Author Topic: Battery Protection Circuit  (Read 856 times)

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Offline jramTopic starter

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  • Country: mt
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Battery Protection Circuit
« on: May 01, 2018, 03:22:56 am »
Hi folks,  Not my first posting but anyone that read my first will realise I'm pretty new to this.  I thought I'd share my 2nd revision of a battery protection system for my LiFePO4 batteries - I live off grid for a good part of the year.

The original circuit and board worked well during last solar season and now I'd like to refine the design and seal it up in a box. (The attached photos will show why I need a new board :))

This is a battery protection system.  The it drives 2 Bistable relays that provide battery protection in case of over-voltage, under-voltage or cell differential by disconnecting the chargers or the loads attached to the batteries.

The board is designed mainly to drive 2 bistable high-current relays. (Blue Sea 7700 http://assets.bluesea.com/files/resources/instructions/990180170.pdf) requiring an 'on' and 'off' signal on separate lines. The IXDN604s http://www.ixysic.com/home/pdfs.nsf/www/IXD_604.pdf/$file/IXD_604.pdf provide a simple solution for driving all kinds of relays - oh, and MOSfets and I had some so I used them.

The LED channels are used to monitor the voltage on the LED output from the relays which allows the status of the relays to be known.
The relay driver channels are driven from an ESP32.

I'd welcome input on any changes or enhancements that might make this a more robust solution.

I previously used an I2C ADC to monitor cell voltages and I'm in 2 minds as to whether just to use the ADC channels on the ESP32 instead so if anyone has any fors or againsts in that department - it would be good to hear as well.

P.S. Please ignore the pinout allocations for the ESP - they are purely placeholders in this schematic.

Many thanks in advance - This forum is fascinating reading.
TVMIA

John
 


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