Switch capacitor for earthbatteries

[janost]

I have figured out a way to charge larger batteries from earthbatteries, treepower, small solarcells etc.

It works with a switched capacitor converter.

In cycle 1 it puts the charged battery in series with the energy source thus the capacitor charges to the battery voltage + the voltage in the energy source.

In cycle 2 the cap, now containing the batteryvolts + the volts from the energy source, dumps back into the battery charging it.

As long as the energy source is more than 0volts the battery recives a charge regardless of the battery voltage.

It needs a 2phase drive signal not shown.

[janost]

Bad post

[citfta]

Ingenious!

Hi janost,
That first circuit is a stroke of genius. I have been looking for a good way to make use of solar cells when they are only putting out a small amount of power. Your first circuit looks like it should do it. And it only uses a minimum of parts.

I am a little confused on the second circuit though. I am only on my first cup of coffee but it looks to me like the diode will block the current flow when in the battery charge cycle. And if you turned it around then it would short out your earth battery when the fet turns on. I don't understand the second circuit, but I want to try the first circuit as soon as I have a little time to build it

Thanks so much for sharing,
Carroll

PS In the first circuit should the #2 fet be a p channel or can we just flip it over since the current is flowing the opposite direction from when #1 fet is on?

[janost]

Hi janost,
That first circuit is a stroke of genius. I have been looking for a good way to make use of solar cells when they are only putting out a small amount of power. Your first circuit looks like it should do it. And it only uses a minimum of parts.

I am a little confused on the second circuit though. I am only on my first cup of coffee but it looks to me like the diode will block the current flow when in the battery charge cycle. And if you turned it around then it would short out your earth battery when the fet turns on. I don't understand the second circuit, but I want to try the first circuit as soon as I have a little time to build it

Thanks so much for sharing,
Carroll

PS In the first circuit should the #2 fet be a p channel or can we just flip it over since the current is flowing the opposite direction from when #1 fet is on?

I saw the error in the second circuit.
Has to be reworked

Both FETs are N-MOSFET
I prefer IRFP-460 Power Mosfets because they normaly don't need heatsinks up to a couple of watts.

The basic principle is as the attached circuit.

[Jeff Pearson]

this would work with a relay set up as a buzzer???

[janost]

this would work with a relay set up as a buzzer???

Only if the relay hits both ends.

As a buzzer it normaly starts to return as soon as it has left the NC position.

[janost]

I'll try and redraw this as a JT that charges a 6-12v battery with a 2-4v solarcell.

I have already created a joule-thief that feeds back to the drive battery.
It's just a matter of adding the solarcell in the feedback path.

[janost]

Here is a Solar Joule-Thief Charger.
It charges a 6-12v battery from a 2-4v tiny solarcell.

If the solarcell is 4v and the battery is replaced with a cap it will start even without a battery and charge the cap to some 40v.

It is a type of chargepump and in every cycle it adds the source potential to the feedback.

And it also works with earthbatteries, treepower etc. but cant selfstart witout the battery if the source potential is less than 3v.
This limit is because of the gate threshold voltage of the mosfet.

Enjoy