Post B5rqT1aze3KNkJmIKm by Unixbigot@aus.social
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(DIR) Post #B5rqT1aze3KNkJmIKm by Unixbigot@aus.social
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THREAD INCOMING: So, you want to power AV gear that expects 12V (LED lights, cameras, monitors etc) and you don't know how to be safe with lithium batteries.🧵 1/n
(DIR) Post #B5rqT1pAnKfcSIPcR6 by Unixbigot@aus.social
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Portable 12v 2/n: Just Buy One.We're all familiar with the 5-volt USB power bank. You can get 12v and variable ones too. The variable ones are good for pre-USBC laptops. At left¹ : a "12v UPS" which has three batteries an a power-in socket and a power-out socket. While both 5.5mm barrel connectors, they have different inside dimensions so you can't mess up the wires. One of these has protected my small-form-factor-PC webserver for half a decade.At center² : a USB power bank that takes 18650 cells, either three or six. It has adjustable output (3.6, 5, 6, 9, 12, 15, 16, 19, 21) up to 21v. Good for laptops or general 12v stuff.At right ³ : a USB power bank that also has a fixed 19v output. Good for laptops. Did you know that most laptops charge at 19v because in the EU the safety testing regulations get more complicated above 20v. ¹ https://www.aliexpress.com/item/1005010541121010.html Pro: really simple Con: no "fuel gauge"² commission: https://s.click.aliexpress.com/e/_c3p6KhvN no track: https://www.aliexpress.com/item/1005001887930676.html pros: adjustable, has display. Cons: bring your own cells.³ exact model is obsolete. Modern equivalent: commission https://s.click.aliexpress.com/e/_c3NF1szp no-tracl: https://www.aliexpress.com/item/1005001887930676.html Pros: solid and fixed output (no accidental overvolt). Cons: expensive and fixed output. Capacity can be exaggerated.ETA: these three models are all basically obsolete. On the other hand this means I've used them for years and they still work. You get newer ones now that have fancy screens and USB PD etc if that floats your boat.
(DIR) Post #B5rqT2CDPf6NblC1Ls by Unixbigot@aus.social
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Portable 12v 3/n: Power tool batteriesI have a number of tools that run on triangular 3S battery packs¹ . These packs can be charged in a "base station" or by just attaching a barrel plug. You might already have these with a tool, you can buy the pack made up, you can get a case kit with no cells, or you can buy just the circuit board and 3D print a base.I also have a lot of "XFinity" brand power tool batteries² from Aldi supermarket. I've designed a clip which attaches to these to give me access to the raw (21v) power.¹ Commission link: https://s.click.aliexpress.com/e/_c3XKDRer no-track link: https://www.aliexpress.com/item/1005008928629636.html. Pros: compact and flexible charging options. Cons: might have to 3d print your own "output" connector² Get the batteries from "Aldi" special buy aisle. Get the 3D files here: https://www.thingiverse.com/thing:4255494ETA: If you already own power tools, probably look at whether there's a commercial or DIY "backpack" available for your brand. Some high end brands have fucking DRM on their chargers.
(DIR) Post #B5rqT2SsPiQgRQzKK0 by Unixbigot@aus.social
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Portable 12v 4/n: Build your ownThe very simplest things you need for your own power pack is 1️⃣ cells and 2️⃣ a protection circuit.Left: this 12v-in-12v-out circuit¹ also charges, balances and protects batteries. 2nd from left: This is the DIY version² of the 12v power tool battery3rd from left: We have a protection and balance board¹ , plus a USB-C charger board. Right: as shown upthread, the inside of an off the shelf UPS is also a combination of protection board and charging board.Not pictured: this board⁴ holds 2 18650 cells and makes 12v with a voltage converter. I've evaluated these and they work.¹ https://www.aliexpress.com/item/1005008051293682.html pros: extremely simple. Cons: you'll need to add your own plugs and if you want status a 2-color LED.² https://www.aliexpress.com/item/1005003913006888.html pros: compact cons: shape might not be suitable for you³ https://www.aliexpress.com/item/1005007148533865.html these balance boards come in different current ratings. A 5A version is fine for AV use with three cells (3s1p). If you had way more cells (say 3s4p or 3s10p) you might want a higher current capacity, in which case the corresponding board looks the same but is larger.You can use a USB-C charger like this https://www.aliexpress.com/item/1005010528229717.html which requires the USB-C supply to support 12-20v output, or get a 5v USB-A (slower!) one like this which has a boost circuit inside the plug https://www.aliexpress.com/item/1005004504372687.html⁴ https://www.aliexpress.com/item/1005006860598580.html pros: nothing to add except an output plug. Cons: always-on power LED
(DIR) Post #B5rqT2jtOS2ZICwuqO by Unixbigot@aus.social
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Portable 12v 5/n: More Power, Scotty! If three cells is not enough, you can use banks of parallel cells. For example if you make parallel banks of four cells each, then place three of those banks in series, you have a 12v battery that is described as "3S4P". Adding more cells in parallel gives you more capacity and current, while keeping the voltage the same.Typically you use a "battery management system" circuit board, which is a more sophisticated charger/protector module which can handle the higher capacity and currents.First picture is a 3s4p battery that I made with 3D printed cell holders, and an off the shelf BMS circuit¹ . I added a second circuit board which allows the power level to be monitored from a Raspberry Pi.The second picture has a 3-cell holder which is 3D printed with the addition of spring clips² which can be bought by the bagful. You can use just 3 cells or stack more holders to get 2p, 3p, etc.¹ https://www.aliexpress.com/item/1005002900136722.html hit me up if you want the 3d printing files. You can also buy clip-together cell holders by the bagful https://www.aliexpress.com/item/1005008166006248.html² https://www.aliexpress.com/item/1005007394265670.html LOL til some sellers call these "battery shrapnel". HMU for the 3D files, I forget whether I have published these. EDIT: now published https://www.thingiverse.com/thing:7344593
(DIR) Post #B5rqT31cKYDcBBF4TI by Unixbigot@aus.social
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Portable 12v 6/6: Give me LUDICROUS POWER.The top of the line on DIY batteries is to use Big Ass Cells¹ and a smart battery management system² . Here I have used 50Ah prismatic lithium-iron-phosphate (LiFePO₄) cells in a 4s1p arrangement, which gives the same voltage as a lead acid battery but for 1/3 the weight and half the size. I also made one with 100AH cells. You can get individual cells up over 300AH if you want.The battery management circuit that I chose has bluetooth radio, so I can use an app to monitor its status and level of charge, and even turn it off and on.¹ https://www.aliexpress.com/item/1005008561347183.htmlhttps://www.aliexpress.com/item/1005006385416774.html² https://www.aliexpress.com/item/1005002897035148.html
(DIR) Post #B5rqTAHpKgLOhTscD2 by Unixbigot@aus.social
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Portable 12v 7/6: Maybe Just Don't.If I was wanting to run a bunch of "dumb" DC appliances (like studio lights, portable monitors, cameras etc) today I would standardise on USB Power Delivery, and convert my devices to eat USB.Options here area) Buy a fat power bank with multiple outputsb) Build a fat power bank by combining this thread with THIS OTHER THREAD https://aus.social/@Unixbigot/116135210085486382c) get a bunch of laptop chargers from teh thrift store or elsewhered) make a bunch of modest USB-pd powerbanksFor each device a "power delivery decoy" board can be inserted either into a cable or inside the battery box. These things are TINY.RT: https://aus.social/users/Unixbigot/statuses/116135210085486382
(DIR) Post #B5rqUyk3E7T9TRwjke by lukesleeman@aus.social
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@Unixbigot basic question - how do you get stuff from AliExpress which actually matches the specs? I noticed when it comes to batteries and solar there are plenty of sellers claiming physically impossible numbers.You can avoid the obvious BS with some research - but how do you differentiate between high spec stuff and lies? Eg, how did you know your 50ah cells weren't just 10ah cells with a made up listing?
(DIR) Post #B5rqUyuKbtgzzKkwm8 by Unixbigot@aus.social
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Tips for avoiding bad products on AliExpress1. Buy your (say) Gonkulators from "Shangdong Gonkulators and Frammistats Inc." not "Shop1234123412 Store" or "Beautiful Life Homewares"2. Test, and demand refund if specs are not met3. Avoid product descriptions with obvious lies (impossible energy ratings) or which show that the seller does not understand what the product does.4. Look at what the seller sells. Do they appear to have an area of speciality. Do they have a reputation to protect? Do they show factory provenance or mention quality testing? Maybe glance at the reviews.