18650 battery holder

[leamcorp]

I've just started building my pack - took longer than imagine.

As mentioned, I've decided to go in completely different direction - a holder that could be taken apart in few minutes to troubleshoot, replace a bad cell, add/delete capacity and allow for easy wiring. My pack is still not finished but this is where I'm at,

It all start with these building block. The block will house the copper strips and plastic wall.


Here's the 1st module. To protect the battery, I've put foam cushioning material on all inside walls. The holes on the side are to align the next modules. The white piece in the middle is spacer that holds the copper strip. Since these strips are long, they tend to flex - this will hold them tight.
View attachment 5

Here's one with A123 batteries - this is a 7 cell parallel pack. I'm building 16s 7p for one of my bike.
View attachment 4

This should make it more clear. This is just one configuration. I was going to go up to 8 modules x 2 but I may change that to fit my rear basket. The flexibility to make any size and shape is what took so long.


Here's close up of the connection between parallel pack. I've only done one and this one uses a 1/2" x 1/16" copper strip. I may go with 4 gauge copper strands instead. The long strips are 3/4" 1/16" pure copper strip - more than enough for any volt/amp.


Here's frontal view - you could put holes anywhere on the strip for addition connection/junction point.


What started all - I'm also making 18650 pack but thats taking a backseat until my A123 pack is done.


Once my pack is finished, I'm going to cover it with plastic sheeting - so that it looks like a box instead of a bomb. One other thing I'm also doing is to make a separate box for LVC/BMS board and wiring.

 

[leamcorp]

I forgot. I've talked to Batteryspace.com and they told me that their 60amp BMS will work with A123. Not to bad at $119 but they don't have it yet. Waiting for shipment from China?

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4941

 

[joe tomten]

Ok, it's a sketchy idea but the 18650's are potentially quite cost effective (leaving aside bms issues for the time being)

The black plastic 3/4" (19mm) water line i use for garden water supply would nicely hold the 18650 cells in a series tube. Five cells per tube gives 325 mm (~12.5") length and 14.5Vnom..

I'm looking to run at 48 - 60 volts so I'd need to series these series by 3 or 4 times, and parallel those up by 10 or 7 strings to get my ~500 watt hour target.

I wonder if there is a relatively simple way to use these as the series containers and then deal with the paralleling in another manner.

I'll continue studying this and other threads.

Any input welcome.

Joe

 

[pwbset]

The problem with that is that it's better to wire parallel first then series... though VRDubLove is doing series first in his tube build (try not to scream when the face pops up.. haha) and doesn't seem to have had any issues so far. I was contemplating using much wider diameter tubes cut into <3" chunks and putting like 6-8 18650s in parallel in those and the series... my current solution is to just do individual tubes.. the advantage is that I can create any combination of series/parallel I want and easily replace any cells that are dying... disadvantage is that it's taking me forever to complete this project and it's going to be heavy. The 98 cells should give me right around 500wh though and fit clean in my triangle.

Do you have a link or can you post a photo of your garden hose material? I wonder if it's lighter that the schedule 80 PVC I'm using. Thanks!

'Bout half way down my ride thread you'll see what I'm taking about... I actually only have one more row to complete tonight then I can build the sides and top and be done finally and get riding!!

http://endless-sphere.com/forums/viewtopic.php?f=6&t=9691&p=161448

 

[joe tomten]

pwbset,

I'm thinking of the black plastic pipe you buy in 100 and 300' rolls at any home depot/plumbing supply store. Wall thickness is like a sixteenth. Rigid when cold, more pliable after sitting in the sun, you don't want it much above 212degF.

I'm starting to understand the requirement for parallel first and then series connections. I need to study the design in your link a bit.

My thinking was to have 4 to 5 cells in a row and the bundling of the 10 to 12inch tubes together would give the (battery lateral) structural support needed.

Still learning about the bms / balancing issue.

4 cells in a tube - 13.2 volts nom. ~ 8" length.
5 cells in atube - 16.5 volts. nom. ~10"

 

[MitchJi]

Hi,

The black plastic 3/4" (19mm) water line i use for garden water supply would nicely hold the 18650 cells in a series tube. Five cells per tube gives 325 mm (~12.5") length and 14.5Vnom..

I'm looking to run at 48 - 60 volts so I'd need to series these series by 3 or 4 times, and parallel those up by 10 or 7 strings to get my ~500 watt hour target.

I wonder if there is a relatively simple way to use these as the series containers and then deal with the paralleling in another manner.

You will have a problem with balancing. For 48v you need about 16s. If (for example) you have groups of 6 parallel cells and then connect them serially for 16s even though you have 96 cells you only need to balance the 16 parallel groups of cells (16 channel BMS). If on other hand you have 16s tubes and connect 6 tubes in parallel you need to balance 96 cells (96 channel BMS ).

my current solution is to just do individual tubes.. the advantage is that I can create any combination of series/parallel I want and easily replace any cells that are dying... disadvantage is that it's taking me forever to complete this project and it's going to be heavy. The 98 cells should give me right around 500wh though and fit clean in my triangle.

'Bout half way down my ride thread you'll see what I'm taking about... I actually only have one more row to complete tonight then I can build the sides and top and be done finally and get riding!!

Two issues. Heavy and there doesn't seem to be any way for heat to dissipate. Have you considered a couple of sheets of some sort of plastic (something like a 1/4" thick), with a bunch of holes (like swiss cheese) mounted on risers to locate the cells? I think the risers would need to be a little higher than the spring length.

 

[pwbset]

there doesn't seem to be any way for heat to dissipate.

Hi Mitch! Heavy is going to be kinda sucky... thinking it's going to be about 20-25lbs all up... we'll see. I'll let you know... the weight will be well balanced in the triangle frame at least, but that is 10lbs heavier than last year's Milwaukee 6-pack, but I'll be gaining about 50-60wh and be able to deliver much more power.

I gave careful consideration to heat and I'm not worried in the slightest about it because the max I'll be bursting this pack is about 4-5C and these konions don't get that warm under that kinda load... I'll usually be running them more like 2-3C sustained I think... plus I live in Montana and work on a mountain so... :wink: Konions are pretty amazing... I've been running a single Bosch fatpack with my 504 recently as a grocery getter and pulling ~1,000watts sustained out of it under heavy sag like 28-30v @ 30-35A... that's around 15C sustained and that gets the pack pretty warm I'll admit... those are the 'VT's so they can handle it. Haha! So worth the $45!

 

[zcream]

Awesome thread. Need a pack to power 50 cameras. This will work ..
For completeness, here are the complete Mouser part numbers..

Mouser #: 12BH209-GR
Mouser #: 12BH228-GR

Here's are some items I've got so far from Mouser.com

Most likely I will be using 209 and 228 to make the holder. If you know of any other, let me know. These you just pop it into the casing and it stays there. I thought 211 will works good too but its a lot of work to screw down each one of those (like 120 or 160 of them).

 

[zcream]

Any consensus on the charger. I will be using 20 18650 in parallel - need 3.7V and about 100A max drain when the cameras are saving the image.
I have the Universal Smart Charger for
Li-Ion/Polymer battery Pack (3.7V-14.8V 1-4 cells) from all-battery.com
http://www.all-battery.com/browseproducts/Universal-Smart-Charger-for-Li-Ion-Polymer-battery-Pack-%283.7V---14.8V--1-4-cells%29.html

A balance charger for so many in parallel will be the problem..

 

[Takemehome]

A balance charger for so many in parallel will be the problem..

If your pack is 1S20P, you don't need any balancing.
Cells charged and discharged in parallel are always balanced.

 

[zcream]

True! Any recommendation for a single cell charger that will have a large enough charge rating ?

 

[methods]

A balance charger for so many in parallel will be the problem..

If your pack is 1S20P, you don't need any balancing.
Cells charged and discharged in parallel are always balanced.

Not true at all.

I have a 20S 48P pack and it goes out of balance *every cycle*. It is true that putting many cells in parallel tends to balance out - as a rule of thumb - but only if the cells are matched to start with. These days more and more packs are built up from salvaged cells (i.e. toolpack cells) that come from many different production runs, have seen many different cycles, different leakage, different IR, different abuse, etc. With packs like these the number of cells in parallel has no correlation to the rate at which banks go out of balance.

A balancer with 1A shunt currents like mine or Gary/Fechter's can easily balance a 100Ah pack. My pack is 140Ah - made from 960 totally random and abused cells.

-methods

 

[Solcar]

Methods, I've sent you a private message that isn't related to this thread topic.

 

[methods]

I have not been answering PM's due to how busy I am... But I will go glance at yours.

-methods

 

[Solcar]

Thanks, swell!

 

[Solcar]

Sincere apology, I've tried to reply, but my PM is inoperative right now. Thanks for giving me that answer. ATB

 

[The Mighty Volt]

I just went to the Turbo Ferret page. Nothing doing. Nothing available for sale.


With regret, Turboferret Industries has ceased production due to personal reasons. Once stocks have run out, trading will stop completely. Please note stock levels for individual parts on the buy page when ordering. These will be updated daily, but may not be totally up to date, so adjustments may be required subsequent to your purchase. Many thanks for all of the support over the past year.

 

[Takemehome]

A balance charger for so many in parallel will be the problem..

If your pack is 1S20P, you don't need any balancing.
Cells charged and discharged in parallel are always balanced.

Not true at all.

I have a 20S 48P pack and it goes out of balance *every cycle*. It is true that putting many cells in parallel tends to balance out - as a rule of thumb - but only if the cells are matched to start with. These days more and more packs are built up from salvaged cells (i.e. toolpack cells) that come from many different production runs, have seen many different cycles, different leakage, different IR, different abuse, etc. With packs like these the number of cells in parallel has no correlation to the rate at which banks go out of balance.

A balancer with 1A shunt currents like mine or Gary/Fechter's can easily balance a 100Ah pack. My pack is 140Ah - made from 960 totally random and abused cells.

-methods

methods, you were tired, when you answered that one. :lol:

There is a BIG difference between a 20S pack and a 1S pack.
In a 20S1P pack, of course the cells can unbalance.
In a 1S(as many as you want)P pack, they cannot.

 

[efreak]

I think I'm now getting the idea. Maybe.

.....

Another option, one I'm exploring right now, is using 16 of the 48V/3.7V DC-DC convertors that Bill Zleman is selling in the "For Sale" section. These are small (1.5" x 2.25") modules that can be used just like the VP chargers to individually charge each cell, but each module can supply up to 20A. They are driven by a 48VDC power source, which can be pretty much any 48V supply you can easily find on ebay. What you can also do is use the same supply/charger that you use to bulk charge the 16s pack, as the source. That would allow you to just use the bulk charger, or use the bulk charger "in series" with these modules. I'm mounting all 16 modules to a 2-1/4 x 12" piece of aluminum, eight to a side. It is acutally very compact.

-- Gary

I first like to knowledge great work by Leamcorp for this topic. The final product is amazing! 8) {many thanks to others as well for their contribution on this forum} the best design yet for no hassle, no soldering, no fuss packs that are easy to fixlater and i would be interested in some of those blocks for a123 cells if they were available.

I can now work on my 80 cell m1 pack


NOW
Question for Mr. Gary Goodrun: how did your charging method using dc converters go?
i know that it works i did a small version with 4 dc-dc converters and have enough for the next charger set up as well as Ps 48 volt to feed them . i do have a 1/4 inch thick aluminum sheet that is near impossible to make holes in for machine screws that are required for mounting.

any details would be appreciated .

efreak

 

[efreak]

on page 7

I've just started building my pack - took longer than imagine.

As mentioned, I've decided to go in completely different direction - a holder that could be taken apart in few minutes to troubleshoot, replace a bad cell, add/delete capacity and allow for easy wiring. My pack is still not finished but this is where I'm at,

It all start with these building block. The block will house the copper strips and plastic wall.
View attachment 6

Here's the 1st module. To protect the battery, I've put foam cushioning material on all inside walls. The holes on the side are to align the next modules. The white piece in the middle is spacer that holds the copper strip. Since these strips are long, they tend to flex - this will hold them tight.
View attachment 5

Here's one with A123 batteries - this is a 7 cell parallel pack. I'm building 16s 7p for one of my bike.
View attachment 4

This should make it more clear. This is just one configuration. I was going to go up to 8 modules x 2 but I may change that to fit my rear basket. The flexibility to make any size and shape is what took so long.
View attachment 3

Here's close up of the connection between parallel pack. I've only done one and this one uses a 1/2" x 1/16" copper strip. I may go with 4 gauge copper strands instead. The long strips are 3/4" 1/16" pure copper strip - more than enough for any volt/amp.
View attachment 2

Here's frontal view - you could put holes anywhere on the strip for addition connection/junction point.
View attachment 1

What started all - I'm also making 18650 pack but thats taking a backseat until my A123 pack is done.


Once my pack is finished, I'm going to cover it with plastic sheeting - so that it looks like a box instead of a bomb. One other thing I'm also doing is to make a separate box for LVC/BMS board and wiring.

this is by far the best design i have seen yet for interchangeable cylindrical battery pack construction period.

can't seem to find any weak points, none.

 

[Hummina Shadeeba]

My impression is that each case should be a paralell group.

Yes! Absolutely make them parallel enough for ebike use and for BMS simplicity etc. etc. Even 4p is too small in my opinion because of realistic ebike loads and I would highly doubt those tenergy/ultrafires etc could handle higher C rates for long term... if you design a really easy modular/snap together structure then you can parallel as many as you want I suppose. Is there a realistic design you can think of that would allow endless 1s1p snap together possibilities? I know for the konions I'm working on 1s10p is going to be the minimum realistic parallel that I'd be looking for personally. Please let us know how we can help!! This is a very exciting project you're doing! 18650s really need an option like this... looong overdue.

How do cells in parallel do since they aren't being monitored? They are balanced by the others in parallel but what if one were a total dud with no capacity how would it effect things?

If I were to run all my cells in parallel and get a higher kv motor would there be enough voltage, at maybe 4 volts, to get the amps through and reach the same amount of power as if they were in series?