Sorry in advance if I say anything stupid, I am in no way an expert in the field. Everything I know is pretty much self taught through years of experience in refurbishing mobile phone.
I deal with hundreds of phones that are sometimes decades old. Most of the batteries are still working, but I need some sort of solution in recharging them. I have reached the internet far and wide for a device to suit my need but at this point I'm not sure one exists so I need your superior expertise.
So here is the situation. A lot of these batteries have been discharged for so long that they will no longer accept charge from the phone, appearing dead. But giving it a couple of seconds boost with a slightly higher than recommended voltage will bring it back to life and most of the times the battery will be working fine and hold good charge after. The problem is, I rely on primitive technology. I have an adjustable DC power supply that can be set between 3v-12v. When I try to resuscitate a battery, I set it to 9v and touch the appropriate pins to the battery a few times for a split second, and when the power supply's LED flickers a little it means the battery draws power, therefore is alive and can now be recharged.
Another method, even more primitive, is this phone charger with a LED indicator on it. When idle is green, when the battery takes charge it goes red, when there is a fault in the battery it goes Orange, when the pins are shorted the LED goes off alltogether.
What I need is some sort of power supply with an active display, maybe able to set voltage and amperage output, (there are many out there) but I also need to see the power it that it is drawn by the battery, maybe the recharge level, some sort of live feed from the battery as it is being recharged.
I the closest thing I found are those Li-po chargers for RC models but not sure if those are safe for li-ion.
I have a few of those cheap Chinese universal battery chargers but are very unreliable and I found only work on good batteries with some charge left in them.
My budget is not very high, I found some industrial grade stuff for hundreds of ££ but for my small business, it would not be a smart investment.
Any help or suggestion would be appreciated!
Best Answer
As your working with what is likely single cell li-ion, and need to just make sure you get them to a chargable state, set your power supply to about 2.7V, and fit a 2.7K resistor in series, this will very slowly trickle charge it back up,
If it does not increase in voltage after a long while, the battery leaks to a point it is not really usable.
Normal lithium safety still applies here, charge them somewhere that if it exploded into fire, it would not harm you or others, the proper way would be something to warn you if it became warm, but at a slow trickle charge, if it became warm, its already breaking down internally.
The lipo chargers for RC vehicles are a suitable option, but many have the same issue that they will not respond when flatter than they expect.