stuart

Thanks for the info, looks like a similar replacement device for the AD7280A is the LTC6803-3. Just double the cost and out of stock everywhere!

Sure, I'd be interested in a PDF schema. Thanks.

Thanks for that. Are you only using 4x cells for a 12V style setup? As luck would have it, I'm also part of a project for a pick and place machine 🙂 https://indexmachines.io/

Heres the PDF of the schematic - https://github.com/stuartpittaway/diyBMS-CurrentShunt/blob/master/CurrentShuntCircuit/export/Schematic.pdf I've spent thousands with JLCPCB this year already ! @nicknorman forgot to ask, what was the cell monitoring chip you used? I'd be interested to use that in my next designs.

Yep, thats what I did - RS485/MODBUS based Current Monitor, with electrically isolated data connection. https://github.com/stuartpittaway/diyBMS-CurrentShunt

Good idea, might try that with an acrylic sheet to bolt everything to.

I agree custom chips are the best way for that. I used the INA228 in my current shunt/monitor and that been super accurate (20bit ADC) When monitoring cells, a lot of people have multiple parallel banks, so that's what the 256 monitors allows for, like 5x16 etc.

Ah, but that's cheating!! 🤣 I wanted the flexibility of a unknown number of cells to monitor, my solution can monitor up to 256 cells and provide about 1amp balance current for each.

I use an external 1.25V reference for measuring via the Atmel chip. I'm using attiny devices and the internal reference wasn't good enough.

Take a look at software antialias filters, or over sampling. You can increase the effective resolution without changes in hardware.

Thanks @Jen-in-Wellies it is a greaseless gland. From the comments above, I think a "normal" float style switch is going to be the best option - I'd hoped that the electronic/no moving parts would have been a better option by now, but alas! Next question - mounting the thing, previous float switch (from boat builder 15 years ago) was mounted on a flat steel plate and thrown into the bilge - this eventually rusted, broke up and clogged up the pump! Any other ideas for fixing both the pump and float switch?

Ok, so once the sensor is cleaned up it works normally? That's why I liked the look of the water witch, as it doesn't trigger on oil or fuel, just water. However not rain water!!

The power usage is tiny, 0.003A on the water witch I mentioned. I've got solar so that would easily cover that. Agreed, I just find over a period of years they jam up with dirt and become unreliable. Does it eventually stop or permanently damage the unit?

I'd like to add an automatic switch to my bilge pump. Not keen on manual float switches as they do seem to get stuck over time. I've a Cruiser stern which generally has a dry bilge but if the rain channels block, rain water can enter the bilge. Had about 6" of water in the bilge after about 6 weeks - this isn't normally the case though, looks like build up of mud had blocked the drain. Any recommendations, for electronic style switches? I looked at the water witch one but that has a warning about rain water not being sensitive to the device.

Good to know thanks @matty40s