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Dead 12V - can it be resurrected for a couple of days?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by bruceha_2000, Nov 13, 2008.

  1. bruceha_2000

    bruceha_2000 Senior Member

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    Hi all,
    My Prius did not start this morning. Very dim interior lights. I hadn't left anything on but:

    1. Lately it has been beeping at me when I get out after shutting down. No 'door ajar' light on, no interior lights on, etc.
    2. I have intermittently gotten the "Caution: The transmission lock mechanism is abnormal" message with increasing frequency when I shut down
    So I read here that #2 can indicate a weak 12V. Perhaps #1 does as well?

    Anyway, I attached my battery charger/starter to the appropriate points under the hood, set the switches for start and plugged it in. The meter bounced all over the place in the 'Start' range so I unplugged it, switched to 10A charge and plugged back in. Meter still bounced, then the charger started SMOKING. Unplugged in a hurry, I think I fried it. I pulled the 12V and see that it says 'do not charge at more than 4.2A' in small print. Could be it caused a high resistance back to the charger?

    I'm thinking of doing the Optima replacement, but that will take 3 days minimum, more likely 5 to 7.

    So, the question:
    I bought a new charger and am now charging the 12V. It started at about 9V. Is it likely that it will live for a few days or do I have to run over to Toyota and get a pricey OEM battery, assuming they have one on the shelf?

    Thanks,
    Bruce
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Bruce,

    The dim lights prove that the 12V battery is low.

    It was a mistake to use the "start" position on the charger, as that forces a relatively high voltage on the battery (to deliver 50A of charging current). That can be very bad for the Prius electronics, not to mention the 12V auxiliary battery. Hope that your car will start after the battery has been charged.

    As you noted, the battery is supposed to be charged at no more than ~4A. If it charges up now, then great.

    If the battery doesn't hold a charge and you want to experiment, you can remove the label on the battery top (the one with a warning not to remove) and then remove the translucent plastic cover over the six battery cells. Add an ounce of water or so to each cell. The point is just to provide a small amount of fluid, you are not trying to cover the cells with water - since the battery uses AGM technology.

    Then put the translucent cover back on and see if the battery can be charged.

    Note that the battery from the Toyota dealer will cost ~$130 to $160 depending upon how usurious your dealer is; this is not much different from the Optima battery.
     
  3. KK6PD

    KK6PD _ . _ . / _ _ . _

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    Toyota makes a charger specific for the Prius. As Patrick stated you need a low charge current to charge the battery. Hopefully your electronics are OK!!

    Good Luck and let us know what develops!!

    73 de Pat KK6PD
     
  4. bruceha_2000

    bruceha_2000 Senior Member

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    DOH! I should have thought of that. "Don't add water" means you CAN add water (only in an emergency of course). When I went out to check, the charger display was flashing and the 'check' light was on. Battery voltage only 10V. So now I'm trying your suggestion. The hardest part so far was peeling that translucent piece of plastic out. When I took the rubber caps off, each gave a little 'pop' noise and popped off. Is it supposed to be under pressure internally?
     
  5. bruceha_2000

    bruceha_2000 Senior Member

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    One more thing. There was about 1/2 cup of water in the battery well. Nice clean stuff, no acid. How did it get there and is there supposed to be a drain?
     
  6. bruceha_2000

    bruceha_2000 Senior Member

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    Another 'one more thing'.
    The battery is now showing 12.7V so adding water definitely helped. But, if it doesn't hold:

    What if a guy happened to have a big deep cycle boat battery. Would it be possible to stick it in the hatch and connect it in place of the 12V for a few days? I know I'd have to get a proper connector for the ground and positive lead, I figure I could bolt things together. Will the car be fussy with a lead acid deep cycle in there??
     
  7. miscrms

    miscrms Plug Envious Member

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    You could keep the big battery in the trunk and use it to "jump" the little battery for startup. I'm not sure it would be a good idea to keep it hooked up the whole time though. In addition to the higher chances of accidentally shorting something with the extra wires running around, the deep cycle battery will be more likely to emit hydrogen gas while charging or discharging. For an inside the car application you generally want a sealed battery. Just to be safe, I'd probably keep the hatch open while jumping, then disconnect. You also want to be able to secure the battery to it doesn't tip over and leak acid. By the same token you could pick up one of those $30-50 jump start boxes that you plug in at home. They have a small sealed 12V battery that should last quite a while with the Priuses minimal current draw. Again I'd just use if for jumping though, not leaving attached.

    On the other hand, if your small battery is bad you could strain the dc:dc converter by leaving it hooked up while driving around. That would only really be a problem if you have a shorted cell, in which case you'd probably never see the battery get up to 12.x volts. If it comes up to that range, but just doesn't hold it after power down you might be ok.

    You do want to be pretty careful back there. There has been at least one reported instance, that I am aware of, of someone frying their inverter due to a short or reversed cables during jumping/charging. Thats probably a several thousand dollar oops, so just be extra careful ;)

    Rob
     
  8. bruceha_2000

    bruceha_2000 Senior Member

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    Thanks Rob, glad I asked, I hadn't thought about the gassing during charging. That would be quite the safety hazard.
    Good point, I will connect it to the tie down rings in the car. I plan to put it in the tray, leaving the false floor out. It is a big and damned heavy 675 CCA, 200 RC Marine Deep Cycle, I don't think it will tip over
    Yeah I looked at those when I bought the charger. I was hoping they had a portable power supply that could ALSO charge batteries. I can't really afford to buy both and I need the charger to get the 12V back up and for the boat battery. Plus, the guy said you have to pre-charge them for 48 hours which means I would be without a car for 2 more days. He also said you HAVE to recharge them every time you use it to jump a car. He might not know just how little juice a Prius uses to start though.
     
  9. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Bruce,

    Glad to hear that you are willing to flout authority by adding water to the battery, and that it seems to be working at least short-term. You are probably the type who thinks nothing of cutting off the tags when you buy a new mattress? :p

    The water in the hatch is a problem. If you don't see any obvious reasons for this, then my guess is that the rubber seal that runs around the hatch opening is leaking or maybe the traction battery air vent is allowing water to enter. I suggest that you use some paper towels or a sponge to remove the existing water, at minimum. Perhaps you might hose down the hatch area while the battery is removed, and see if you can determine how the water is entering the car.

    Electrically, there's no problem with using another 12V battery on a temporary basis. However you need to ensure that the battery doesn't fall over, short out, etc and this may not be easy to achieve.

    Regarding the pop sound that you heard when you removed the rubber caps, this might be due to the tension in each rubber cap. The battery is vented so that pressure should not build up.
     
  10. warrior

    warrior New Member

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    Dit-dah-Dit;)
     
  11. bruceha_2000

    bruceha_2000 Senior Member

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    Me? NEVER! it says "Do not remove under penalty of law!" :) Actually, I'm not against fudging the rules a bit in a pinch. At new employee orientation 29 years ago, they said "Do not use your badge as an ice scraper". Well don't you know it gets cold and I hadn't bought a scraper yet and there was a thin film of ice on my windshield one morning. DANG those laminated badges work well on thin ice :D Probably wouldn't have thought to use it if they hadn't told us not to. They work MUCH better for the thin stuff than a regular ice scraper. Cleans the gunk off the window at the same time too.

    Too late, battery charged up to 12.9V and put back in. Finishing the charge on the Marine battery over night to put in the back tomorrow morning. I did clean the water out. I'll have to keep an eye on it. Should be easy at the moment with the back all opened up waiting for the Optima and kit to arrive. I would lean toward the air vent since I've never seen water on the cargo area floor. I would expect that if the hatch seal was leaking.
    BUT the vent seems to be ABOVE the rubber caps, in the area sealed by the translucent plastic piece. Seems like the only time anything would get to the vent hose is if a cap blew off and the plastic piece holds them down. Is a puzzlement!
     
  12. andyprius

    andyprius Senior Member

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    I drove a car for 10 years with a lead acid battery inside . The car : A VW Bug. Gassing is not a problem. H2SO4 spillage is. My emergency backup battery is a spade terminal 7.5 Amp. It works fine. Cost: $15-20.
     
  13. V8Cobrakid

    V8Cobrakid Green Handyman

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    my battery dies on occasion.. start ups are slow and dim.

    you should take the battery out, and charge it. the charging system on the prius is really only a topper ( or so it seems )

    i've done all kinds of jumps with my prius... things you guys would freak out about ( like indipendently trilkle jumping a 24v system.. then jumping the 12v side while starting... on a tractor...) so.. i jumped a really large diesel. haha. (muscle cars, civis, accords, jeeps, lexus,.. all kinds of cars)
     
  14. V8Cobrakid

    V8Cobrakid Green Handyman

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    btw, i first experianced a dead 12v battery around 43k miles...
     
  15. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Bruce,

    What was the voltage reading this morning, after the battery rested overnight undisturbed?

    Am wondering whether your rehydrated 12V battery was successful in starting your Prius without further assistance required.
     
  16. bruceha_2000

    bruceha_2000 Senior Member

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    Hi Patrick,
    thanks for checking up :) Battery still at 12.5V this AM, car started fine. Checked it again when I got to work and also when I got out 9 hours later. Still at 12.5V. Looks like I should be good to go until the Optima arrives. If not, I do have some jumper cables and that bigass Marine Deep Cycle lashed in.

    The only problem I have is that I turned off the SKS figuring I don't need any parasitic losses and I keep forgetting I have to put the fob in the slot. Foot on the brake, push power, NOTHING! Why won't it start, is the battery TOTALLY dead? DOH. It also beeps at me a lot when I get out of the car because I forget I have to REMOVE the fob from the slot.
     
  17. andyprius

    andyprius Senior Member

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    Glad to hear that the battery was able to be restored by the addition of a small amount of water and charging. Thanks to Pat, also for purposes of study you might totally defer the optima purchase and keep us informed of how long your rehab'd auxiliary is lasting. Like every year or two???
     
  18. philmcneal

    philmcneal Taxi!

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    i heard toyota offered an improved model for the 2g prius battery, so is the optima worth the upgrade with the kit you have to buy to make it optima compatible?
     
  19. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Phil,

    I am not aware of this. If you have details please provide. 2G has been shipped with either of two 12V batteries; a smaller one for the base model and a larger one for models equipped with SE/SS.

    TSB EL014-03 was issued for Classic Prius which allowed installation of a larger battery made by Panasonic. This required installation of a new battery bracket and battery cable connectors.

    2G base model has the same size battery as was originally shipped with Classic (except that the battery terminal polarity was reversed.) This is interesting since Toyota felt the need to issue TSB EL014-03 for Classic, while I am not aware of a similar TSB for 2G.
     

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  20. bruceha_2000

    bruceha_2000 Senior Member

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    All is well now. The package from e-Learnaid arrived on Friday, quite appreciated since the original expected date was today. Installed on Saturday, along with the swap to winter tires.

    Thanks again to Patrick for suggesting a successful temporary remedy. The old battery read 12.22V when I pulled it Saturday. Glad I can use the SKS, what a pain to have to use the fob, especially now that is has gotten cold (mid 20's F) and gloves are a necessity! How easily I got used to SKS! Never even had a car with remote lock/unlock before.

    My one comment to all is - have your battery fail BEFORE it gets cold. It would be much easier to replace it without gloves or frozen fingers.

    To keep this thread clean, I posted my install notes in another existing thread:
    http://priuschat.com/forums/care-maintenance-troubleshooting/39664-12v-battery-choices-7.html