its always somethin

[JR.]

Had some new drama while building drum tuners today...

The photo is showing the - end of the battery. The shiny spot at roughly 2 o'clock on the outer rim is where the battery spring contact pierced the plastic battery wrap. While I never inspected the batteries very closely apparently the metal casing of the battery is positive, with the negative electrode floating centered in the big end.

The spring with a sharp edge from the coiled wire apparently pierced the insulation and shorted the battery. The initial symptom was some extra distortion at the very LF end of the frequency scan, so apparently low battery voltage. Which I confirmed with a quick measurement across the 4 cell battery pack.

Then I noticed unusual heat coming from behind the top PCB. In over a decade of building these and probably hundreds of these exact batteries, this is a first.

Since one speaker sounded nastier than the other, I swapped the speaker and battery. FWIW the tuner, correctly completed the original scan and read the correct note (I have a lot of headroom engineered into the PS), but I suspect the shorted battery would have caused more mischief over time.

It looks like I have a new concern when assembling these, make sure the spring contact is centered. Only we can prevent house fires.

JR

[mediatechnology]

In one of my weather instruments using AA batteries the negative coiled spring gets pushed off-center by the battery. When I remove the battery the spring is hung in place and I have to flick it to get it to extend before installing the replacement battery. It looks just like all the other springs so I can't see what causes it.

I suppose its only a matter of time before that one shorts out.

Some time ago I posted a pic from Radio World of a reversed-polarity 9V. I can't remember if it was just the marking or it had the wrong type of snap connector installed.

Now if someone could just explain why the DC leakage current from my kitchen faucet to earth ground reverses polarity when the water is turned on. It's a current mirror!

......Or maybe a current "sink."
(rimshot)

[JR.]

Now if someone could just explain why the DC leakage current from my kitchen faucet to earth ground reverses polarity when the water is turned on. It's a current mirror!

......Or maybe a current "sink."
(rimshot)

There is apparently some weirdness from metal content in the sundry faucet parts.. flowing water may change the metal sections dominating the voltage/current.

or in other words, I don't know.

JR

[JR.]

Now if someone could just explain why the DC leakage current from my kitchen faucet to earth ground reverses polarity when the water is turned on. It's a current mirror!

......Or maybe a current "sink."
(rimshot)

There is apparently some weirdness from metal content in the sundry faucet parts.. flowing water may change the metal sections dominating the voltage/current.

or in other words, I don't know.

JR

In hindsight I am liking my old guess... When the faucet is open, the galvanic potential difference is between the local metal and the rest of the house plumbing. When faucet is closed the galvanic circuit is reacting with different metals nearby.
=====
I have been doing some research about galvanic current wrt to my hot water heater... I recently commissioned my local plumber the pull out the sacrificial anode that I couldn't break loose even with an impact wrench. He will hire a strong back to help him/us.

I was speculating that the galvanic current welds the anode in place, and the hot water heater manufacturers don't much care, because stuck anodes help them sell more water heaters. My plumber confirmed that more than once he has replaced entire heaters with a balky anode. The manufacturers size the anodes to last just long enough for the warranty, no longer.

I am a sucker for gadgets and found an active anode that injects a current to neutralize the galvanic potential. The major market for this is to manage hydrogen sulfide production that causes stinky rotten egg smelling water (not my problem), but preserving the steel tank forever sounds good.

https://www.hotwater.com/Water-Heaters/ ... de-System/
---

I wonder if I don't have some hydrogen sulfide causing my occasional smelly hot water.... hmmm could be a win-win and fix more than I was targeting. I ASSumed my hot water tank was not the problem because the water from it does not smell... very interesting.

JR

[mediatechnology]

Very interesting...

I downloaded the spec sheet and its operating current is adaptive depending on water conditions.
It looked like the only thing missing from the AO Smith powered anode is an internet connection for all IoT all the time.

I recall seeing a lot of thread dope on most anodes.
I wouldn't want the job of unsticking it since I have a mental image of twisting the entire water heater.

BTW I know yours is electric but the new Honeywell Electronic Gas valves have left two neighbors without hot water.
They're still thermocouple-based and battery-less but just die after a couple of years.
Thermocouple OK, controller not OK.
It's about time to replace my water heater and I'm going to have to try to avoid these valves.

[JR.]

Very interesting...

I downloaded the spec sheet and its operating current is adaptive depending on water conditions.
It looked like the only thing missing from the AO Smith powered anode is an internet connection for all IoT all the time.

I recall seeing a lot of thread dope on most anodes.
I wouldn't want the job of unsticking it since I have a mental image of twisting the entire water heater.

BTW I know yours is electric but the new Honeywell Electronic Gas valves have left two neighbors without hot water.
They're still thermocouple-based and battery-less but just die after a couple of years.
Thermocouple OK, controller not OK.
It's about time to replace my water heater and I'm going to have to try to avoid these valves.

Pipe dope is not advised as the anode bonds to the tank by that thread... I was thinking of using pipe dope on the replacement and ground it separately, before finding this gadget. Just in case the galvanic current is somehow welding the anode in place.
===
They claim their device is patented but I do not see a number. I could not find a patent easily searching USPTO database. Apparently it is a strategy used in large commercial heaters, boats, whatever.

I suspect it is cheaper than dirt just a current source to bias the galvanic flow to plate the steel, rather than erode it, but too much current will trash the sacrificial anode. So perhaps a sensitive regulation of whatever voltage it takes to make some modest current flow in the right galvanic direction.

JR

PS: I am still kind of irritated by the hot water heater MFR... they could make the anodes easier to remove... I wouldn't be surprised if they used some kind of locking thread on the original assembly just to sell more units, when they can't be serviced.

[billshurv]

Look at landrovers Designed on purpose for the chassis to be the sacrificial anode to the bodywork!

[JR.]

Look at landrovers Designed on purpose for the chassis to be the sacrificial anode to the bodywork!

It is a major issue for boats and the sacrificial anode works if refreshed when depleted. My complaint is about how difficult it is to remove. My plumber shared that he has replaced entire heaters before when the anode could not be removed. I doubt the manufacturer has any motivation to work longer than the warranty period.

JR

[billshurv]

It does amaze me that modern cruise liners swap to Al half way up to save weight without things going horribly wrong. I suspect some significant R&D spend there.

But yes increasingly things are only specd to last the warranty period. Sob.

[JR.]

It does amaze me that modern cruise liners swap to Al half way up to save weight without things going horribly wrong. I suspect some significant R&D spend there.

But yes increasingly things are only specd to last the warranty period. Sob.

The old telephone company business model where they only rented the equipment gave us robust designs.

JR