battery is dead

It seems a bit premature for a battery on a Prius V to fail so soon. I don't understand why you need to tow a car with a dead battery. Jump starting should work, unless there are other problems.

 

Pilot error can cause a 12V drained battery at any age, even a single day. A previous model also suffered a batch of bad 12V batteries, and it is possible for a similar problem to crop up again.

Errors in jump starting any Prius can be hideously expensive. Unless the owner if very confident about doing it correctly, a tow is cheap insurance against a mid-4-digit electrical repair bill.

 

Can you touch a bit on properly jumping a Prius v (lowercase v for the Prius v wagon because only 2010 Prius used uppercase Roman numerals for model designation) ? I operate a v (lowercase v for the Prius v wagon because only 2010 Prius used uppercase Roman numerals for model designation) at my work as a full blown live news vehicle, and it has probably 20AMPS tops being sucked through it with all the radios scanners and battery chargers turned on and pumping. The car has been in service for about 4 months now with no problems, but has been "unused" for the last week, and has been having a dead battery several days when tested. We can't find any gear that is still hooked up and drawing power while the car was in "out of service" mode, and I am wondering if the high drain and READY charge cycle, as well as the dead battery a few times, has perhaps killed the tiny 12v battery. Another operator used the v (lowercase v for the Prius v wagon because only 2010 Prius used uppercase Roman numerals for model designation) to jump start a V10 live truck that had a dead battery a few weeks ago. I cringed when I heard that. I am in the v (lowercase v for the Prius v wagon because only 2010 Prius used uppercase Roman numerals for model designation) for my 9+ hour shift every night, and always ensure that it is in READY if at all possible.

Is the 12v system used for actually turning over the gas engine when you start the car, or simply to get the electrical system up and ready to link in the drive battery for starting? Can anyone recommend the BEST 12v replacement battery for the v (lowercase v for the Prius v wagon because only 2010 Prius used uppercase Roman numerals for model designation) ?I am not sure they make an Optima in that size, but I would think a BLUE TOP marine battery would be well suited for the type of power draw and low CCA need of the Prius V power system.

Any advice would be helpful. Thanks.

Paul

 

The 12v battery does not start the ICE. That is done with the HV battery.

You could replace the 12v with a higher capacity battery, even if it doesn't fit the compartment. The charger will charge and maintain the larger battery. The charging system doesn't differentiate between the larger or smaller battery. It only recognizes the voltage or the state of charge of the battery.

 

DS46B24R YELLOWTOP® Prius® Auxiliary Battery 8171-767 | OPTIMABATTERIES

Is this the correct Optima for the v (lowercase v for the Prius v wagon because only 2010 Prius used uppercase Roman numerals for model designation) ? My research seems to indicate that the drive battery provides the juice to start the car, and that the 12v battery provides the juice to connect the necessary systems to the drive battery for "starting" the car. is that also correct?

Paul

 

yes. when jumping a prius, it is of utmost importance to get the polarity correct. reverse polarity will blow a big fuse at best, or be very expensive repair at worst.

 

I cringe too. This has the potential to do a lot of damage. I might consent to jump another Prius in a serious pinch, but will not jump a traditional-type vehicle unless the situation is more important than the risk of $5k of damage.

Even if refusal to lend a jumpstart from my Prius meant I was forced to pay for someone else's service call, I'd still pay to avoid the damage risk.

Yes, but I'll describe it slightly differently. The Prius has no 12V starter or alternator. The high voltage (HV) motor-generators (MG1 and MG2) do both those jobs along with their propulsion and 'transmission' jobs.

The 12V battery boots up the computers and all the low voltage systems and accessories. The computers then flip a relay inside the HV or traction battery case, which provides power to the HV inverter electronics. These operate the MGs and also provide charging current to the 12V battery. MG1 then spins to start up the gas engine, both for the initial cold start and for every hot restart during normal operation.

Honda hybrids are different. They (or at least some of them) are usually started with the high voltage system, but do have a 12V backup starter for use if the high voltage system dies. In Toyota hybrids, the high voltage is much more central and essential to vehicle operation, and it couldn't move with dead HV even if the engine could be started. So a 12V starter is pointless, and left out.

 

I will be keeping a small jump start box in the trunk until my issues are sorted out. Looking closely at the smallest 70LB Optima Bluetop battery.......as long as it will (can be made to) fit in the "area" of the stock battery, and can be secured in the event of a crash.

Paul

 

OK for an emergency, but frankly once the 12v batt has been damaged by being drained, it needs to be replaced. The correct Optima batt will provide considerably longer and more reliable service than the OEM batt. Because the batt is inside the passenger area, use ONLY the correct type and fit. But its safe to say your current battery issues will only get worse unless its replaced.

 

Type, yes. Including venting style, so the exhaust vent tube can be connected to shunt the sulfuric acid fumes outside.

But if by fit, you mean size and shape and electrical capacity, I'm not so sure that is a safety issue. If he is handy at squeezing in and securing a larger capacity battery of the correct AGM and venting style, I'd think he should be fine.

 

Not that much of a problem with sulfuric acid fumes as with HYDROGEN which can cause an explosion.

The 2010+ Gen III Prii don't use a vent tube. The battery compartment is vented.

 

Does the HV battery constantly charge the 12v battery when the car is in READY?

Paul

 

My car just did the same thing pretty much, the lifgate wouldn't open and I was stranded, if I could do it over again I would have just bought a new battery and replaced it in the parking lot.

 

What small jump start box? Link? Wondering what the minimum battery requirements are?

 

Yes, via an inverter. It appears that once the car is in Ready, the 12V battery doesn't even need to be there.

 

I was able to get my Prius into ready mode with one of these:

I have had this thing for years (wife got it for me for fathers day - guessing it has been at least 3 years now). Never used it for anything other than a tire inflator until last week. I left the rear driver-side door open in the garage for 4 days and the battery was completely dead. I opened the bag that the jumper cables were in, plugged them into the back of the unit, hooked them up to the jump points described in the Prius owners manual, and tried putting it in ready mode. Initially it didn't flip to ready, but I cycled the power switch back to off, gave it a minute, and tried again. This time it went to ready mode and I was off.

I suspect that when the battery is completely flat, it may help to allow the pair of batteries that are connected in parallel to "equalize" for a moment. This probably isn't necessary when there is a bit more voltage remaining in the prius 12v battery.

The car has been fine since this episode so far, but I know that the 12v battery is probably running on borrowed time. I want to do a voltage check on it after an overnight and see what the voltage looks like before attempting to enter the car (pop the hood by getting in through the passenger side). The car is a 2010, bought new in Jan 2011 - currently just a bit over 40000 miles.

EDIT: I have been carrying the B&D unit in the back of the car for the last week "just in case"...