I am loaned a prototype of an industrial device (running some Linux with an Android flavor). Each time I turn it off, it loses time, and I need to connect it to some Ethernet network then login by SSH to adjust it. The thing is going on tour for a demo (we make the application,) and our salesman hates it.

Sneaking in, I see this. To me it looks like a 3V battery holder without battery, perhaps because there is apparently not enough clearance around to insert one. I could fix this with wires and hot-melt, but I need to be sure.

Can someone confirm/infirm the intended use of this component?

Note: I would make sure the PCB is not attempting to charge the battery before, and after connecting one. Last thing I want is an explosion inside the thing!

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    \$\begingroup\$ Yes, it is..... \$\endgroup\$
    – DKNguyen
    Jun 18, 2020 at 14:56
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    \$\begingroup\$ Just the board designer had vague ideas about maybe supporting a battery backup doesn't mean that the circuity actually works or that the software would make any use of whatever the battery might back. You probably need to pursue this with those who created this prototype. \$\endgroup\$ Jun 18, 2020 at 14:59
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    \$\begingroup\$ Ask the people who loaned you the prototype! Yes, it's a battery holder, but perhaps there's a good reason there's no battery in there. It is a prototype after all. \$\endgroup\$
    – marcelm
    Jun 18, 2020 at 15:01

1 Answer 1


Yes, it is called a "coin cell retainer" and other various names. Small lithium coin cells are often used to keep a real time clock running for computers and embedded systems when they are off/sleeping.

Example MPD Datasheet


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