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

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

#151

Post by kpil »

jononor wrote: post #95
Dylan16807 wrote: post #84

Earlier quoted context omitted.

High voltage, sure, but outside of an inverter that you can/should buy prepackaged none of this needs to be high voltage. The system in the embedded video has 14 sets of cells in series, meaning 40-60 volts.

Danger of electrocution is not particularly high, but can easy start a serious fire with such batteries. The energy capacity with create a seriously hot arc if shorted, and there is a potential for thermal runaway of the battery cells.

I once saw two marine lead-acid batteries explode and catch fire in the boat next to mine when the owner had dropped something big enough to short circuit and not disintegrate itself. Instead a fat copper cable exploded and then probably both batteries boiled, exploded and then everything caught fire. It took about 3 seconds.

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.

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

#152

Post by monochromatic »

askvictor wrote: post #5
ficklepickle wrote: post #3

This sounds like it could be rather dangerous, no? Connecting up a bunch of old lithium cells of unknown origin and using them hard. 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.

If they're from laptops the cells should be safe (as opposed to unknown new cells from AliExpress which may or may not be to spec); albeit not necessarily at maximum capacity. As long as appropriate protection circuitry is used, I don't see how using then hard would make any difference (laptops use batteries hard too).

Laptops catch fire sometimes.

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

#153

Post by Dylan16807 »

cat199 wrote: post #109
sumoboy wrote: post #55

Earlier quoted context omitted.

If it's not in the policy "we don't cover homemade lithium projects", your covered. Very few things a home policy won't cover like nuclear war, terrorist acts for example. If your operating as a home business building these then that could be an issue, otherwise you can be an idiot and build whatever you want and your covered.

We don't cover !@#$ing with the utilities in ways that are not standard is probably in there somewhere..

The tie-in to the utility can easily be professional or professionally verified. That's quite separate from the battery bank itself.

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

#154

Post by ZenoArrow »

noddy1 wrote: post #70

Question.. All my device lithium batteries seem to lose ~70% of their ability to hold charge after 500-1000 cycles, however the tesla car batteries/powerwall claim to give a decade+ of use despite being built of the same cells. How does that work?

Are they built of the same cells though? There's not just one single type of lithium battery, there are multiple different lithium battery chemistries, with different strengths and weaknesses.

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

#155

Post by agumonkey »

Dylan16807 wrote: post #146
PeachPlum wrote: post #121

Earlier quoted context omitted.

High voltage is 1000V AC or 1500V dc https://en.wikipedia.org/wiki/High_voltage

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.

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

#156

Post by agumonkey »

dmix wrote: post #147
seabird wrote: post #46

I appreciate the engineering and time people are putting into these projects. I absolutely hate the way this article is portraying these people's work. 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 cu…

DIY projects always get glorified like this. As if people figured out this secret trick to bypass consumer capitalism. When the whole idea of capitalism is about not having to invest a ton of effort into learning a new craft every time we want to use a new product/service. We pay companies to master that craft for us with money we earn from focusing on our own individual skills. It'd be more accurate to sell it as a…

That's the early on naive version of distribution of effort and mastery. The market evolves into a very average product quality and all kinds of tricks (focus on shallow quality, brand name versus longevity, repairability...) to improve benefits, which is the core signal in capitalistic feedback loops.

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.

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

#157

Post by agumonkey »

askvictor wrote: post #5
ficklepickle wrote: post #3

This sounds like it could be rather dangerous, no? Connecting up a bunch of old lithium cells of unknown origin and using them hard. 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.

If they're from laptops the cells should be safe (as opposed to unknown new cells from AliExpress which may or may not be to spec); albeit not necessarily at maximum capacity. As long as appropriate protection circuitry is used, I don't see how using then hard would make any difference (laptops use batteries hard too).

Most of the videos on the subject I've seen have a simple idea: depending on the battery, one cell could turn a whole pack off for safety. Pulling them apart, and rewiring them to a new (and probably better) Battery Management Chip, could make the N-1 pack working. They also often charge them a few times individually to assess their stability.

[1] one bad cell could force too much current elsewhere or overheat IIUC

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

#158

Post by agumonkey »

Baeocystin wrote: post #4
ficklepickle wrote: post #3

This sounds like it could be rather dangerous, no? Connecting up a bunch of old lithium cells of unknown origin and using them hard. 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.

Kind of dangerous seems like quite the understatement, considering the nature of lithium batteries! 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.

BTW I've seen lithium cell safety bags, that can hold the flame enough. I wonder how a case could be done in a similar way to at least contain the heat and gas.

Also, could there be a thermoelectric powered fan to slow down the heat rise when cell(s) starts to fail or burn ?

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

#159

Post by agumonkey »

Baeocystin wrote: post #111
noddy1 wrote: post #70

Question.. All my device lithium batteries seem to lose ~70% of their ability to hold charge after 500-1000 cycles, however the tesla car batteries/powerwall claim to give a decade+ of use despite being built of the same cells. How does that work?

If you never discharged below ~30% or charged above ~80% of their true capacity, and made sure they always stayed within a comparatively narrow thermal envelope, your batteries would achieve the same lifespan. 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.

From what I gathered, lack of internal voltage allow for different chemical reactions and structural changes that either create resistance, or actual shorts.

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

#160

Post by hwillis »

captainmuon wrote: post #83
hwillis wrote: post #15

Earlier quoted context omitted.

Tesla supported Kevin Mahaffey and Marc Rogers when they were hacking at their friends model S and trying to get root access. The model 3 repair support guide just came out and has diagrams of the battery pack down to the cells. Yes, they dont put the design of the car on github. They are hardly "incredibly proprietary" though.

Yeah but if you hack your Tesla even to change the color theme of the display, you'll probably loose warranty, loose certification status or whatever it is called (so you can't have any new parts installed unless it is expensively recertified), you'll get a call from Tesla asking what the hell you are doing, and so on. On the other hand, I can replace almost every part in my conventional car without ill effects from…

doing work on your car always voided your warranty, with good reason. That's not a realistic thing to ask. It's realistic to ask for the UI and apps to be open-source (say, something like android), but even that would be an incredibly open thing for a non-software company to do. I still think it's very unfair to call them extremely closed.

However, I really do wish they'd adopt a more android-like ecosystem.

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