I thought I was clear in understanding the polarity of the charger was reversed as is shown in post #4. but in post #36 all's well.

OH. Missed it.

Below are photos of the charger that I have taken over the past day. For some bizarre reason the charger is now for back to normal. There is something about this charger which is very mysterious. It seems I have to check which end is positive and negative before I put a battery on charge.

 

Loose nut behind the charger?

Just kidding. I respect all members of AAC.

 

If whatever has happened is real, it really calls for a genuine investigation. I am (so must be a lot of others) who wants to get to the bottom of how and why it happened. And I don't believe in Magic.

 

As I said in the first post, when I wanted to charge up the battery, I put the battery into the charger as anyone would with the negative end (the flat end) towards the spring. But the battery did not charge and the green light remained on the whole time. I tested the charger with a meter and discovered that the spring end was now positive and the pad end was now negative. (The polarities had reversed).
So I placed the battery into the charger the incorrect way and the red light came on and the battery eventually charged up when the green light came on.
I put the battery into a torch and the torch worked perfectly. I discharged the battery and when I tried to recharge the battery I discovered the charger connections had restored back to normal with the spring the negative and the pad end positive. I placed the battery into the charger and the battery charged normally.
This is very bizarre as to what happened. I've never known anything like this before.

 

If whatever has happened is real, it really calls for a genuine investigation. I am (so must be a lot of others) who wants to get to the bottom of how and why it happened. And I don't believe in Magic.

Trust me, I'm not joking and if you still believe I'm not speaking the truth then I invite you (or anyone) here to look yourself...that's if if does the same as in post #1
There's something very strange about this charger.

 

The charger is a switch-mode AC-DC buck converter which conventionally has a diode near its output to rectify the secondary winding voltage of a high frequency transformer to give DC.
Clutching at straws here, but if that diode breaks down it could let AC get through to the output. Perhaps the controller IC can tolerate the AC and still manage to regulate the output, albeit with arbitrary polarity?
Do you have a 'scope to check for AC on the charger output?

 

Firstly number 1 is an utterly ridiculous accusation and should be ignored and erased.

By what definition is what I said an accusation?
I said a possible explanation was that someone pulled a prank by switching the wires and asked you if that was possible. Your response was to say the you, not someone, had never opened the box. Do you always think everyone that uses the term “someone” is referring to you and you alone?

I am the only one who uses the charger no one else is here to touch it.

And I was supposed to know this how?

I would think you would be more courteous to the only one in this thread that has given a viable explanation within the constraints of the information you have provided.

Instead, you have called me a “geezer”, said that you should believed above me (even though I never contradicted you) because of the years each of us have been members (even though I have made over 5000 posts and you in the 200’s), and said I was being ridiculous for not knowing your living situation.

 

Please calm down, both of you. What we have been shown is a truly baffling phenomenon. Fortunately for Ford Perfect the problem reversed itself.

Number 1, (that somebody played a joke by switching the wires) was mentioned because it was on of the few possible explanations for the phenomenon. When coming into an unusual problem like this, one needs to be able to think freely and not reject possible explanations out of hand. Personally, I think this should be considers, as remote as it seems.

We need to all be courteous to on-another. I suspect the "Geezer" comment was a knee-jerk reaction to what seemed to be what seemed to be a terrible reaction to an unexpected response.

 

I know when to have a joke and I would make the joke so obvious that everyone can see it as a joke, and this posting is not a joke or prank.

I wasn't sure whether to create the thread because I was hoping I could work it out but this strange occurrence baffled me for ages and I couldn't work out what was causing it so I created the post hoping that someone could give me a simple, cogent and intelligent answer.
Personally I don't know whether the charger will remain working correctly, tomorrow it may reverse itself again. But I think I may have to test it each time with a meter before I put a battery in it to see where the positive and negative terminals are. I'm just now wondering if all of these charger models sometimes have this bizarre characteristic. I would love to contact the makers to ask them if this has been reported to them before.
I haven't yet taken it apart but I might at sometime soon just out of interest of how it's made up.

 

Several faithful years of service - now in failure mode; are they that expensive? It may be time to buy new.

Gotta agree. Why chance hurting other batteries? Or why chance a catastrophic failure that could lead to damage of property? My dad taught me that "If it did it once it will do it again." The charger I have connects to a USB port. Whether I plug it into a wall wart type or a computer (or other USP source) its polarity should never change.

But in the interest of solving the question of why did it change; further diagnostics is in order. Time to open it up and start having a go at the electronics to determine what's what and why (or why not).

As for the notion that someone is messing with you - you've stated that you're the only one in the house who has access to it. Back in the 70's at a church camp we messed with the cook. She had a dripping faucet and asked us maintenance guys to fix it. We did. But as a joke we reversed the hot and cold water valves so that when turning the water on (Hot was counter-clockwise and Cold was clockwise) the valves operated in the opposite direction. This resulted in her splashing herself a number of times because she was used to turning the valves a certain way and the water responded accordingly. She didn't find the joke very funny. But we did.

Could someone be messing with you? Not likely. But not beyond the realm of possibly.
Could you be messing with us? Again, not likely. But again, not beyond the possible.
Sometimes we get a question stuck in our heads and can't let go of it. To be honest, the thought of you messing with us crossed my mind too. And if you were messing with us - that doesn't make you a bad person. Just allows us the opportunity to wonder if you might be.

OK. OK. You're not messing with us. And OK, no one else could be messing with you. If the unit fails from time to time then I'd recommend replacing it. Just like Pan said.

 

I request Ford Perfect to open that charger and let us all have a look inside.

 

Trust me, I'm not joking and if you still believe I'm not speaking the truth then I invite you (or anyone) here to look yourself...that's if if does the same as in post #1
There's something very strange about this charger.

Why are you getting so defensive? I said nothing about anybody joking or speaking untruths.

 

I request Ford Perfect to open that charger and let us all have a look inside.

Yes, unless the battery holder is driven by an H-bridge or DPDT relay there is no electronic way I can think of for it to reverse and operate properly reversed. But can’t consider this unlikely as well, as this appears to be a cheap Chinese unbranded product that would not have added that unnecessary expense.

Also, If there was tampering, it might have left visibie evidence, but I consider that unlikely now that we have the additional information that no one else had access to it, which is why I asked that when proposing that possible explanation.

The biggest mystery to me, however, is why the TS thinks I or someone else have accused him of lying or playing a joke on us.

If it were me, I would carefully try inserting the battery backwards and see what happens. But I do not suggest that because it could literally blow up.

 

I request Ford Perfect to open that charger and let us all have a look inside.

Ok, this is not a problem. I can do this tomorrow morning in the daylight and take several photos.

 

The battery needed charging the other day so I placed the battery in the charger as I do and left it to charge but the green LED light remained on as if the battery was already charged.

but this strange occurrence baffled me for ages and I couldn't work out what was causing it so I created the post hoping that someone could

Interesting.

 

Ok, as promised here are the insides of the charger.

Maybe someone can reverse engineer this and let's all see and work out the circuit.
So far, there is one thing I have noticed on this circuit which I think is incorrect - (not terribly important).

I can take some more photos if required and also some very close up photos. Let me know.

 

HT3582D is a universal charger built-in reference voltage control chip, with automatic identification battery polarity, short circuit protection, over temperature protection
Protection and other functions.

So my guess 2 was correct, it automatically reverses the polarity if the battery is in backwards. Now the only mystery is why it did not charge when put in correctly once.

Possibly, the battery voltage was so low that it could not correctly determine the polarity and chose to reverse it. Of course it did not charge that way.

So, then when you reversed it, it charged normally.

If I am correct, you can put the battery in either way, which is a clever feature implemented by that chip. Thanks for providing the close up of the chip so I could look it up.

 

So my guess 2 was correct, it automatically reverses the polarity if the battery is in backwards. Now the only mystery is why it did not charge when put in correctly once.

Possibly, the battery voltage was so low that it could not correctly determine the polarity and chose to reverse it. Of course it did not charge that way.

So, then when you reversed it, it charged normally.

If I am correct, you can put the battery in either way, which is a clever feature implemented by that chip. Thanks for providing the clise ip of the chip so I could look it up.

You're right, Bob.

Here's a 'traced from PCB' or 'Reverse engineered' schematic.

https://danyk.cz/reverz30_en.html




And the accompanying text.

Schematic of a Chinese 3.7V Li-Ion / Li-Pol mains charger for 18650 (and also AA) rechargeable cells. Very simple switching power supply with just a single transistor 13001 and a single half-wave rectifier. No fuse, no inrush resistor, no EMI filter, no snubber network on primary winding. Very poor isolation in the transformer and on the PCB board. Totally non-compliant in EU, US, UK, etc. Contains HT3582DM Li-Ion charging controller chip with red/green LED indicator and automatic polarity detection. The cell can be inserted both ways around.

Nandu.

 

If I am correct, you can put the battery in either way, which is a clever feature implemented by that chip. Thanks for providing the close up of the chip so I could look it up.

No it seems you can't put the battery either way because as I mentioned above, I originally put the battery in the charger the 'correct' way (negative end of the battery towards the spring) and the green light remained on and the battery did not charge up.

Only when I placed the battery in the charger the 'incorrect' way (positive end of the battery towards the spring) did the red light come on and eventually after several hours the green light came on and the battery was fully charged.

I would certainly like to see the circuit diagram of this charger as I've never come across this situation before nor has probably many other people.

 

I gave my possible explanation in my previous post. You mentioned in your first post that the battery read only a few millivolts. My guess is that it could not detect the polarity at that level.

I am willing to bet that you could take a battery discharged to about 3V and it will charge whichever way you insert it.