Battery terminals

The charger can connect to two individual battery packs, which can be connected to the board through two sets of screw-terminals. Refer to Figure 1 to identify the battery terminals (Battery A and Battery B).

The battery connectors (J500 and J501) support various types of battery packs. Therefore, in addition to the positive and negative battery poles, the connector has additional terminals (see Table 1).

Table 1. Terminals on the battery connectors
Terminal label Use
BATTERY+ Positive pole of the battery
BATTERY- Negative pole of the battery
RID/NTCFOOTNOTE.html For batteries that have either a Resistor ID (RID) or Negative Temperature Coefficient resistor (NTC) line.
1-WIRE/SDA For batteries that have a built-in 1-Wire EEPROM (from where battery parameters can be read). Alternative, a TWI/SMBus data line can be connected to this line (for a smart battery charger)
SCLFOOTNOTE.html A TWI/SMBus clock line can be connected to this line (for a smart battery charger)
ENABLE Can be connected if the battery has an enable line.

The buck converter outputs are connected to the terminals through relays, to make it possible to connect two batteries to one charger. The relays are default open (not conducting), and should therefore be actively closed to connect a battery. The two relays should not be closed at the same time unless the two batteries are having the same voltage level. When a relay is closed the corresponding active-LED (D500 and D501) will light up.

When using an ATtinyx5 to charge a battery, only one battery pack should be connected unless the battery packs are meant to be in parallel. Note that the ATtinyx5 cannot control the relays, due to the lack of available pins. It is therefore required to either program the ATtinyx61 to enable the relay(s) or to short pin 7 (battery A enable) / pin 8 (battery B enable) of the ATtinyx61 socket to V3P3A (pin 5).


In applications were both NTC and RID are used the SCL terminal can be used as alternative RID input.