18650 pack build using plastic battery holders

Batteries, Chargers, and Battery Management Systems.
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Re: How to build a 18650 pack in an off-the-shelf metal box

Post by www.recumbents.com » Sep 17 2015 11:48am

If the pack has a 3 volt sag during the 80amp peak for the 3 seconds during a fast start it does not bother me. The fact that this tiny pack will be able to deliver the big peak current and still behave itself during the other 99.9% of the time when I am cruising or charging is fantastic.

Last night I added the balance wires to the bottom conductors. I cannot for the life of me get the silver solder to stick to the copper, so I am just using my old tin-lead solder. Is there a trick to using silver-tin solder?

-Warren

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Re: How to build a 18650 pack in an off-the-shelf metal box

Post by markz » Sep 17 2015 1:16pm

Perhaps the trick is using flux and tinning both surfaces.

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Re: How to build a 18650 pack in an off-the-shelf metal box

Post by www.recumbents.com » Sep 23 2015 12:42pm

markz - hmm, I did not think of that, maybe the silver solder is flux-free. I'll try the flux and see what happens.

I laid up more fiberglass to use for the perimeter box to hold the 48 batteries in place. Once the epoxy cured I cut out the flat panels to make the sides of the box. Here they are held together with tape. I will use more fiberglass on the corners to fasten it all together permanently and make it strong.

Image

Also I tested the voltage of all the batteries, they were all 3.64 volts except 4 of them which were 3.63v.

-Warren.

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Re: How to build a 18650 pack in an off-the-shelf metal box

Post by www.recumbents.com » Sep 26 2015 8:09pm

This weekend I glued the conductors down to the bottom of the fiberglass substrate with automotive grade RTV silicone glue, then fastened the fiberglass box together with more fiberglass. The plastic wrap helps press the wet fiberglass to the sides of the box and keeps the mess contained.

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Re: How to build a 18650 pack in an off-the-shelf metal box

Post by www.recumbents.com » Sep 27 2015 7:09pm

I put the fiberglass box in the metal box, and jammed all the batteries in. It's a tight fit. I sure hope the top lid makes good contact to all the batteries and now I'm getting concerned because I won't be able to test to verify it with the lid on.

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Re: How to build a 18650 pack in an off-the-shelf metal box

Post by Hillhater » Sep 27 2015 11:54pm

Warren,
Please read the last few posts today on Rodney's 18650 build thread..
https://endless-sphere.com/forums/viewt ... 6#p1103146
I am a little concerned that your pack with "loose" cells may be prone to can to can shorting from vibration.
This forum owes its existence to Justin of ebikes.ca

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Re: How to build a 18650 pack in an off-the-shelf metal box

Post by www.recumbents.com » Sep 30 2015 7:58pm

There is no room in the box for more insulation. There may not even be room for wires. I have put a lot of time into this, but I'm thinking about abandoning it and trying something else. I'm thinking now that for my bike I'd rather have a flat and wide battery than a box. Time to rethink it...

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Re: Abandoned build of 18650 pack in an off-the-shelf metal

Post by www.recumbents.com » Oct 01 2015 1:58pm

I am abandoning the aluminum box pack build. Instead I am planning on using 18650 battery holders that hold 4 batteries in series or parallel. They look reasonably beefy. Revised plan is:

* Use the batteries in each holder in parallel.
* Add add bus bars to connect 12 of them in series.
* Mount them flat in a 3 x 4 arrangement on a sheet of Lexan.
* Pop-rivet sides on the flat sheet.
* Screw the Lexan top down.

It should be about 11" x 12" and about 1.5" thick. This will be easier to mount on my bike, and I'll also have a spot to mount the CC HV160 controller and the DC-DC converter, etc. As you can see below, a good mounting location will be on the shelf below the seat bag.

Image

Now I just have to wait an indeterminate amount of time for them to be shipped from Hong Kong.

I recently took this bike all apart, painted it rattle-can loss black, and am now re-assembling it.

-Warren
Last edited by www.recumbents.com on Nov 07 2015 6:56pm, edited 1 time in total.

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Re: Abandoned build of 18650 pack in an off-the-shelf metal

Post by 999zip999 » Oct 01 2015 5:26pm

Most never get to the plate and swing the bat. Thanks for sharing. Step back. Things will get clearer.

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Re: Abandoned build of 18650 pack in an off-the-shelf metal

Post by clockwork247 » Oct 01 2015 5:50pm

www.recumbents.com wrote:I am abandoning this for now as there are too many potential problems. Instead I am planning on using 18650 battery holders that hold 4 batteries in series or parallel. They look reasonably beefy. Revised plan is:

* Use the batteries in each holder in parallel.
* Add add bus bars to connect 12 of them in series.
* Mount them flat in a 3 x 4 arrangement on a sheet of Lexan.
* Pop-rivet sides on the flat sheet.
* Screw the Lexan top down.

It should be about 11" x 12" and about 1.5" thick. This will be easier to mount on my bike, and I'll also have a spot to mount the CC HV160 controller and the DC-DC converter, etc. As you can see below, a good mounting location will be on the shelf below the seat bag.

Image

Now I just have to wait an indeterminate amount of time for them to be shipped from Hong Kong.

I recently took this bike all apart, painted it rattle-can loss black, and am now re-assembling it.

-Warren
the holders are expensive IMO... I saw them but scrape the idea, I wanted a pack with tons of battery, and this will cost too much. I've seen some design using them and it's really nice.

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Re: Abandoned build of 18650 pack in an off-the-shelf metal

Post by markz » Oct 01 2015 6:17pm

Yeah those holders are expensive, lucky they are a bit cheaper on ebay but still works out to $0.50 for each battery. $0.25 for each connection.
For a 100 pc battery, thats $50 on a $300 battery or 17% of the cost.

Whats wrong with these?
http://www.batterysupports.com/battery- ... 53_57.html
Works out to $3 for 10pc 3x unit. So 30 connects, 15 batteries. $0.20. Plus shipping $11 for
supower 231.jpg
supower 231.jpg (129.35 KiB) Viewed 2750 times
But $8 shipping minus the 2650 holders. I dunno about their shipping speed. Would be good to know before I buy from them.

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Re: Abandoned build of 18650 pack in an off-the-shelf metal

Post by www.recumbents.com » Oct 01 2015 7:58pm

I agree, they aren't cheap and I probably could have purchased a pre-built pack for the cost of the cells and various other parts needed to build a pack. The items from supower are just battery holders. The ones I ordered have the spring tabs built in.

Image

Thanks guys I won't give up, just changing plans...

-Warren

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Re: Abandoned build of 18650 pack in an off-the-shelf metal

Post by markz » Oct 01 2015 8:13pm

Spring tabs for low power batteries, or low draw.

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Re: Abandoned build of 18650 pack in an off-the-shelf metal

Post by www.recumbents.com » Oct 02 2015 11:08am

I am planning to use copper sheet in front of them to create maximum beefyness.

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Re: Abandoned build of 18650 pack in an off-the-shelf metal

Post by markw » Oct 16 2015 1:30pm

In terms of holding the batteries together in configuration, are you opposed to using hot glue? I seen this used in multiple 18650 battery assembly videos and it seems to be very successful!
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Re: 18650 pack build using plastic 18650 battery holders

Post by www.recumbents.com » Nov 07 2015 6:32pm

The cell packs finally arrived. I think they were $12 for each pack of five 4 cell holders, with free shipping from Hiflungpoo. I have 15 holders now. Initially they sent me one pack of 4 cell holders and two packs of 3 cell holders and I had to post some bad reviews, etc before they acquiesced and send the other two packs of 4 cell holders. Fun.

To build this battery I will need 12 of these holders. Each battery holder will have 4 groups of cells in parallel, and the 12 cell groups will be arranged in a flat 3 x 4 array. I will end up with a pack that is about 12" x 9", and will be about 1.5" thick. This will fit well on the the rack of my ebike. The whole pack will be inside a box built of Lexan (polycarbonate). It will be nearly bulletproof.

I initially thought I would connected them using tabs made from copper sheet, but I decided that thick copper wire would be better. This is 14 gauge wire from a house wiring project. I bent clips to go between the tabs on adjacent battery packs.

Image

Next I soldered the clips to the tabs, and to a "bus bar" connecting all the cells groups in parallel. Not perfect but I think the solder connections are solid.
I was happy to see that these plastic packs are fairly heat resistant, and that the soldering does not make them melt down. They do melt but it takes a lot of high heat to do it.

This technique is much easier than the method I tried previously and abandoned. It will probably take about 10-12 hours to get the pack all soldered together.

Image

Here's a test fit of the batteries. They still fit (whew!). They are very tight, and will require a ribbon or a strip of cloth under each group of cells to make it easy to pop the cells out of the holder.
There will be three rows of four packs in series.

Image

The ends of each row will use some thick copper plate as a bus bar to connect to the next row, and as the main battery pack positive and negative terminal.

I'll post more in a couple days when the pack connections are done.

-Warren

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Re: 18650 pack build using plastic battery holders

Post by markz » Nov 07 2015 9:29pm

This is a clever idea, even without pre-bought plastic 18650 holders, which I find to be too expensive.
If I can find a way to make the holders, out of plastic, or wood then your bus bar idea would work for SURE!!!!

It gives me renewed hope for a solderless/tabless battery setup.

Have you thought about using duct tape, or something else to make the batteries absolutely secure, even with the tight fit they still could pop out.



I have to look into how to build holders, maybe I can buy a 3d printer. I have to look into that, I've seen cheap ones for sale and used ones.

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 07 2015 10:20pm

Markz - I will probably just use some foam or something between the batteries and the cover to ensure that they don't ever bounce loose.

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Re: 18650 pack build using plastic battery holders

Post by markz » Nov 07 2015 11:39pm

Yeah that will work, I didnt realize they had covers. RIght now I'm looking into Acrylic Sheets from HomeDepot and Acrylic Glue, 3d printers and cnc's are too pricey. Its hard to find that stuff, luckily I just found a place in town that sells it all. Rather buy local then pay extra to ship stuff in.

You are using 14awg solid copper for house wiring?

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 08 2015 8:04am

No, the battery holders don't have covers, I am building a polycarbonate cover for the entire pack. Yes I'm pretty sure that the wires are 14 awg. 12 awg is too thick for me to bend and solder easily. Did you already buy a bunch of loose 18650 cells? Half of the reason I bought these cell holders is for the spring clips. Those will be hard to make with any kind of precision by hand. Note that acrylic cracks pretty easily.

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 08 2015 10:09am

The ends of each row use some thick copper plate as a bus bar to connect to the next row, and as the main battery pack positive and negative terminal. It's pretty hard to solder to the thick copper.
The battery holders have nice slots to allow them to be fastened together with plastic wire ties. I'm about half done.

Image

Warren

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Re: 18650 pack build using plastic battery holders

Post by parabellum » Nov 08 2015 10:54am

markz wrote:This is a clever idea, even without pre-bought plastic 18650 holders, which I find to be too expensive.
If I can find a way to make the holders, out of plastic, or wood then your bus bar idea would work for SURE!!!!

It gives me renewed hope for a solderless/tabless battery setup.

Have you thought about using duct tape, or something else to make the batteries absolutely secure, even with the tight fit they still could pop out.



I have to look into how to build holders, maybe I can buy a 3d printer. I have to look into that, I've seen cheap ones for sale and used ones.
Expensive? It always depends, versatility and ease to reconfigure exchange cells is priceless. I did 4x 6s4p packs out of those holders to make 24s4P battery for my bike, but because I still have my lipos holding strong and no spare 400US$+ for new cutting edge 18650cells, I took old konions reversed half of the cells in every pack and use them as 3s32p in one 12V Inverter (We have some electricity problems here). Week ago, I noticed 1 group out of ballance, took group cells out, found the sucker cell and replaced it, 5 min job. :D

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 08 2015 11:35am

Exactly. 2 years from now when 18650 cells are 5000 mah and 20S for a reasonable price I can just swap out all the cells quickly and be done with it.

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 10 2015 7:41pm

It took me about 8 hours to build the basic pack. This picture shows 12 batteries in series (one in each holder), producing 43.7 volts. The ribbon of cloth is in place to help remove the batteries as they are very tight.

I took it to the garage to see how it fits on the bike and its a bit larger than the shelf but will work fine.

Image

Now I need to add the main power wires and the balance wires and build the Lexan box.

-Warren

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Re: 18650 pack build using plastic battery holders

Post by www.recumbents.com » Nov 14 2015 6:29pm

Added wires to the pack and removed the motor controller (ESC and wiring from my old LiPo pack. I cut out and bent up the bottom half of the polycarbonate plastic case. As shown it has room to mount the ESC and stash the wires.

Image

Here's the top cover. The jumble of wires will be hidden in one compartment of the case. The controller will be screwed to the bottom of the case and be exposed for cooling. The case is 1 1/8" thick, 13" wide and 14" deep with a notch to clear the set stays.

Image

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