Differences

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--- life_hacks:battery_tips [2025/11/18 12:11] – [Li-Ion/Li-Po charger modules] admin
+++ life_hacks:battery_tips [2025/11/20 23:03] (current) – [IEC LiPo size convention] admin
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 __How lithium works__: Lithium ions shuttle between the cathode and graphite anode during charge and discharge, storing and releasing energy. \\
-**Nominal Voltage is ~3.7 V per cell, 4.2 V per cell when fully charged.** \\
+**Voltage is 4.2 V per cell when fully charged. \\
+Nominal Voltage per cell is 3.6V for Li-ion (cylindrical / LiCoO₂) and nominal 3.7V for Li-Po (pouch cells). ** \\
+==== IEC LiPo size convention ====
+According to **IEC** LiPo sizing convention e.g. a 404343 battery is 4.0x43x43 (Height x Width x Length in mm). \\
 ==== Charging ====
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 Empty storing (aka forgetting the battery): Do not store lithium batteries empty. They die if voltage drops below 3.0V. Safe minimum under normal use is 3.3 V. Everything below 2.5V per cell is a danger zone (don’t attempt revival)! Do not attempt to trickle charge them for revival. \\
 When voltage drops too low, copper from the anode can dissolve into the electrolyte. On recharge, this copper can plate back onto the cathode as tiny dendrites, which may pierce the separator and cause internal shorts — leading to swelling, overheating, or fire. Recycle deep discharged battery. \\
 ==== BMS salvage and re-cell ====
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    * **DRM**: authenticate as original battery (some systems refuse to work with 3rd party batteries) - this is why you need to keep the BMS board!
-Due to the protection feature it can be that you measure 0V on an empty battery - the cell itself can still have a charge. This does not necessarily mean that the cell is dead, it still can have ~3V and be safely rechargeable. When disposing of the battery, cut off the BMS and discharge the cell itself. \\
+Due to the protection feature it can be that you measure 0V on an empty battery - the cell itself can still have a charge. This does not necessarily mean that the cell is dead, it still can have ~3V and be safely rechargeable. Before disposing of the battery, measure cell voltage. Cut off the BMS (keep it!) and discharge the cell itself - (I normally take a 6V bicycle light bulb). \\
+==== Multi Cell batteries ====
+Cells in Series → voltages add, capacity stays the same. \\
+Cells in Parallel → capacity adds, voltage stays the same. \\
+^ Connection     ^ Balancing needed         ^ BMS Needed?           ^ Best use case                        ^ Pros                                         ^ Cons                                         ^
+| Series (S)     | Yes                       | Yes                   | Devices needing higher voltage       | Higher voltage, simpler wiring for high-voltage devices | Needs balancing, single weak cell limits pack, higher safety risk |
+| Parallel (P)   | Usually no (should be similar voltage)   | Optional             | Devices needing longer runtime / high current | Higher capacity, lower internal resistance, self-balancing | Voltage of single cell, more complex wiring for many cells |
+| Series+Parallel (S×P) | Yes, for series groups     | Yes (for series groups) | High voltage & high capacity devices | Combines high voltage and high capacity | Requires BMS for series groups, more complex wiring |
+'Balancing' means that the battery cells need to have the same voltage. \\
+Be aware that multi-cells need to be supported and configured properly with the BMS and charger! \\
 ==== Li-Ion/Li-Po charger modules ====
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 For bi-directional boards, to use multiple cells for a power bank, see [[:projects:drill-powerbank-pd#diy_power_bank_pcb_options|DIY power bank PCBs]]. \\
 ===== Lithium-titanate batteries =====