Hi all,
I am building (trying to build) a mini underwater ROV for a bit of fun. I have everything working except, I have overlooked the charging of the battery, and more specifically the electrolysis of the charging contacts when in salt water. I am mainly concerned with:
- Maintaining exposed charge contacts (so that the ROV can sit on a charging cradle without the hassle of unscrewing ports)
- Ensuring that the battery is fully and properly charged by the external charger (I do not wish to integrate the charger into the ROV, due to heat dissipation issues)
- Charging a single cell Li-ion at 2.5A (max 5A if possible)
My initial thought was a diode between port and battery, i.e. between battery and charger. This has many issues the most significant being that the voltage drop across the diode would change the charging characteristics.
My next thought was a MOSFET which was 'switched' on when the charger was connected, which then lead me to an ideal diode design such as the LTC4352.
My question is, how would you guys stop the reveres current from the battery and how would you ensure the battery charger was charging the battery correctly, considering there is probably going to be a voltage drop across any switch or diode used?
It is worth noting: I have a microcontroller monitoring battery voltage and so there are a few I/O pins free which could be used to implement some sort of switching, and the charger I am using can have the voltage parameters altered i.e. if the was going to be a constant voltage drop independent of current I could increase the charger CC/CV voltage characteristics. I have included two high-level schematics, the first 'basic' is what I hope to achieve bare minimum, where as the second also includes a rectifier so the polarity of the charger contacts is interchangeable.
Any help confirming my direction would be much appreciated!
James
I am building (trying to build) a mini underwater ROV for a bit of fun. I have everything working except, I have overlooked the charging of the battery, and more specifically the electrolysis of the charging contacts when in salt water. I am mainly concerned with:
- Maintaining exposed charge contacts (so that the ROV can sit on a charging cradle without the hassle of unscrewing ports)
- Ensuring that the battery is fully and properly charged by the external charger (I do not wish to integrate the charger into the ROV, due to heat dissipation issues)
- Charging a single cell Li-ion at 2.5A (max 5A if possible)
My initial thought was a diode between port and battery, i.e. between battery and charger. This has many issues the most significant being that the voltage drop across the diode would change the charging characteristics.
My next thought was a MOSFET which was 'switched' on when the charger was connected, which then lead me to an ideal diode design such as the LTC4352.
My question is, how would you guys stop the reveres current from the battery and how would you ensure the battery charger was charging the battery correctly, considering there is probably going to be a voltage drop across any switch or diode used?
It is worth noting: I have a microcontroller monitoring battery voltage and so there are a few I/O pins free which could be used to implement some sort of switching, and the charger I am using can have the voltage parameters altered i.e. if the was going to be a constant voltage drop independent of current I could increase the charger CC/CV voltage characteristics. I have included two high-level schematics, the first 'basic' is what I hope to achieve bare minimum, where as the second also includes a rectifier so the polarity of the charger contacts is interchangeable.
Any help confirming my direction would be much appreciated!
James
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