Info on Laptop 18650 LiCo cells

Batteries, Chargers, and Battery Management Systems.
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veloman   1 GW

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Re: Info on Laptop 18650 LiCo cells

Post by veloman » Jan 14 2013 8:50pm

lol, well she only needs 10 to go to work and back. the lifepo4 main pack on her bike is beat and only gives about 5ah :shock:
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Re: Info on Laptop 18650 LiCo cells

Post by Hillhater » Jan 14 2013 10:59pm

SamTexas wrote:..It's beyond my imagination how anyone can put up with a 20 miles range, let alone 10.
There is no point in carrying more battery weight ( and cost) than you actually need.
20 miles would probably cover 80% of most cycling commuters.
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Re: Info on Laptop 18650 LiCo cells

Post by SamTexas » Jan 16 2013 11:29am

New info added to Page 1 of 2.

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Re: Info on Laptop 18650 LiCo cells - Pictures

Post by DrkAngel » Feb 14 2013 9:57am

2008 build - 37V 20.8Ah

Image

2008 Build - 25.9V 31.2Ah

Image

2011 Build - 25.9V 31.2Ah in an eZip oem pack.

Image

2013 builds?
22.2V 41.6Ah in an eZip oem pack = .932 kWh (oem SLA = .240 kWh but < .150 usable)
44.4V 20.8Ah in an eZip oem pack = .932 kWh (2 packs run parallel = 44.4V 41.6Ah!)
Modular - 11.1V modules. 22.2V, 33.3V, 44.4V, 55.5V etc. easy and quick builds.
Adjustable "bulk chargers".
Cheap V monitor LV alarms available! - Use multiple for > 8s.
Rebuilding 5 - 2008 builds - re-evaluating, capacity rating-matching and reassembly of 400+ cells.
18650 cells paralleled with small RC Lipo packs for better surge capability? ... Will try it.
(33.3V 20.8Ah Laptop + 33.3V 5.7Ah RC Lipo = 33.3V 26.5Ah that fits in eZip pack.)
Much neater builds, 9-10 gauge tinned copper braid for power rails, 22ga solid tinned copper balance connection wires/

Homemade Battery Packs - very large thread!
Last edited by DrkAngel on Mar 02 2013 7:18pm, edited 1 time in total.
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SamTexas   100 MW

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Re: Info on Laptop 18650 LiCo cells

Post by SamTexas » Feb 14 2013 10:43am

DrkAngel,
One of the more difficult task in assembling packs is the soldering process. Seems to me that you have that down really well. Would you explain the process you use, any trick you have to make it faster and more robust? Temp, solder type (lead or lead-free), flux or no flux. Solder on tabs vs on the cells. etc...

You are welcome to do it here or in your thread.
Sam

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Soldering - Laptop 18650 LiCo cells

Post by DrkAngel » Feb 14 2013 1:01pm

SamTexas wrote:DrkAngel,
One of the more difficult task in assembling packs is the soldering process. Seems to me that you have that down really well. Would you explain the process you use, any trick you have to make it faster and more robust? Temp, solder type (lead or lead-free), flux or no flux. Solder on tabs vs on the cells. etc...
Sam
Leave cells connected!

Tabs are much easier to solder than cells.

1st, you must abrade solder points, dremel grinder-sander, file or even scrape with knife etc.
Flux - I use a Q-tip to spread a thin amount.
40w iron recommended (25w might work)
A hotter soldering iron transfers less heat to cells - less contact time required!
"Pre-tin" - apply solder to all solder points.
Apply a small drip of solder to tip ... allow to regain heat, apply to fluxed solder point, try 2 sec, if not good allow to cool then try 3 seconds.
(Keep a few bad cells for test soldering!)
After all contact points tinned, reapply flux.
Position for final solder apply heat till solder melds together. (Hold solder points together with chromed metal probe, small screwdriver etc.)
Test all solder connections with pick or similar.

Direct to cells is similar but usually requires slightly longer contact time, test on bad cells!


Quick Review
Abrade solder points
Flux all solder points
Hot soldering iron
Pretin solder points
Reflux
Collapse pretined solder points onto each other
Use metal probe to position

Rejoice!

Do many cells at once each step for all, then next step for all etc.
Practice-repetition makes perfect
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SamTexas   100 MW

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Re: Info on Laptop 18650 LiCo cells

Post by SamTexas » Feb 14 2013 3:02pm

Pretty much what I did. Lots of practice and I still dread soldering.

Lead or leadfree solder? I have a tough time with leadfree, so now I use lead (63/37).

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Re: Info on Laptop 18650 LiCo cells - Soldering

Post by DrkAngel » Feb 14 2013 4:05pm

Solder type
I use Lead solder - electronic grade preferred, non flux core, (not rosin nor acid), I put all the solder on irons tip first, so flux on surface is needed anyhow.
Oops! Just rechecked ... using 60-40 rosin core ... on my latest builds, anyhow.
0% cracked solder joints! But I did stabilize builds inside eZip cases.

Tinned Copper Braid
Ideal for connecting separated cells!
The flex between cells helps prevent cracked solder connections.
Hunt for good price - Just found 200' 22ga for ~$18.99 on ebay. (Good for parallel-balance wiring)
10ga? for full amperage.
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veloman   1 GW

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Re: Info on Laptop 18650 LiCo cells - Soldering

Post by veloman » Feb 14 2013 5:11pm

DrkAngel wrote:
Tinned Copper Braid
Ideal for connecting separated cells!
The flex between cells helps prevent cracked solder connections.
Hunt for good price - Just found 200' 22ga for ~$18.99 on ebay. (Good for parallel-balance wiring)
10ga? for full amperage.
Who is the seller? A few minutes of searching didn't find anything close to that price.
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Re: Info on Laptop 18650 LiCo cells - Soldering

Post by DrkAngel » Feb 14 2013 5:27pm

veloman wrote:
DrkAngel wrote:
Tinned Copper Braid
Ideal for connecting separated cells!
The flex between cells helps prevent cracked solder connections.
Hunt for good price - Just found 200' 22ga for ~$18.99 on ebay. (Good for parallel-balance wiring)
10ga? for full amperage.
Who is the seller? A few minutes of searching didn't find anything close to that price.
7 - 2x100' lots left - http://www.ebay.com/itm/Cable-Shielding ... 2a288ac33b
A little learning is a dangerous thing;
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veloman   1 GW

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Re: Info on Laptop 18650 LiCo cells

Post by veloman » Feb 14 2013 5:53pm

Awesome, thanks!
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Re: Info on Laptop 18650 LiCo cells

Post by DrkAngel » Feb 19 2014 12:15am

More 18650 builds

37V 20.8Ah - 10s8p - 2008

Image
Image

Power tool rebuild - 4s2p - 2011

Image

22.2V 41.6Ah - 6s16p - 2013

Image

29.6V 31.2Ah - 8s12p - 2013
Image

33.3V 31.2Ah - 9s12p
Image

"My" Homemade Battery Packs
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Re: Info on Laptop 18650 LiCo cells

Post by auarhau » Mar 02 2014 12:57pm

Nice battery packs! I am curious about the power tool pack. How does the 18650 cells handle a drill? I was afraid the low discharge rating on those cells made them unsuitable for a drill. Also I have been sourcing some 18650 cells from old laptop batteries, but after reading about them I got very worried about fires etc. How low voltage can they be, and still be safe for me to recharge and use? So far I tossed away batteries below 3v, but that leaves me with very few good ones.

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Re: Info on Laptop 18650 LiCo cells

Post by DrkAngel » Mar 02 2014 4:42pm

I try charging up ... then testing, all cells ... with any voltage.
Name brand Laptop cells are probably the safest technology available.
See - "Explosion" - "Fireball" tests! ala LFP

The pictured Sanyo cell in the power pack were low discharge rated but sufficient for screwing computer screws.
Differing cells have differing C rates.
I recently tested some Sanyo 2200mAh with excellent discharge capability.
2350mAh Samsung also provide decent power tool capability.
Test each fully charged cell for C rate. - Use a discharge device of 1 - 2A, measure voltage sag and compare between all cells.
Those with the least sag have a better discharge capability.
5Ah laptop cells at 2C = 10A (30 min run time) is equal to 1.2Ah NiCd at 8.3C (7 min run time).
4.4Ah laptop cells at 4C brief surge = 17.6A is equal to 1.2Ah NiCd at 14.66C.
Last edited by DrkAngel on Mar 03 2014 10:51pm, edited 1 time in total.
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Re: Info on Laptop 18650 LiCo cells

Post by veloman » Mar 03 2014 2:59am

Do you separate the cells with anything to protect against shorting if the plastic wrap wore away?

What do you consider a 0.2v drop under 1amp load for a pair? That's about 5% sag for 1/3c (I estimate the average capacity of used laptop cells to be around 1.5ah each from what I have seen in my testing). Some pairs drop .4v, and I wonder if those are still okay to use, for example, in parallel with the lower sag cells?

I don't plan to build anything with under 60ah capacity. Will likely have 120ah for use on my lightweight motorcycle (limited to around 100amps peak, and 30-40 constant.)
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Re: Info on Laptop 18650 LiCo cells

Post by DrkAngel » Mar 03 2014 7:50am

veloman wrote:Do you separate the cells with anything to protect against shorting if the plastic wrap wore away?

What do you consider a 0.2v drop under 1amp load for a pair?
No, I wrap cells together tightly, so there is no wear.
I have never had any wear through, even with loosely wrapped cells in a soft pack.
Now, I tightly wrap cells with clear boxing tape and immobilize in rigid "bricks", stabilized with sheets of closed cell foam padding.

I forgot to mention ...
I began testing cells at ~ 4.10V.
This bypasses the excessive sag from 4.20V, which with some cells, is a region of miniscule energy capacity.
Especially when comparing batches of cells it is important to maintain a reasonable-warm equal temperature for all cells. 10 degree F difference will skew reading noticeably.
Best reading was .16V sag from 4000mAh pair, s3p2 with 12V 2.8A drain (fan) (sag measured at each pair), but this was a HD formulation built for massive discharge(?), capacity sacrificed to provide good surge capability, (I saved these for power tool pack build).

See - Homemade Battery Packs - Index
You might find interesting - Watts = MPH eMotorcycle - some info is outdated - my knowledge-understanding has progressed - will try to update-enhance my posts, as time allows. (Thread got twisted into voltage as SOC gauge debate, opponent(s) was only familiar with LiFePO4 (flat discharge curve), while I was using LiCoO2, with a much broader voltage range.
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Re: Info on Laptop 18650 LiCo cells

Post by kje » Mar 07 2014 1:44pm

How do you store Laptop 18650 LiCo cells if you have a lot?

I have a lot of cells in a big plastic box. Should I protect the ends of each cell? (+ and -) If one cell touch the opposite polarity on another cell would that harm the cell and maybe cause some danger?

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Re: Info on Laptop 18650 LiCo cells

Post by DAND214 » Mar 07 2014 3:33pm

If the cells have any tabs on them, YES. bBare ends with not tabs, not much a concern.

Dan

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Re: Info on Laptop 18650 LiCo cells

Post by DrkAngel » Mar 07 2014 5:16pm

kje wrote:How do you store Laptop 18650 LiCo cells if you have a lot?

I have a lot of cells in a big plastic box. Should I protect the ends of each cell? (+ and -) If one cell touch the opposite polarity on another cell would that harm the cell and maybe cause some danger?
Find a box about same width as cells, (cd-rom box?), place cells in box, stacked on side with pos in one direction neg in other.
Each end against cardboard.
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Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

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Re: Info on Laptop 18650 LiCo cells

Post by kje » Mar 07 2014 6:05pm

Thank you!
I`ve stored a lot of fully charged cells with tabs in a big plastic box for a long time. Could some of the cells been drained from weaker cells?

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