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We have different battery packs that can plugged into our circuit, we're wanting to identify exactly which battery pack has been plugged in, but, as ever, in a very low-cost way.

I'm thinking RFID tags, but using a wired connection instead of RF... I've found unique id chips from Maxim (http://www.digikey.com.au/product-detail/en/maxim-integrated/DS2411R-T-R/DS2411R-CT-ND/2045729) but the cost is 10's of cent, and I'm looking for a solution for that's <10cents. (I'm guessing this price difference between RFID and unique ID chips is partly to do with die size)

There's a micro that's monitoring the cell, which would be doing the comms with whatever is on the battery. We're looking for a solution that effectively (24bit+ 1,000,000+unique ids)

Ideas: Passives? Crystal? Read RFID tag directly without RF? Lower cost unique ID chip?

Has anyone looked at this before?

Many thanks!

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  • 1
    Do you have just bare cells or is there some sort of management IC per battery? – Ignacio Vazquez-Abrams May 12 '16 at 1:42
  • You make it seem like RFID's are a good solution. Maybe the best you can do is check around (E-Bay, etc) for bulk sales of large quantities at a lower price. Be sure to get detailed specs before buying. – Sparky256 May 12 '16 at 1:52
  • How many pins do you have to play with? – ThreePhaseEel May 12 '16 at 3:52
  • What would happen if a second battery was left lying in close proximity to your RFID reader? Go for wired solution. You have to plug in a battery anyway so plug in the data lines too. – Transistor May 12 '16 at 19:14
  • @IgnacioVazquez-Abrams it's pretty much just bare cells, no intelligence in there at the moment. – Daniel Crowley May 14 '16 at 5:03
up vote 1 down vote accepted

I would think some cheap EEPROM memory could be what you're looking for. You can get 2 kilobit (~1e77 unique options) memory modules for about $0.11 each, assuming quantities of 100+. Here is a quick link to Digikey (many other vendors exist). This method requires a physical connection and some pins for communication, but it probably one of the cheapest.

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  • I think my common sense let me down here, I was expecting 64bit of memory to be less than 2kb... the power of scale. Cheers! – Daniel Crowley May 14 '16 at 5:05
up vote 3 down vote

I agree with Alex's suggestion of using an EEPROM but I would get one with a unique serial number already burnt on it. Such as Microchip's 24AA02E48 (datasheet Here). It has a 48-bit globally unique ID or there is a 64-bit option if needed. They are in the $0.20 price range.

Plus you have the EEPROM to store future additional data, like batt. charge cycles, etc.

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