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Li-ion charger with vacuum tubes?

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Conundrum

Fri Sept 08 2017, 05:25AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Hi,

Just occurs to me that as many folks have low power tubes in their spares boxes, making a basic voltage limited current cutoff charger should be trivial in a SHTF extreme Carrington event/EMP scenario.

Li-ions should still work fine but worst case the protection circuitry will be history depending what hit it.
Usually the fuse goes so the cell inside will still be OK if a way could be found to charge them.

-A

Sulaiman

Fri Sept 08 2017, 08:08AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

After your "SHTF extreme Carrington event/EMP scenario"
one of my least significant concerns will be cell-balancing

and what are you expecting to power with your fully charged and balanced lithium batteries ?

Even now, for a lot of my diy stuff I use cells from dead laptop battery packs,
I charge them individually then use them as a pack ... tedious, but no problems so far.

radiotech

Fri Sept 08 2017, 07:05PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

Since you showed an audio output transformer and mentioned Li-ion calls I suggest this (for kids).

Divert a portion of the audio power driving the speakers, to charge one Li-ion battery.

Use another Li-ion battery to power the amplifier. This cell is charged by a foot or hand power generator.

When the battery runs down after playing music, the kid swaps the cell with the one charged by the speaker circuit,

There will develop a relationship between how loud, and how long the music can be had, and how much work is needed.

After a while, offer a piano, violin, or any other instrument with lessons.

hen918

Fri Sept 08 2017, 09:11PM

Registered Member #11591 Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 556

Sulaiman wrote ...

After your "SHTF extreme Carrington event/EMP scenario"
one of my least significant concerns will be cell-balancing

I designed and only half built so far (I meant to do it this summer) a complete standalone, microcontrolled 18650 laptop battery analyser with two channels and an SD card slot to store the results on. It will do a number of charge - discharge cycles logging the voltage and current every second. This will then be graphed or used in a program I have yet to write that automatically searches a database of tested batteries to find the perfect matches for putting them into packs.

Seems a far cry from Conundrum's circuit!

Conundrum

Sun Sept 10 2017, 05:49AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

A simple solar shunt regulator would be fine.
With most Li-ion regulating them to 3.97V will store 95% charge and extend life considerably, though one circuit will be needed per cell.
For something like a device able to keep freezers running you'd need a large solar panel and a UPS, though there are ways around that.
I found on one of the amateur radio sites a basic Royer circuit based on two tubes (eg 833A, other power triodes also work) which can be used in multimode to either get maximum power for radio or high power low frequency for mains power.

Sulaiman

Sun Sept 10 2017, 07:31AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

As solar panels are just arrays of semiconductor diodes,
woldn't they be killed bt EMP etc. ?

Conundrum

Sun Sept 10 2017, 11:22AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

You'd think, but usually the diode (intended to prevent lightning damage/shading/etc) goes first.

WizardG

Sun Oct 08 2017, 09:13PM

Registered Member #43481 Joined: Tue Mar 11 2014, 06:15PM
Location: directly above the center of the earth
Posts: 4

A P/N junction does not a diode make. Check it yourself with an ohmmeter. Measure the forward and reverse resistance of a solar cell with the active surface of the solar cell blacked out.

Proud Mary

Wed Oct 11 2017, 02:56PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

EBF83 - a double diode pentode - was designed to operate happily with as little as 6V on the anode in car radio applications.

Two Lion cells such as 18650 in series are all that is needed for anode voltage for EBF83 and its car radio valve kin such as nifty double triode ECC86.

Conundrum

Sat Oct 14 2017, 06:27AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

thanks!

Also does anyone have a spare EC92 please?

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