Noobie planning an Electric bike with >30 mph

[macribs]

Lastly, if you must build your battery pack look at the headways. They are designed to be connected via a system of connectors without doing any welding or wiring. They offer formed plastic holders to make a variety of pack sizes. To me, this is actually in the range of a DIYer without having to start buying spot welders and such.

You can do the same with 18650 cell brackets and metal strips, don't you?

Google image search
http://tinyurl.com/qaa8nk9

But how will one get them 18650 packs to work correctly with a BMS and bulk charger? It seems those brackets are good for making cells and packs.
And top off with them nickel sheet strips to connect them together. A BMS will need to be hooked up to each and every piece of battery to do a correct balancing, yes?

Or could the BMS be hooked up to each cell only rather then each battery and still function properly?

 

[macribs]

Interesting thread; I've been following this awhile.

Lastly, if you must build your battery pack look at the headways. They are designed to be connected via a system of connectors without doing any welding or wiring. They offer formed plastic holders to make a variety of pack sizes. To me, this is actually in the range of a DIYer without having to start buying spot welders and such.

You can do the same with 18650 cell brackets and metal strips, don't you?

Google image search
http://tinyurl.com/qaa8nk9

You still need to spot weld the 18650s. The Headways screw together.

Maybe not if you look at this clever strips:
http://www.aliexpress.com/item/lithium-battery-connection-nickel-sheet-18650-cell-nickel-strip-Wholesale-and-retail/1316845801.html?

And there are various types of strips to choose from. As long as one can find a way to get a BMS to work properly with cells and packs like that maybe spotwelding is not needed? It seems them metal strips connects to each battery. Doing the work. Maybe there are strips for both parallel and series hook up?

 

[windtrader]

The link shows the raw connector. It is just a building block part. Once you cut and fit the connector you then need to spot weld at each connection. The picture shows them before any spot welding. Welding is needed with18650 so not a preferred DIY path.
Headway batteries solve the tab spot welding but all the other aspects of battery design are in play and need to be addressed adequately .

 

[999zip999]

Yes need to be spot welded to work on a bouncing and working ebike going down the road.

 

[molybdenum]

Maybe not if you look at this clever strips:
http://www.aliexpress.com/item/lithium- ... 45801.html?

Looking at the linked page, It seems these nickel strips are meant to be spot welded, as you can see from the pattern of 4 dots above the battery terminals in the image I took from their website:

Some forum members are experimenting with solderless/weldless systems which rely on the even compaction of plates onto the cells, for example: https://www.endless-sphere.com/forums/viewtopic.php?f=14&t=60517&hilit=Solderless The trick is to have very good contact to all cells for high amperage systems (spring loaded cartridges aren't enough).

I have yet to see a workable commercially available solderless/weldless system (other than Headway) and soldering directly on the naked battery terminals is very tricky, so most people building with new 18650 cells opt to buy or build a spot welder. Alternatively, you can often order cells pre-spot welded into parallel groups, thereby simplifying the battery build. Soldering on top of the spotwelded nickel tabs is very easy and many forum members have soldered wire or bus bar onto nickel tabs pre-spotwelded by the supplier - or even soldered onto the folded nickel tabs deliberately left on 18650 cells recycled from high discharge powertool battery packs.

 

[999zip999]

Macribs you started this july 22. Do you know what build you going to do yet ?

 

[chriss]

Would soldering work equally well as spot welding? That seems more doable to me.

@mac, yes there are single line strips available just as there are plates for custom cutting

http://www.aliexpress.com/item/Free-shipping-18650-battery-connection-nickel-plate-Cylindrical-lithium-ion-cells-nickel-strip-Wholesale-and-retail/1316876105.html

http://www.aliexpress.com/item/Universal-battery-nickel-piece-18650-battery-spot-welding-special-nickel-belt-nickel-plated-steel-strips-0/853673548.html

But how will one get them 18650 packs to work correctly with a BMS and bulk charger? It seems those brackets are good for making cells and packs.
And top off with them nickel sheet strips to connect them together. A BMS will need to be hooked up to each and every piece of battery to do a correct balancing, yes?
Or could the BMS be hooked up to each cell only rather then each battery and still function properly?

Yes, that is what I'm struggling with as well. Say I get these cell brackets and solder my batteries with nickel strips to the appropriate form and pack size. Next I would need connectors for each cell (right?) that will later be hooked up to a BMS. Do these connectors have a specfic name to look for? Are there different connectors for lipo /lico / lifepo batteries? Can I simply solder them on top of each cell/strip?

 

[macribs]

Macribs you started this july 22. Do you know what build you going to do yet ?

Nope. Can't say that I do

Every time I seem to gain some understanding on one part of the build, it seems the choices made for parts in different places of the build will interfere in some way or another. So it will not be enough for me to learn a little about batteries, controllers and a little about motor choices. I need to learn a lot on each part of the build that will impact other areas or the whole build will just be a chances games, like slot machines. Yep I might get lucky but chances for the jackpot is slim.

So I need to educate myself even more before deciding any more details. And as these matters has a high learning curve for me, as it is all new stuff. The learning part it just
takes up so much time. And fitting all that into a normal schedule with family life, work, kids and whatever else life throws at you, well it is a much bigger task then I first imagined when I first posted here.

But I will try to keep up the spirit, motivation and keep reading and grasp a better understanding of things/parts and how they interact together in the best possible way.
Then I will be able to start to take things to the next level.

 

[chriss]

Can anyone tell me what kind of cable/adaptor this is? I noticed that it may be cheaper to purchase battery packs that were designed for applications other than ebikes. Obviously, I would need to add several of those in series and parallel to achieve the desired battery capacity and voltage. Just not sure how to proceed if the pack comes with an adaptor like this. Would I need to open the battery pack and remove the adaptor in order to work with the standard plus/minus poles?

 

[macribs]

Don't know that battery or that cable. But for sure there is at the least a plus and a minus cable. So just to connect that pack to other packs you could just cut the wire in front of that unknown connector. Then you could hook up with more packs. But that will just get you battery pack of your own choice in volt and Ah. How will you take care of your pack, regarding overcharge, balanced charge etc? Seems like you need a BMS anyway. And that might lead you to be forced to open those packs to get all the wiring needed for BMS.


If you are lucky when cutting into that cable there might even be additional wires in there for a BMS.

 

[chriss]

How will you take care of your pack, regarding overcharge, balanced charge etc? Seems like you need a BMS anyway. And that might lead you to be forced to open those packs to get all the wiring needed for BMS.

Many of these small battery packs come with a PCB, so the single pack is "protected" for overcharge. I was thinking there might be a way to hook each pack to a BMS rather than each cell in a pack.

I'm also looking into Sony Konion cells that are said to be drift free and wouldn't need a BMS at all. But they are expensive.

 

[chriss]

Go BMS! It is money very well spent.

What you want, as a minimum is:
* individual cell low and high voltage protection.
* overcharge protection
* over-discharge protection
* balancing function (bleed-type is ok)

OK, but why the need for a BMS AND protection at the individual cell level. Seems to me that there is a redundant layer of protection here: A curcuit board attached to each cell and then another larger curcuit board to protect a bunch of cells.

Can I safely charge and discharge unprotected lico cells using a balancer (safe charging) and a BMS (safe discharging)?

I noticed that high discharge 18650 cells (5C+) are usually unprotected. So there is another compromise to be made here. Either chosse batteries with desirable characteristics or choose an extra level of protection (which may not be needed?).

 

[999zip999]

Yes one cell dosn't need ( 4.2v ) in series a bms is advised or 2p to xxp is best to have a bms. Just get a battery for an ebike. It's a good and ez working pack. Cheap can cost alot more money.

 

[macribs]

Chriss is you like to pursue the option for cheap batteries you might wanna take a look at this thread, they will even custom build a pack for you to your spec and size requirements. Batteries comes with BMS and prices are very nice. They use good brands batteries like Sony, Samsung25R and a123 pouch batteries.
Then you will receive batteries ready made, spot welded, BMS integrated and all heat wrapped and ready to mount.

http://endless-sphere.com/forums/viewtopic.php?f=31&t=59628

 

[chriss]

@mac, thanks will check it out.

 

[MadRhino]

OK, but why the need for a BMS AND protection at the individual cell level. Seems to me that there is a redundant layer of protection here: A curcuit board attached to each cell and then another larger curcuit board to protect a bunch of cells.

Can I safely charge and discharge unprotected lico cells using a balancer (safe charging) and a BMS (safe discharging)?

I noticed that high discharge 18650 cells (5C+) are usually unprotected. So there is another compromise to be made here. Either chosse batteries with desirable characteristics or choose an extra level of protection (which may not be needed?).

Of course you can. You can be your own BMS, that is what many of us are doing. You just need to know your batteries and monitor them yourself. If you are not the distracted type and can be conscious of your cells at all time, you can do better than a BMS (that Luke liked to call "Battery Murdering System").