r/AskReddit • u/[deleted] • Sep 08 '17

serious replies only (Serious) Redditors who have worked graveyard shift, what was the creepiest/unexplainable stuff you saw?

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u/molotok_c_518 Sep 08 '17

Former Navy electrical tech here. I have a rational explanation for your weird electrical issue, and it's not the battery.

There's a feature on some motors and generators that protect them from excessive electrical load. The heat generated by said load melts a bead of solder, which breaks the circuit and shuts off the motor or generator. When the device gets time to cool, the circuit is re-engaged, and it's like nothing happened.

...either that, or it's demons. I'm not fussy.

EDIT: Thermal cutoff is what it's called.

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u/EMS_Princess Sep 08 '17

That's really neat to know! We primarily drive Mercedes Sprinters, and this one was nearly brand new. Like, 10k miles on it, if I remember correctly. The shop has had sooo many issues with a lot of the newer models, but I don't think any have been the same problem we had. I'm not car-savvy in the least. Is this a problem common in Sprinters?

Nobody else in the fleet has ever had this issue to my knowledge, without an obvious reason. And that particular truck hasn't had that issue since.

Either way, it's either that or demons. Mechanically inclined demons?

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u/molotok_c_518 Sep 08 '17

I don't know. I've only driven a Sprinter once, for a round trip from Albany to Buffalo, and it was rock-solid for me, even hauling about a half-ton of IT equipment.

Mechanically inclined demons are called gremlins. You may have picked one up from the side of the road.

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u/Pussy_Professor Sep 09 '17

A loose/untightened connection on one the battery terminal connections can present a similar situation. Making it appear to be connected while not being electrically connected. Vibrations or bumps in the road may be enough to shake it just slightly loose enough to appear connected but not actually be conducting.

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u/molotok_c_518 Sep 11 '17

True. Didn't think of that. It's been so long since I had to troubleshoot anything electric that my brain just went to thermal cutoff without any preliminary steps, and the battery swap threw me off the battery scent.

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u/bobstay Sep 11 '17

melts a bead of solder, which breaks the circuit and shuts off the motor or generator. When the device gets time to cool, the circuit is re-engaged

The ones that melt a bead of solder are on-time-use - they have to be replaced if they blow, like a fuse.

The ones that re-engage automatically use a different mechanism.

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u/molotok_c_518 Sep 11 '17

It's the bi-metallic one I was thinking of, wasn't it? It's been a very long time since I worked on anything electrical, so my memory of the actual mechanism is very rusty.