# Looking for general information - how many load sensors max, and approach

I have a project where I would like to monitor 12 different opaque vessels, and the easiest way (no flow meters, no floats, etc.) would be to just measure weight and convert to volume. I don't need very fine resolution (although it would be nice), and the weights will be anywhere from about 2-50 lbs (1 lb increments is probably sufficient in reality).

I've been reviewing project logs, and I have two main questions;

1. the projects that seem to be fairly successful seem to use 4 load sensors per "item", which means I would need 48 total (which seems pricey)- can anyone recommended arduino-friendly, low cost load sensors available in this quantity at low price?

2. How many arduino would I need to collect all of this input (48+ signals?) and convert it into 12 distinct measurements? I'm assuming that different models will have different numbers of inputs, so recommendations would be great. Is there any way to run all of this off one Arduino, so I don't have to integrate data from multiple boards into my output (whatever that ends up being, maybe LCD panel)?

I welcome any and all feedback/advice

You could go with a bank of 8-channel ADCs, use 1 per 2 vessels, so 6 chips.
Use standard Arduino to read SPI from 6 chips.

Question to OP: What are you putting in these vessels? If there's heat or high voltages present that changes the answer. Usually when someone asks this type of question they're making beer or moonshine or something.

The reason why four are used is to balance the load. You can use a single point sensor if you can guarantee that nobody is dropping things on it and twisting the platform (and you can build a strong platform, i.e. welded steel) but that's typically unrealistic. At any rate it's not worth the effort when you can buy four, half bridge load cells for under \$10. A full bridge, single point load cell usually costs more than that.

You could go with a bank of 8-channel ADCs, use 1 per 2 vessels, so 6 chips.

You're thinking that you would build two half bridges and use the ADC to figure out the differential voltage? I'm honestly curious what you're proposing. I know he's only asking for ~6 bits of precision but without any amplification are you sure that would work?

Chagrin:
Question to OP: What are you putting in these vessels?

Your guess was close- this is for a 12-keg tap system, where it will not be convenient to open up and manually access each keg to determine remaining contents. Weight seemed like the most straightforward option.

It won't be for the actual brew cycle, where you might have heat or other high voltages (like heating elements)- this will just be to monitor the kegs that are tapped and being emptied over time.

I might actually increase the number of sensors, so that the CO2 canisters can also be tracked (if the approach ends up being affordable and within my technical skills)

Thanks!