Better Batteries For Electronic Gadgets

We’re not using 9 Volt batteries to power our projects anymore; the world of hobby electronics has moved on to cheap LiPo batteries for most of our mobile power storage. LiPos aren’t the best solution, evidenced by hundreds of YouTube videos of exploding batteries, and more than a few puffy cells in our junk drawer. The solution? LiFePO4, or lithium iron phosphate cells. They’re a safer chemistry, they have low self discharge, and have more recharge than other chemistry of lithium cells.

LiFePO4 cells aren’t easy to deal with if you’re working with breadboard electronics, though. Most of that is because there aren’t many breakout boards for these cells. [Patrick] is working on changing that with his LiFePO4werd USB charger.

The concept is simple: use an off-the-shelf part for LiFePO4 batteries – in this case an MCP73123 – and make a board that charges the batteries with a USB port. It’s exactly the same idea as the many USB LiPo chargers out there, only this one uses a better battery chemistry.

[Patrick] is using a 550mAh battery for this project, but there’s no reason why it couldn’t be upgraded to a 18650-sized cell with more than 2000mAh stuffed inside. Add a boost converter to the circuit, and he’ll have the perfect power source for every portable electronics project imaginable.

46 thoughts on “Better Batteries For Electronic Gadgets

    1. Usually it puffs on people that don’t know how to handle them and have it at full or empty charge for long time.. I still got unpuffed lipos from when I started with RC hobby 4+ years ago. Altho LiFe are safer and won’t blow on you, poor handling will damage them (lower capacity, higher internal resistance) as any other lithium battery.. also they are quite heavier than standard lipo per A/h.

      1. Don’t know, or don’t care? I have a draw full of them, but they are all mounted in some piece of electronics that has been relegated to the spare parts bin. First time I need something I typically pull out the cell, toss it, and scavenge the part I needed out of the old device, and then back into the parts bin it goes.

    1. Ditto. These are so cheap that it’s well worth it to just buy them then go to the work of building the equivalent.
      Though I have a stash of good quality 18650’s I’ve recovered from laptop batteries and I swap them for the questionable, and lower capacity, batteries that come with these USB packs.

  1. I have bunch of discarded laptop batteries, you can find them these days for next-to-nothing price. I disassembled them, and to my surprise lots of 18650 cells was around 2000mAh (out of original 2400-2600mAh), and few of them was around 1000-1500mAh. Tested with proper battery tester at 1000mA discharge current.
    Next step, buy DIY power bank on eBay, one that holds two 18650 is $1.50. They have integrated Li-Ion charger (via micro USB), and step-up converter that provides 5V at about 1A via classic USB connector. They usually have short-circuit protection so you won’t fry your powerbank, it will just go off and to reactivate it you need to press reset button or if it’s not present just connect bank to charger for one second. Converter shuts down when battery voltage drops below around 3V so you can’t over-discharge battery.
    So my power source for uC projects costs me about $2 (bank and batteries). You can get bigger banks that hold 4-5-6 batteries and provides voltages from 5 to 21 volts and few amps, but for most projects small one at 1A is just enough.

  2. Another solution is to reuse a 0.5 $ usb phone battery pack and a 0.40 5v to 3.3v ldo if you want to power an esp8266.

    You’ll lose 10 % of efficiency but the cost is unbeatable and includes a powerswitch…

    1. You can get them for 50c? How’s that even possible?

      Sounds like the famous laptop charger that stopped working. Guy opened it up, found a mains connector fastened to nothing, and a bunch of C-cell batteries connected to the output. And nothing else!

        1. Ah!

          I did get a nice charger from a pound shop. Cost a pound, obv. Takes an AA battery and charges your mobile phone. Nice metal case too. The whole thing’s only a bit bigger than the battery inside it, there’s just a teeny circuit on a round PCB at the top that’s presumably a boost convertor.

          I don’t imagine the output waveform is too stable, but then it’s just charging a battery, and there’s plenty of expensive, proper, electronics in the phone itself. It’s invaluable. Particularly since I knackered my new phone and have had to go back to the old one with the failing battery.

          Any ideas on what to do with a phone that works perfectly, but won’t charge, after it got wet? Attempting to charge makes the USB plug get hot, and there’s a hot spot in the case too when charging. Obviously water is quite high resistance, but doesn’t mean it can’t fuck up some control circuit for a more powerful thing.

          Yes, I’ve done the bag of rice. It’s been weeks since, still not got better. Is this a fixable problem, or do I need a new one?

          1. Not that I know of. Still maybe I could use another phone to charge it, improvise a connector with a bit of tape etc. Would be a bit of an ugly hack tho, without being able to fix it properly I’m best getting a new one. Pain though that is.

  3. Id like to give these a try but the postage from the US to UK is just too much.
    Looked at his ebay and tindie options.
    Are there any UK or european resellers?

    Otherwise ill have to make it up myself.
    Its very good of him to supply the hardware files as open source.
    But would have been nice to have been able to get one complete to try out.

    1. On eBay you can get charger modules based on TP4056 for less than dollar, with free international shipping. More expensive ones include protection circuit. Add any cheap boost module (1-3USD on eBay) from China and Bob’s your uncle!

    2. £4.95 shipping (via Tindie w/o battery, which you can get easily enough in the UK) from the US isn’t really exorbitant, especially compared to the £19.32 shipping via eBay.

    1. Hm, might wanna put a resistor or a fuse in line there. Could just as easily melt a breadboard, or even explode it, with a bit of wrong wiring.

      OTOH it’s a nice stable supply. I wonder why “audiophiles”, who actually spend real money on specially treated mains fuses (yes, they really, really do. One company zaps the fuses with a Tesla coil, or at least does SOMETHING with a Tesla coil), and mains cable, and think there’s a correct way up to insert a fuse, don’t use batteries to power their stuff?

      Much more stable supply. Much less to spend money on (although that might be the point, come to think of it). No need to filter out supply noise. You could just keep 40V worth, or whatever your amp uses, of batteries, with a second set on charge if you needed.

      There’s probably money in connoisseur lead-acid batteries with solid gold terminals, for someone who’s willing to talk the talk and is suitably shameless.

      Sorry to be a bit snarky. Those people are just so depressing. But the question about using batteries to power amps is serious.

      1. The audiophile world has two groups. One is the raving idiots that believe spending money is the answer, it’s the largest group. the other is the group that has the education to use real math to discover what matters, they are the ones that prove that the gold plated connectors are stupid, and the gold plated TOSLINK optical cables are even dumber and then get shouted down by the people that paid $600 for a directional ethernet cable.

        1. See, the second group I wouldn’t call “audiophiles”, I think that word by now pretty much has to have connotations of ostentatious stupidity.

          For my own question I looked it up, and you CAN buy battery-powered amplifiers. Over-priced ones, of course! Actually some people swear by UPSes, which is really bloody stupid cos a UPS will give out a worse mains signal than the huge rotary generators of the actual mains. Will be loaded with noise.

          But some people just use batteries to power the thing in DC directly. There’s one little 10-watt board, 4 inches square, runs off a battery. For 6,000 Euros (that’s six thousand)! From the look of the thing it’s just an IC amp! Battery not included.

          It really does tempt me to enter the line of business. Basic electronic knowledge, and a huge and shameless capacity for bullshit. Sure I could learn the latter. In fact you don’t really need the electronics knowledge to sell basically-copper-wire for a thousand times it’s worth.

          Anyone else would have had the Fraud Squad called, but not audiophiles. Shine on, you stupid diamonds!

  4. you dont need special charging circuits for Lifepo4 batteries. they take to overcharging quite decently, in fact you can abuse them as hard as a lead acid as I replaced my motorcycle battery with a LifePo4 battery last year. 1/2 the weight and all the amps and is doing great even though it is getting a full boat charging current all the time the bike is running.

    1. Lithium is fairly simple to charge, a (deliberately) whimpy (can’t supply more then max. current) constant voltage supply set to max. cell voltage is all it takes, can be done with a tl317 and a wall wart…downside is poor charging speed…

    1. There is *absolutely* nothing special about this other than the form factor.
      Everything – battery holder, LiFePO4 battery, external charger can be ordered from China with “Free shipping”. Li batteries especially ones that are not inside electronics with proper cases are prohibited to be shipped by air in International mail, so the only ways are by boat or very expensive couriers. So it will take some time to arrive, but sometimes they might be sneaking it through regular mail by ignorance or by luck.

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