12V 60A car battery , maybe dead?

[tonyben25]

hello
@ Groungloop

This is my first post although i have always followed the development in this forum.
I will like to ask, did you at any time measure the frequency of oscillation of your circuit? i will appreciate if you can give the frequency of air core design and the ferrite core design.
I thinking the higher the frequency the better the charger abilty to desulphate. Correct me if  i am wrong.

[Groundloop]

hello
@ Groungloop

This is my first post although i have always followed the development in this forum.
I will like to ask, did you at any time measure the frequency of oscillation of your circuit? i will appreciate if you can give the frequency of air core design and the ferrite core design.
I thinking the higher the frequency the better the charger abilty to desulphate. Correct me if  i am wrong.

@tonyben25,

I do not have the air core version anymore, but I did measure the Ferrite version today.
The oscillator fundamental frequency is in the high audio range but since the pulses
are "spiky" then there is a lot of RF spectrum up to approx. 5MHz. Attached is a spectrum
plot from 0 to 5Mhz. Sorry for the time it took to answer you question. I never did see this
post until today.

GL.

[Bob Smith]

tonyben and Groundloop,
I built mine a few years back with an air core, and was able to get the frequency up to about 20MHz using a potentiometer in place of a resistor. It's been awhile, but I think it was either a 5K or 10K pot. I also swapped out one of the caps - tried a few different ones to get the highest frequency possible.
Bob

[Rodelu]

I've been looking for a good battery charger/desulfator and I found Groundloop's circuit called "best_battery_charger_ever", I built it, tested it, and have to say that it lives up to its name!

Thank you Groundloop for guiding me thru this project via PMs!

The transistor:
the BUX80 is no longer in production, it can be found on eBay (US) but here in Europe there is no chance to get one. I substituted it for a BU208A (NPN-700V 5A) and works just fine.

The diodes:
BYV29-500 is also hard to find here, so I used BY329 (1000V 8A).

The coil:
Twisting together (evenly) 3 strands of 1mm wire, 75 meters long (each strand) was also a challenge, but after two failed attempts... success!

My first try was with a 12V / 7.2Ah half dead battery, and it came back to life after 5 discharge/charge cycles.

Thank you again Groundloop for this great circuit and all your help in the process of replicating it!!


Rodelu

[Groundloop]

Rodelu,

Very nice looking boxed charger! :-) Good job on the build.

What is the digital meter showing?

GL.