These units are available suspiciously cheaply from eBay and are designed to charge a wide range of lithium cells using a long spring loaded battery contact. The charge current is variable according to the cell voltage, with the current progressively reducing as the cell charges.
The circuitry is basically a super-minimalist flyback switcher powering a generic lithium charger chip which seems to have the useful facility of detecting the cell voltage and swapping the charge contact polarity accordingly.
Rather predictably, track isolation is minimal and the transformers internal separation is an unknown variable. I'd suggest not touching the contacts of these units while they're plugged in.
If you enjoy the videos on this channel you can help support it with a dollar for coffee, cookies and non-compliant chargers at https://www.patreon.com/bigclive
The circuitry is basically a super-minimalist flyback switcher powering a generic lithium charger chip which seems to have the useful facility of detecting the cell voltage and swapping the charge contact polarity accordingly.
Rather predictably, track isolation is minimal and the transformers internal separation is an unknown variable. I'd suggest not touching the contacts of these units while they're plugged in.
If you enjoy the videos on this channel you can help support it with a dollar for coffee, cookies and non-compliant chargers at https://www.patreon.com/bigclive
Aren't those isolation slits great?
I have several of those chargers, they came with every laser pointer I purchased.
It's very easy to see why that transistor went bang. Also when it fails it will go BANG! if the first diode doesn't fail first. Also that 400V 1uf has more potential to go bang than you think if there's significant transient spikes on the mains supply. It's a right and proper little banger this thing 😂
Really old video but thought I'd mention that I have a couple chargers that look just like the single one here, but with US/120V plug. This video caused me to look at the labels more closely, and mine doesn't say anything about battery polarity, just plus and minus. But the label also says the input is 110-220V which I found surprising. I wonder if/how the output would change, if at all. Oh, and mine is only a 450mA output, not 500 like yours, so I feel cheated… 🙂
i got an old battery pack with a nearly dead cell (has maybe half it's og capacity) and i'm tempted to repurpose the electronics on a new cell
I have 3 of the single cell chargers. They work a treat keep my fleet of salvage laptop cells topped up for my fleet of cheap LED torches. Thank you for the explanation.
Never had a problem
The cheap chargers work very well ATTENDED. Most chargers are off these little chargers are on the money. A reference point for Hobby chargers. Those Alarm buzzers are notoriously off. BUT USABLE AS ALARM. USING HOBBY CHARGER W NO BMS
Anyone who bought this & blame the maker is confirmed a cheapskate.
So to complain about it is an admission of the cheapskate in the mirror. Seriously, what do you expect for $1 when you cant even take a public bus home with it? On the other hand, the amt of technology going into it & logistics is much much more, yet the maker is so ingenious to send it to yr home for $1. So losers out there- eat yr heart out if you blame the maker/seller for it. You are a cheapskate for ordering somethg cheap and blaming it for being cheap.
Nice
Thanku brother
I bought two chargers of these Chinese
I ask: It is dangerous to put the battery with the reverse polarity, I think it can cause a short circuit
I have checked that if the battery is first placed in the charger before placing it in the AC outlet, the polarity is correct …
For the cheap price it is better to change the internal circuit for a Tp4056 and a USB connection and we have a charger with a retractable slot.
Greetings from Venezuela.
How big is the capacitor next to the small transformer? Thanks
I want circuit charger battery4.2volt indicator led green led red drive by transistor not ic
lol that is the EXACT charger that came with my non-Ebay flashlight. Which, of course, only turns green when you jiggle it.