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An Elegant Capacitance Battery Charger !!WARNING HIGH VOLTAGE!!

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petcnc

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After experimenting with a Basic Battery Capacitance Charger (BBCC) I decided to build a better one with more capabilities and options.
Some changes to basic schematic were necessary.
Schem2.jpg

As you can see above, 3 capacitors of values 6, 16 and 20 uF are used in order to have a range of output power.

SW1 SW2 SW3 AMPS
ON OFF OFF 0.2
OFF ON OFF 0.5
ON ON OFF 0.7
OFF OFF ON 1
ON OFF ON 1.2
OFF ON ON 1.5
ON ON ON 2

I have a range of capacitors and high voltage rectifier bridges (removed from computer PSUs)
Caps&Bridges.jpg

A dead computer PSU could provide the enclosure for the parts
BoxPrep.jpg


Guts removed and parts fit nicely inside
BoxPrep3a.jpg


Original SPST Switch changed for a DPST so when is OFF both lines (L & N) will be cut off)
BoxPrep4.jpg

I made a rectangle hole for a Voltmeter – Ammeter
BoxPrep2a.jpg

This AMMETER can measure up to 300V and 10A, but needs to be powered from 7 to 30 volts DC. So a small transformer 230 to 7,5v AC from an old cell phone PSU had to be modified adding a rectifier and a filter capacitor to provide 12,3V for the AMMETER.
TrafoAll.jpg

It fits in the box nicely
Trafo5.jpg

A metal panel had to be prepared for the 3 rocker switches.
Panel.jpg

A paper pattern and a few dremel cutting disks later it was ready.
Front Panel1.jpg

A label will make the box look nicer. It is a printout on special inkjet paper with two coats of clear varnish on top.
Label2.jpg

And the box is ready
Label4.jpg

Unfortunately the VOLT-AMMETER I have measures up to 100V so I have to wait for the new one (from ebay) to have the unit fully functional.
AMMETER.jpg

Until then I use my multimeter to read the battery voltage.
Thanks for reading

Petros
 

markba633csi

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Be careful with that Petros, you have NO isolation from the mains...very real shock hazard potential. Plus a shorted cap could cause an explosion or ruptured battery; don't leave it unattended
Mark
 

petcnc

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Be careful with that Petros, you have NO isolation from the mains...very real shock hazard potential. Plus a shorted cap could cause an explosion or ruptured battery; don't leave it unattended
Mark
Thanks Mark I am aware of all the dangers and I take all usual precautions. It is nice you underline them for anybody else that would like to build it as well.
Petros
 

Karl_T

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Say, I took notice of your printed panel. Can you tell me more about what paper and how to bond it to the metal face?
 

petcnc

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Say, I took notice of your printed panel. Can you tell me more about what paper and how to bond it to the metal face?
Pretty simple!
I made a sketch with the dimensions of the face I wanted to cover, the approximate positions of Voltmeter and switches then in Photoshop I created a paper of the same size, the lines I wanted and pasted the Danger sign. (thank you google) Initially I created wide rectangles around switches and voltmeter but as I was not sure I made exact measurements I only left the voltmeter rectangle.
Panel sketch.jpg

Next I printed it on a "coated" inkjet paper. Plain paper will do also but after varnishing it turns out a little grayish!

To be on the safe side I dublicated the original sketch and pasted a few more danger signs
Panel1.jpg
Then I sprayed with clear varnish on both sides and let it dry.
Label2.jpg
The printout hanging after spraying to dry

After drying I cut it to size, put it on the box cut all openings tested switches and voltmeter.
Labeltest.jpg
Testing label on the box.

And Finally it was a matter of some glue spray on the metal and fixing the paper in place (well its no longer paper it resembles plastic) on the metal
label3.jpg

Job done!
 

jim18655

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I followed plans once for a de-sulfator and it used a fly-back inductor that was switched by a MOSFET and a 555 timer. The output was around 50-60 volts DC and it worked well on several old batteries. The theory was the intermittent high-voltage pulses from the collapsing field didn't over heat the battery but burned through the sulfation. Your circuit puts high voltage DC on the battery continuously. Will it overheat? Do you use a timer to control time on?
 

petcnc

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I followed plans once for a de-sulfator and it used a fly-back inductor that was switched by a MOSFET and a 555 timer. The output was around 50-60 volts DC and it worked well on several old batteries. The theory was the intermittent high-voltage pulses from the collapsing field didn't over heat the battery but burned through the sulfation. Your circuit puts high voltage DC on the battery continuously. Will it overheat? Do you use a timer to control time on?
Charging starts with high voltage and in a matter of minutes drops to normal. On test It overheated some Sealed Lead Acid batteries (SLAs) that had some cells shorted. Overheated the particular cells not the whole battery. There was no problem on other SLAs (just warm in touch) and no heat at all on motorcycle Wet Cell ones (capacity 8 AH). I had not tested bigger capacity ones yet as I have to travel some 30 miles to get my old ones.
I use no timer as I constantly monitor the voltage not to let it exceed 15.3V.

I will post results on bigger batteries shortly.

Petros
 
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