too many pull up resistors

Hi
I have a problem I want to build a circuit that for the prototyping will be made with ready made off the shelf modules, final version will be on a single board.

all chips I want to use are available on modules with their own built in pull up resistor when I change to all on one board what pull up resistor should I use.

I will be using a own design arduino board with only the pins I need used, to save space and fit the room available.

Multiple I2C bidirectional isolators will be used as well as 8CH multiplexers.

for testing is it alright to build a circuit with a pull up resistor with the extra ones in the overall circuit or should I bypass the onboard resistors.
kendrick

Multiple I2C bidirectional isolators will be used as well as 8CH multiplexers.

Does that mean 8 channel I2C multiplexers? In this case each bus needs pull-ups.

all chips I want to use are available on modules with their own built in pull up resistor when I change to all on one board what pull up resistor should I use.

Even with the prebuilt boards you should have only one set of pull-ups on the complete bus. If necessary you should desolder the installed pull-ups on all but one board.

I understand that each I2C bus will need its own set of pull up resistors what value would you suggest remember this will be built around a custom main board with an atmel mega328p at its heart, I'm not sure if the chip has built in pull up resistors.

The 2 unusual chips I will be using are the multiplexer chips several of them and the isolator chips, 1 isolator chip per sub board of which there will be many. each of those sub boards will have an isolated I2C bus with their own pull up resistors this will allow the sub boards to have a floating ground.

the multiplexer chip may allow for multiple address isolated I2C busses but all the busses have a common ground hence the need for an isolator chip.

kendrick

I understand that each I2C bus will need its own set of pull up resistors what value would you suggest remember this will be built around a custom main board with an atmel mega328p at its heart, I'm not sure if the chip has built in pull up resistors.

Depends on the actual circuit (bus capacitance) but for many cases a 4k7 might do the job. The ATmega328p has built-in pullups and they are activated by the Arduino Wire library by default but they are very weak, so this is probably OK in most situations. If you use bus multiplexers anyway the internal pullups probably aren't relevant.

The 2 unusual chips I will be using are the multiplexer chips several of them and the isolator chips, 1 isolator chip per sub board of which there will be many. each of those sub boards will have an isolated I2C bus with their own pull up resistors this will allow the sub boards to have a floating ground.

Are you sure what you're doing? Sounds a bit weird. It would help if you post schematics...
What's a floating ground in this context? According to the Wikipedia definition most circuits have floating grounds as they have seldom an earth connection.

I'm building a smart BMS that is as versatile as possible.

The reason for using the term floating ground is that to make the measurement of the cells as accurate as possible each ADS1115 will mesure 4 cells in series, to measure the next 4 in series you can either split the pack or isolate the ADS1115 from the rest of the battery.

The isolator performs the job perfectly, SCK, SDA, 5V, AND GND are all isolated in this chip.

the simplest version of this BMS will be for 16 cells in series, for this all that will be used is the controller board and 4 sub boards with 1 ADS1115(set to a different address) on each sub board, an I2C switch extender will be on each board and will also require a different address.

Over 16 cells multiplexer chips will be required the total number of cells that can be controlled with one main board I have not yet calculated but with just 1 multiplexer 128 cells could be handled, this would allow (if the price could be kept low enough) cells would no longer have to be managed in parallel only in series reducing the cost of fixing a battery pack when a cell went wrong.

Most fixed value BMS boards use values that will reduce the lifetime of a battery pack if reached(3v and 4.2v for LiPo for example) by reducing the range the distance able to travel per charge will not diminish that much but the battery life will increase dramatically causing the total number of miles per battery to go up. One BMS could handle any battery chemistry, all that would be needed would be to alter the settings.

A removable display would be available to monitor the battery pack. when not in use use after a few minutes the controller board would go into balance mode once that was over it would change to deep sleep mode to save on battery power.

kendrick