modules, each connected to 12 batteries. Kinda just looking for confirmation on that.

I have the links to the parts that I'm using below.
BMS:
http://www.ebay.com/itm/321108395908?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Charger:
http://www.ebay.com/itm/221368329225?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Motor/Controller:
http://www.ebay.com/itm/200936205559?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Any help would be really appreciated. I'm really struggling to figure out what I need to be doing, and in what order these guys go together, and if I have selected components that are even suited for each other. Thanks!

You can wire the "4P" batteries together first, and then series them into 12S. Each "4P" bunch will act as one "16.8"Ah cell.
(FYI, Ultrafire greatly exaggerates their capacities. You'll likely only get ~2.5Ah from each cell or about 10Ah in 4P, and you will have problems with discharge rate higher than ~10-15 Amps, and your battery will die pretty quick.)
I would recommend trying to source some high-power cells like the Samsung 25R for your application, or better yet, just get a plug & play battery from Em3ev.com

teslanv said:

You can wire the "4P" batteries together first, and then series them into 12S. Each "4P" bunch will act as one "16.8"Ah cell.
(FYI, Ultrafire greatly exaggerates their capacities. You'll likely only get ~2.5Ah from each cell or about 10Ah in 4P, and you will have problems with discharge rate higher than ~10-15 Amps, and your battery will die pretty quick.)
I would recommend trying to source some high-power cells like the Samsung 25R for your application, or better yet, just get a plug & play battery from Em3ev.com

Click to expand...

Ditto on what he said. Why over stated and rated. they take the left overs from the rejects and put new shrink on them.

You want a mid drive? Get a Bafang, much better and much easier to assemble. Cost much more but a much better system

the BMS was a 13s not 12s, not sure if you can leae the last channel open.

Don't buy the cheapest thing you see without researching and/or asking.
You will pay more by the time you get the first build done if you don't!
Ask that and see what most say.

Dan

teslanv said:

You can wire the "4P" batteries together first, and then series them into 12S. Each "4P" bunch will act as one "16.8"Ah cell.
(FYI, Ultrafire greatly exaggerates their capacities. You'll likely only get ~2.5Ah from each cell or about 10Ah in 4P, and you will have problems with discharge rate higher than ~10-15 Amps, and your battery will die pretty quick.)
I would recommend trying to source some high-power cells like the Samsung 25R for your application, or better yet, just get a plug & play battery from Em3ev.com

Click to expand...

Ditto on what he said. Way over stated and rated. they take the left overs from the rejects and put new shrink on them.

You want a mid drive? Get a Bafang, much better and much easier to assemble. Cost much more but a much better system

the BMS was a 13s not 12s, not sure if you can leae the last channel open.

Don't buy the cheapest thing you see without researching and/or asking.
You will pay more by the time you get the first build done if you don't!
Ask that and see what most say.

Dan

You're right, it's a 13S, I had gotten it before I realized 13S didn't make sense with the way I was planning on organizing my battery packs. They have a 12S model as well. And I also read that about Ultrafire recently, but I'll at the very least use the batteries I have to test my project out, and long term I'll definitely look into sourcing some higher quality batteries.

But besides those issues, I was still wondering about my other questions. Sure I could go the 4P12S route, but isn't the cell balancing less effective if the BMS is trying to balance multiple cells at once? Any one of the 4P batteries could be imbalanced.

Additionally, I'm still confused on how I would even go about connecting my BMS to the what, controller? motor? That's my main issue here

better to stay away from Ultrafire, except to operate flashlights and similar ....
they are mixed rejects, recycled , improperly stored, plain insanely old crap.
When asked for current, often they vent ...
I bought few, did some test, ouch

have fun!

Haha okay I'll definitely take your word for it.

Any advice on the other topics?

asifpow said:

Haha okay I'll definitely take your word for it.

Any advice on the other topics?

Click to expand...

If you stay below 45A , 1piece of that bms will suffice. charger could be ok
motor kit is possibly requiring a lot of effort to be mounted properly. why not an hub?
you need proper battery ...

have fun!

If you have the cells, ok. How are you planning on connecting them?
You might ask the seller if the 13s li-ion bms will do just 12 or do you need a 12s one. Most 12s BMS are for LiFePo4 cells.

When you put the cells into a p group the sells are mow ONE. If there is a weak one it pulls them all down. Before you parallel them they should be tested and rated before so. 1 bad cell destroys all in that group

You can get a complete rear hub or frt for less than 300 on Ebay or Amazon. Much easier and more reliable.

The charger will work if you have a BMS. Other wise you need an adjustable one to match pack voltage, to not destroy or burn they up.

Dan

Thanks DAND214 for your advice. Yeah I emailed the seller earlier today, but he (and others) also sell 12S BMS that I'm considering getting. I think I'm set for the mid-drive motor because it's better for up hill and I'm planning on making the bike a fixie. So I think that would be an effective combination, and I'm packing my batteries onto the front tube so I'd like to reduce my cable length by keeping the motor close.

My next question... where does the controller come into play? Do I connect the controller to the BMS and connect the motor to the controller? How does that work and what purpose is my controller serving?

If you go with a bafang mid drive, they integrate the controller into the motor itself. Bad for heat dissapation, but good for noob installs.

I've had the BBS02 for almost 8 months and 1000+ miles, and still loving it.

http://endless-sphere.com/forums/viewtopic.php?f=6&t=56512

Battery connects to the controller, controller to the motor. throttle connects to the controller for your speed adjustment.

Good luck on your build.

Not my choice for the mid drive or the batteries.

You still didn't say how you will connect the cells togeather. Tab weld, solder. The later will make the cells look even worse in AH, do to the heat used to connect them.

Dan

I have a friend with equipment to tab weld my batteries together. You're right, the Ultrafires were a poorly informed choice, but I'm looking into getting fresh and reliable batteries from a reputable distributor. It's more important for me to have a consistently reliable approach, because I'd like to have a formula down for building these bikes and then build a couple for my friends. Also, heat dissipation is why I wouldn't want a Bafang mid drive, at least not for this project. Since it's a 1000W motor I think it'll be generating too much heat on its own for an integrated controller. So I'm planning on housing that elsewhere.

So if the battery connects to the controller, where does the BMS only connect to the batteries? And when you say connect, based on the components that I found, I'm going to have to solder most of these parts together right? The BMS indicates little P and B terminals, but I'm not sure what part of the controller I'm supposed to solder to those terminals.

How did you guys pick up on little nuances like precisely how to go about connecting each of these devices? It's been a struggle finding resources not only on how these devices work, but how they work together as a system.

Lots of reading on ES. And YouTube. And broken parts that got fried from hooking up incorrectly

What the Ebay said was, a 1000w controller.
I have 4 Macs a couple Bafangs, BMC and a Q128.

All are rated under 1000watts. But if I reprogram my controller I can exceed that 1000w even more than 3000 watts. Non will lastvery long.
The mid drive you are seeking is a direct drive, with not gear variables. So by going single speed or as you said Fixie, you will be working that motor more than the Bafang mid drive 750. Also killing your batteries in short order.

As for how does the BMS come into play. It becomes part of the battery, not a seperate piece. The batteries power channele thru the BMS in both directions. Being charged or being discharged is thru the BMS. hERE IS A ROUGH WIRING DIA OF A bms. http://www.bmsbattery.com/smart/330-lifepo4lithium-ion-smart-bms-for-513-cells-in-series.html Click on the files to see how they are wired. Like I said it's just a rough idea. Ask the supplier where you decide to get on for a DIAGRAM.

Dan

do not connect them in parallel first like all the dittoes above.

the battery current flows in series, not in parallel. you only connect them in parallel so they can balance together under the BMS.

so use the large conductor for the serial connection and then after all four rows of 13S are built and connected you can go back and wire the individual cells together in parallel with very small wire, around 26AWG.

do not solder to the middle of the case on the bottom. use only a conductor large enuff to handle the serial current which is gonna be about 10A max worst case so you can even make the serial connections from 18-16AWG wire. four in parallel will carry 40A.

solder to the edge of the bottom of the case to reduce the damage from heating caused by soldering and you need to pretin both the spot on the edge at the bottom of the case where you solder the link and pretin the wire, then solder them together quickly and as soon as the solder reflows, remove the soldering iron and use the wet sponge applied immediately to the hot solder to soak up the heat as fast as possible.

the other end of the serial link to the anode nipple needs to be pretinned also and it can be soldered directly to the center of the anode, and then hit it with the sponge to cool it off.

then when all 4 rows are soldered together you can solder the 26AWG parallel link to the conductors in the space between the cells, away from the spots where it is soldered to the cans. do not solder the parallel link onto the top of the anode spot or to the spot on the edge of the can at the base. solder the parallel link in the middle of that serial link for each channel.

Thanks guys, you've really answered a lot of my questions.

Now, I was wondering, presuming I'm able to connect my batteries into a 12S configuration, I would like to connect 3-4 packs of 12S batteries together. Now I believe that I'll need 1 12S BMS for each set of 12 batteries. In this case, do I wire all 3-4 BMS together and have the last one connect directly to the controller and charger? How would I go about doing this?

Thanks again for the help!

you only need one BMS once the 4 rows are connected together in parallel. each channel is wired in parallel at that point so you need only one sense wire going to each node in the series.

Can you post a link to the specific packs you want to build your battery with?
I have a hunch you may want to parallel connect the smaller packs first, and then in series, and as dnmun advised, only one BMS will be necessary.