Hey guys. So a few months back I bought a cheap USB battery which claims to be holding 2200 mah which is total bullshit cause it only charges my phone about 30% and only if I let it idle. Today I decided to open the shit and see what kind of battery is in there. To my surprise it was a laptop battery cell. No inscriptions on it though. Then I thought why don't I replace it with a cell from my old laptops battery. The cells look exactly alike except there is some information on these ones (lgcas31865 i3011008413 ij281a1s3). Anyway the cells didn't have any juice in them but they had .something voltage. I hooked one to the shit battery pack circuitry and I restored its voltage (3.6-3.7) and when I measured amps the multimeter went through the roof (old ass tool with needle pointer and DC 500 mah max). Then I thought why not make a mega battery pack. I hooked all 6 of them in parallel and let it charge for a few hours. Everything worked great and I could charge my phone completely (about 1200 mah from 50% to 100%) and it was still going. It was charging even if I was using my phone so thats great. Now my question is how safe is this thing? Can I let it charge overnight and still wake up? Is there a risk for the batteries to explode in my pocket or backpack? The laptop battery: pa3534u-1brs and it was pretty done when I stopped using that laptop. They haven't been charged for years.
>when I measured amps the multimeter went through the roof
Never do this. Your multimeter measures current by checking the voltage drop across a resistor of a few milliohms. Putting the probes directly across your battery is almost the same as shorting it which can cause overheating and explosions.
> Is there a risk for the batteries to explode in my pocket or backpack?
The LiPo and LiIon batteries used by hobbyists often have built in overcurrent protection to stop meltdowns, but it doesn't sound like yours do. Without protection power wires just lightly brushing against each other can weld themselves together. I had some batteries glow white hot and burn through my workbench before I had time to grab safety goggles and wire cutters. I was planning on putting those batteries right next to my skull in an LED helmet.
if you mess you LiPos, you can get a fireball in your pocket. just disassemble everything and throw it away, then thank Zeus you're still alive.
Do you guys think I should change my Nexus 5's LiPo battery with a LiIon one even though it's a Chinese knock off ? Also on my nexus' battery its inscriptioned LiPo LiIon. Which one the hell is it?
wikipedia: "These cells are sometimes designated as "LiPo"; however, from a technological point of view, they are the same as the ones marketed simply as "Li-ion", since the underlying electrochemistry is the same."
I actually said Jesus fucking Christ out loud.
I've never seen the damn things blow up before.
also this might be my last post on 4shit. Ive "selected all street signs" 10 fucking times.
fuck you moot, for making this mess
fuck you gook, for not cleaning it up and making it worse by adding flash ads on archived threads. that crash flash player like clockwork fucking up everything from loading times to making captcha simply not work.
I move for another exodus
>mfw jewt was a better admin that gook
Safety mainly depends on how good(stable,safe) your charger is
a good charger will not overcharge / overheat the cells
post a closeup of the chip on the circuitboard so i can read the number
Measuring battery voltage is fine, but when you have a multimeter set to measure current there's only a few milliohms of resistance between the probes. You measure current by putting the probes in series with the battery and a load. Putting current probes directly across a battery is almost the same as shorting the battery with a regular piece of wire, and that can make a LiPo battery fail catastrophically.
Op, batteries are fun and I love them, but you have to respect how dangerous they are and that if you don't know what you're doing you could fuck your laptop bag, house, or life up horribly.
Never, EVER leave a diy thing like this charging overnight.
NEVER, FUCKING NEVER GOD DAMMM EVER CHARGE MORE THAN ONE CELL, ONE BATTERY, OFF THE SAME CHIP.
One battery exploding is bad? Know what's worse? SIX OF THE FUCKING THINGS EXPLODING.
If ONE, just fucking ONE of them is a bit off the others and you charge them all together you've increased your change of them all going up by about 10x.
You need a charger circuit per cell.
I hope to god that picture's not yours.
Li-pol is just flattened Li-ion.
No, stop fucking around, you don't know enough.
Go watch all of bigclivedotcom's videos on power banks, then all his other videos, then all the EEV blog videos, then tones of other videos and projects and papers on power banks, then, THEN you can do this shit yourself.
Here's the circuitry. Idk man the batteries aren't heating up at all and what's wrong with 6 batteries if they are in parallel?
Also here are the batteries. I had to solder directly in them because the solder wouldn't stick to the piece of metal that was welded on them. Can I make this safer? I really wanna use it.
Using the voltmeter function is safe but using the ammeter function is very dangerous unless you place it in series with a load to limit the current flow (which is really the only way you'll learn anything useful from the ammeter function anyways).
>Never, EVER leave a diy thing like this charging overnight.
>You need a charger circuit per cell.
Not if they're in parallel.
Chill out, dude.
So are you saying that I should charge them individually until they are full or at the same level and then pack them up? Why can't i let this thing charge fully so what if one battery is a little bit charged? Isn't this thing gonna calibrate itself?
as long as your battery is between 2.2 and 4.4 you can use as many cells as necesary.
string them all together in parallel and charge them all together.
i would use a 500mA usb charger.
2A or more might overheat the cells
Okay so this thing has been charging for a while now. Tried it with 2A chargher and 1A, regardless the chip is getting pretty hot.
Go look at multicell hobby chargers (the ones for stuff like drone batteries) the cheap good ones are around $80. What these things do differently is instead of monitoring total voltage, they monitor voltage of individual cells, so if you start off with one battery that's significantly differently charged than the others, it'll not throw off the charge of another...say you hook up two batteries and one has a charge of 9V and the other has a charge of 3V...instead of seeing that as a total charge of somewhere in between those two numbers (thus overcharging the 9V one and under charging the 3V) it sees the 9V as 9V and 3V as 3V so it cuts off the charge to the 9V once it hits whatever voltage total it's supposed to have, and continues charging the 3V until it gets to whatever total it's supposed to have. (numbers pulled out of ass for illustrative purposes)
There is nothing fundamentally wrong with what OP does. Cells connected in parallel will just look like one bigger cell to any circuits attached. If a circuit works with one cell, it will also work with n cells in parallel. Before connecting cells in parallel however, it should be made sure that each of them is in good working order, and they are within 0.1V difference to each other. Old laptop cells are perfectly fine if tested. I salvaged around 50 old cells so far, but for the 50 good ones, I also had a couple duds. Some would begin to charge fine, but then get hot when they reached a specific voltage. So test dubious cells with a cooking pot over them for safet reasons.
I personally use this power bank to my satisfaction:
A single chip like OPs will work fine as well, but only connect known good cells.
Well I checked the cells before this but they were almost dead. I connected one to the circuit trying to see if I can restore them and it regained its voltage but I didn't do the same with the other five. They have been charging for half a day now and none is heating up at all.
"Fundamentally" guy here again. Good to read none of your cells blew up so far. The only other issue is that some of the cells might have so little usable capacity left that they are essentially worthless. But you can only determine by testing them individually. The "Liitokala Lii - 300" charger would be good for this, pic related.
No problem, as long as they are know good with a usable capacity left as described above. By putting all cells in parallel, it spares you the grief ob "balance charging" as the RC hobby charger guy said.
I own around 1000$ worth of chargers (Junsi iChargers mostly), and did not pay for a single one as I get them for testing and ironing out bugs. So believe me when I say that paralleling cells ins the way to go for your application.
Allright guys this seems to be working quite well. I let it charge for 7 hours first day then second day I let it 3 hours. So with about 10 hours of charging at 2A I have some results. I have a Nexus 5 with 2300 mah battery.