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Solid State Amplifiers => The Newcomer's Forum => Topic started by: saturated on July 28, 2026, 06:11:43 AM

Title: The capacitor that wasn't
Post by: saturated on July 28, 2026, 06:11:43 AM
I dug this out of some dirt while weed eating and thought hey cool it's a capacitor

IMG_20260727_195842936 (1).jpg

Like maybe someone got mad at a TV when their kicker missed a field goal or tried to recreate Wendy O's flaming school bus through a wall of TVs  xP

But now it looks like a battery

IMG_20260727_195850224 (1).jpg

True story I have an elderly customer she had a Toyota hybrid SUV said it was a great car had it like 12 years but anyway it ended up getting totaled she was unhurt but told me about a hundred times she was so glad it didn't catch on fire like the big batteries or whatever.
Anyhow I believed her but it didn't really sink in I was like yeah ok yeah good thing  xP
About a month later I was mowing this guy's grass he's a young buck really good guy but a wild man I'm making a pass and hit something with my mower a loud thump it stops the engine I start cussing and pull it back....and there's a small fire  :grr  :grr
So I'm trying to wrap my head around this wondering ok maybe the blade sparked and ignited the dry grass...yeah kind of a long shot but who knows .... meanwhile I see some strange debris where the fire 🔥 is  :loco

About that time he runs out and says "oh wow you found my phone" and says him and his gf were fighting and drinking and she had thrown it out into the yard  xP

So I went back and told that lady wow now I know what you meant  xP
Title: Re: The capacitor that wasn't
Post by: J M Fahey on July 28, 2026, 09:48:52 AM
It IS a battery.
Does it take charge?
Use a 12 V supply and charge this through a 50-100 ohm resistor.
Title: Re: The capacitor that wasn't
Post by: g1 on July 28, 2026, 11:43:50 AM
Yes, it's rechargeable lithium type like you find in modern cordless drill battery packs etc.  Many batteries in series or series-parallel arrangements to make a 18V or 24V battery pack.
They used to use Ni-Cad type for all the rechargeable stuff, but they are using lithium-ion types more and more, which is where you get the fire hazards.  "Don't park your e-bike inside!" etc.
Title: Re: The capacitor that wasn't
Post by: saturated on July 28, 2026, 10:09:23 PM
Omg...... :lmao:  :lmao:  :lmao:  8|  :loco  :loco


So I spent like an hour soldering leads to the battery no matter what the battery had like an anti solder force field around it and the solder buggers clinging to the iron  :grr  :grr  :grr
Then I kept getting this sticky green scum so I kept scraping and cleaning

Somehow by miracle I got two leads to stick and now I cant believe what I'm seeing


xP  :loco  :lmao:

IMG_20260728_210313728 (1).jpg

The whole time I thought well no way it's holding any charge but the deal here is if you guys tell me to do something I have to do it

WOW
Title: Re: The capacitor that wasn't
Post by: saturated on July 28, 2026, 10:33:43 PM
IMG_20260728_212904609 (1).jpg

Illuminati confirmed  :tu:

IMG_20260728_212857487_HDR (1).jpg

 xP
Title: Re: The capacitor that wasn't
Post by: Kaz Kylheku on July 29, 2026, 01:33:31 AM
The battery was likely "recycled into the weeds" by someone who found the run-time degraded, not because it was totally dead.

I have a phone with a battery that charges it and powers it well enough to use, except you have to do that twice a day even though it's mostly on standby.
Title: Re: The capacitor that wasn't
Post by: saturated on July 29, 2026, 05:33:27 AM
Yes sir thanks I was actually in a pickle 🥒 driving to work wondering what exactly is the difference between a capacitor and a battery?!?!

I'm gonna have to think about it
They both charge up and have polarity at the terminals

:loco

Edit: one possible clue is a capacitor is not gonna supply a steady voltage or current for any length of time and requires constant recharging
Title: Re: The capacitor that wasn't
Post by: J M Fahey on July 29, 2026, 06:49:17 AM
Quote from: saturated on July 29, 2026, 05:33:27 AMYes sir thanks I was actually in a pickle 🥒 driving to work wondering what exactly is the difference between a capacitor and a battery?!?!

I'm gonna have to think about it
They both charge up and have polarity at the terminals

:loco

Edit: one possible clue is a capacitor is not gonna supply a steady voltage or current for any length of time and requires constant recharging
A capacitor will charge to any voltage you apply, batteries have a built-in "fixed" voltage which comes from a chemical reaction.

Also in principle most capacitors are bipolar, batteries are always single polarity.
Title: Re: The capacitor that wasn't
Post by: Kaz Kylheku on July 29, 2026, 04:37:15 PM
The word "battery" originally referred to an array of (i.e. "battery of") capacitors connected in parallel!

What is the difference between a modern battery and cap?

A battery (chemical cell) generates electricity from a chemical reaction. When a rechargeable battery is charged, the chemical reaction is basically forced to go backwards.

A capacitor only stores charge directly, like on metal plates that are separated by a small gap.

The smaller the gap, the bigger the capacitance.

Even the electrolytic capacitor is nothing like a battery. There isn't a chemical reaction going on in it. Electrolytic caps have a high capacity because the gap is so small: it consists of just the oxide layer on the aluminum anode. (Or tantalum.)  The electrolytic gel provides the cathode, so it forms a close contact with every surface imperfection of the anode for maximal area.

There are supercaps in which there is a chemical reaction in the electrolyte: they are kind of halfway between a capacitor and battery.

Other differences between capacitors and batteries is that:

Title: Re: The capacitor that wasn't
Post by: saturated on July 29, 2026, 06:30:20 PM
Hey guys you rock thanks for taking the time to help out with this c :dbtu:

I wonder now if getting the little battery hot with the soldering iron kinda percolated everything inside and helped it generate some more voltage  xP

Title: Re: The capacitor that wasn't
Post by: J M Fahey on July 29, 2026, 08:47:28 PM
Quote from: saturated on July 29, 2026, 06:30:20 PMHey guys you rock thanks for taking the time to help out with this c :dbtu:

I wonder now if getting the little battery hot with the soldering iron kinda percolated everything inside and helped it generate some more voltage  xP


Using solder and a soldering iron is actually bad for batteries.
The joint between outside terminal and inside actual battery is damaged by heat, so battery packs are made by soldering steel tabs to battery body , using a special spot welder, which turns metal red hot for a fraction of a second but not long enough to let it go inside.

I HAVE soldered brass or copper terminals to batteries but sanding body very well and using a very hot iron, so it´s very quick.
Worst is to spend minutes there because of dirty surface or inadequate iron.