Have a battery from an oxygen generator. Labeled at 14.4V Nominal 5.8Ah. It consists of 16 batteries in series/parallel of 4 packs of four batteries. They have sat uncharged for a long time and have no power. There's a test button and four indicators that doesn't seem to be working. I've opened the pack and read battery voltages directly from the packs of batteries. They have read less than 1 volt. However, they WILL take a charge if I force them to. By that I mean applying 13.8V to a single pack - or a pack of 8 series/parallel or the whole 16 batteries again in their original series/parallel configuration.
I KNOW there's a limit to the amount of current required AND I KNOW there's a current charging profile that should be followed.
These batteries don't seem to want to charge the normal way via the oxygen generator - and I don't want to hurt the generator either. Since these batteries won't charge the proper way I'm looking to learn more about charging them. I've read a couple threads regarding charging Li-Ion's but haven't learned anything I could find useful.
The batteries are marked 18650 3.6V and no other markings. No Ah ratings, nothing more. Reading from a site called Battery University they state {quote}: "Voltage calculations include measuring the mid-way point from a full-charge of 4.20V/cell to the 3.0V/cell cutoff with a 0.5C load." {end quote} What I don't understand is what they mean by "0.5C load". And I'm not able to find anything more specific about charging current other than the site said {quote} "Full charge occurs when the battery reaches the voltage threshold and the current drops to 3 percent of the rated current." {end quote} That "3% of the rated current" doesn't help if you don't know the capacity of the battery (Ah). Since the battery doesn't state this - I can't (won't) go forward with attempting to charge them until I know how to achieve proper charging.
I have a smart charger that can charge a single cell at a time and do a nice job at that. however, I don't want to start busting these batteries apart. I'd rather keep them in their configuration of four parallel packs of four series batteries. If needed I can draw a picture.
So what would be considered a safe charging current if I were to just push a voltage into them without a smart charger? Yeah, I know that wouldn't' be smart. But the packs are 14.4 volts and I'm able to push 13.8 volts at the most. And at present I have almost no ability to monitor temperature either.
I KNOW there's a limit to the amount of current required AND I KNOW there's a current charging profile that should be followed.
These batteries don't seem to want to charge the normal way via the oxygen generator - and I don't want to hurt the generator either. Since these batteries won't charge the proper way I'm looking to learn more about charging them. I've read a couple threads regarding charging Li-Ion's but haven't learned anything I could find useful.
The batteries are marked 18650 3.6V and no other markings. No Ah ratings, nothing more. Reading from a site called Battery University they state {quote}: "Voltage calculations include measuring the mid-way point from a full-charge of 4.20V/cell to the 3.0V/cell cutoff with a 0.5C load." {end quote} What I don't understand is what they mean by "0.5C load". And I'm not able to find anything more specific about charging current other than the site said {quote} "Full charge occurs when the battery reaches the voltage threshold and the current drops to 3 percent of the rated current." {end quote} That "3% of the rated current" doesn't help if you don't know the capacity of the battery (Ah). Since the battery doesn't state this - I can't (won't) go forward with attempting to charge them until I know how to achieve proper charging.
I have a smart charger that can charge a single cell at a time and do a nice job at that. however, I don't want to start busting these batteries apart. I'd rather keep them in their configuration of four parallel packs of four series batteries. If needed I can draw a picture.
So what would be considered a safe charging current if I were to just push a voltage into them without a smart charger? Yeah, I know that wouldn't' be smart. But the packs are 14.4 volts and I'm able to push 13.8 volts at the most. And at present I have almost no ability to monitor temperature either.