
Using old laptop batteries to build homemade powerwalls - jonbaer
https://futurism.com/people-are-using-old-laptop-batteries-to-build-their-own-versions-of-teslas-powerwall/
======
phil21
The comments here are more evidence the "hacker" part of hacker news really no
longer applies :)

In seriousness - of course putting this in your house is a a pretty risky and
likely dumb idea. I absolutely have plans to do this though, just with a fire
resistant (concrete block) "power shed" 50 yards away from my house.

Someone that can build a working DIY powerwall can cheaply build a cinder-
block shack and run conduit back to the living quarters. If you can't afford
to do that I'd say you can't afford to do the project at all.

~~~
thaumaturgy
"Hackers" historically developed such a depth of understanding of some system
that it allowed them to modify and subvert the system to suit their needs. The
people here who have built power systems for Battlebots and are familiar with
the variability in specifications for 18650 cells and are saying that this
isn't a good idea for reason X, Y, and Z, those people are the hackers.

The people that are saying, "a battery's a battery, I'll just put it in a
shed" are dabblers. They don't understand the technology well enough to do it
safely, so they just build it with the assumption that it's going to go FOOF
someday.

~~~
amphibian87
A battery _is_ a battery, any lithium battery from a drill to a tesla is
simply a 1.5 volt cylindrical cell stacked in series to produce the desired
Voltage, then these stacks are connected in parallel or series again as needed
(depends on application) to increase the load it can handle (Amperage).

The safety features you're so worried about are just fuses. And maybe some
diodes if you're that worried. I can say that installing a bank on a piece of
plywood on your garage wall _is_ obviously stupid, but a simple opening of the
NEC book will show the code for a battery bank, _shall_ have clearance from a
wall and rest on non-flammable/non-conductive material, usually in a nuclear
power plant or a substation we would build a rack out of metal then install
ABS plastic shields.

Source: I'm an industrial electrician and went through an IBEW apprenticeship,

~~~
vvanders
Nope, different lithium batteries have different chemistry compositions.

A LiFePO4 will happily catch on fire if you charge it with the same
voltage/current curve as a LiPo(3.6v vs 4.2v).

[edit]

To expand a bit, this[1] is a fantastic reference on exactly how complicated
and involved the different chemistries can be. This is talking about Lead ->
LiFePo4 but a lot of stuff applies to LiPo and other variants as well.

[1] [https://marinehowto.com/lifepo4-batteries-on-
boats/](https://marinehowto.com/lifepo4-batteries-on-boats/)

~~~
ScottBurson
From your linked article:

> Please note that in all 68 of these RUINED LFP banks, that I have to date,
> there was not one incident of fire, explosion or dangerous off-gassing.

So you can destroy them easily by overcharging or other mistake, but LiFePO4
is probably the safest of the lithium chemistries as far as fire goes.

~~~
vvanders
Fair enough, I'm used to pushing the packs a bit harder on discharge so I
swapped that around(charge/discharge).

------
Roritharr
This seems like a great way to burn down your house and potentially injure
firefighters coming to your rescue. Seriously this is quite a few leagues
above normal DIY territory. Proceed with caution.

~~~
ChuckMcM
Exactly right. It will catch on fire, it will burn down the house. I expect
the insurance would not cover it (just like it doesn't cover fires caused by
storing gas or propane in your garage)

I got a crash course on battery charging subtleties when building battle bots
and there are _many_ ways this can so south quickly, not the least of which is
a battery in the middle of the pack developing dendrites and deciding its time
to burn. The only way to prevent that is to have temperature sensors on every
battery and a good enough model of the heat convection between the internal
battery and the surface to recognize the temperature rise of a battery on its
way to failing. Even with modern "battery monitor" chips like the ones Maxim
and others sell there are corners in charge rate/temperature/battery that can
get away from the algorithm before it recognizes a battery failure.

The reasons this is "easy" with flooded lead/acid batteries is that, when they
fail, the lead doesn't then turn into a torch at 500 - 600 degrees F. So you
have a chance to fix failures and move on.

~~~
fr0sty
> I expect the insurance would not cover it.

I see this blanket assertion in lots of comment threads, but never with a
citation.

> (just like it doesn't cover fires caused by storing gas or propane in your
> garage)?

This is an assertion I have never seen before. It is extremely common to keep
gas cans in the garage around here (IL, USA), where else would you keep them
that is safer?

~~~
ChuckMcM
I have discussed it at length with the USAA insurance people, I expect there
are policy documents on their web site. The _exact_ discussion was, "If the
source of the fire is tracked back to a leaking gas can or a propane tank we
won't cover the loss, we recommend you store flammables in a shed away from
your house."

My impression from them was they were very dubious about "off book" uses of
things as well, which leads to my expectation that they would push back on
covering a loss due to a "home made" battery wall. Could I sue them and get
them to cover it? I don't know, perhaps. But, as with my propane tanks, I
would keep this stuff out away from the house to limit my losses and avoid
having to go there.

------
danielvf
Once I volunteered at a large tech non-profit. Between projects, I took over
an unused desk in the sysadmin team cave. After lunch one day, I heard a loud
noise. I went to the cave door - it looked out over a large cubicle farm.

There were now a dozen fires burning over a forty foot diameter, along with
little bits of smoldering cubicle wall.

Someone had apparently removed the battery from a laptop, plugged it into a
bench power supply, and then gone off to lunch. It exploded in their absence.
It gave me an instant respect for li-ion batteries, plus a small concern every
time I fly in a small metal tube full of a couple hundred laptop and phone
batteries.

But several hundred used laptop batteries, with no balancing, in my garage,
mounted on wood. NO FREAKING WAY EVER.

------
elago
As a counterpoint to the hysteria expressed in most of these comments, a few
years ago I was watching a youtube series by "Rinoa Super Genius" where a
similar project was undertaken to create an e-bike battery from disassembled
laptop batteries.

The videos are done by an interested amateur with basically a pocket knife and
a large soldering iron. I'd highly recommend it if you want practical and
confidence building knowledge on the actual behavior and safety of batteries,
rather than this comment section which is filled with outrage and "experts"
referencing their credentials and years of experience.

I'm an experimenter not an entrepreneur so I'll never claim I can produce
battery packs in my basement safe enough to sell to grandma, but I've had no
problem ripping apart broken electronics, charging old cells with a DIY dc
power supply, and using cells in all kinds of 'dangerous' manners.

Personally I think chance of injury is far higher with dozens of other
technologies used every day by non professionals: chainsaws, cars, and many
other types of motorized or heavy equipment.

~~~
vvanders
> chainsaws, cars, and many other types of motorized or heavy equipment

You know what a bunch of those have in common? A ton of effing safety
measures.

Chainsaw chaps, ROPS, etc all exist exactly because those things are so
dangerous. The power density of an e-bike is at least one if not more orders
of magnitude less than a 40kWh bank of batteries.

He also has the potential to not only burn down his house but kill a lineman
working on the line if the power ever goes out.

~~~
elago
All the table saws I've ever used have been super dangerous. Car crashes are a
leading cause of death for young people. I could go on, these sorts of things
can't be made safe while still being useful. Beyond a point, it's up to the
user to understand the danger, learn behavior that minimizes risk, and pay
attention when using the tool.

With all of those things, like batteries, it's not good to assume the general
public can use them, so they shouldn't be as common as elevators, shopping
carts, and other ubiquitous tools/machines. But it's very dis-empowering to
claim only elites can use these tools.

Your final comment regarding lineman safety is completely decoupled from DIY
battery pack with re-used cells. That would be a failure of the inverter in a
grid-tied system. You could have an unsafe grid-tied inverter with a 100%
functional battery pack with every certification in the universe and backfeed
the utility lines, or I could connect a faulty battery to a proper grid-tied
inverter and it would not cause the utility lines to be energized by my house
when the utility shuts off the power upstream.

Additionally, you can use a home storage battery without a grid-tie inverter
at all.

~~~
vvanders
Your tablesaw example doesn't really disprove anything, that's why they now
have riving knives[1], push sticks and lifting guards that make them a heck of
a lot safer.

It's not that they can't be made perfectly safe, but that you take reasonable
safety measures and mitigate risks appropriately. If he had this off in a shed
~40ft from the house that's a lot different than inside the garage.

The article didn't mention how he's connecting it to the grid so there's a
very real possibility that he could have an inverter directly connected which
is why we have building codes and inspections to catch things that have the
possibility to kill people or do significant property damage.

[1]
[https://en.wikipedia.org/wiki/Riving_knife](https://en.wikipedia.org/wiki/Riving_knife)

~~~
elago
But the dangerous tables saws were still used to build things by lots of
people before 2009 when riving knifes were mandated.

I don't see why it's a crime to build a battery pack if you aren't working for
Tesla.

I still don't get how you can bring up mis-wired inverter as anything related
to a DIY battery pack. Without using _any_ batteries, I can go take a wire
strippers and 2 extension cords, make a male-male 120VAC cable, plug it into
the gas generator in my shed and plug it into an outlet in my house when the
powers out and shock a lineman.

In the country I live in we have building codes that describe how the work
must be done. An owner without a license is allowed to perform that work and
have it inspected and permitted. Screwdrivers aren't like lightsabers that can
only work if you're a jedi (or have a college degree or certification).

I disagree with lumping every form of DIY together. Incompetent DIY projects
are dangerous therefore all DIY projects are dangerous?

~~~
vvanders
> Without using any batteries, I can go take a wire strippers and 2 extension
> cords, make a male-male 120VAC cable, plug it into the gas generator in my
> shed and plug it into an outlet in my house when the powers out and shock a
> lineman.

Yup, and that's _highly_ illegal because it can kill someone. If you want to
do that you're required by code + law to have a mains transfer switch.

I don't think anyone is saying you can't play with battery packs, it's just
that this guy is a freaking idiot for doing it in his house where any
miscalculation can cause a chain reaction that may kill him and his family.

It's about orders of magnitude and safety mitigations.

Look at blackpowder/low power explosive regulations. You can keep a small
quantity in your house to reload/etc. However if you want to store more you
need a separate shed + BATF is allowed to show up at your house and inspect it
any time. Back when I was involved with amateur rocketry all of the our
vendors went through this process. It's a standard thing when you're involved
with elements that have a high potential energy and can go wrong if not
treated with the right respect.

~~~
fr0sty
> Yup, and that's highly illegal

Which part? Powering your house w/out transfer switch (when disconnected to
the utility), or actually back-feeding power to the utility? I would be
surprised if the former was uniformly illegal across the US, but the latter
certainly is.

~~~
vvanders
NEC requires a proper transfer switch:
[https://diy.stackexchange.com/questions/22154/are-
generator-...](https://diy.stackexchange.com/questions/22154/are-generator-
interlock-kits-permitted-in-residential-applications)

------
leggomylibro
18650 cells are great!

But be sure to protect them, and be aware that most commercial li-ion chargers
and off-the-shelf protection circuits are designed to maximize _short-term_
battery life. They'll charge to 4.2V, and many won't cut off until 2.5V.

Also know what to do if they short and catch fire; have an appropriate
extinguisher and a plan for quickly getting failed cells outside and onto an
inert surface like concrete.

If you want to make a 'powerwall' whose batteries could last you for a
significant amount of time (e.g. decades), you'll also probably want to design
your own charging and undervoltage protection circuits.

There's some good information here:
[http://batteryuniversity.com/learn/article/how_to_prolong_li...](http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries)

~~~
throwaway1X2
> have an appropriate extinguisher and a plan for quickly getting failed cells
> outside and onto an inert surface like concrete.

There are two problems:

a) There is no appropriate extinguisher when you have a thermal runaway on 20
kWh of chemical energy.

b) This isn't some shielded, extinguisher-nearby, one-time experiment, when
you, for example, solder something off and then while yelling "see, I'm still
alive!" run outside and throw it out. This is something that is intended to be
running 24/7 at your home (and maybe mounted on wooden wall like the pictures
in the link...). Unless you post guard duty shifts around the clock, there
simply may be no person to perform the plan of getting failed cells onto
concrete.

I see this as super-dangerous, especially when dealing with cells from many
different vendors scavenged from thrown-out laptops.

~~~
smileysteve
On A) a diyer could solve this the "nuclear" way by storing the batteries
underground or submerged in a deep tank of fluid.

Of course, then you run into cooling and maintenance access issues.

~~~
Piskvorrr
That's _quite_ an understatement. Venting superheated steam is no walk in the
park, either.

~~~
MertsA
Well it certainly wouldn't be superheated steam and it's not like it would be
a ton of steam in the grand scheme of things. It takes about 2500 kJ of energy
to boil a liter of room temperature water. Someone else mentioned 20 kWh of
batteries which in a catastrophic failure I'm assuming the cells might release
a little more than that amount of energy but for the sake of argument since I
don't know exactly what percent to tack onto that we'll just look at the
nominal capacity of the cells. 20 kWh is 72 MJ so that's only enough to boil a
bit less than 30 liters of water. Submerging a burning lithium ion pack in
something like a bathtub full of water is a great way to absorb all of that
energy.

------
useful
in middle school for a science project I converted non-rechargable batteries
into rechargables. They all worked, they all held 80-90% of their original
capacity.

They all leaked/exploded 6 months later while they were idle in flashlights
and rc cars. The chemistry is different but that experience taught me to be
more careful with 'outside spec' electronics.

------
rdl
I see lots of people doing this in Puerto Rico, but mainly they are installing
them in outbuildings, such that even a complete runaway fire will probably not
really damage anything else. In that case, worth the risk I think.

~~~
saalweachter
Hell, I'm planning to buy a commercial solution, and I am still going to put
it into an outbuilding. It's not an option for everyone, but when you start
planning for failure, there's a lot of sense in not putting anything into your
house itself that you don't have to.

------
saas_co_de
> While there are some risks to building a powerwall if you don’t have the
> proper tools and resources

understatement of the century there. DIY electricity is risky. DIY li-ion at
scale with used batteries is suicidal.

------
godelski
Jehu Garcia [1] does a bunch of youtube videos on old batteries and different
DIY powerwall designs. I'd say to always double check his work, because I've
seen some stuff that looked a little dangerous, but for the most part what
I've seen is good.

[1]
[https://www.youtube.com/channel/UCcMfCkN1juSa49DJFYltOTw](https://www.youtube.com/channel/UCcMfCkN1juSa49DJFYltOTw)

------
PaulHoule
I recently bought an APC UPC to protect my DSL modem and phone when the power
goes out. I have enough battery powered devices that I can be in communication
as much as I need.

Those two devices draw about 8 watts, but the UPC I bought can run for only
about 10 hours on that load. It could run a lot longer except that the
inverter is scaled to handle a larger load so efficiency is bad. And why the
hell is it converting AC to DC, then converting to AC, then converting it to
DC in some awful wall-warts.

Since you don't run the inverter for really long times, there is a pressure to
put in a cheap, inefficient inverter. However, if you took out the
inefficiencies, you could afford to use lithium batteries and produce a much
better product for this market. Hell, maybe the thing supplies power to the
phone and modem through USB-C and it is just a super-powerbank.

Basically a "micro-powerwall". Safety issues still concern me but smaller
scale reduces the odds.

~~~
haldean
Something like this 50Ah battery pack?

[https://www.amazon.com/Laptops-External-50000mAh-Portable-
No...](https://www.amazon.com/Laptops-External-50000mAh-Portable-
Notebook/dp/B073R6NKLW)

Google around for external laptop batteries, they make some really big ones.

~~~
PaulHoule
That is close. The single 12V port packs enough amperage that I could wire the
two devices in parallel. I'd still have to make cables to connect to the
devices. (The phone in question is a cordless phone connected to a landline.
It probably should take usb-c but it does not.)

------
lev99
People aren't making hacked versions of Tesla's powerwall. Tesla is making
cooperate versions of preexisting diy power storage solutions.

------
rmason
There's a startup incubator West of Lansing, Michigan in the little town of
Grand Ledge called The Fledge
[http://grandledgefledge.com/](http://grandledgefledge.com/) It's really a
cross between a makerspace and an incubator.

I toured there and among the projects I saw was someone who had made a Tesla
Powerwall from laptop batteries. Another was a solar array on a trailer which
they explained could be shuttled between your house as well as a cottage up
North.

Course building a project is less than half the journey to successfully
commercializing it however it was inspiring to see what people were creating.

------
dalbasal
This is a tangent^: How many people dump a laptop with a usable battery. My
experience has always been that the battery is first to fail/suck.

^to the main point, this is a cool project. go DIYers. try not to get killed

~~~
Obi_Juan_Kenobi
Typically what happens is only some proportion of the cells are bad, but that
makes the whole battery unusable. Scavenging these batteries requires testing
each cell individually to find which are suitable for reuse.

~~~
dalbasal
Cheers.

------
solarkraft
This isn't news. People have been doing this before the Powerwall has come out
(except jehu has started branding them this way after it did). Newer Li-on
batteries aren't all that dangerous, especially the round cells. Even when
overcharged absurdly they don't combust nowadays.

~~~
solarkraft
The real downside is that according to my calculation, at least from German
E-bay, DIYing gets about the same price per capacity without all the added
technology and convenience of buying from someone.

~~~
MertsA
It's not much cheaper but you can get good deals on 18650 cells. It's not
unheard of to find deals on genuine cells for as low as $1 a cell.

[https://www.youtube.com/watch?v=Hpv4G6HY2Rs](https://www.youtube.com/watch?v=Hpv4G6HY2Rs)

Then there's the option of buying lightly used battery packs like a single
module from a Tesla.

[https://www.ebay.com/itm/Tesla-Smart-Lithium-Ion-
Battery-186...](https://www.ebay.com/itm/Tesla-Smart-Lithium-Ion-
Battery-18650-EV-Module-57-Volt-3kWh-SOLAR-POWERWALL-/252144461952)

That's $690 for 3kWh that is all assembled, tested, cooling is taken care of,
BMS included, individually fused cells as well as a 100A fuse on the entire
pack. That's not too shabby, slap an inverter and a charger on that pack and
you've got yourself a somewhat decent diy powerwall for like $1100 bucks.

------
908087
Seems like a really stupid thing to DIY to save money, and a great way to burn
your house down.

~~~
peterwwillis
You can unplug from the electrical grid with one of these. If you don't have 5
grand to plunk down on a giant battery I'd say it's a pretty effective way to
save money.

You don't have to keep it in your house. If you have a small section of land
which would otherwise normally house a shed, you can build a fireproof
enclosure outside to house the pack. If it burns down, your house doesn't. And
if you're building it from scratch, you can include enough sensors for it to
auto-shut down when an unsafe voltage or temperature is detected. (the linked
video mentions all this)

When people build their own car, they're also taking their life in their
hands. But if you learn the right way to do it, you won't blow yourself up.

------
wglb
If I were to do this, I would go the old-school lead-acid deep-discharge
marine battery route. They are safe enough to put in the basement or garage.
How to do this is well understood and doable by hackers.

Lithium batteries are pretty scary. For example,
[https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_...](https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems)
is pretty frightening.

------
tsumnia
To at least satisfy all of the "fire" comments, what if you designed a
Powerwall with many interchangeable batteries? Like a street light, instead of
having a massive bulb that is expensive to repair/replace, hundreds of tiny
little lights that are cheap and the repair/replace of a single failed unit is
not as detrimental.

Could the home battery then be formed in a similar manner to this article,
without the scary "fire" danger?

~~~
aphextron
That's how a power wall works. They are made up of thousands of 18650 cells.
The problem is charge balancing. When you have a pack with thousands of
different cells from different origins with different internal resistances,
keeping the charges balanced becomes a really tricky thing to do.

------
dmix
TIL you can get 18650 batteries from old laptops, which is something I use in
my mechanical vape..

[https://www.youtube.com/watch?v=6GpvOvw5oEc](https://www.youtube.com/watch?v=6GpvOvw5oEc)

~~~
droidist2
Yeah true I use these for vaping, although regulated mod not mechanical mod.

------
muthdra
I'm personally using old laptop fan and hard drive motors to build my own
version of Tesla's Roadster.

~~~
test6554
Dont forget to use the wifi adapter to ward off evil spirits

------
deft
To people coming into this thread, let me sum it up "don't do this it's
dangerous let tesla handle it"

------
ngvrnd
There will be fires.

------
olivermarks
My paranoid side wonders if this is more clever marketing/pr by or for Tesla.
Why headline this 'powerwall' rather than 'home battery packs' or
'rechargeable lithium-ion battery home energy storage'?

'Powerwall' is like a prelaunch version of 'Hoover' for vacuum cleaners, a
brand name used to describe a generic. People have been experimenting with
capturing energy from solar panels for years. We know it is fraught with
risks.

Powerwalls are really expensive, barely launched and not a proven household
name with reputation like Hoover. Is this ultimately a 'better choose safety
and choose the known brand' gambit?

~~~
drb91
Eh, a powerwall is a well defined product with well-defined uses. “Home
battery pack” is nearly meaningless—are you talking about a UPS unit, or
something that backs your home power, or is it something that feeds back into
the grid?

Not saying you’re wrong, but I think the name is undeniably useful at quickly
describing a set of functionality. This could also be a case of poor
evangelism on behalf of people who care/competitors.

~~~
olivermarks
[https://www.fool.com/investing/2018/03/04/energy-storage-
war...](https://www.fool.com/investing/2018/03/04/energy-storage-
wars-3-products-going-head-to-head.aspx)

