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

#181

Post by dfox » Mon, Aug 28, 2017, 6:02 PM UTC

SwellJoe wrote: post #148

dfox wrote: post #145

Earlier quoted context omitted.

Difference between messing with mains wiring and messing with high capacity batteries and/or solar panels is that mains always has some kind of fuse somewhere on the power company side and thus you will not see circuit that is completely unfused and will supply high currents until something blows up spectacularly and dangerously. This holds for significantly smaller things than DIY powerwall, eg. car batteries and ev…

I can't imagine Tesla would ship that battery bank without fuse protection inside (and I imagine it is a "no user serviceable parts inside" kind of design...it looks like a black box device). Every solar deployment design has fuses on either side of the batteries.

One neat engineering trick in tesla battery packs is that the last resort fusing is part of the battery pack construction itself (the spot-welded connection to the actual cell is intentionaly surprisingly weak to act as a last resort fuse)

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.

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

#182

Post by cucuuc » Mon, Aug 28, 2017, 6:30 PM UTC

SwellJoe wrote: post #143

cucuuc wrote: post #140

Earlier quoted context omitted.

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. 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 h…

"This community takes it as a given that "email is too hard" for an amateur to do right." 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 wir…

If you know what you're doing go ahead. I certainly won't stop a hacker from hacking. Don't expect your insurance company to share my general liberalism towards DIY.

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.

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

#183

Post by SwellJoe » Tue, Aug 29, 2017, 2:56 AM UTC

cucuuc wrote: post #182

SwellJoe wrote: post #143

Earlier quoted context omitted.

"This community takes it as a given that "email is too hard" for an amateur to do right." 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 wir…

If you know what you're doing go ahead. I certainly won't stop a hacker from hacking. Don't expect your insurance company to share my general liberalism towards DIY. 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 be…

You're talking about building a Powerwall from scratch. I'm talking about installing a pre-fab Powerwall as sold by Tesla.