-
Publication date for the next issue will be a week later than originally announced: 11th October.
This delay will allow those who take out a subscription at Hidden Earth to be included in our mailing list.
If you are not currently a subscriber, sign up on our website by 29 September – or come by our stand at Hidden Earth; we would love to say hi!
Charging 18650 batteries
- Thread starter Fulk
- Start date
royfellows
Well-known member
Fulk said:
Lithium Ion batteries cannot be discharged completely. There is a minimum voltage limit, usually controlled by electronics, of about 2.5 volts, individual manufactured cells may vary. Discharging below that level will destroy the cells and absolute discharge may cause internal short circuits that can cause the cell to explode, especially upon a charging attempt. This is why 'Protected cells' are recommended. But dont worry too much, dedicated chargers and the cell protection electronics have built in safeguards.
They do not suffer from 'memory effect', this is mainly a phenomena of Ni MH and should be top up charged before any mission critical use.
As a point of interest, phones and devices usually come with apparently 'flat' batteries. No so. They are electronically disconnected and the circuits 'activate' upon charging.
For any device, read the manual.
Final lesson from a recent lamp sale
Customer. How do you..........................
Me. Its in the manual
Customer. Oh, I threw that away
Addy
Member
Roy has eloquently pointed out the dos and don'ts with Li-Ions so I'll not repeat.
It is generally Nickel Cadmium batteries that suffer a memory effect and have been, to a large degree (apart from where very high current capacity was required), superseded by Nickel Metal Hydride which suffer this effect to a much lower degree.
NiCd and NiMH also have considerable self discharge rates and, as has been said, should be topped up before use.
Li-Ion batteries show hardly any self discharge and I have used them singly or in parallel in caving lamps I've built for years - both with and without protection cells (although I do fit a Polyfuse) and had no real issues (except with salt water...
). I've found that batteries charged 6 months previously retain 95% of their charge when discharged into a measurement load although that could be partly due to having no management circuit.
Charging them is simple - a 4.1V or 4.2V (depending upon spec) current regulated supply works perfectly. When they stop drawing current, they're charged.
It is generally Nickel Cadmium batteries that suffer a memory effect and have been, to a large degree (apart from where very high current capacity was required), superseded by Nickel Metal Hydride which suffer this effect to a much lower degree.
NiCd and NiMH also have considerable self discharge rates and, as has been said, should be topped up before use.
Li-Ion batteries show hardly any self discharge and I have used them singly or in parallel in caving lamps I've built for years - both with and without protection cells (although I do fit a Polyfuse) and had no real issues (except with salt water...
). I've found that batteries charged 6 months previously retain 95% of their charge when discharged into a measurement load although that could be partly due to having no management circuit.Charging them is simple - a 4.1V or 4.2V (depending upon spec) current regulated supply works perfectly. When they stop drawing current, they're charged.
crickleymal
New member
ChrisJC said:
That's what the Battery University recommend. Charge at constant current until it reaches close to the maximum voltage then it goes onto constant voltage until the current drops to something like 1% of the capacity.