Best value ($ per mAh) on 18650 cells?

ryansoh3 said:

Haha, I didn't realize that the cell holders had protection PCB's.
That's really cool!
Once again, you've never failed to amaze us with your nice builds, from lasers to battery packs. :wave:

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The ones in that original thread didn't, they were just cheap DigiKey parts. But the ones from BatterySpace do (and you can get them in a number of configurations).

I have purchased these several times and been very happy with them. They have a good discharge rate and I trust the rating from batteryspace although I have never tested or seen any testing done by a third party. They are about $5 a cell in a 10 pack shipped US but I have no idea what they would charge for shipping to Canada. They will also add tabs if you need them.

Li-ion 18650 Cylindrical Rechargeable Cell: 3.7V 2200mAh (8.14Wh)

Is this a troll thread? If all you want is the highest claimed mAh / $ why are you even posting this inane thread? Just go to eBay, DX, DD, or whatever Chinese site, search for the cells yourself, and determine the ratio.

This is just silly and a huge waste of time.

Bionic-Badger said:

Is this a troll thread? If all you want is the highest claimed mAh / $ why are you even posting this inane thread? Just go to eBay, DX, DD, or whatever Chinese site, search for the cells yourself, and determine the ratio.

This is just silly and a huge waste of time.

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I think you're the troll here. Or you're having trouble reading:

rhd said:

Since I don't usually buy those kind of cells, I have no idea whether they're usually "labelled 3000 mAh but actually 500mAh" or more like "labelled 300mAh but actually 2000mAh". It makes a huge difference.

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You can't just "go to eBay, DX, DD, or whatever Chinese site, search for the cells yourself, and determine the ratio" because the specs listed on those sites are almost meaningless. You should know this. That's why I was looking for input from others. Remember when BLF members found the IMR gems hidden among BestInOne's cheap XYZfire lithium-ions? Those have been fantastic resources for a lot of members. There are gems out there to be had, and there's nothing wrong with asking for input on where they might be.

Don't be a snob, don't be obnoxious. I asked for input on something very specific; parameters that we don't typically use to evaluate cells (mAh per $). It's not often that someone has a scenario where almost nothing but that single ratio is of concern. If you don't think anyone should ever be asking about inexpensive cells, then just ignore the thread. I had/have a situation with a slightly different objective, where this question made sense to ask (because nobody had asked it before). But don't come in here like a child and talk about "trolling" because I asked a legitimate question that you don't think I should have asked. That sir, is being a troll yourself.

So did I win with my new laptop battery at 19$ giving me $3.17 per cell at lets say 2.4 per cell?

Make sure to test each cell independently with a full charge and discharge. Some cells are really just place-holders to fill in the blank spots in a crate of cells that were sold in bulk. Some cells really are built like crap from the start. But there are some china manufacturers who make completely acceptable products. Either way, you want to make sure you know what you have from the start, instead of assuming that they're all from the same batch and therefore, all just as fine as the one you fully tested.

If you don't mind my asking, what protection circuits are you using, the TI bq series chipset? If you are using a chipset from a laptop battery pack, would you be open to sharing info on how you adapted it for your purpose? I've been wanting to make a 6-cell charger out of one of these packs

BShanahan14rulz said:

Make sure to test each cell independently with a full charge and discharge. Some cells are really just place-holders to fill in the blank spots in a crate of cells that were sold in bulk. Some cells really are built like crap from the start. But there are some china manufacturers who make completely acceptable products. Either way, you want to make sure you know what you have from the start, instead of assuming that they're all from the same batch and therefore, all just as fine as the one you fully tested.

If you don't mind my asking, what protection circuits are you using, the TI bq series chipset? If you are using a chipset from a laptop battery pack, would you be open to sharing info on how you adapted it for your purpose? I've been wanting to make a 6-cell charger out of one of these packs

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I do test each cell, in fact I really *had to* when the cells I was using were primarily laptop harvests. so I'm in that groove, and I expect that I'll continue that process with the 20x cells I grab from cheap-China. I have a device that lets the current flow through it and out into a test load (in this case, a 10 ohm 50 watt chassis-mount resistor, which I submerge in water). It tracks the V & A over the full run of the discharge, which allows it to continuously compute the mAh of a single cell.

In terms of chipset, I don't know - I didn't design the PCBs I'm using from scratch. I'm using two things. First, there are these integrated 18650 holders with protection PCBs built-in:
Battery holder : Li-Ion 18650 Battery Holder (4S1P) With 2.6" long 20AWG & PCB

Going forward, I'm ordering these:
Protection Circuit Module ( PCB ) for 14.8v Li-Ion / 12.8V LFP Battery Pack (4.0A Limit) (PCM-L04S04-492) -For 26650 4S1P battery pack

Which appear to be appropriate for setups where you don't want to use an integrated holder + PCB. Although I haven't put them through the ringer yet, so I can't vouch for that second option. The first, works great. I've tried all sorts of fun stuff to try and get an undesirable reaction from the cells, and they don't budge.

Going forward even further, I'd love to find a chipset that would allow me to make my own PCBs. The 4S1P pack size is a really versatile one. You can grab buck circuits VERY inexpensively (< $5) that will pull their output down to a consistent 12V. On a lark, I connected two 4S1P packs (of 18650s) up to a 12V buck, and then into a power inverter meant for cars. I plugged a 110V bedside lamp (containing a CFL) into the inverter, and to my surprise, it worked really well. That's not my intended purpose for these packs of course, but it was pretty cool to see.

You can also grab relatively inexpensive (again, < $5) 5V USB buck circuits, that let you fairly efficiently take the 4S1P output down to 5V for charging devices.

At $6.99, the BatterySpace PCBs are hardly an expensive route, but I always like making my own stuff where that's an option. Do you know of a chipset intended for 4S1P packs?

HEY RHD.....

Ive seen just a bit of what I am certain is an enormous asset and pillar of this community you are. As a fellow "good guy" Ive become a firm believer that good guys most often finish last, but every once in a while a good dawg has his day.

today is yours sir. I need a response via pm with an address I can ups your 10 assorted 18650cells.

From a rookie nerd just coming up and learning about lasers & such I thank you for the wealth of knowledge, experience, and quality parts/service you share with us all.

B33M said:

HEY RHD.....

Ive seen just a bit of what I am certain is an enormous asset and pillar of this community you are. As a fellow "good guy" Ive become a firm believer that good guys most often finish last, but every once in a while a good dawg has his day.

today is yours sir. I need a response via pm with an address I can ups your 10 assorted 18650cells.

From a rookie nerd just coming up and learning about lasers & such I thank you for the wealth of knowledge, experience, and quality parts/service you share with us all.

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That is super-kind of you to offer, but I could never accept 10 free cells. That would be too much of an imposition.

I'm really touched by the offer though. Perhaps there's something of value that I could offer you in return? Let's chat via PM!

absolutely understood..... indeed some context surrounding myself and these cells should have been a no brainer... anyhoo pm on its way and either way you deserve a good ole thanks and those cant be turned down bub!

B33M said:

absolutely understood..... indeed some context surrounding myself and these cells should have been a no brainer... anyhoo pm on its way and either way you deserve a good ole thanks and those cant be turned down bub!

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Well then thank you, muchly

I'll keep my eye open for an incoming PM.

And I'll stalk some of your recent posts to see if I can figure out something to send ya in return

rhd said:

Again, my sole parameter is mAh per $. It's touching that other people are applying additional parameter's that aim to protect my best interests here. However, truly, I gave you guys my parameters, and I didn't forget or overlook any

My parameter is highest mAh per $, with perhaps a secondary qualification that the cell would have to be at least 500mAh, or it starts to be not worth it's own weight (literally). But that's it. I don't have any secondary considerations. Maximizing that one single ratio, is my objective.

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Having used hundreds of 18650 cells in demanding appilcations . . .

I have more parameters that I look at:

1. Reliability - I tried many ____fire cells in my UV lights.
They had ten times the failure rate compared to name-brand cells.

2. Safety - MUST meet U.L. 1642 standards

My recommendation would be the Sanyo 2600mah cells for best overall value.

I sell them for $5 per cell + shipping.

They will last a long time with minimal care.

LarryDFW

LarryDFW said:

Having used hundreds of 18650 cells in demanding appilcations . . .

I have more parameters that I look at:

(...) MUST meet U.L. 1642 standards

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That might be a good parameter for you, for your usage of cells, but it doesn't make logical sense here. I'm got Sanyos and IMRs to take for things like flashlights, powerbanks for phones, etc. But why would the cells being used in the crazy invention I've been talking about here, need to pass UL 1642?

Some of it, sure. But the short circuit test? Fact is that I have a protection circuit added to the cells for precisely that purpose. I would question whether the cells used in commercial OEM battery packs (where protection circuits are used for safety purposes) are always able to pass UL 1642. I don't know much about it, but it would strike me that that wouldn't be a requirement of each individual cell.

I'm not suggesting that I'm as smart as the people who design battery packs, but I'm also not selling my creation. So assuming that I haven't completely messed up the protection circuitry, why is passing a short-circuit test in 1642 necessary? Or for that matter, why do my cells need to be able to pass the shock-test? This unit is secured inside a Pelican case that can supposed be driven over by a car without sustaining damage. In fact, that "case" that houses my contraption is also supposedly bullet-proof (literally), although I would suggest that this depends largely on the size of the bullet.

At any rate, I know we all get a little peeved when people pursue "cheep", so I would encourage you to look at this particular case a little differently - the way I do:

- If you were trying to maximize your energy supply for a short period of time, while away from mains power, would you rather have a single high quality, reliable cell that spec'd out at a true 2600mAh, or would you rather have 4x low quality, less reliable cells that spec'd out at 1600mAh each?

Before you let your "quality instinct" lead you to the former, really put some thought into it. What if your own survival relied on having energy for as many hours as possible? Suppose the cells were somehow keeping you alive, and the longer you had power, the more likely you would be to be rescued. Would you really go for a reliable 2600mAh, when you could have 2 of 4 cheap cells fail on you, and still be ahead of the game?

Apart from the whole "survival" thing (because lets face it, I'm just a nerd that wants lots of power for gadgets while camping!), the above is not such a far-fetched scenario above ^. For the price of a good Sanyo cell, I can buy 4x cheap/generic/crappy cells. So don't think of the dichotomy as:
"should I spend a lot of money on cells not?"
Instead, think of it as:
"I'm going to spend the same amount of money on cells either way, so which approach will give me the greatest capacity?"

In that particular case:

Used Sanyo cells . .

MUCH more reliable.

LarryDFW

LarryDFW said:

In that particular case:

Used Sanyo cells . .

MUCH more reliable.

LarryDFW

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See - I'm not disagreeing with you. I think that may be the disconnect. I'm not disagreeing with anyone about the virtues of good cells. That's why I don't have any crappy ones to put into this project. I don't buy crappy cells. That's also the reason that I haven't the faintest clue which are the better of the crappy cells. I'm going to let this thread drop after this post, because I feel like I'm battling a wall of misunderstanding.

I want to preface what I'm about to say with the disclaimer that I want everyone to understand that I'm saying this with a :yh::yh: smile :yh::yh: on my face, and I'm not in the least bit angry or upset! In fact, this has been an eye opening thread for me. The lesson for me, is that it's really fraking frustrating when you ask for help making a decision based on very specific parameters, that you've deliberately chosen, only to have everyone under the sun tell you that you should have chosen other parameters.

I've done that myself, in many threads, and I can tell you one thing: I'm going to try not to do it in the future. It's one thing if someone comes and asks for help with a decision that they are basing on poor parameters out of ignorance. For example, if someone wants a 445nm laser that runs on AA batteries to "save money", it's probably not horrible to explain to them that their parameters might not be the best parameters to go with, for various reasons that they weren't aware of. That's a kind and helpful way to assist someone.

But it's an entirely different scenario when someone has parameters, again with shortfalls, but with shortfalls that they are conscious of and acknowledge. If someone is aware of those shortfalls and nevertheless chooses to go down a specific path after thinking through the ramifications, then debating them on that decision is no longer kind and helpful, it's patronizing. I've done that many times, and I'm going to make a genuine effort not to in the future. It's not productive, and it just frustrates the person who is trying to get some potentially helpful recommendations within a narrow set of parameters. It can be difficult enough to make decisions that have narrow parameters, it's all the more frustrating when people try to battle those parameters.

I don't think there was any of that negative stuff described above ^ in this thread - but that's part of the reason that I think it's a good idea to shut it down now and say "question closed, thanks for all the help, lets move on to a new discussion".


Again, I really do have a smile on my face right now. I'm not frustrated in my "heart", I'm grinning there. The frustration was mostly eye rolling, mixed with the little bit of excitement that comes when you think you've experienced a new side of the internet for the first time

I think Larry's onto something there. Ask someone in the IT helpdesk field if they have any old battery packs you can have. At the very least, you'll end up with a handfull of cells that, while used, have all been used at about the same rate and amount. To them, it's trash because the computer won't use it. Usually that means they are at maybe 70-80% of their original capacity at the currents that the computer would be drawing from them. To us, it's more than capable of loading a single diode and its supporting components, and I'd imagine your use would be just as "light" a load on the cells as our lasers and such.

Not to mention the tabs are already welded into usually 3s2p configuration, meaning fewer connections for you to make.