scornflake
New Member
All - firstly, thanks in advance for reading.
I'd like to embark on building a charging system for mobile devices of many kinds from reclaimed 3.7v (nominal) 18650 cells from old laptop batteries. I'd configure the battery pack in 3S, but understanding the voltage of these cells fluctuates between 3v (fully discharged) and 4.2v (fully charged) it occurs to me I might need some sort of variable input on a voltage regulator to deal with the varying voltage of these cells in a 3S configuration (9v-12.6v depending on the state of charge of the pack).
I've seen variable input and output step up (for example: https://www.amazon.com/DROK-Adjusta...8&qid=1424789189&sr=8-1&keywords=drok+step+up) and step down (https://www.amazon.com/DROK-Adjusta...tabilizers/dp/B00BYTEHQO/ref=cm_cd_ql_qh_dp_t) regulators , but it's unclear if the input voltage on these can be variable (see above) or if you have to specifically select your input voltage as it changes from 12.6v (fully charged) to 9v (fully discharged).
1) Is anyone aware of a voltage converter that'll deal with the fluctuating input voltage (again, from 9-12.6v it seems to me) on the fly?
2) suggestions on limiting the whole system to stop discharging once 9v (3.0v per cell in series) is reached?
3) any other suggestions on this project?
Thanks
I'd like to embark on building a charging system for mobile devices of many kinds from reclaimed 3.7v (nominal) 18650 cells from old laptop batteries. I'd configure the battery pack in 3S, but understanding the voltage of these cells fluctuates between 3v (fully discharged) and 4.2v (fully charged) it occurs to me I might need some sort of variable input on a voltage regulator to deal with the varying voltage of these cells in a 3S configuration (9v-12.6v depending on the state of charge of the pack).
I've seen variable input and output step up (for example: https://www.amazon.com/DROK-Adjusta...8&qid=1424789189&sr=8-1&keywords=drok+step+up) and step down (https://www.amazon.com/DROK-Adjusta...tabilizers/dp/B00BYTEHQO/ref=cm_cd_ql_qh_dp_t) regulators , but it's unclear if the input voltage on these can be variable (see above) or if you have to specifically select your input voltage as it changes from 12.6v (fully charged) to 9v (fully discharged).
1) Is anyone aware of a voltage converter that'll deal with the fluctuating input voltage (again, from 9-12.6v it seems to me) on the fly?
2) suggestions on limiting the whole system to stop discharging once 9v (3.0v per cell in series) is reached?
3) any other suggestions on this project?
Thanks