I'm going to go ahead and sling mud at iFixit for using a Battery pack instead of individual cells and springs. It also doesn't seem that this expensive power supply supports power pass-through. A soldering iron shouldn't have a shelf life. Easily replaceable commodity batteries with spring terminals are massively superior to packs. What a gross product that makes me think significantly less of iFixit.
They seem to have gotten so caught up in the "things should be repairable" that they've forgotten the true thing most people care about is, "I shouldn't have to replace my stuff". They are acting like parts salesmen, not consumer advocates.
$200(? looks like you get the iron when you buy the power supply) would be a fair price for the base if it allowed me to charge and use any 6 18650s(bonus points if it can accept a variety of cell sizes) as a power bank and had circuitry to do pass through as well as charging. It would also be nice if you could use it charge batteries to a specified amount, and use custom charge patterns. Considering this is iFixit, it should also have a way to use it as a DC power supply as well. $250 for a glorified power brick is pathetic.
I agree with you. We wanted to use individual 18650 cells so badly! We designed the whole thing that way. We did exactly what you proposed, and built cell balancing circuitry and code. It worked great! Then we went to the safety certification bodies and they said, absolutely not, there is no way you can sell that.
We tried so many avenues to persuade them, from proposing 18650s with built-in safety circuitry to showing the safety system that we designed into the pack. No dice.
There are a variety of safety standards to blame, but the primary one is UL 1642. It needs to change. I'm planning to join the standards body to see if I can shift things.
After my initial consternation about the temperature control costing $170, I think I have an idea that may placate my concerns.
A compact temperature control widget without batteries at all.
It accepts the appropriate USB PD power input in a standards-compliant way. It has a knob, and also a screen for status. It talks to the soldering iron and provides power to it. It does not have batteries or any special facilities for batteries *though if a user chooses to use it with an appropriate USB PD battery then they certainly can). This all seems possible, and adherence to USB PD specifications should tend to make it safe by default.
The rub, and this may not be possible at all, is that it must be substantially cheaper than soldering iron itself.
But because you've done the right thing and documented the protocol, then maybe someone else will implement this (as DIY or otherwise) and it won't be your problem at all. :)
Out of curiosity - why not offer tool battery adapters, e.g. DeWalt/Makita/Milwaukee/Bosch (depending which color you bleed). Those are ubiquitous 18v - have fast charging, and drawing 100W is fine even for the 1P types, e.g 2Ah. As a bonus they have excellent mechanical properties (usually PA6 or PC/ABC bodies - so even dropping the soldering iron on them would be okay)
Of course, a pack of 6x MJ1 is relatively trial to built (except it'd require some decent plastic body)- esp for 2s/3p, still not very useful aside running that particular iron/tool (and most likely end up charging it w/ the power supply...)
Sorry to hear that, and good luck. Additionally I apologize for the undue cynicism, but as a flashlight enthusiast I've been frustrated with this problem for years and years. The form factor of a battery charger and USB powerbrick/supply would be so nice! It's massively annoying to me that I own many 18650s and still need to buy and replace power banks.
Worse, it seems like the manufacturers best suited to make the product I desire(anker and nitecore) are directly incentivized by obsolescence to not ever make it. The best thing I've found so far is the Nitecore LC10, but it was discontinued. :(
I sort of suspected that it might be the case of safety bodies getting in the way. I really hope you make progress with UL. I'm rooting for you. There should be a way of overcoming this problem.
>Easily replaceable commodity batteries with spring terminals are massively superior to packs.
Spring terminals would be sub optimal drawing 10A off them as they are made of steel - high resistance. Developing any oxidation would make matters worse. Personally I'd not want 18650/21700 not properly secured (aside the rare case of running a fan with a single cell).
This (phosphor bronze springs) is, actually, pretty nice. 10A still should require either crimping or soldering, though. The flashlights draw significantly less current.
I can personally report that at 5A draw(the highest reported from any of my flashlights), these spring battery terminals still don't get hot. I'm not sure why I would need/want to push 10A to each battery? Drawing 5A already requires select cells.
I would rather batteries be field swapable than having a faster charge, which I try to avoid for the sake of their longevity anyway, personally.
> I'm not sure why I would need/want to push 10A to each battery?
Because the soldering iron in question dissipates 100W, and 100W is a substantial amount of power?
If a soldering iron is drawing 100W from a 2S pair of 18650 batteries, then:
The cells are supplying ~13.5A of current through their contacts.
To get below 5A, we'd need a six 18650s in a 6S configuration. Certainly doable (a relatively inexpensive [for a packaged battery] 24V Kobalt power tool battery has 6S 18650s), but beginning to be chonky.
But I guess I'm assuming that 100W is an ideal figure based on fully-charged cells of ~3.7v instead of a constant 100W, since that's the normal (if somewhat carpetbagging-esque) way to describe things in marketing world. This assumption points to 6s as staying below 5a.
At 3V per cell and 100W output, it takes 7s to stay below 5A. (7S little weird, and even chonkier, but not that weird.)
They seem to have gotten so caught up in the "things should be repairable" that they've forgotten the true thing most people care about is, "I shouldn't have to replace my stuff". They are acting like parts salesmen, not consumer advocates.
$200(? looks like you get the iron when you buy the power supply) would be a fair price for the base if it allowed me to charge and use any 6 18650s(bonus points if it can accept a variety of cell sizes) as a power bank and had circuitry to do pass through as well as charging. It would also be nice if you could use it charge batteries to a specified amount, and use custom charge patterns. Considering this is iFixit, it should also have a way to use it as a DC power supply as well. $250 for a glorified power brick is pathetic.