Since the Lee Hart Battery Bridge has come up a number of times it has been suggested I start a thread on the topic.
For the Buggy I'm looking into some type of Lee Hart style battery bridge so the car can be shut down easily with no parasitic pack loads. Just disconnecting the bridge pack + and pack - connections would remove the entire load from the system. I've been thinking about 2 different approaches to this.
One would be a 2 comparators forming a voltage window detection circuit. If the common input was the center of the pack and the references where about 1/4 volt above and below the virtual center of the pack the voltage window would be exited if any one cell swung 1/2 volt out of line. The output of the comparators would drive a optical isolator and then a typical 12v system control setup could drive the alerts. My Clean Power Auto BMS head end board could be used.
The other idea is to build the system with diodes like Lee designed it but instead of red LEDs use the LEDs in a 2 channel optical isolator. Then the isolated output of those LEDs could drive the warning/shutdown systems. Since this would operate the isolator output transistors is a more analog mode I would guess each channel would require a trim pot to adjust an output stage that would most likely be a TLV431.
It probably is a good idea. Quite a few different approaches have been suggested. I've posted a couple of basic ideas above for how one might be constructed. I'd like to hear more ideas on how to accomplish this, as well as how to use and/or display the results.What about starting a thread for something like this. I have a couple of emails from Lee Heart about two other ways to do this. One of them is to use a zero centered ammeter in with a +-50 uA range. The meter could be calibrated to represent any voltage difference desired. The other circuit would be some sort of comparison circuit. A couple of designs could be created with possible source of components for each one.
What do you think?