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The main goal of this post is to gather external opinions regarding the circuit below, so please feel free to point out any concerns and provide ideas for improvement.
I have been working on a 6V SLA battery charger. The idea is to keep the number of components as low as possible, use common parts, and ensure the circuit works properly without stressing the battery.
The circuit will be used alongside an MCU, so integration is possible.
The goal is to maintain a minimum voltage of 5.5V and cut off charging (current) when the voltage across the battery reaches 7.5V. Besides using a relay or a MOSFET driven by an MCU to disconnect the battery when it drops below 5.5V, to avoid damaging the battery and put unecessary stress on Q3, what other cheap and efficient methods can achieve this?
The 1.5ohm resistor (can be 1.2 for slightly higher current 600mA) will set the charging current to about 500mA or 0.1C, the current curve can be observed in the plot below:
Note in images below I probe is reversed by mistake but does not affect results.
Lowest safe voltage 5.5V @ 450mA
Full charge at 7.5V @ 400uA
The battery:
I have been working on a 6V SLA battery charger. The idea is to keep the number of components as low as possible, use common parts, and ensure the circuit works properly without stressing the battery.
The circuit will be used alongside an MCU, so integration is possible.
The goal is to maintain a minimum voltage of 5.5V and cut off charging (current) when the voltage across the battery reaches 7.5V. Besides using a relay or a MOSFET driven by an MCU to disconnect the battery when it drops below 5.5V, to avoid damaging the battery and put unecessary stress on Q3, what other cheap and efficient methods can achieve this?
The 1.5ohm resistor (can be 1.2 for slightly higher current 600mA) will set the charging current to about 500mA or 0.1C, the current curve can be observed in the plot below:
Note in images below I probe is reversed by mistake but does not affect results.
Lowest safe voltage 5.5V @ 450mA
Full charge at 7.5V @ 400uA
The battery:
