DIY Powerwall Builders Are Using Recycled Laptop Batteries to Power Their Homes
motherboard.vice.com
motherboard.vice.com
These are not "consumers who can't afford commercially produced powerwalls." These are people who could probably work professionally in the field if they're not already. These projects are not "a little research, invested time, and a little ingenuity," they are the culmination of years of experience and passion, along with extreme respect for the technology.
Don't get me wrong, I want people to do this. However, acting like people can safely dive in to high-energy electronics/electrical projects head-first is stupid.
Awhile ago I did a some volunteer work at a radio station. One of my tasks was to check for arcing. That involved going into the transformer room, disabling the safety systems, unracking some of the electrical components, powering the system on, turning off the lights and then looking for flashes from electrical arcs. It also involved going out at night with night vision goggles to check for arcing on the antenna. If we saw anything we knew what needed to be fixed. Safety was important there, but I developed a healthy respect for electricity. After working there I'm a little freaked out about the idea of dealing with high voltage systems.
http://batteryuniversity.com/learn/article/safety_concerns_w...
[edited to add link]
Banks would object to policies that excluded unpermitted work, since it's relatively common and this type of exclusion would leave them with lots of exposure.
So, they may decide to drop you like a hot potato afterward, but a fire from your homebrew powerwall would likely be covered. Read your policy fine print to be sure.
18650s are just as safe as any other battery chemistry in everyday use, but they're a high energy lithium cell. In particular, if you do bad things to them, they may light on fire. It's not that hard to take appropriate precautions to avoid that, and reasonably sized lithium-ion battery fires can generally be put out with a standard househould fire extinguisher.
It also appears the community is collaborating to spread good information about powercell design to avoid/manage fires inside the units, in the unlikely event a cell starts a fire. If the container for the powercell is designed correctly, it can contain a complete unit burndown: https://electrek.co/2016/12/19/tesla-fire-powerpack-test-saf...
In short, you're overestimating the risks and underestimating the level of safety attainable with these products.
No. When it comes to things that might produce fire inside your house, there is no such thing as overestimation. You cannot be over protective when it comes to fire safety.
Source: I was a firefighter for +7 years.
Ridiculous. There are obvious examples of overestimation of risk, why not prohibit electricity in homes entirely for example? Should I get rid of my kitchen stove?
This kind of absolute rhetoric is banal, obviously absurd, and is not helping anyone.
Effective safety measures involve accurately quantifying and balancing risk.
Have you ensured your house is built exclusively of fire resistant materials, and avoided buying modern furniture with inflammable fabric covering and interior padding? Have you installed a Halon system in your home and all physically adjoining structures?
What an absurd statement.
I did the same to fix one of those $40 dollar Swiffers (i.e., we're not really talking about powering industrial steel chop-saws powering through I-beams). It drew ~2.5 amps at no-load, no problem.
OSHA[1]:
"17-90mA" : Death is possible.
"90mA+" : Death is likely.
And remember breakers blow only when the sub-circuit's current exceeds the threshold (generally ~15amps in the US) so you can spec a standard gauge of wiring sufficient to consistently draw that current, not overheat and burn your house down. It's (generally) not checking to see if the current sunk = current sourced. You need GFCIs("RCD"s in other locales) to actually get that functionality.
The rule of thumb I've heard is 50mA passing through your heart is where the v-fib dangers begin. The real risk begins at as low as 20mA, because thats when your hands lose their muscular control. You can't let go of the source, and your heart enters v-fib (~100 mA) and you get oxygen starvation and brain death[3]. You have tales of people using one hand to support themselves on a grounded breaker box, using the other hand to just have a look-see, and not even realizing they're in v-fib, feeling a little 'off', sitting down for a bit to catch their breath and found dead 20 minutes later next to the box.
Your body basically acts as a resistor in parallel with the circuit. Here's the ASME's resistance model of an adult males' body[2]. As you can see, you're body is definitely not a 10meg resistor. If you're working in damp, humid, or hot (i.e., you're perspiring through your hands, and that Na+ is just looking for a donor electron!), the risk increases. Whether you're working on a 460v3ph 15 horsepower Hardinge lathe or a Swiffer, the best piece of advice I ever got was "have a healthy respect (and fear) for your tools". Use isolation transformers, current limiters, and CAT-rated gear and read a sufficient amount of information to inform yourself in advance of the potential risks[4].
======
[1] http://web.archive.org/web/20130428070054/http://www.osha.go...
[2] http://risk.asmedigitalcollection.asme.org/article.aspx?arti...
[3] Brain death I've always heard is ~5 minutes for an average adult male with a decent pulmonary system and respiration capacity-- less if you're a couch potato with less lung VO2 capacity, more if you're Lance Armstrong. Obviously not a physician.
[4] I was googling to pick find a diagram to depict the resistance model of a human and stumbled across Allaboutcircuit's safety text (chapter 3, for those who are wondering). It's pretty good for "general" electronics. Obviously if you're working with things like tubes ('valves'), transformers, and other subsets, you're going to want to read about the safety precautions you want to take for those specific areas as well.
Luckily he avoided the acid spray, but he had to empty 4 large fire extinguishers from the nearby boats to put out the fire and cool down the remains of the batteries enough so they did not immediately catch fire again.
I have a huge respect for what a huge solar array and a big bank of batteries can do after seeing what a relatively puny battery could actually do.
A standard AC system can't deliver even a percentage of that current.
Driving home in the rain, and the tail light wires were submerged in water that was pooling in the trunk and shorting out. As I put my foot on the brakes - on the freeway in the pouring rain - the fusible link in the engine bay decided to just catch on fire instead of being a fusible link. The battery quickly boiled and I had a sudden and catastrophic engine bay fire on a crowded road.
A car battery has enough amps to literally use as a welder (two jumper leads, an arc welding rod and a 550CCA car battery is enough to stick most things together in an emergency :P ), and is more than enough to create a massive fire.
I wouldn't go anywhere near a diy power bank without proper knowledge and training.
For (2) the exact configuration basically does not matter, because generally speaking all battery packs capable of storing a large amount of energy are also able to release a large amount of energy in short time. So if you cause a short you'll always get a nice arc. Note that most kinds of protections are way too slow to suppress arcing, so you can always burn yourself. Arc-fault detection is more difficult in DC systems as well.
(1) is mostly a matter of doing things right. This means active temperature monitoring and measures (cooling, venting, shut-off) for larger packs. Independent over-voltage and over-current monitoring. And of course the little things, like wiring things up the right way and placing sense wires at the proper locations. For example, this is a simple thing of doing things wrong:
+ Charger -
| |
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
| |
+ Sense -
——————
I did a few things with a few types of batteries (lithium ion and lead) and these little cells can cause an impressive amount of uh "disturbance" in short order. I admit I am almost as careful (in a different way, obviously) with them as when handling high-voltage things like the HV oscillator in an old 'scope.
+ Charger -
| |
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
| |
+ Sense -
EDIT: Wait, I think I know. You also need independent current measurement at each cell to detect internal shorts. And probably a way to automatically isolate such cells.
Technically it depends on the cell chemistry and how they fail.
If the voltage feedback (assuming there is any) is taken from the lower side, then a reduced voltage (by U=Rbus×Ibus) will be measured, which is lower than the voltage present at the cell terminals. Siblings mentioned that you want protection against internal cell shorts, using fuse wires or similar.
A better configuration would look like
+ Charger
|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|- Cell -|
|
Charger -
In casual conversation it can mean close to mains voltage or higher.
That article itself quotes a bunch of wildly different standards.
Years of effort and learning have culminated with these projects that they've undertaken and executed.
We should NOT undervalue that.
https://www.reddit.com/r/AskElectronics/wiki/beginners
tl;dr; do not attempt anything with powerelectricity without safety precautions
ps: there are many electric safety pdf issued from various US states such as https://www.dir.ca.gov/dosh/dosh_publications/Electrical_Saf...
It'd be more accurate to sell it as a rewarding experience to do as a hobby rather than a clever cost-saving commercial solution.
If money and ROI is the primary focus then most specialized knowledge could be better utilized in other ways than simply building a product once for yourself in your spare time.
It's also good to do stuff on your own. I have to admit, I am too dogmatic about not buying new things. It's only good if you have time to invest it's true. But after a threshold it's of great value. I remember the fear of electronics and household appliances, it's now gone. Capitalism turned optimization into blindness.
If you want to build your own open source battery storage system, battery management system firmware, and distribute it online (think Backblaze), I'd encourage you to do so. But Tesla has enough to worry about as it is.
A similar argument exists for why DIY battery banks are not ideal. It's not inconceivable that some dedicated hobbyist engineer pulls it off in a safe way. But how would you feel if you were over in your neighbors garage and noticed he had haphazardly wired 600 18650 cells together based on a design he found on the internet?
This is exactly the type of attitude that leads to the proliferation of vulnerabilities on the web.
"It's not like we're using it to fly planes, so who cares if we're not checking every SQL statement for injection vulnerability"
Then the code gets used on some ecommerce site, the site inevitably gets hacked, and customers' PII gets leaked.
Don't forget John Deere tractors!
I think there are as many or more car hackers than ever - CAN bus opened car hacking from the world of the gear head to the world of the computer geek.
I so strongly disagree with this assumption. We got a nascent not even close to open source scene on x86 and a few hobbyist tweak boards. They still use proprietary hardware, the firmware is still almost always proprietary, the drivers are often proprietary, and for general users 99% of their OSes are proprietary.
And the consequences of that world that doesn't care about right to repair or software freedoms or having control of computers impacts me. I can't get an x86 pc now without a hardware backdoor, I can't use 802.11an wifi without proprietary code, I can't display visuals to a screen without proprietary code. The screen itself is running a ton of proprietary code. My hard drive has a computer in it and thats wholly proprietary.
And that was in an ecosystem where moddability was handed to us on a silver platter with ACPI which only existed for IBM and Microsofts sake, not for anyone elses. It was not a charity. That is why we still have no mobile platforms that use a standard hardware abstraction layer that you can run a generic OS on.
The Internet of Things never developed an open source ecosystem. SmartTVs never developed an open source ecosystem. Set top boxes and consoles never devleoped an open source ecosystem. Cars almost certainly will never develop an even remotely functional open source ecosystem - companies will use open source code, because someone else did the work for them and they can save money. They won't contribute back, they won't respect their users, and they won't respect the developers that put in thousands of hours of free labor by sponsoring them. That isn't open source winning, that is corporate profits winning.
Look at John Deere. That is where we are going. This is not going to be a simple matter of find the ethernet jack, telnet into a shell, and start running code. This is signed payloads, read only rom, and no way to access the firmware.
If there is an open source car ecosystem, it will be like the open source phone OS world. A joke, that cannot practically run on anything, that at best is ripping half of the Android equivalent out of itself to even run. And I guarantee Ford et al will never be as philanthropic as Google was in open sourcing Android to release their car OSes middleware like that.
You can't 'throw hackers' at something like that.
The car manufacturers have all of the control, and in a sense, it is black magic.
The right to repair died once magic computers came into the world. Before that trying to tell anyone their mechanical / electrical systems were undocumented proprietary and warranty breaking if you tried to repair them would have caused a riot. But since computers were sufficiently magical that a critical enough mass of people wrote off trying to understand them, the industry and all resulting industries undermined the right to actually own anything related to them.
On the other hand, I can replace almost every part in my conventional car without ill effects from the manufacturer.
Was trying to help a relative with some issue with their car the other day, and the wiring diagram for the part and related controls almost seemed to run in reverse depending on how the switch was set.
However, I really do wish they'd adopt a more android-like ecosystem.
Sure, it would be nice if they could make service manuals and service parts more freely available, but the same could be said of all car manufacturers.
There are guys on YouTube who have re-built entire Teslas from near-scratch using salvaged parts from multiple vehicles. Guys with no formal training and no previous experience with EVs. Tesla does not do anything to make their cars hard to repair.
I'm not in the EV or Tesla communities, but I remember reading something about "activation" being required?
If you can prove that the vehicle has been appropriately repaired (by a qualified body shop, since it's a safety issue in the case of structural damage), it can be re-activated.
But Tesla does not remotely disable vehicles or anything like that. Even if it's been written off, theres nothing to prevent it being driven just like any normal car once repaired.
There's making parts "more freely available" and then there's "you can't have this from us, for any price". Fortunately the ludicrous amount of power in the Model S and people's inability to control the car (or themselves) means there's a good sized underground market of salvaged Model S' bodies and parts, even if there's no office service manual available to amateurs.
Meanwhile, Chevrolet will just sell you the engine from a corvette in a crate. (Okay, it's ~$12k, but they're willing to do it.)
I say this as someone with a Model 3 reservation, mind you. Tesla wants to build the iPhones of the electric car industry - no user-serviceable components inside, and the battery isn't removable by us mere mortals who don't work at Tesla. (Abandoned battery replacement tech demos from a few years ago aside.)
But certainly on the Model S, the battery is not that difficult to remove/replace - again, there's plenty of YouTubers who have done this.
You can even, in many cases, swap a higher capacity pack into older/lower-spec models if you're so inclined. There is no DRM or software checks that prevent this from working!
They do actually make the manuals available to anyone, just for a hefty fee if you're not Tesla-certified:
I understand why they do it, but it means that for the segment of the population that enjoys that kind of thing, and knows how (I've done my own solar installations, and helped others, on multiple RVs) I have to use much less awesome components. I wanna play with the tech and save a few thousand dollars, but that's not an option for Tesla solar and Powerwall gear. I also want to use it in ways Tesla won't allow (Powerwall can't be installed in RVs or manufactured housing like a tiny house on wheels, for example, even if one were to design the house around safely doing so).
Big retailers like Lowes cultivate a reputation of catering to construction workers while also being approachable to weekend warriors, which insulates them from the downside of product safety issues, somewhat.
I can also go to the same store and walk out with a roof-sized pile of roofing tiles. No one will stop me from putting on my own roof.
Hell, Tesla sells cars. The single most deadly consumer product, by far, in the world. Admittedly, people have tried to sue them about their autonomous features, but still, cars are really deadly and no one blames manufacturers for those deaths (though, we do, as a nation, impose some safety standards...but, it doesn't stop tens of thousands of deaths every year). Tesla is arguably much better about not killing their customers than some other manufacturers, but they already operate in the most deadly industry (aside from, say, coal or fossil fuels, but the deaths caused by those industries are generally an amorphous statistical blob of health problems rather than distinct deadly events).
My point is: Unless Tesla has built a dangerous product, there's no safety-related reason it should be treated differently than other home improvement items that require the same types of skills to safely install them. Electrical and solar power are well-understood by plenty of non-professionals. I do see the appeal of making it turn-key; they're aiming for average home owners, particularly at the time of construction or roof replacement, when there are already contractors involved and a mortgage to pay for everything. A large-scale solar power installation is expensive, and it makes sense for most people to work it into their mortgage.
But, it's frustrating for me; when I build a house (and I'm kinda shopping for land now in a casual way), I plan to self-fund it and do a lot of the work myself because I enjoy that sort of thing. There won't be a mortgage, and I won't be paying for contractors to do things I can do myself. Electrical work is well within my comfort zone. So, it's frustrating that when I install solar, it'll have to be the somewhat less attractive panels rather than nice-looking tiles.
It's certainly Tesla's right to sell their product however they like. But, I reckon I can complain about it, too.
Everything you said is 100% correct, but just look at all the extra news and scrutiny that's given to every Tesla crash. Or the people warning of the dangers of fidget spinners:
http://www.goodhousekeeping.com/life/parenting/news/a44415/m...
Which ppl manage to f. up all the time anyway (missing ground, neutral and live swapped, splices used in lieu of a longer length of cable, improper gauge, poor cabling technique)
This community takes it as a given that "email is too hard" for an amateur to do right. Then how is wiring a house considered easy when the electrical code books are thick as bricks?
I don't.
I work on software (http://www.virtualmin.com) that helps over 100,000 people manage mail servers (and web servers, and databases, etc.) for themselves. So, I disagree with the premise that email is too hard.
"Unless you're an EE and an expert in power supplies, this is way more dangerous than splicing some copper wires and following some building codes."
Is it? I don't understand how. It is a battery bank. You hook up your charge controller (two wires) and your inverter (again, two wires). Same as you would for any battery bank...it's just a better battery bank, and battery installation aint rocket surgery. (Here's a diagram: http://i.imgur.com/jXuag5l.jpg )
If one can understand a solar panel installation in the general case, it seems pretty clear that one can understand Powerwall installation. In fact, building your own battery bank is more complicated than the Powerwall, since you have to wire up all of the batteries, and figure out how to protect them from over-charging and over-discharging. Tesla provides the smarts and bundles up all of the batteries for you.
Some people like to be self-reliant and understand how things work.
Again, I can't stop Tesla from selling their products this way. It's certainly their right, and I'm still pleased with Tesla's existence (and I have a standing buy order for TSLA if it ever drops low enough, as I regret selling the TSLA I was holding a few years ago). I believe in Tesla. I just wish I could buy Tesla products and use them the way I want to.
Edit: for instance accidently shorting net 30 to ground when working on car electrics might well end in the car being completely destroyed by ensuing fire (I have friend who totalled his car in this way, he is licensed electrician). On new cars the fuse between 30 and 30a is usually placed directly on the battery to prevent exactly this issue, but even 30a will supply enough current to wreak havoc.
On the other hand, the difference is in that for the mains there is always going to be some kind of fusing, that is not part of what the tinkerer owns and probably does not even know where it is located. For solar and huge battery packs you own the whole thing and can mess with anything in the system, even more so when you build the thing from individual cells instead of buying COTS solution with bunch of "no user servicable parts inside" labels.
If you don't know what you're doing, go right ahead anyways. It's not my house and my family in there.
But this is hard.
Did you know that DC can't use AC switches rated for the same voltage?
How about cooling the packs? whats the appropriate distance between the packs as the geometry of the heat dissipation changes from 1D to 2D to 3D?
Are you going to cool with forced air or passively? If forced, what if there's a power outage during battery bank failure (highly correlated know that you wired the bank to the mains). If passive, how do you ensure that the environment is always providing suitable cooling?
That's a bit of domain knowledge that most ppl who know how to wire a socket don't know. That's also a house fire type mistake when your dealing with a battery bank.
and its headline news whenever their cars kill someone
I certainly hope that Tesla will provide manuals to highly trained electricians at some point, but if Jone Doe tries to fix his electric vehicle by himself and makes a fatal mistake (or maybe even starts a fire), that will only make national news and scare more people into thinking electric vehicles are inherently more dangerous then traditional cars (which they are not).
I can understand why Tesla does not want to take that risk.
So are all cars. Under-skilled people routinely (and legally) repair and maintain the systems that make these vehicles drivable (brakes, steering, suspension, etc).
Some folks are killed in doing so, much like any activity, but not any number that is out of proportion and typical with any activity where small mistakes can cost lives.
>There is a reason why you are not allowed to do wiring and a lot of electronics in your house by yourself.
That's not true in many places, much of the United States included. Only inspection is mandatory in most cases, barring specific regional laws. Again : Those that do their own work aren't just dropping like flies. A few accidents occur, but nothing of any proportion to require legislating more strict laws regarding such things.
>I can understand why Tesla does not want to take that risk.
My understanding of why Tesla acts the way they do has nothing to do with the complexity in their systems and danger in working around such complexity, but rather their interest in more protection for their IP, their desire for keeping customers within their own 'walled garden' of service options, and for controlling public perception of their product, all to the disservice of the customer (much like John Deere's behavior these past decade or two).
We aren't strangers to 'killer machines'. This isn't any new phenomenon. It's being framed that way by some to rationalize over-protective and controlling corporate behavior towards the consumer, and Tesla isn't alone in exercising such power.
I've found that a few people here really don't understand some industries; yet are adamant about their opinions on said industries.
A few weeks back I was just in an argument with someone (may have been another account, though) about high-voltage lines in the US used for dryers, and how "magically converting a 120V line" (paraphrasing) to 240V was just super dangerous and a death sentence. Point is, arguer had no knowledge of two phased 120V lines in US electricity and combining the two was sure to burn a house down. But they sure did have an argument.
FWIW, this form is so much more argumentative than others online about other topics not understood. I think that's part of the IT/techy/hacker culture.
Yet, for some reason, you seem super concerned about what other people might do.
Is there a term for this kind of bizzare nanny behaviour?
Why pretend that you know what you are talking about and then take a step further and not only suggest ridiculous 'solutions' but push for regulations.
Or their house. Especially with blanket statements that prohibit "working on" your own home.
I'd also worry about an insurance claim being denied if it burned my house down.
However, I very much approve of the DIY ingenuity and repurposing of old stuff.
It'd be fun to play with something like this for the learning, but I wouldn't actually run one unless it was in its own shed, many dozens of yards from the nearest anything else. Lithium fires are no joke.
But also, on the video, they shows each pack of cells he uses has individual over and underchange and temperature sensors, so the system is able to tell if any individual section is going bad. It's a pretty neat, and external installation, so I don't think it is very harmful on a "massive heat incident".
Notice how many qualifiers are used in that statement.
Also, could there be a thermoelectric powered fan to slow down the heat rise when cell(s) starts to fail or burn ?
Thanks nonetheless for the return
Many of those are actually recycled old cells, likely from laptop batteries, and could still have a lot of capacity left --- often, what happens is that one of the cells in the pack fails/goes out of balance and the protection circuit disables the whole thing, meaning the rest of them are still very much usable.
[1] one bad cell could force too much current elsewhere or overheat IIUC
But there's no explosion risk unless there's something very wrong with the way they're packaged.
> Even new pouch cells are way safer than they used to be.
Right, because these packs filled with recycled cells are going to have the latest protections.
> Unregulated 18650 cells are quite safe if the correct circuitry is used.
Which is my whole point, I'm not sure I trust the guy down the street to correctly wire and have adequate circuit protection for his DIY battery pack in his garage.
> The only dependable way to ignite them is to smash completely open them at full charge.
That, to my untrained eye, looks like enough batteries to take down nearby structures if they went up, and packaged in such a way that a runaway in one cell that caused it to vent would propagate to other cells nearby.
Granted they're pretty reasonably protected by 2-3 layers of electronic monitoring and on-cell fuses, but lord, a small fire would burn the neighborhood.
I think all that it would take to render them marginally safer is a firewall between the different packs made of some good steel or refractory material.
Or if an unrelated fire occurs in the garage/basement where it's located...
This is certainly enough stored energy to seriously ruin a firefighter's day if they didn't know it was there and how to properly deal with (or, more properly, to not bother dealing with it until it burns out).
The last flashlight I bought requires them too.
You can find 18650s for sale on walmart.com . I'm not sure if the physical stores carry them, because there aren't any where I live, but I know that in Shenzhen/HK and other parts of Asia you can easily find 18650s for sale amongst other batteries in physical stores.
Because of the high discharge you can hurt yourself or start a fire much more easily. Just look at the stories of people with burns on their thighs from throwing them into a pocket with keys/change.
NiCd/NiMH can also source huge currents if shorted.
Flashlight geek here. Several people on flashlight forums have reported finding the Westinghouse branded 18650s in physical Walmart stores. They have a low capacity - 2000 mAh, compared to 3000-3500 for the latest cells from Sony/LG/Samsung/Sanyo/Panasonic. They also use a cell of unknown manufacture, so I can't be sure of the quality.
Specialty battery stores, higher-end outdoor gear stores and vape shops have 18650s, but it's best to get them online from dealers that know what they're doing. In the US, good options include Illumn, MTNelectronics and Li-ion Wholesale. These places have the gear to test batteries to make sure their suppliers didn't send them fakes, and usually have very competitive prices.
Can I ask a flashlight question? :) How do I tell how many lumens a flashlight really is? I go on Amazon and I see XyzFire flashlights that claim to give out many more lumens than would make sense, and many times they're inconsistent on the page itself. I don't know how to really tell. (If it matters, I'm trying to find a flashlight that fits in my pocket, is < $20, is ideally zoomable, and is as bright as possible. Best one I've found so far is this: https://www.amazon.com/gp/product/B011B1U2QS)
As to your request, a couple general recommendations first: skip the zoom, and don't chase output numbers. Zoom is pretty optically inefficient, and small zoomable flashlights don't end up with much more throw distance than similar size fixed reflector flashlights. They don't do wide-angle illumination as well either. A good reflector with sufficient output provides both at once. As for brightness, human perception of brightness is roughly logarithmic (with a base between 2 and 3), so it takes four times the output to look twice as bright. Anything over about 500 in a pocketable flashlight is pretty decent, and most 18650 lights have more.
Specific recommendation: the Wowtac/Atactical (both names show up on Amazon sometimes) A2. This is one of the smallest 18650 lights, has shortcuts to low, high and last-used modes from off and has a right-angle configuration that works equally well handheld of as a headlamp. A pocket clip, headband and 18650 battery with built-in USB charging port are included. It costs $20, and I have no idea how they make a profit given all the stuff it comes with. Go with the neutral white tint if you can find it; this looks more like sunlight and won't wash out colors as much as the cool white.
* Convoy: 330416
* Eagle Eye: 1735126
* Maxtoch: 314381
All three make good stuff that has been popular with flashlight geeks. Convoys with "new firmware" or "Biscotti" have an open source firmware: http://bazaar.launchpad.net/~toykeeper/flashlight-firmware/t...
But if you're here, there's a good chance you're the sort of person who could get an AVR programmer and tweak something if you don't like it. Different modes? Timed stepdowns to prevent overheating or not, or more sophisticated thermal regulation for the attiny25 based drivers that have a temperature sensor? A firmware with completely different behavior like near-continuous ramping instead of fixed modes?
It's hackable, and hackable is good.
They are, but IME the sourcing on some of those (especially through Amazon.com, which comingles items from different sources) is hinky. That 18650s can be dangerous if misused or if counterfeit isn't an argument for restricting availability, it's an argument for making them available directly to consumers from legitimate authentic sources.
This isn't much more dangerous than putting batteries in a toy car, or putting gasoline into a hybrid.
Edit: Thanks for the answers. 2 questions:
1. Why would you not do this?
2. Were you to do this, what precautions would you take?
Someone must have a PE to sign off on certain things when dealing with regulators and so forth. Which makes getting a PE in certain situations important. But not having a PE is hardly equivalent to calling yourself a lawyer if you haven't passed the bar in a state.
http://www.mystatesman.com/news/state--regional-govt--politi...
And the relevant court case:
http://www.soah.texas.gov/pfdsearch/pfds/460/16/460-16-0550-...
I'd note that's a case where a business is representing themselves as an engineering firm and, and in some situations, it would be reasonable to expect that meant they employed licensed engineers. (The specific case is pretty silly though so is calling themselves engineers.) But individuals certainly call themselves and are called engineers all the time who aren't licensed in Texas and everyplace else.
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doesn't seem to have scared too many away from the title..
What area do you work in?
http://www.popularmechanics.com/home/interior-projects/how-t...
http://www.candlepowerforums.com/vb/showthread.php?141137-In...
And also: http://budgetlightforum.com/node/45314
I bought the latest version of the C2 and it charges perfectly.
The last quarter-charge in either direction is where ~80% of the lifecycle wear comes in, and temperature excursions account for much of the rest.
With all the added work, buying just one type of cell seems way better. But really, why not buy deep cycle lead acids and an auto-watering system? No hype!
18650s are great! It's awesome to know you can easily and cheaply fix an old laptop battery to better than it's ever been by replacing the cells with some nice new VTC5s or 25Rs.
Hooking up tons of them with varying capacities and levels of resistance is surely not wise.
Ecig user knows using even an un-married pair of 18650s in a dual 18650 mod is a recipe for blowing up in your face sooner or later.
Idk, maybe there's something with such a large number that makes it less likely to fail catastrophically?
Okay, fine, take some risks you innovators you! Just don't expect me to play a sad song if the experiment burns down your house, your neighbor's house, and results in criminal charges. Really, I'm not being glib. I will continue not being glib if what I foresee comes to pass, with potential serious damage to life and/or property. GL, HF.
I think it could be bad if the resistance of one increases and you have a bunch of them in series...
https://motherboard.vice.com/en_us/article/kzz7zm/diy-powerw...