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I am designing an battery powered instrument with around 20-40Ah 3S li-ion batteries in it along with a 10A 3S(12.6v) external charger.

Due to ease of availability and the current capacity I have used an IEC 60320 connector to charge the battery.

enter image description here

My problem is that the same connector is a standard connector used for AC power usually for PC's and other electronics. I don't want someone to plug in a power cord directly in here because it is directly connected to the battery.

I have looked into over voltage protection using crowbar circuit but it seems it blows the fuse every time,

enter image description here

so is there any smarter way of doing this?

Thanks for your help

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    \$\begingroup\$ Don't use the wrong connector. As for the crowbar, blowing the fuse is exactly what it is designed to do. \$\endgroup\$ – Chris Stratton Jan 29 at 16:41
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    \$\begingroup\$ I'm pretty sure using that connector for anything other than mains input is violating some standard or another... \$\endgroup\$ – Hearth Jan 29 at 16:56
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    \$\begingroup\$ Standardized connectors are only as good as the designers agreeing to follow the standard. The more we re-purpose them, the less functional the standard becomes. cough Apple cough \$\endgroup\$ – Chris Fernandez Jan 29 at 16:59
  • \$\begingroup\$ Thanks for your input, seems like I need to go for a DC barrel connector but I suppose the problem still persists as there could be several power supplies with different voltages using the DC barrel jack. (Unless I chose a not so standard connector ) \$\endgroup\$ – Ashlesh Bhat Jan 29 at 18:35
  • \$\begingroup\$ But with the barrel jack, you could bring the DC into a switching regulator set for whatever output voltage you wanted. What current do you need to charge the batteries? \$\endgroup\$ – CrossRoads Jan 29 at 19:37
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It's a really bad idea to use a standard connector type for a non-standard purpose, especially if the consequence of connecting a standard cable (i.e. AC mains) to your nonstandard equipment could be hazardous.

Wikipedia has a good overview of connectors typically used for DC power. As the article notes, 'barrel jack' connectors are usually only rated for a few amps, although they are seen on laptop power supplies at higher currents.

Out of the choices in the Wikipedia article I would suggest you use a 4-pin XLR connector (chassis plug and line socket), wiring pins 1+2 negative and 3+4 positive as it describes. These are not too expensive if you look around, are rated for your required current and you would be using them in line with an existing standard.

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