Battery Tender...temporary solution?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Kimbrie, Oct 4, 2012.

  1. Kimbrie

    Kimbrie New Member

    Oct 4, 2012
    Tumwater, Washington
    2005 Prius
    I have a 2005 toyota 12 volt battery went bad a few months ago, so have been jumping it off a battery I keep in my car to get it started each time...I don't drive it very much and am in college so can't afford a new battery right now. I found a "battery tender" online for $40 and it says it continuously charges it and shuts off when it is fully charged. Is this a viable option for me until I can afford to replace the battery(probably after 1st of year)...I copied a few of the bulleted features below hoping that would help whoever is giving me advice on this issue...I also included the link to the battery page as well.

    • Complete 4-step charging program (initialization, bulk charge, absorption mode and float mode) that maintains batteries at full charge without overcharging via its 4-step charging system
    • Automatically switches to float/maintenance mode voltage after fully charging the battery
    • Temperature compensated to ensure optimum charge voltage according to ambient temperature, and spark proof and reverse polarity protected; 10-year limited warranty
    Battery Tender 021-0128 Battery Tender Plus 12V Battery Charger : : Automotive

    thanks for any assistance you can offer me...


    starving college student :)
  2. cwerdna

    cwerdna Senior Member

    Sep 4, 2005
    SF Bay Area, CA
    2006 Prius
    If you're still on your original 12 volt. It's toast. Replace it. Many recommend the Optima Yellow Top w/the right size terminals for the Prius (example: Optima DS46B24R Optima battery direct fit replacement for Prius 2004 +). I bought Toyota Prius 12 Volt Auxiliary Battery with install kit for 2004 - 11 before the version w/the proper size terminals existed. I replaced mine in my 06 more than a year ago.

    I can't speak to that tender, but I personally bought TecMate TM-141DUAL OptiMate 4DUAL 0.8Amp Weatherproof Desulfating Charger/Maintainer : : Automotive recently and have used it recently. Seems to work fine. My car doesn't get driven on long drives much, so I expect to hook it up at least once a month to keep it topped off.
  3. Paradox

    Paradox Prius Enthusiast / Moderator
    Staff Member

    Sep 22, 2005
    2014 Prius v wagon
    Moved to the Gen II maintenance and troubleshooting forum out of the Prius c forum.
  4. PriusCamper

    PriusCamper Senior Member

    Mar 3, 2012
    Pacific Northwest, USA
    2007 Prius
    Hey Kimbrie... I'm in the Olympia area and I've a small 600ma 12volt 12watt trickle charger you can borrow. It doesn't shut off on its own but it charges at a slow rate (you can even lower it to 200ma). Main thing is to find a new battery asap... Exide seems to be the lowest price that guarantees a perfect match, but others on PriusChat recently discussed buying 12 volt wheel chair batteries because they are much cheaper and equivalent if not better in performance and capacity. So you might want to do a search for that thread and ask them.... Also the longer it takes to get the battery, the more money you're losing in lost gas mileage. So sooner you can find something the better.
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

    Mar 8, 2008
    Green Valley, AZ
    2015 Prius
    The current capacity of that unit is only 1.25A. If your battery is "bad" it may not respond to charging especially with such a small available current. Really, the best solution would be for you to replace the battery now.

    If you must continue the practice of a jump start, please make sure you get the battery polarity correct as a mixup may cause the inverter to fail, resulting in a healthy four-digit repair cost.

    After you replace the 12V battery, it would be good to use a battery tender to keep the battery charged up assuming you don't drive much and have an AC outlet available for your use where you park.
  6. Britprius

    Britprius Senior Member

    Jun 14, 2010
    Herefordshire England
    2008 Prius
    Hi Kimbrie I posted about using mobility batteries in Prius, but I do understand the difficulty with spending on a battery at the moment. Any 12 volt battery that will fit in the small space in the Prius will work and get you out of trouble. Look at mower batteries or even a battery from a breakers the 2 important things about the battery are:-

    (1) size the depth of the battery from front to back cannot be more than 5.5 inches, Height no more than 9 inches to the top of the posts, the length is not very critical. These sizes are maximum smaller does not matter
    (2) The position of the battery posts. The positive (+) post must be on the left with the posts closes to you.

    Even a good small motorbike battery will work but make sure whatever you use is fastened down even if you need to pack it out with pieces of wood.

    Fastening to the terminals is your next problem but any method that is mechanically sound will work as the Prius does not need large amounts of current from the battery. The positive terminals should have no possibility of touching ground.

    If your Prius battery is as bad as you suggest a battery tender will not help you will get stuck away from home.

    John (Britprius)

    The battery you keep in the car will also work if you can fasten it down. Connect the negative(-) post to ground remove the negative lead from the Prius battery and connect a lead from the positive post (+) of the Prius battery to the positive post of your starter battery.