Integrating charging circuit and battery inside the pedal. How?

[nguitar12]

http://www.diystompboxes.com/smfforum/index.php?topic=107128.0

So after reading the thread I am totally interested in building a rechargeable pedal.
Just wondering how can I Integrating charging circuit in to the pedal so that they will share the same DC socket like cell phone did?

Here is my idea of the connection.



The problems on this connection is I don't know whether the battery can keep connecting to the charging board even if there is no DC supply. Also I don't even know whether this 4 pin DC socket existed.

Any help will be appreciated.

[PRR]

Image is not showing.

The usual trick is to charge a 6V battery with a 9V supply, through a resistor to limit the current. Run the load on the battery. If charge is available, it really runs on the charger; if not, it sucks the battery.

For four AA NiCads (closer to 5V) we would use maybe 100 Ohms to limit current to (9V-5V)/100r = 40mA.

(For a 12.6V car-battery we use a 10V-20V alternator rigged with a regulator which limits current to 30 Amps or 14 Volts.)

That assumes your pedal will work at 6V or 5V. The charging supply has to be higher voltage than the battery.

Cell-phones these days take 5V from USB and charge a 3.3V battery. But modern batteries (not lead, not NiCad) need more complicated charging circuits. A simple resistor is not good enough to avoid under-charge or over-charge (and over-charge on modern batts can be explosive).

[nguitar12]

Image is not showing.

The usual trick is to charge a 6V battery with a 9V supply, through a resistor to limit the current. Run the load on the battery. If charge is available, it really runs on the charger; if not, it sucks the battery.

For four AA NiCads (closer to 5V) we would use maybe 100 Ohms to limit current to (9V-5V)/100r = 40mA.

(For a 12.6V car-battery we use a 10V-20V alternator rigged with a regulator which limits current to 30 Amps or 14 Volts.)

That assumes your pedal will work at 6V or 5V. The charging supply has to be higher voltage than the battery.

Cell-phones these days take 5V from USB and charge a 3.3V battery. But modern batteries (not lead, not NiCad) need more complicated charging circuits. A simple resistor is not good enough to avoid under-charge or over-charge (and over-charge on modern batts can be explosive).

Actually I am going to use the 3.7v li-ion battery (fully charged at 4.2v). I can easily get some pre-made charging board for this cell.
I want to build a pedal with internal li-ion battery and

So when the 9V DC adapter is plugged in:
It will charge the battery through the charging board and
provide the power to the pedal circuit.

And when the DC adapter is disconnected.
The pedal circuit will take the power from the charged battery. ( battery voltage will be Boosted by MAX1044 circuit)

In this case only one dc socket is used. no switch is used to select supply mode or charging mode. Just like how you operate a cell phone.
Can this be achieved?

[tempus]

Ever considered something like this?

http://www.dx.com/p/universal-portable-5v-30000mah-li-ion-battery-dual-usb-solar-powered-power-bank-w-led-indicator-279255?utm_source=dx&utm_medium=edm&utm_campaign=20140612subscriberjune#.U5iQOECwWas

[PRR]

Usually you connect the external power to the charger, the charger to the battery, the battery to the pedal.

Usually no switching is needed.

If there is external power, the battery charges-up and powers the pedal.

If there is no external power, the battery dis-charges and powers the pedal (until it gets too weak).

The only issue I see: some batteries, if you dis-charge them FLAT, they get sick and never recover completely. Most batteries will get sick if you pull a heavy load and let it drain all the way to Zero Volts. But perhaps a cell-phone battery would not be harmed by a Fuzz-Face or similar low-current load.

I guess you do need a switch (can be the guitar-jack switch) to disconnect the pedal from the battery when you are not using it.

Ideally you would have a Low Voltage Monitor chip to disconnect the battery when its voltage gets too low while you are playing. Similar to the way a cellphone can be working one moment, then shut-down because the battery got weak. Since the cellphone is a complicated computer, they prefer to use the computer's "please shut down" command so that files are closed and settings saved. But our pedals can just be disconnected. (A frill would be a signal to the player to say "I am about to shut-down, you might like to bypass me or patch in some other pedal." But in performance, such a signal might be missed.)