How can I wire the "cigarette lighter" to stay on?

Discussion in 'Gen 3 Prius Main Forum' started by herqulees, Feb 24, 2018.

  1. herqulees

    herqulees Junior Member

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    Before I type anything else I first want to say please do not post anything talking about how the Prius has a tiny 12v battery that is easy to drain, I'll do it for you.
    For everyone reading: the Prius has a very small 12v battery and thus it is easy to run it down, and also thus it is not recommended to keep things running off the battery because of this. HOWEVER leaving a phone charger plugged in with the car off for weeks isn't going to drain it. If it does you have a bad quality phone charger or a failing battery IMO. A power inverter, fan, coffee pot, mini fridge, etc. I would never leave plugged in.
    With that out of the way obviously I know the risks and am okay with it. I'm wanting to know if there is an easy way to keep at least one of the "cigarette lighters" on at all times. I know some cars (not sure if any Toyotas) you can simply move a fuse in the fuse box and I was hoping that was true with the Prius too. I can't find anything for the Gen 3 on this by searching around Google and PriusChat. Does anyone know how?
     
  2. Lucifer

    Lucifer Senior Member

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  3. frodoz737

    frodoz737 Top Wrench

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    Since you don't have the 2014 prints, borrow a meter.

    Verify the power and ground wires at the lighter/power socket. Turn off the vehicle, disconnect the 12VDC battery negative terminal and isolate it. Remove, cap and stow the power wire from the lighter/power socket for safety and so it can be restored later. Remove and store it's associated fuse. Attach and run a fused wire (next gauge larger) from your 12VDC battery positive terminal to that location and attach it to the socket terminal previously used...all using industry standards, materials and tooling. It's very important to fuse that wire close to the battery and 15A should do. Restore your vehicle to normal and test. Use the attached print for a 2010 "for reference only". Any advise or information given or provided here is "for reference only", use of is at your own risk and I am not responsible for any and/or all damages to persons, animals or property. If you drain or otherwise damage your battery using this modification...you were warned.

    In other words...just run a new hot wire from the battery. ;)
     

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  4. RobH

    RobH Senior Member

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    The power outlets in my Ford Transit Connect are always ON. At least Ford thinks it's OK.
     
  5. Sam Spade

    Sam Spade Senior Member

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    Yes it CAN and WILL......and that does not necessarily mean the battery is somehow bad.
    If you intend to leave ANYTHING that draws power connected there.......this is a BAD idea.

    Doing what you suggest is a good idea though because it gives you easy access to connect things like battery tenders when the car is "off for weeks". Depending on how many weeks, the built-in electronics can actually discharge the battery significantly.
     
  6. RobH

    RobH Senior Member

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    I really doubt that leaving a cell phone plugged into an always ON power outlet would discharge the battery significantly. The battery will self discharge faster than the cell phone load.

    The only way to really find out is to test it. Get one of those voltmeter/USB outlet devices that plugs into the power outlet. Then see what happens.

    Here's an example of the device:
    http://www.amazon.com/Charger-Adapter-Display-Battery-Voltage/dp/B0773BYS6P/ref=sr_1_15?ie=UTF8&qid=1519575955&sr=8-15&keywords=12v+usb+car+charger+voltmeter
     
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  7. Grit

    Grit Senior Member

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    Technically, its true. In the Prius if you leave a cigarette lighter phone charger in the socket connected to a phone, the 12v battery won't drain at all because it doesn't even supply power to the socket when Prius is off :p

    The other side is if you have a charger than puts out 4.2 ampere such as smart charge device, it will drain your Prius 12v battery quick unless you have a battery like Raytheeagle that has 510 amps capacity.

    Where are the people telling Raytheeagle that's his battery was an "overkill", need those people to chime in on this thread.
     
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  8. Sam Spade

    Sam Spade Senior Member

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    Absolutely, totally wrong.
    You can "doubt" it all you want; that does not change the facts.

    Most or all of these batteries are AGM type and their self-discharge rate is practically zero.......unless the battery is really old and worn out.
    The draw from a phone charger is not practically zero.

    Whether or not it is significant depends on the charger and the length of time involved.
     
  9. Johnny Cakes

    Johnny Cakes Senior Member

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    People, that is the question asked. The OP is an adult and has said that he wants to assume the risk of draining the battery. So battery drain is not part of the discussion.

    Is there an always hot fuse that he could tap with add a fuse and just run new wiring to the cigarette lighter. Other than probing with a volt meter to figure it out, I don't know the answer to that -- does anyone?

    When I first purchased my Prius, I wanted to have 12v in the rear of the car so I installed a outlet in a panel near the battery and just ran a fused connection directly to the battery. Of course, now that I have learned about the Prius and the 12v battery, I'm scared to use the darn thing. :)
     
  10. Lucifer

    Lucifer Senior Member

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    Conduction, it allows pre-amps to make beautiful music, it drains live battery's when a live connection is hooked to anything, even a turned off phone.
    Bad idea, yes an adult can make a decision, but if children are left away from heat and safety, bad idea.
     
  11. bobzchemist

    bobzchemist Active Member

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    It looks like this device or something similar would work to shut your phone charger off if the car battery gets too low: Battery Saver, Discharge Protector Cut-out Switch With ATtiny85 for Lead Acid Car or Lipo Battery: 6 Steps
    Probably running a dedicated, fused connection directly from the battery would be safer than re-wiring an existing socket.

    However, If it were me doing this, I wouldn't rewire anything. Instead, I'd get the highest capacity portable jump-starter I could find/afford, leave it plugged into the cigarette lighter, and plug the phone charger into it. When the car is off, you'd charge the phone from the jumpstarters battery only. That way, not only would you protect your main battery, you'd have a charged jumpstarter ready if/when you needed one.
     
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