DIY Powerwall Builders Are Using Recycled Laptop Batteries to Power Their Homes • Hacker News Board

Re: DIY Powerwall Builders Are Using Recycled Laptop Batteries to Power Their Homes

#171

Post by Zak » Mon, Aug 28, 2017, 7:21 AM UTC

voltagex_ wrote: post #164

Zak wrote: post #119

Earlier quoted context omitted.

You need to find a review written by an enthusiast with measuring, or at least estimating equipment. Assume all the *fire brands are outright lying. Cheap stuff claiming more than about 1500 lumens per 18650 is usually lying. There is, however a pocketable, $40 flashlight that makes an honest 4000+ lumens on a single 18650: the Emisar D4. There's a catch though: it's dissipating about 80 watts of power to do that and…

Any way to buy off Aliexpress without getting fakes?

A few of the budget brands like Convoy, Eagle Eye, and Maxtoch have official Aliexpress stores. I'm not sure about linking Aliexpress here, as the filter might think I sold my account to a spambot, but their store IDs are:

* 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...

Re: DIY Powerwall Builders Are Using Recycled Laptop Batteries to Power Their Homes

#172

Post by voltagex_ » Mon, Aug 28, 2017, 7:24 AM UTC

Zak wrote: post #171

voltagex_ wrote: post #164

Earlier quoted context omitted.

Any way to buy off Aliexpress without getting fakes?

A few of the budget brands like Convoy, Eagle Eye, and Maxtoch have official Aliexpress stores. I'm not sure about linking Aliexpress here, as the filter might think I sold my account to a spambot, but their store IDs are: * 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…

Forgive me for my ignorance, but why do I need my flashlight to have open firmware?

Re: DIY Powerwall Builders Are Using Recycled Laptop Batteries to Power Their Homes

#173

Post by parimm » Mon, Aug 28, 2017, 9:31 AM UTC

squarefoot wrote: post #124

One thing that often strikes me is the use of 18650 cells in an unpractical, though technically and economically correct way. Even low power laptops today employ series of multiple 18650 cells in parallel, so why not make an effort to bring down the price of bigger cells such as the 26650 or 32650? today the 32650 costs more than the sum of the 18650 cells it replaces, which clearly explains the wide use of 18650s, b…

18650's have a 18mm diameter. a 32650 would make most laptops too thick

Re: DIY Powerwall Builders Are Using Recycled Laptop Batteries to Power Their Homes

#174

Post by jhgb » Mon, Aug 28, 2017, 1:18 PM UTC

agumonkey wrote: post #155

Dylan16807 wrote: post #146

Earlier quoted context omitted.

If you're an electrician, yes. In casual conversation it can mean close to mains voltage or higher. That article itself quotes a bunch of wildly different standards.

I guess anything that can hurt enough to consider medical help is high voltage.

So that would be six volts or something like that? ;)

Re: DIY Powerwall Builders Are Using Recycled Laptop Batteries to Power Their Homes

#175

Post by dom0 » Mon, Aug 28, 2017, 1:22 PM UTC

dreamcompiler wrote: post #133

dom0 wrote: post #116

Earlier quoted context omitted.

With batteries (and even small battery packs) there are two main safety issues: (1) chemical combustion (due to mechanical damage or stress or electrical stress i.e. over-charging) (2) Burns and fires caused by arcing. 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…

> + Charger - | | |- Cell -| |- Cell -| |- Cell -| |- Cell -| |- Cell -| |- Cell -| |- Cell -| |- Cell -| |- Cell -| |- Cell -| | | + Sense - What is being sensed here and why is it wrong? If voltage is being sensed and the busses are fat chunks of copper, this seems entirely proper. What am I missing? EDIT: Wait, I think I know. You also need independent current measurement at each cell to detect internal shorts. An…

"Charger" would of course also be for discharge. "Sense" can either be charge sense, but that's not very common (due to CCCV charging), or monitoring. In either case, in this way of wiring things up the uppermost cell has a lower resistance connection to the charge/discharge port compared to the lowermost cell. So that uppermost cell will handle higher currents and overall will degrade more quickly. (This frequently applies when connecting "identical" parts in parallel in power electronics, e.g. capacitor banks).

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  -

As you can see the total length of wire/bus between the pack's poles and each cell is the same length, so has the same resistance.

Re: DIY Powerwall Builders Are Using Recycled Laptop Batteries to Power Their Homes

#176

Post by Zak » Mon, Aug 28, 2017, 3:40 PM UTC

voltagex_ wrote: post #172

Zak wrote: post #171

Earlier quoted context omitted.

A few of the budget brands like Convoy, Eagle Eye, and Maxtoch have official Aliexpress stores. I'm not sure about linking Aliexpress here, as the filter might think I sold my account to a spambot, but their store IDs are: * 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…

Forgive me for my ignorance, but why do I need my flashlight to have open firmware?

This is Hacker News. Open source is generally appreciated here even when there isn't a direct, concrete benefit to most end users.

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.

Re: DIY Powerwall Builders Are Using Recycled Laptop Batteries to Power Their Homes

#177

Post by korzun » Mon, Aug 28, 2017, 3:41 PM UTC

jerkstate wrote: post #165

korzun wrote: post #125

Earlier quoted context omitted.

The barrier of entry is ownership of a modern vehicle that you are willing to brick at your own expense. 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.

Well, what can I say. A lot of people are apparently taking that risk.

I know this industry well. Who is 'a lot' of people?

Re: DIY Powerwall Builders Are Using Recycled Laptop Batteries to Power Their Homes

#178

Post by EADGBE » Mon, Aug 28, 2017, 4:10 PM UTC

gruez wrote: post #51

JustSomeNobody wrote: post #37

Earlier quoted context omitted.

About the same as I feel about 95% of software running on the internet being copied from StackOverflow. Rather Meh. I would worry if the engineers at Boeing did it, but a bunch of crappy javascript apps running on the web? No. As for the neighbor, I don't live on a zero lot line, so let him burn his house down all he wants.

>About the same as I feel about 95% of software running on the internet being copied from StackOverflow. Rather Meh. I would worry if the engineers at Boeing did it, but a bunch of crappy javascript apps running on the web? No 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 sta…

I blame deadlines for most of the shortcuts taken, not necessarily "taking someone else's code".

Re: DIY Powerwall Builders Are Using Recycled Laptop Batteries to Power Their Homes

#179

Post by EADGBE » Mon, Aug 28, 2017, 4:13 PM UTC

korzun wrote: post #123

Matt3o12_ wrote: post #85

Earlier quoted context omitted.

Tesla‘s are literally killer machines. Accessing the high voltage cables is not difficult (they are only covered by a plastic cover which is easily removable). Those power lines can easily kill you. Even if you are very careful, even a small mistake with the wiring can have fatal consequences. There is a reason why you are not allowed to do wiring and a lot of electronics in your house by yourself. I certainly hope t…

I can tell by your post that you never did any sort of meaningful repair on a car. 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.

> I can tell by your post that you never did any sort of meaningful repair on a car.

Or their house. Especially with blanket statements that prohibit "working on" your own home.

Re: DIY Powerwall Builders Are Using Recycled Laptop Batteries to Power Their Homes

#180

Post by EADGBE » Mon, Aug 28, 2017, 4:17 PM UTC

serf wrote: post #92

Matt3o12_ wrote: post #85

Earlier quoted context omitted.

Tesla‘s are literally killer machines. Accessing the high voltage cables is not difficult (they are only covered by a plastic cover which is easily removable). Those power lines can easily kill you. Even if you are very careful, even a small mistake with the wiring can have fatal consequences. There is a reason why you are not allowed to do wiring and a lot of electronics in your house by yourself. I certainly hope t…

>Tesla‘s are literally killer machines. 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 t…

> There is a reason why you are not allowed to do wiring and a lot of electronics in your house by yourself.

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.