Charge phone while car is off

2010 Prius ii

I just want to be able to charge my phone while my prius is turned off. NOT in "aux" or "ready" mode. (I have my reasons).

After reading and reading there is no compelling concensus on whether or not it will directly cause my Prius 12v battery to eventually be rendered useless. (I am welcome to being proved wrong one day when I try to start my Prius. I'm scientific...I have a semi-sound hypothesis and I'm going to test it out)

I'm very tempted to (and probably will) wire tap the headlight's or the horn's power supply (since those seem to have access to power when the car is off).

I'd then connect that into one of the cigarette lighter ports and voila! Constant power to charge my phone without needing to go into Aux or Ready mode.

I also attached a picture of battery specs from the battery that was in my 2007 V6 Chevy Impala and the specs for a yellow top Optima Prius battery.

My Chevy charged my phone when it was completely off. For 8 years and No problems. The Chevy needed the bigger battery due to higher starting demands. The prius doesn't have such high 12v starting demands. Hence a smaller battery..things here are relatively downsized.

The Prius battery is about 66 aH. My phone battery is 3 ah (3000 maH). The Prius battery's weight is about 20% less than the Chevy's and the approximate aH are 30% less (to the best I can tell). But again, the demand of the Prius on the 12v battery is Much less in day to day use.

SO, I can't imagine charing my phone will translate into me eventually killing my Prius 12v battery with my smartphone's 3 aH battery.

Love to hear thoughts. And I will update if things do or don't work out for me.

Also check out my post about how I ripped out the center console bridge (flying buttress).

 

1. I already considered this. But I want to avoid driving around with an aftermarket battery pack like this constantly charging it self full...I see room for failure and perhaps fire. (I'll save you the time and admit it's slightly paranoia. But I'll take a dead battery over a melted/burned one).

2. The other guy mentioned that he already used fuse taps with success.

SO, I still feel that I will tap into the car's 12v (which I feel is safer than having the aftermarket jumper constantly charging and topping it self off). I may try Fiss's idea and tap into the power windows...if not, then into the headlights or the horn.

BUT JimboPalmer...your input has lead me now to buy this little jumper incase I do kill my battery. I'll have it, but I just won't be constantly having it charge itself as I drive everyday.

(Plus to do the fuse tap thing....I already have everything from previous projects so no cost for me there. I'll just spend $25-50 for that mini jumper for added security. It looks like something I want now regardless if I was doing this little project or not)

 

Fiss...how long have you been using your fuse tap setup?

( I take you have had no dead/low battery issues with that dash-cam constantly accessing your 12v battery )