What the heck is wrong with my Prius??

Won't ruin your car, but be careful about carbon monoxide poisoning. That's a real danger if you run it in an enclosed garage. ICE will periodically turn on to keep the HV battery charged.

If you run it outside...well, someone could come and steal it. They can drive away w/o the smart key in their possession, but won't be able to restart it once they power off the car (unless they have the key).

I bought TecMate TM-141DUAL OptiMate 4DUAL 0.8Amp Weatherproof Desulfating Charger/Maintainer : Amazon.com : Automotive to keep the 12 volt topped off. It would take forever to use that to charge from dead though. But at least it shouldn't cause any electrolyte boiling or anything...

 

Yep. You'll hear the inverter pump and ICE turning on/off. Dash lights and MFD will be on, etc.

You can check the voltage again tomorrow and again after the car has sat many hours or overnight.

 

...as mentioned the newer Optima has pencil posts (skinny) so easier no adapter.
Give youself some time experts can do it quick but took me hour or so (ok 2 hrs).
eLearnaid had nice step-by-step instructs to go with it, but I am out of date on it (got the older model).

 

Hey kid just pony up a few Benjamin's for a new battery and chalk it up to maintenance before it doesn't start and you have to pay for the tow or jump and the battery and miss your class. No biggy just life.

 

For me, it took me like 1.5 hours (Optima D51 battery - why elearnaid? Seattle area installers? | PriusChat) w/the old version. The direct replacement version should be quicker to install since there's no need to change the positive terminal and negative cable.

 

No, unfortunately, not a proper AGM battery. Google for

Code:

site:priuschat.com flooded battery acid rear ended

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Basically the only two choices I know in the US that are readily available are the Toyota OEM or Optima Yellow Top.

New 12v Battery, Part #28800-21171 | PriusChat documented a pricing glitch on the OEM.

The $50 to $80 is about right for conventional flooded lead acid batteries, at least in other sizes.

 

Dude, you should know better! 9.8 really?? Your 12 Battery is dead. You can recharge, but once you kill it, it's gonna get you again in the future at the worst possible moment!
Wait, that's Murphys Law!

Yellowtop it, worth the money. It.s simple to replace. I replaced mine at 25K!

 

1) Leaving lights on overnight probably would not have caused this. You might have a large drain on the system normally that makes it marginal to begin with. But the fact that the 12v was in the 9volt range means it is way beyond dead. A 12v battery that reads 12v or below when sitting is dead. Yours was a zombie.

2) Changing the battery is needed. Whether or not it fixes everything doesn't matter. That battery will leave you stranded, it NEEDS to be replaced.

 

The relays need 8.5v or so to turn on. A battery in the 11v range will drop to 9v or so under load before the inverter kicks on but the car is READY. The battery you have now would not start a conventional car. It would chug a few times and die.

 

No guarantees, but you should be fine. If not, jump it. Just don't leave your headlights or dome lights or do any non-READY power draws like leavin your dome light on or listening to radio in a parking lot.

 

I would be happy to replace your battery. I can get a few different ones such as OEM, Optima and soon Exide. Feel free to give me a call.

Avi

 

It might be your door sensor. Try looking there first. The red triangle comes on if you put your car in drive with door open. Your 12v is also not up to par.

 

Yep. I would bring along a charged "jump box" (portable lead acid battery with cable and clamps), just in case. Just be absolutely sure you don't reverse the polarity as that could toast (heh) the inverter, leading to a 4 digit repair.

 

Let us know the outcome.

 

If you want to check the Toyota price at the local stealer, call the parts dept. and ask them for a price on 00544-21171-325 List price on my invoice was $203.02, I managed to get one for $183.67 out the door. That was from Jake over at Champion Toyota here in Houston. That is a drop in battery that fits the 09 Prius with SKS.

Also, check with O'Riley Auto Parts if you have in the area. Recently I saw post's that they have a drop in battery also.

List: Battery - Automotive - 2009 Toyota Prius | O'Reilly Auto Parts

The link above show's both the True Start and the Yellow Top. IIRC, the poster I saw here on PC said he got the True Start one and that it was a drop in battery also. YMMV

I can't vouch for the battery from O Riley, but I can vouch for the part # I gave you. I bought one of them on Jan 5, 2013 directly from Toyota. It solved all of my problems for me. Sorry I don't have pics of the battery. It looked very similar to the one I pulled out of it.

As other's have said, use a jump box or a charger to keep the old one charged enough until you get the new one. I do agree that you need to change the battery. Your numbers are very low. A NEW AGM type battery that is fully charged will read at least 13.0 volts across the post's with a digital volt meter with no load. Make sure whatever battery you end up with is fully charged BEFORE you install it. Use a digital volt meter. The one I bought read 13.0 volts, also a fully charged Yellow Top as per Optima Jim and Patrick Wong here on PC should read 13.1 volts.

One final note, IF your Prius does NOT have SKS and you buy the Optima battery, you will have to change the tray to make the battery fit properly. You can get the alternate tray from Toyota for a few bucks.

2009 TOYOTA PRIUS Parts - AutoNation Toyota Gulf Freeway Parts

The part's guy at Toyota should know what you are talking about.

Ron