I am in the very rudimentary stages of a self education involving EE, let me lead by saying that as I really am trying to discovery learn while building toys for myself. I have no formal education in EE, but I can read and use a soldering iron.
Problems I am running into:
1: I do not know exactly which FETs to use for items 7,8,9. I have found the right ones for 1-6 though (I have also found a single FET array that will work with one chip to do all the 1-6 switching, that is 3x3 mm) :P
2: I am not sure of what FETs to use and their associated values, so I am not sure how to filter through vendors etc to find the correct items.
3: Even if I could find the correct FETs I really don't know how to figure out what resistor values to use, or if it is even safe to connect the resistors the way I have or if each FET requires its' own resistor.
4: If there is a way to allow series to parallel switching using a single IC to avoid the mess of this whole ordeal I don't know how to find it and could use a hand doing so!
Enough of the don't knows, here is the circuit I could use a helping hand to check if it is in fact correct and free of shorts as well as safe if anyone is interested
Here is my concept for the auto switching series to parallel internal USB charging to allow series dicharge while plugged in to the USB charger.
FETs 1-6 would not allow current from D to S until voltage is applied to G. FETs 7-9 are the opposite and allow voltage from D to S until G is powered.
When powered from the Mini USB connection the MCP73831T #1 attached to the switch would power all the FETs, changing the configuration from series to parallel. When the switch is depressed the voltage would be cut to the FETs, putting the batteries from parallel to series and grounding 7-9 FETs to the 12.6 volt ground pulling them low, allowing you to discharge in series while connected to the USB plug and it will resume a parallel charging configuration as soon as the switch is released and energizing the G on all the FETs.
The 1 amp fuses are to prevent high currents between the batteries during charging and avoid overheating possibilities due to uneven discharge. The charging circuit (MCP73831T #2) only charges at 500ma, so the whole parallel charging circuit can be built with very small components and thinner wire.
If I get the circuit down and safe, as well as finding the right parts, I'll prototype using the board in this thread and 3 18650s, then probably move onto miniaturization using Li-Po batteries to to a 4s version. 4s (16v) is where the DC-DC converter options start to get really interesting.
Problems I am running into:
1: I do not know exactly which FETs to use for items 7,8,9. I have found the right ones for 1-6 though (I have also found a single FET array that will work with one chip to do all the 1-6 switching, that is 3x3 mm) :P
2: I am not sure of what FETs to use and their associated values, so I am not sure how to filter through vendors etc to find the correct items.
3: Even if I could find the correct FETs I really don't know how to figure out what resistor values to use, or if it is even safe to connect the resistors the way I have or if each FET requires its' own resistor.
4: If there is a way to allow series to parallel switching using a single IC to avoid the mess of this whole ordeal I don't know how to find it and could use a hand doing so!
Enough of the don't knows, here is the circuit I could use a helping hand to check if it is in fact correct and free of shorts as well as safe if anyone is interested
Here is my concept for the auto switching series to parallel internal USB charging to allow series dicharge while plugged in to the USB charger.
FETs 1-6 would not allow current from D to S until voltage is applied to G. FETs 7-9 are the opposite and allow voltage from D to S until G is powered.
When powered from the Mini USB connection the MCP73831T #1 attached to the switch would power all the FETs, changing the configuration from series to parallel. When the switch is depressed the voltage would be cut to the FETs, putting the batteries from parallel to series and grounding 7-9 FETs to the 12.6 volt ground pulling them low, allowing you to discharge in series while connected to the USB plug and it will resume a parallel charging configuration as soon as the switch is released and energizing the G on all the FETs.
The 1 amp fuses are to prevent high currents between the batteries during charging and avoid overheating possibilities due to uneven discharge. The charging circuit (MCP73831T #2) only charges at 500ma, so the whole parallel charging circuit can be built with very small components and thinner wire.
If I get the circuit down and safe, as well as finding the right parts, I'll prototype using the board in this thread and 3 18650s, then probably move onto miniaturization using Li-Po batteries to to a 4s version. 4s (16v) is where the DC-DC converter options start to get really interesting.
