So I chose the mux: DG408DY from Vishay and the ADC: LTC2452ITS8 from LT (backup choice: LTC2470CMS form LT) they are basically the least expensive components who fit what I need (and sorry but the ADC is only available in a 0.65 mm pin pitch package, the least expensive ADC in a SOIC package is around $10 so I'm not going that path...). Also, given the low price of the mux and high price of multi-channels ADCs I'll use one more mux to mutualize the single channel ADC between voltage, temp and current measurements.
Ah ok, this explain that
What you're trying to do is basically creating a mux (multiplexer) with relays/mosfet/bjt. You can do it but it'll be expensive, have a high parts count, be power hungry, use a lot of space, ... then for a few $ max you have an already made mux (and it takes binary as an input so only 3 wires for 8:1 or 4 wires for 16:1) who is better on all levels, so I highly recommend that path.
I am using LTO cells max volts of 2.8 per cell or a total of 33.6 volts
Ah ok, this explain that
Again please excuse my ignorance of electrical engineering. What I have done is used 2 8 channel relay boards to measure the voltage of each cell starting from cell 1 and subtracting the previous cumulative voltages for cells 2 through 12 this gives me the voltage of each cell. It works quite fine but 2 8 channel relay boards are very large and I'm sure inefficient. I ran each measurement through a single voltage divider between my relays and the measuring device to overcome the high voltage of the upper cells in the series.
What I tried next was using mosfets to iterate through the cells but quickly found out that they don't exactly work that way.
Is there a way to use mosfets or BJT's to do this?
What you're trying to do is basically creating a mux (multiplexer) with relays/mosfet/bjt. You can do it but it'll be expensive, have a high parts count, be power hungry, use a lot of space, ... then for a few $ max you have an already made mux (and it takes binary as an input so only 3 wires for 8:1 or 4 wires for 16:1) who is better on all levels, so I highly recommend that path.