Ok to connect solar trickle charger directly to battery?

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by vestibule, Mar 18, 2018.

  1. vestibule

    vestibule Junior Member

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    Going on a long trip and my Prius V will be parked for 2 weeks. I bought a battery pack for jump starting it, but would rather not have to jump start it if possible. I bought a cheap 5W solar panel which I'm hoping is enough to keep it topped off (but not enough to overcharge it). I don't particularly want to mount the panel on the dashboard and try to run the cable out the door, under the hood, and to the fuse box, is there any issue with connecting it directly to the battery in the trunk? Other than more of a pain to access and less sunlight from the rear window?

    I did also buy an obd connector which I'd prefer to use but apparently some people have had issues with the panel having non-standard polarity so don't want to rely on that.
     
  2. taxibuddy

    taxibuddy Junior Member

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    If your battery is any good you should just be able to park it, come back in two weeks and restart it without doing anything special. Hopefully you bought a PV panel with an integrated charger instead of just the panel. You're going to lose a lot of power through the window, but maybe it will still be enough since zero should be enough for two weeks. I don't see why you couldn't wire it straight to the battery. Any decent charger will have reverse polarity protection.

    If plug in power is an option, there are cheap but good battery tenders available that will do the job with less hassle.
     
  3. rjparker

    rjparker Senior Member

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    Personally, I would buy a "Battery Tender Jr" if the car will be home. If not, I would use one of the Lithium Battery Jump packs since they will hold a charge and be there when you need it. With that said, I have parked for a month in an airport lot and had no problems since the 12v is just for the computer systems, not for the actual starting. Rotating the internal combustion engine is only done with the high voltage battery. The HV battery won't charge from a Battery Tender or a solar panel.
     
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  4. vestibule

    vestibule Junior Member

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    This will be at a long term airport parking lot, so no plug in option.

    I have a battery pack jumper but I'd rather not have to use it if possible. I'll use a multimeter to make sure the 12V is coming out the correct pin on the obd connector

    I looked around some more and it sounds like someone else on this forum had a solar panel permanently wired up to the rear window and battery in the trunk. That'll be my plan C (plan B being to swap the polarity on the connector)
     
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  5. bisco

    bisco cookie crumbler

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    all the best!(y)

    i just got back from 7 weeks away. will be interesting to see what happens when i try to start mine tomorrow.
     
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  6. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    Most airport park lots I use for long term parking (commercial outfits off the airport grounds) have jumping capabilities. Recall the 12v isn't used for cranking over a motor but rather just starting a computer.
     
  7. taxibuddy

    taxibuddy Junior Member

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    Also picking up contactors which is a tougher load due to the inrush.
     
  8. PriusV17

    PriusV17 Active Member

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    Some of the car solar panels are cheap out there with cheap diodes that can end up draining the battery during the night. I would invest in a good solar controller rather than use straight solar to battery. And I would test the entire system for a few days before leaving it for a few weeks. Monitor battery voltage to make sure it's within safe range. A good solar controller should display battery voltage.
     
  9. El Dobro

    El Dobro A Member

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  10. Mendel Leisk

    Mendel Leisk Titanic Social Director

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    ^ I used to notice all the cars at a nearby VW dealership sporting little solar panels on the dash. Seemed like a good idea. This was 5~10 years back; don't think they're doing it any more though, not sure why.

    @vestibule Your best bet, in airport situation, might be to disconnect-and-isolate the battery's negative lead after parking. It's constant low level loads when the car's off that kills the battery; this will effectively avoid that. Be prepared to unlock the car with the manual key, and you will need to crawl through to the back to release the hatch, practice in advance.

    You can gamble that 2 weeks is not too much, and that's not a bad bet. OTOH, even if you manage to start up, that 2 weeks of parasitic drain will take a toll.
     
    #10 Mendel Leisk, Mar 21, 2018
    Last edited: Mar 21, 2018
  11. padroo

    padroo Senior Member

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    Pin 16 on the OBD II connector is always positive according to the OBD II standard.
     
  12. El Dobro

    El Dobro A Member

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    It was sitting in the trunk of one of the VWs I bought. I guess they forgot to take it back.
     
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  13. Sam Spade

    Sam Spade Senior Member

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    Charge the battery up and leave it sit.
    If it won't last 2 weeks it needs to be replaced.......before it leaves you stranded somewhere.
    Honestly.
     
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  14. rdgrimes

    rdgrimes Senior Member

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    ^^^+1
    If a 12v battery won't last a month of being parked, its well past needing to be replaced.
     
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  15. Air_Boss

    Air_Boss Senior Member

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    The sports car 12V has gone an entire "winter" (December-February) without a battery manager installed.
     
  16. PriusV17

    PriusV17 Active Member

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    If you're going to leave a lithium jump starter pack in your car for 2 weeks. I recommend storing it in an ammo box. In case a cell might explode. Costco carries them.
     

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  17. PriusV17

    PriusV17 Active Member

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    bisco, how did your Prius start up after 7 weeks? Is this the Plugin? What is the longest time anyone ever left their Prius before starting it up without a problem?

    I left the fan running in my V for 3+ hours and I was not able to start up my car after that. Had to use a jumper. After that I keep a solar panel and lithium jumper in my car. I can't imagine taking the V out on a road trip and not be prepared. I also keep a usb charger that also shows battery voltage reading so I know I'm in safe range.


    usb-voltage-meter.jpg

    The lithium jump starters are very small and very convenient and very easy to use. The only problem is that lithium can be unstable and extra safety is needed to store it in the car.
     
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  18. bisco

    bisco cookie crumbler

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    it started fine. was 12.19v when we got home, but after charging it up, it has benn holding at 12.6 for the last 5 days.

    the problem with judging by someone else's experience is that you don't know the condition of their battery before they went away. mine was in perfect condition for its age. i monitor it all the time, and have never drained it.

    you'r smart to carry the jump pack.(y)
     
  19. bisco

    bisco cookie crumbler

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    btw, don't you have to be in 'ready' to have the fan running?
     
  20. PriusV17

    PriusV17 Active Member

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    I powered up the car without stepping foot on the brake. This allowed the electronics to function and the engine stayed off. I was hoping that all electronics would function off the HV battery since I just wanted to use the fan. Now I know.
     
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