Assumptions
18650 Battery Assumptions
| Specification | Value |
|---|---|
| Nominal Voltage | 3.7v |
| Max Voltage | 4.2v |
| Cutoff Voltage | 3.0v |
| Capacity | 2500mAh |
Configuration Options
3S (9V-12.6V)
| Specification | Value |
|---|---|
| Nominal Voltage (3 x 3.7v) | 11.1v |
| Max Voltage (3 x 4.2v) | 12.6 |
| Min Voltage (3 x 3.0v) | 9v |
| Cells in Series for Voltage | 3 |
Pros:
- Can charge it from the car
- Works with most chargers (solar and car chargers)
Cons:
- Would not get full capacity when using with an inverter. The inverter would shut off at 10.5v.
4S (12V-16.8V)
| Specification | Value |
|---|---|
| Nominal Voltage (4 x 3.7v) | 14.8v |
| Max Voltage (4 x 4.2v) | 16.8v |
| Min Voltage (4 x 3.0v) | 12.0v |
| Cells in Series for Voltage | 4 |
Pros:
- Would be able to use the full capacity of the battery when converting to AC.
Cons:
- Would need to step down the voltage to 12v which may introduce some losses.
- Could not charge it off of the car
Battery Pack
3S30P - 60Ah
| Specification | Value |
|---|---|
| Nominal Voltage (3 x 3.7v) | 11.1v |
| Max Voltage (3 x 4.2v) | 12.6 |
| Min Voltage (3 x 3.0v) | 9v |
| Cells in Series for Voltage | 3 |
Parallel Cells to Get Capacity 60Ah/2.0Ah | 30 |
| Total Cells Required | 90 |
Dimensions (mm) | (long pack) =18*3 x 18*30 x 65 =54mm x 540 mm x 65mm (3 rows on 30 cells) =18*9 x 18*10 * 65 =162 x 180 x 65 4.25” x 10.6” x 2.6” |
If battery stops being useful at 10.8 for some appliances (AC Inverter), then we would end up getting 50% the capacity of the 3S battery pack.
My solar battery charger supports the 3S configuration.
Pack Distribution
Using rePackr.com:
Pack Dimensions
| Dimension | mm | inches |
|---|---|---|
| Width | 108 mm | 4.25" |
| Length | 270 mm | 10.6" |
| Height | 65 mm | 2.6" |
Other Possible Packs
Battery Spec 3S40P - 80Ah
| Specification | Value |
|---|---|
| Nominal Voltage (3 x 3.7v) | 11.1v |
| Max Voltage (3 x 4.2v) | 12.6 |
| Min Voltage (3 x 3.0v) | 9v |
| Cells in Series for Voltage | 3 |
Parallel Cells to Get Capacity 80Ah/2.0Ah | 40 |
| Total Cells Required | 120 |
Battery Spec 4S20P - 40Ah
| Specification | Value |
|---|---|
| Nominal Voltage (4 x 3.7v) | 14.8v |
| Max Voltage (4 x 4.2v) | 16.8v |
| Min Voltage (4 x 3.0v) | 12.0v |
| Cells in Series for Voltage | 4 |
Parallel Cells to Get Capacity 40Ah/2.0Ah | 20 |
| Total Cells Required | 80 |
Battery Management System
3S 100A Li-ion Lithium 18650 BMS Battery Charger Protection Board with Balance
| Feature | Details |
|---|---|
| Large discharge current | 100A |
| Instantaneous discharge current | 150A |
| Charging voltage | 12.6V |
| Large charge current | 10A |
| Overcharge detection voltage | 4.28±0.05V |
| Overcharge protection delay | 0.5S |
| Overcharge release voltage | 4.08±0.1V |
| Power balance detection voltage | 4.20±0.05V |
| Power balance release voltage | 4.20±0.05V |
| Electricity balance current | 42±5mA |
| Over discharge detection voltage | 2.8±0.1V |
| Overdischarge detection delay | 0.1S |
| Over discharge release voltage | 3.0±0.1V |
| Overcurrent detection voltage | 150mV |
| Overcurrent detection delay | 9mS |
| Overcurrent protection current | 200±10A |
| Overcurrent protection release condition | Disconnect the load |
| Short circuit protection conditions | External load short circuit |
| Short circuit detection delay | 250uS |
| Main circuit conduction resistance | ≤25mΩ |
| Working current | ≤20uA |
| Sleep current (when battery is over) | ≤10uA |
| Size | 8.2x5.1cm/3.23x2.01inch |
Test Results of Batteries
Spreadsheet: 88af-18650.xls
Battery Hookup Modem Batteries
COMES OUT TO ONLY $70/KWH!
Only 56 cents per cell! For $4.50 you get a modem battery with 8 LG 2200mah LGDAS31865 cells! Get them while they last! Last time we listed these a company bought almost all of them.
We spot tested tens of thousands of these cells and they came out around full capacity overall. These are a great source of genuine LG 2200mah cells because the modem batteries are either never used at all or they were used as backup only with less than 3 cycles. Modem batteries only gets cycled hen a house loses power which is very rare in our region.
| Brand: | LG |
| Model: | LGDAS31865 (ICR18650S3) |
| Capacity: | 2200mAh Rated |
| Voltage: | 3.60V Nominal |
| Charging: | 4.20V Maximum 1075mA Standard 2150mA Maximum |
| Discharging: | 3.00V Cutoff 430mA Standard 3225mA Maximum |
| Description: | Blue Cell Wrapper White Insulator Ring 18650 Form Factor |
Almost every pack we opened had the light blue lg cells, some had dark blue lg cells with the same specs. Either way they are all name brand cells, the best ones out there
I purchased 16x8 = 128 cells.
References
| Reference | URL |
|---|---|
| Buying Used Batteries | https://batteryhookup.com/ |
| Battery Pack Calculator | http://repackr.com/ |