Beginners Guide to Processing 18650 Cells | Cell Database


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DIY 8-Cell portable charger
#1
Not DIY in the sense that I built it from scratch. For about $5 (US), you get basically the whole thing except you add your own cells. I figured I'd run it through a few tests and see how well it performs, and share with you all what I find.

This particular unit I got on eBay, though I also found it for a little more money on Amazon.

[Image: ad6153b6c20e16bdc062baee413e1dc7.jpg]

I selected 8 cells of the same make and model, and with similar capacities.
[Image: 02ed0dccdd44cf9e0944385facf88089.jpg]

Charging from storage (3.77V) to full took a long time on the single USB port. But the charging did terminate at 4.21V. So that's good.
I thought I'd also compare it to a fully store-bought unit which cost significantly more, but only has 6 18650 cells.
[Image: ccfedfc7493672b038fe522255947337.jpg]

Supposedly, you can get faster charging if you plug in 2 USB chargers at once. I plan to test that.
[Image: 8a1d3d2a48e0062f821ee30e45cc76b5.jpg]

So tests I intend to do are:
- does it in fact, charge faster using two USB chargers.
- how many times can it charge something vs. the store bought unit.
- compare various characteristics between the DIY unit and the store bought unit.
- other things I haven't thought of yet.

If y'all are curious about some aspect of this device, let me know and I'll try to test it.
BlueSwordM likes this post
-Mike G
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#2
Nice Smile I'm doing the same thing, but only with non-18650 cells. And my cases are DIY (Duct-It-Yourself) Big Grin :

 

The middle one will get a laser-cutted wooden case, will be a birthday present for my dad Smile .

Have sun!
Oliver
rebelrider.mike likes this post

Cells tested: 4238 (overall: 8077 Ah, average: 1906 mAh)
Cells in production: 2240 (overall: 4704 Ah, average: 2100 mAh)
Powerwall config: 7s320p, 672 Ah, 16 kWh
What's left: my current grid consumption

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#3
(08-18-2017, 08:42 AM)rebelrider.mike Wrote: Not DIY in the sense that I built it from scratch. For about $5 (US), you get basically the whole thing except you add your own cells. I figured I'd run it through a few tests and see how well it performs, and share with you all what I find.

This particular unit I got on eBay, though I also found it for a little more money on Amazon.

[Image: ad6153b6c20e16bdc062baee413e1dc7.jpg]

I selected 8 cells of the same make and model, and with similar capacities.
[Image: 02ed0dccdd44cf9e0944385facf88089.jpg]

Charging from storage (3.77V) to full took a long time on the single USB port. But the charging did terminate at 4.21V. So that's good.
I thought I'd also compare it to a fully store-bought unit which cost significantly more, but only has 6 18650 cells.
[Image: ccfedfc7493672b038fe522255947337.jpg]

Supposedly, you can get faster charging if you plug in 2 USB chargers at once. I plan to test that.
[Image: 8a1d3d2a48e0062f821ee30e45cc76b5.jpg]

So tests I intend to do are:
- does it in fact, charge faster using two USB chargers.
- how many times can it charge something vs. the store bought unit.
- compare various characteristics between the DIY unit and the store bought unit.
- other things I haven't thought of yet.

If y'all are curious about some aspect of this device, let me know and I'll try to test it.
These aren't bad I've had a few of them. 

Only issues I had were the springs can get a bit compressed the steel is a bit light maybe.

Be careful not to reverse polarity as this fries them ?
BlueSwordM likes this post
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#4
I received a couple tools in the mail yesterday. An in-line USB power meter, and a 1-2A USB load tester. I'm still debating how best to confirm the accuracy of the load tester, but for now, I'm assuming it pretty close. As for the power meter, I checked the voltage, and its within 0.01V or so. Plenty close enough for me. Smile
[Image: 023ae4d696dd6515fc00c5715921df24.jpg]
Amps are trickier, so at some point I may build or modify a cable so I can put an amp meter inline.

Anyway, I tried these guys out on the store-bought Gorilla Gadgets charger, and the green DIY charger to see how they compare. Here is what I found:
[Image: 343db9d158d11dc4da1eecaf672362ce.jpg]
On the 1A port, the DIY seems to be closer to delivering the ideal Volts and Amps. Just for fun, I tried drawing 2A from the 1A port. I kind of expected there to be a 1A limit of some kind, but what I found is the DIY still made an attempt to deliver 2A, while the Gorilla actually has a safety shut-off. I tried it twice just to be sure I didn't fry something inside instead, but yep. The whole unit shuts itself off if you try to draw too much current through the 1A port.

[Image: 5472542c24f7dd0611ec9c987ea5ae35.jpg]
Again, the 2A port on the DIY seems to deliver closer to the ideal power than the Gorilla. Whether that be drawing 1 or 2 Amps. I wonder if the Gorilla would shut off the 2A port if I tried to draw 3 or 4 Amps through it?

So what I'm taking away from this test, is that while both of these units are close to delivering the advertised power, the DIY seems closer to the ideal. But then the Gorilla has an over-current protection thing.

More tests to come...
Korishan and Geek like this post
-Mike G
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#5
The Gorilla is going to shut down above two amps, as the limit of BC 1.2 USB charging is 2.1A, and Apple's variant of it is 2.4A. The second one necessitates a special PCB and circuit
Also, if you could buy a QC 3.0 power bank like this: http://www.ebay.com/itm/QC3-0-2-Input-Ty...sWqt032jCQ and stick springs inside, this could become very interesting, as you'd be possibly drawing from 5V2.5A up to 12 1.5A.

Also, why are both dropping voltage? They shouldn't. Especially at a current of 2A. Probably their circuits not being able to cope with the load.
The power of lithium ion is in our hands!
We'll show them what we're made of!
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#6
Thanks for sharing. 8 Cells would be great for my cells that don't do too well. I get quite a few that don't hold more than 1ah. I considered soldering my cells to reduce resistance, or the chance of a connection going bad. Be interesting to see how the two USB chargers work, and if it does charge faster. That would be an excellent feature (if it works  Smile)
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#7
Well, I've got some good news.
The DIY portable does in fact use both input ports to charge simultaneously. I put 8 low capacity cells through the Opus to discharge. Then charged my phone with the DIY until it shut down. Turns out the unit considers the cells discharged at 3.2V.

Observing while it was charging, I saw 1.09A on one cable, and 1.2A on the other. I also saw on the display, a reading of "IN 5.0V 2.1A". Now, this is a mode display only. Not an actual reading of Volts or Amps. So it managed to pull around 2.29A total. Although, the Voltage was a little low, 4.8V or so.
[Image: 9fce5e2bc6932a5365c85e4862669947.jpg]

Once the charger moved over to constant voltage, the Amps went down, but the device was still splitting the current between the two cables.
The display at some point switched to "IN 5.0V 1.0A" and was drawing around 0.62A and 0.26A, or 0.88A total.
[Image: 8bfed0958ad2d46e12b8264d8bfe62fb.jpg]

I'm not sure how long it took to charge up. It happened while I wasn't looking. But it was at 99% after about 4 hours. It got full sometime before 6 hours.
Next will be a full discharge and then a full recharge but only with a single cable.
Korishan likes this post
-Mike G
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#8
Ok, the DIY charger finally finished charging with the single cable after about 14 hours, vs. the 6 hours it took for two cables. Huge difference there!
One curious thing to note is on the back of the unit its advertized as having 30Ah of capacity. How would they know? Its empty! To get that, I'd have to find cells at 3,750mAh each. Not likely with my recycled cells, LOL.

So that's about all the things I can think of to try out on this guy. If you all have other things you'd like to know, I'll see if I can test those too.

Just for curiosity, I opened up my Gorilla Gadget charger to see what's inside:
[Image: 5d4eef36076098eade226c8ba42b7b74.jpg]

The cells are Chang Jiang brand which, if i understand right, are not typically found in laptop batteries, but can often be found in other products... like portable chargers. Although, I did come across some blue Chang Jiangs in an aftermarket laptop battery once.
[Image: 603b26249893eeafda227861b1175621.jpg]

I couldn't find any specs on these, but the case is labeled as having 16.8Ah of capacity. So 2,800mAh per cell. Seems a bit optimistic. If only there was a way to test that...
Oh, yeah! I've just remembered that I've been 18650ed! Capacity testing is no problem.
[Image: 35f01e7f1dd5ab01989efc47e8050503.jpg]

I probably should have tested at 1A, but I didn't think of it until several hours into the discharge, and I didn't want to start over. So 32 hours later, the cells as a group, yielded 15.92Ah. Now, I can't remember when I bought this, but I've been using it for several years, so 15.92Ah actual vs. 16.8Ah advertized isn't to bad, I think. That's 2,653mAh per cell. I've not seen 2,800mAh Chang Jiangs for sale, but there are 2,600mAh ones available out on the internet. I suspect these are them, though they don't have the same model number.

If anyone knows where I could find datasheets on these Chang Jiang cells, I'd love to see them! Not a big deal, I'm just curious. Smile
-Mike G
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#9
These are FST batteries actually. Their highest capacity cells are 3400mAh 20650, and they are blue ones, and they look like this: http://www.firstbattery.com/en/h-pd-114.html
I found them mainly in Tzumi powerbanks. For some reason, they can handle 10A without any problems, without going either hot or ballistic on me. Though their capacity drops to 3250mAh.

The idiots at Walmart, if they don't sell them all in a week, actually throw away perfectly good new cells. If I was adventurous like last time, I would've taken the whole BIN of powerbanks. But I don't have the time, nor the resources to do so.
The power of lithium ion is in our hands!
We'll show them what we're made of!
Reply
#10
(08-18-2017, 11:15 AM)Wattsup Wrote:
(08-18-2017, 08:42 AM)rebelrider.mike Wrote: Not DIY in the sense that I built it from scratch. For about $5 (US), you get basically the whole thing except you add your own cells. I figured I'd run it through a few tests and see how well it performs, and share with you all what I find.

This particular unit I got on eBay, though I also found it for a little more money on Amazon.

[Image: ad6153b6c20e16bdc062baee413e1dc7.jpg]

I selected 8 cells of the same make and model, and with similar capacities.
[Image: 02ed0dccdd44cf9e0944385facf88089.jpg]

Charging from storage (3.77V) to full took a long time on the single USB port. But the charging did terminate at 4.21V. So that's good.
I thought I'd also compare it to a fully store-bought unit which cost significantly more, but only has 6 18650 cells.
[Image: ccfedfc7493672b038fe522255947337.jpg]

Supposedly, you can get faster charging if you plug in 2 USB chargers at once. I plan to test that.
[Image: 8a1d3d2a48e0062f821ee30e45cc76b5.jpg]

So tests I intend to do are:
- does it in fact, charge faster using two USB chargers.
- how many times can it charge something vs. the store bought unit.
- compare various characteristics between the DIY unit and the store bought unit.
- other things I haven't thought of yet.

If y'all are curious about some aspect of this device, let me know and I'll try to test it.
These aren't bad I've had a few of them. 

Only issues I had were the springs can get a bit compressed the steel is a bit light maybe.

Be careful not to reverse polarity as this fries them ?

I use two of them for precharging cells before I put them into the Opus. (Saves time in testing) On another one, I also desoldered the control board and wired my iMax to the cell leads for more versatility. (cheeper than 2 of the 4x battery holders)

As far as their usefulness as they were originally intended, I made one up for my son using 1700mAh cells and he was able to charge his iPhone from near zero to full 5 times. He is now marketing them to all his buddies at school. Gotta love the kid.
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