Charging a power pack

[Munroast]

I have a small power pack (5v lithium thing) that I like to charge from the cars 12v outlet (cigarette lighter socket) I like to just leave this plugged in and t gets charged when ever I am on the move

Problem is - when i leave the van the power from the power pack must be flowing back into the dash cam and causes problems. how can I stop this happening (other than to unplug the power pack every time i stop then plug it back in the next time I use the van)

 

[Jurassicspark]

Add a diode in series from the plus side.?

 

[Munroast]

what do I buy ?

 

[Harry Bloomfield]

what do I buy ?

A 1N4000 would do it, assuming less than a 1amp load. However, the 0.6v drop across the diode, might cause an issue with charging, in which case probably better to use a relay to disconnect....

You would need a 12v dc relay, powered via a source when the ignition was turned on, and your charger wired via a normally open pair of contacts of the relay.

 

[Jurassicspark]

A 1N4000 would do it, assuming less than a 1amp load. However, the 0.6v drop across the diode, might cause an issue with charging, in which case probably better to use a relay to disconnect....

Or get a schottky diode.

The relay idea is more easier to do though.

 

[Munroast]

A 1N4000 would do it, assuming less than a 1amp load. However, the 0.6v drop across the diode, might cause an issue with charging, in which case probably better to use a relay to disconnect....

You would need a 12v dc relay, powered via a source when the ignition was turned on, and your charger wired via a normally open pair of contacts of the relay.

I didn't think of the obvious - of course a relay is the solution, and i will probably have one

Just to explain the nonsense with the charger and the dashcam. When I leave the charger plug in (that is charging a 5v USB battery) some of that voltage must be making its way back to the camera and the camera has not been shutting down correctly, it normally saves to the the SD card as soon as the ignition is turned off, but with the 5v battery attached, about a third of the time, the camera stops without saving to the SD card.

anyway the relay will solve that problem