Building replacement proprietary battery packs
hallaminventions.com
hallaminventions.com
With that knowledge, you can replace the battery in any gadget (small ones are usually 3.7V, or 1S), if you know how to care for it. Replacing the battery in a MiniDisk like this, I would maybe not trust the internal MiniDisk charger and charge by hand, but it should otherwise work identically to the factory battery.
edit: http://forums.sonyinsider.com/topic/29187-lip-4wm-battery-re...
A review of the original pack teardown reveals it has a small pcb with what looks like some voltage cutoff or thermal fuse.
They can also be stacks of plates though, so buy a sample of a particular brand before you decide bulk-buying them is a great/cheap source of cells!
The crucial missing detail is that battery packs are assembled from identically matched cells, which age together as a unit. As soon as you replace a single cell with a new cell of the exact same model, or a new cell of a different capacity and charge characteristics, that cell will charge differently than the rest of the battery pack. This results in an unbalanced charge situation.
If the battery pack has a battery management system with leads in between each cell to balance the pack, this might work. The BMS can drain off excess charge from the unbalanced cells and convert it to heat.
If the battery pack does not have a BMS, the unbalanced charge situation can lead to pack failure, with varying degrees of smoke and flame depending on the battery chemistry.
When in doubt, play it safe and just get a new battery pack.
and if you're really concerned about it, you can match cells for impedence yourself, but it's generally not a problem if you replace all the cells at once with cells of the same kind/batch/etc.
More advanced controllers can use flyback transformers to move charge from one cell to another. This is vastly more expensive than just using a resistor, though, so it's only used in applications where energy conservation is key, like solar projects or where heat is a constraint. The LTC3300 is a good example: https://www.analog.com/en/products/ltc3300-1.html#
The problem with that is that each wire has to be able to handle the full charge current, but at a low voltage. So, if you're dealing with, say, an electric car with dozens or hundreds of cells and thick copper cables the size of garden hoses it's no longer practical. Instead, you charge it the simple way (by applying a large voltage to the whole series string through a positive and negative lead) and use a battery management system that measures voltages between cells and drains any high-voltage cells gradually through a resistor. It's kind of wasteful, but it's fairly simple and if your batteries are well balanced the BMS shouldn't have to do much at all.
Using the high cells to charge the low cells would be a nice feature; I'm not aware of any EV BMS that does that, but I'm not an expert and I'm really only aware of what's going on with DIY conversions. I don't know what the state of the art is for BMSs in commercially manufactured vehicles.
I imagine it will require some creative wiring, but charging efficiency should then go through the roof, right? I image I went e-biking and returned to my car to recharge - having individually chargeable cell should reduce the overall charge time a lot.
You still charge the pack in series, but the BMS will discharge cells that have a higher voltage than others. This results in all cells having similar charge levels.
It doesn't change the charge time, though. You're putting the same amount of energy into the pack either way. 14.8V @ 100mA applied to 4 cells in series is the same energy as 3.7V @ 100mA applied to 4 cells individually. Can't escape the laws of physics.
If power efficiency is critical (solar applications, for example), the BMS might have fancy switching circuitry to re-route energy from overcharged cells to undercharged cells. This is expensive, though, so most BMSs just use resistors to burn off extra charge from overcharged cells.
I understand that's how it's done, but can we charge faster if we DECIDE NOT to charge in series? I take it the answer is no?
Imagine a series of 14 cells. I could charge them as a whole, but there is normally some limit on how much power I can pump into it. Now suppose that I disassembled the series and now I have 14 cells that I can charge independently before re-assembling them back. If I did that, would I gain anything? If nothing else this should prevent unbalanced charging, reducing overall heat of the pack and allowing higher current overall?
I can see that some packs advertise 5a charge current and other packs of the same capacity offer 10a or even 15a. Wonder why is there such difference.
Also, it seems like you're imagining that you can charge batteries with more power if you charge them in parallel instead of series. This isn't true since you're just trading a higher voltage/lower current for a lower voltage/higher current.
I was considering a design where there was a PCB on every cell with an individual charger, but it's just more cost and parts to break, plus no redundancy (unlike having two big chargers in parallel).
Let's make a few 3-series batteries and charge them. When done charging we stack four of them together to get a single 12-series to power an e-bike. Would that allow for much faster charging?
A popular $22 balancing charger for hobby RC drones: https://hobbyking.com/en_us/turnigy-accucel-6-50w-6a-balance...
A $15 sensor that plugs into the balance port and sends telemetry data about each cell: https://alofthobbies.com/frsky-sp-flvs-smart-port-lipo-volta...
A similar sensor that beeps really loudly when any cell falls to 3.5 volts (these are very popular for people without telemetry systems): https://outofdarts.com/products/lipo-voltage-alarm-1-mini-si...
An article explaining balance ports in RC aircraft batteries: http://www.tjinguytech.com/charging-how-tos/balance-connecto...
You have a discharge circuit, in series, and a charge circuit, wired separately to each cell. You're only using one at a time, as long as everything is properly grounded they don't get in each other's way.
It's not really about charge time though: any vehicle battery is going to discharge faster than it charges, so it's practical to just dump a bunch of current across the pack if you're charging using the same circuit.
What it does, is takes good care of each individual cell, and if you log some metrics you can detect underperforming cells and replace them.
I will say that for most applications, charging off the series wiring, and adding an overvoltage module that shuts off charge to each cell when it's topped off, is going to be much simpler and good enough.
But it can be done.
The actual power required does not change..
At least with lithium-ion technologies, for larger applications, this ignores a lot of the degradation phenomena and electrochemistry of the battery.
I might also recommend getting a tiny whoop instead, those are very small drones for inside the house, they are super fun and you can fly them whenever you want, vs having to make a trip to a suitable location.
That should get you started. Nowadays I much prefer acrobatic wings, though, I made a Flitetest Versa from Depron foam for like $30 and it's amazing fun.
https://m.banggood.com/RadioMaster-TX16S-Hall-Sensor-Gimbals...
very small drones for inside the house, they are super fun and you can fly them whenever you want
Why wouldn't you? It has same voltage and even same capacity (weird considering evolution, but maybe choice was deliberate). I dunno, but maybe MiniDisk charger even has temperature sensor.
Perhaps to most critical element in these "smart" batteries is the temperature sensor which dials back the current when they start getting hot to avoid thermal runaway. (source of MANY battery fires in laptops from counterfeit battery packs).
As for matching the cells, in our battlebot we would take each "unit" (which in our case was 20 NiMH batteries) and condition it by draining it and charging it in cycles while monitoring voltages to level out the batteries and "sync" their charge levels. We still ended up with a couple of fires but that was because we were charging them right at the limit of what is reasonable to do because the time between bouts could be pretty short.
https://www.thingiverse.com/dosman33/collections/two-way-rad... https://www.thingiverse.com/dosman33/collections/power-tool-...
I also released a universal battery charging cradle system I call the Gadget Hamper to help people out who design new battery packs: https://github.com/dosman33/Gadget-Hamper
You definitely don't want your battery pack shattering if you drop it.
The 3D printer world today seems to have an unfortunate love affair with PLA which is for both temperature and durability reasons a very bad choice for battery pack enclosures, and a bad choice for just about everything else. I'm really not sure how to get the word out there that PLA is outdated and should be deprecated for just about every 3D print use case. (Personally I use PETG For just about everything, but for a battery pack I'd probably want something carbon-fiber reinforced.)
Also PET-G has the added benefit of not giving me cancer like ABS. It definitely has a learning curve and I wouldn't fault anyone for going other routes rather than taking the time to get a feel for it.
My printer prints PETG pretty cleanly with no fuss. I imagine if someone used the same exact printer (Prusa i3 MK3), the same exact filament (eSun), my same exact settings (https://github.com/dheera/3d/blob/master/settings/slic3r-con...), and my same exact textured bed sheet, same exact procedure (Windex, then Magigoo, then print), they should have zero problems as well. It's not even tricky. It prints just like PLA with this "recipe".
The only problem seems to be that there is a lot of conflicting information about what works for PETG but people just need to think in terms of configuration sets like the above. If you use the Prusa PETG settings with eSun filament it fails miserably -- the prints come off the bed mid-print.
So, if your printing anything that has a likelyhood of catching fire you should probably be doing it with something like: https://www.3dxtech.com/flame-retardant-filaments/firewire-f... or just wrapping that part of the design in sheet metal.
I've been hesitant to use lithium batteries in home robotics projects, but I can't find charging and power mux boards for NiMH, so that has been a huge blocker in making robots that charge and operate at the same time.
Also I wonder if it is possible to put mini pressurized CO2 balls inside the battery enclosure such that if a fire happens they explode and release CO2, putting out the fire?
But the general theory as I understand it generally is not that the plastic may not burn, only that they are self extinguishing. V-0 like that filament means it will extinguish itself within a maximum of 10 seconds after the ignition source is removed.
Regular filament acts more like an accelerant, put a flame near it and it burns quite vigorously, and for a long time. Meaning anything near it that can burn will likely catch fire too.
No, that may momentarily put out the flames but as long as the thermal runaway condition is still present it will reignite. The only way to stop a battery fire, which is actually a metal fire, is to permanently suffocate it - usually by dumping heaps of salt, cement or salt on it which melts and so removes oxygen from the fault area - and then, at least for electric cars, to dump the car in a container full of water and keep it there until dismantling, so that the water acts as a thermal buffer to prevent reignition.
Also I'm sure that most of this market violates someones IP so again, this ensures that this type of thing (custom making battery enclosures) will never reach a critical mass where worrying about the world burning down due to non-fireretardent plastics is something to be concerned about.
But if a person is very concerned about this issue then certainly there are options out there.
It works fine for 90% of use cases and is easy to use. Aside from that, you can buy virgin PLA filament which is pretty darn nontoxic. Most other plastics have a variety of negative effects on humans, from physical interaction with the finished product but also from the printing process.
Sony and Panasonic are good 18650 vendors.
The absolute series voltage matters in that you don't want to over- or undervolt it by 3.7V usually.
They may be worth $5/cell new, but not so much in their current state.
And if you're recycling cells from other packs, they are likely to have remnants of old tabs still connected, so you can solder to the tabs instead of directly on to the cells, which gives a little more thermal wiggle room.
Definitely file this under "bad advice you probably shouldn't follow, and don't tell them I sent you", but 'allegedly' this works...
It would be extremely, extremely risky to sell a product which could be destroyed by leaving it in the car in the winter.
I think this advice only earns one "extremely" or maybe a mere "very"...
Have a good look around on the internet.
It's a lot of work, but the validation was all automated via the charger. The pack I ended up with had healthy cells all within 10% of each other in terms of capacity.
You can get a cheap analyzing slot charger ($30-40) and do it yourself. That won't be quite as accurate as a big expensive industrial battery tester, but it will be accurate enough to make safe battery packs for consumer electronics.
Usually only one of them in a dead pack is bad and the rest are great.
(though usually I use flashlights that take one 18650).
If the flashlight has a low-voltage shutoff for the series at 2.5V per cell, it would take a series of four before that's possible, and even then it's pretty improbable. You'd have to mix a discharged cell with three full cells; a moderate difference in capacity or internal resistance wouldn't be enough by itself.
It is easily possible to over-discharge a cell under those conditions, after which charging and using it again is risky, but if you're salvaging laptop cells you probably already know that.
[this also reaffirms my decision to store lion batteries and their charger in a metal cabinet in a detached garage... because clearly I didn't know all the ways I could turn them into bombs.]
Multi-cell devices require a little more knowledge and care, but the main thing is just to make sure the cells match. Being the same model and charged to full before installation will do for new cells, but salvaged ones need to be tested and binned.
https://hackaday.com/2020/09/02/building-an-open-source-thin...
And the related HN discussion: https://news.ycombinator.com/item?id=24319839
I don't really know what I'm talking about though.
Simple 18650 cell can't be safe. Normal consumer may just put/charge raw 18650 cell, then burn.
It seems that no one intend to make standard Li-On battery. Some manufacturers just use other brand's battery. (e.g. Blackmagic products uses Canon's battery)
I understand that major consumer-product companies are reluctant to offer a product with any risk of attracting personal injury lawsuits, but I'm still classing it as a bad reason.
As a case in point, this Slovenian company makes sustainer systems for sailplanes, which is awesome, but their system is limited to two battery packs. I imagine that pack design, form factor and availability is a big limiting factor in projects such as these.
Apart from that, I wouldn’t feel comfortable creating packs that could be fire hazards if the users do things like mix cell types or quality or capacity.
My point is, I'm sure there's a market for modular battery packs that have actually made these considerations, along with charging/discharging management, power electronics, insulation/cooling/heating and so on.
There are few providers doing something similar (Vruzend off the top of my head), but they all have huge downsides.
What I would love is: 1.) Integrated high quality BMS. 2.) Modular design so that I can add capacity or voltage simply without welding. 3.) High amp discharge capability. 4.) SAFETY! Can be used in electric mountain bikes, eFoils, electric paramotors, whatever. Vibration, drops, etc. do not disturb the cells or the pack.
If you could accomplish this then you would unlock so many cool features. 1.) Construct your own packs regardless of voltage or size requirements. 2.) Travel on airplanes with your batteries! Deconstruct the pack simply and store in <100Wh battery blocks or as 18650 cells and you can take theoretically an unlimited amount of lithium across oceans (likely limited somehow). 3.) No vendor lock in. 4.) When your BMS tells you that a certain subpack has failed just pop the cells out easily and replace the one that is busted. 5.) Because of #4 far better for the environment and cheaper.
Does anybody have any thoughts about how to bring this to fruition?
The Vruzend thing works but is clunky, has low amperage capacity because of the bus bars, and the BMS is not integrated.
If anybody has thoughts I would VERY much appreciate it.
https://ebikes.ca/product-info/grin-products/ligo-batteries....
By the way, the company that makes this, Grin Technologies, is really great. I've toured their facility and met the owner. (I don't have any sort of stake in them, though).
I have an old Nikon D1h SLR which I loved, but it used horrible Ni-MH battery packs that didn't last long--both in terms of shots per charge, and total lifetime. They're all dead and I can't bring myself to order another one, now that I'm used to li-ion packs in modern cameras. There's one German company that makes a compatible li-ion pack but they don't sell to the U.S. for some reason.
There's a bunch of blog posts about how to take one of these old battery packs and jerry-rig it to accept a couple of rechargeable li-ion cells. But it looks like a pain--cutting open the old pack with a razor blade, gluing in battery tabs, etc. Maybe 3D printing would offer a better way to do the same thing...
Shipping lithium batteries by themselves (as opposed to installed in/packed with equipment) is a huge pain in the ass to do internationally.
Console MD player/recorders were ridiculously expensive in the US. Portable players were expensive but not nearly as bad as the mains powered console ones. This meant most people just went for CD players.
Because they didn't sell well here music labels didn't release many (any?) MD albums in the US. That meant you were buying new albums from the "import" section of the store (if you had a record store that sold imports) for full integer multiples of CD album prices.
Unless you were stupid rich then you bought blank MDs and recorded your own music on them. That didn't mean dropping tracks onto a playlist and pressing the "Burn" button. You had to plug your MD deck into an audio source, hit record, and then play the track/disc back in real-time. If you just did a whole CD at once it would record as one long track but you could go back and mark start and end points to break it into actual song tracks.
So you either spent tons of money buying commercial MD albums or bought blank discs to make your own. Making your own discs meant every album you listened to required the cost of the blank disc and at least an hour of your time to record it.
Or you could just save yourself tons of money and effort and listen to CDs.
Source: a friend of mine was obsessed with MiniDiscs and I thought they were cool until I spent an afternoon recording two discs. I realized my DiscMan was a way better deal.
If you were loading music from MP3 or WMA the software was transcoding those formats to ATRAC, NetMD players didn't natively support either format. So you went from one lossy compression to another. If your MP3s were already at the minimum threshold of quality because they came out of a shitty encoder they were just going to get worse in ATRAC.
If you were loading WAVs into SonicStage your quality would be way better but you first had to rip your CD to disk and then load it in to SonicStage. So you had no time savings over ripping to MP3. ATRAC also had a bunch of DRM so it limited how many discs your could load a track on. Not an automatic problem but putting a song on more than a couple discs wouldn't work.
Keep in mind that by the time NetMD players were out CD-R drive's were cheap and pretty common. A lot of CD players had also started supporting native MP3 playback and dedicated MP3 players were readily available.
The extremely inconvenient NetMD experience was up against cheap CD-Rs, much more convenient MP3 players (including the iPod), and in general a better MP3 experience. The whole MiniDisc ecosystem was just inconvenient unless you had spent a lot of money to live in some sort of end-to-end MiniDisc world.
My apartment was burgled in 2003, and the insurance payout covered an iPod to replace the stolen minidisk player.
Night and day, no comparison, that iPod was the coolest thing I owned at the time, and stayed that way for many years. It's in storage right now, but the last time I plugged it in, a couple years ago, it still worked. The battery is toast, though.
I now have a little Tascam pocket digital recorder that I love.
DIY super capacity BATTERY PACK
He didn't really talk about any of that, so this approach feels like quite the fire hazard.
I clicked through and the ebay link mentions: "Built-in protection circuit PCM for prevent over charging or over discharging."