NANO-20 Operation Guide
Practical recommendations, program settings, and charging advice for different battery types. This section will grow over time.
Section Topics
12V LiFePO4: quick view
Quick recommendations for charging 12V LiFePO4 batteries
There are two basic ways to charge 12V LiFePO4 batteries with NANO-20.
Option 1. CAt program
Suitable when the battery capacity is above 20 Ah. Set the charge voltage to 14.0 V. After charging is complete, the charger will switch to the battery storage stage.
Option 2. Manual program
Set the charge voltage to 14.0 V and set the charge current to the maximum 20 A, or to the current recommended by the battery manufacturer. When the green indicator is on, the charger can be disconnected from the battery.
Why 14.0 V is recommended
LiFePO4 batteries often show 14.6 V on the case, but in practice each manufacturer configures the built-in BMS at its own discretion. The threshold can range from 3.5 V per cell to 3.65 V.
Batteries of the same model and manufacturer, but from different production batches, have been observed with different threshold settings.
A 12V LiFePO4 battery consists of 4 cells connected in series.
In practice, batteries with a 3.65 V per-cell charge-end setting have not been observed. Most are configured close to 3.57 V, while some recent units are closer to 3.50 V. A LiFePO4 cell can charge at 3.50 V, and its service life will be higher than when charging to 3.65 V.
What happens if 14.6 V is set
If NANO-20 is set to 14.6 V and the battery BMS disconnects charging earlier, for example at its own 14.4 V threshold, the voltage value on the upper line of the charger display may change chaotically. In fact, the charger will be disconnected from the battery by the BMS control elements. The cells will most likely not be fully charged and balanced, so this situation should be avoided.
Signs of a correct charge-end threshold
As the voltage approaches the configured threshold, the charge current starts to decrease and eventually reaches a minimum value. At this stage, the BMS balances the battery cells, gradually equalizing their charge.
PR.1 program for LiFePO4
The PR.1 program can be used to charge 12V LiFePO4 batteries, i.e. 4S packs. Set the charge voltage no higher than 14.0 V. The battery must have a working BMS.
Example for a 50 Ah battery
After charging is complete, the program switches to maintaining about 13.6 V. For LiFePO4 4S, this is about 3.4 V per cell, a safe float voltage. However, keeping the battery at this voltage continuously for months or years is unnecessary. For long-term storage, it is better to charge the battery and disconnect the charger.
PR.1 parameters
| Parameter | Value | Purpose |
|---|---|---|
| 3P.V | 14.0 V | main charge voltage |
| 3P.A | 0.1C-1C | main charge current |
| 3P.t | 30-60 s | charge period duration |
| 3o.A | 0.01C-0.05C | main charge completion current |
| PO.t | 0 | discharge period time |
| PO.A | 0 | discharge period current |
| dЗ.V | 13.8-14.0 V | top-up charge voltage |
| dЗ.A | 0.02C-0.05C | top-up current, if used |
| dЗ.t | 0 | top-up charge disabled |
| -F- | off | do not use frequency charge |