My lesson on that (NEVER to be forgotten!)?
I laid a 12-inch, 3/8s Snap-On extension, inadvertently, across the top of a battery.
Yes, they replaced both halves with a new one.
Batteries have been known to blow up doing that.
Yes: this one didn’t.
I did, one time, unhook a battery charger from a 510 Datsun battery, that had been cooking for an hour, w/o shutting off the charger.
Never did that again.
My ancient but fully functional battery charger had to be unplugged to shut it off. I performed a bit of surgery and installed a heavy duty on-off toggle switch in the front panel. Much more convenient.
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Interesting thread…I have qualifications in Electronics, but always something new to learn
A while back, while de-rusting using electrolysis, I allowed the 12V with a car battery to pass across my chest with the + power in one hand, and my other hand in the solution
It caused a weird sensation across the heart area, so I decided rubber gloves would be more sensible than finding a novel way to induce a heart attack
one analogy I heard with respect to voltage vs amps;
If something was to strike you, Voltage is how fast it strikes, and Amps is how heavy the object is
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No one ever paid me for doing that!
My FIL was an EE. When I told him that 1 Farad caps were readily available, he didn’t believe me. Really, at the time he was learning his profession, such a thing was inconceivable.
I have a matched pair of 1/4 Farad caps up in my attic. Somebody sent them to me in the midst of some online discussion, but I never put them to use. IIRC, these things must be directly connected to the battery, as any switch or contact between them would be vaporized. And when you first connect them up, you have to connect them through a resistor to allow them to build a charge gradually before you connect them directly. And if you need to disconnect the battery, you have to go through a similar disconnect and discharge procedure.
Just read all this and some people seem to not understand the relationship of voltage, current and amperage.
Barnyard DC electronics theory:
Voltage- is pressure. Same as the air pressure in in your air compressor tank. The air pressure gauge is a “voltmeter” Notice the pressure can just “sit” there doing nothing like leaning against a locked door.
Amperage- is current flow “kinda” (electrons don’t actually move very far but just bump into each other. The bumping is a “wave” that travels close to the speed of light.) Water moving in a stream mimics amperage. An in line water meter is an ammeter of sorts.
Resistance - is a restriction in in the conductor be it a stream or wire.
The Mississippi river is a high current low voltage system. Think 12 vdc starter.
A pinhole in the bottom of a dam is a high voltage low current system. Think tiny stream squirting 20 feet. Can’t do much work.
Voltage = resistance times current i.e. E=IR. By extension E/R = I and E/I=R (E is voltage and I is current)
Work or watts = Voltage times current
A lot of work or watts could be represented by a big pipe feeding a generator at the bottom of a large dam.
Was this helpful to anyone?
Double “E”'s I am not talking to you.
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Worked as an EE, but spent much time repairing electronics on the side. Repaired many thousands of units over the 40 years I did that. First time I encountered a super capacitor it was a 5.6F used to retain tuning information in a stereo receiver. It was buried in the unit between two PC boards so I had no idea it was there. I noticed a bad connection on the board and tried soldering it, blew solder all over the room, ended up pealing it off my safety glasses. Learned much respect for them that day, never had it happen again. Batteries have nothing on them for delivering massive amounts of current, but they are a bit fussy.
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Yes indeed Robert but it was related to the issue of how electricity can cause problems many different ways. Mine was VERY painful.
5.6F! Wow! How big was it?
5.6F is nothing these days! Here is one that is 166F@48.6V:
https://americas.rsdelivers.com/product/eaton/xlr-48r6167-r/eaton-166f-supercapacitor-edlc-0-20-tolerance-xlr/1351073?cm_mmc=US-PLA-DS3A--google--PLA_US_EN_Passive_Components_CA--Capacitors%7CElectric_Double_Layer_Capacitors--PRODUCT_GROUP&matchtype=&pla-675491928945&gclid=Cj0KCQiA2ITuBRDkARIsAMK9Q7PP-EVMyc2PAs3ZUGi3uztOqV2VWwKfQ9P916DrN9l-GlKk0qgKfLIaAlcEEALw_wcB&gclsrc=aw.ds
Edison helped design one, using graphene, that is 10,000F!
Regards,
Ray L.
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There was useable amounts of graphene, back in Edison’s time???
That’s still mighty tiny for a 166 farad cap rated for 48V! Being the size of a semi truck would be more to my expectation. They’ve clearly done a lot of development on the materials used.
Not that large, maybe 1.5 inch tall by 3/4 diameter.
Unbelieveable. The 1/4 Farad caps I have are about the size of short stubby beer cans.
When I worked as a junior Electrical Engineer with the Sydney supply authority we used to get involved with electrocution deaths. One of the more insidious ways to die is in a poorly isolated or earthed swimming pool or one with a faulty pool light. As little as 3V/m (as a distribution in the water) and a handful of milliamps current will produce paralysis - and potentially drowning - such is the way skin resistance is compromised.
AFAIK, swimming pool lights here in FL are required to be 12V, but I think they are 12VAC. Is that good enough? I’d hope they had a GFI breaker on them, too, but I dunno if you can get a 12V GFI breaker.
Here’s what a 1 Farad capacitor looks like today:
I’m trying to figure out why others would be so much smaller.
Here is an example: http://www.kemet.com/Lists/ProductCatalog/Attachments/464/KEM_S6014_FT.pdf
The 5.6 is a little under 2" in diameter, and about 3/4" tall (low profile). I suspect the difference is the voltage rating, and duty cycle.