Jump starting a car with a Cell Phone

[Weisshund]

I call shens

For one, cell phone charge has diodes in it, power goes from car, to voltage step down, to phone.
It wont go the other way, it’s a one way path.

Two, cell battery is only between something like 1800Ma to 3000Ma
I think even the small car batteries are like 400A or 500A?
Little problem of capacity, like trying to fill a 2 liter bottle by having a flying squirrel pee in it.

Three simple problem of trying to charge a large capacity 12V device, from a low capacity 5V device.
5V wont put power in unless the 12V device is less than 5V, and it would stop once it got to 5V which is much too little to crank the car.
And stepping the 5V up to 12V comes at a cost, it will take a whole lot of 5V to power the step up, to get enough to charge the 12V.
Little cell phone batt be long dead before the car battery is charged.

[running_coach]

@Weisshund

I call shens

For one, cell phone charge has diodes in it, power goes from car, to voltage step down, to phone.
It wont go the other way, it’s a one way path.

Two, cell battery is only between something like 1800Ma to 3000Ma
I think even the small car batteries are like 400A or 500A?
Little problem of capacity, like trying to fill a 2 liter bottle by having a flying squirrel pee in it.

Three simple problem of trying to charge a large capacity 12V device, from a low capacity 5V device.
5V wont put power in unless the 12V device is less than 5V, and it would stop once it got to 5V which is much too little to crank the car.
And stepping the 5V up to 12V comes at a cost, it will take a whole lot of 5V to power the step up, to get enough to charge the 12V.
Little cell phone batt be long dead before the car battery is charged.

There are cell phone power banks up to 23000MaH. You don’t need to fully charge a car battery to start a car.

And if you want to go bigger. Amazon portable car chargers.