Prius balks at starting

Things like this happen every now and then. I wouldn't worry about it unless it happens more often. Sometimes even if you think your holding your foot firmly on the brake maybe you hit the start button a microsecond too soon, things like that...

 

Twice in two weeks I had a similar problem with my '05 Prius; when I depressed the brake and hit the start button, the warning lights (including the exclamation) came on, the video screen DID NOT, and the car was unresponsive --pressing the start button did nothing. I could finally get it to shut off by taking my foot OFF of the brake and pressing the start button. Then I put my foot on the brake, pressed the start button and it started right up. Anyone ever had this happen? It sounds a bit like what was mentioned above, and once would just be a freak occurrence, but twice in two weeks makes me suspicious.
Could there be a problem with the brake-pedal sensing switch?

John

 

Do you have the original 12v. battery? If you do you might want to get it checked out. When the 12v. battery starts to go sometimes it does weird things.

Southjerseycraig has yours acted up again?

 

I do; 5 years might be a good time to check it, eh? Hadn't thought of that. Will do. Is that a pretty standard battery, or a Toyota special?

John

 

It's a special size. Optima makes one that will fit, but you need to buy the mounting kit with it. A quick search on this site will give you all of the information.

Tom

 

It's not a special size, it's a Japanese standard (JIS) size. US batteries are supplied to Battery Council 'International' sizes, which are completely different. ('International' in quotes because the EU use European Type Number or, older, DIN sizes. It's about as international as the World Series ). JIS D 5301 appears to be the right standard but I'm not paying £63 (about $100) to find out.

You have to find a Japanese battery manufacturer with a US distributor to get one that will fit properly. As a JIS-standard battery, the terminal posts are also JIS standard, not SAE. That's why you need adapters.

It's proving very difficult to find out any information about the actual battery in question - I can't see anything about the (tentative, since there are stickers obscuring some of it) S34B in Hobbit's description. There could well be more letters or digits after the B.

The Australian GS Yuasa importer suggests an NS40ZL or NS40ZLX battery. The size (195x127x228mm) appears to roughly match what Hobbit measured. The Z (part of the standard name) appears to be a higher capacity of the NS40L, the X an even higher capacity specific to GS Yuasa. The 'L' indicates that the terminals are the other way around compared to the 'standard' type, though having just looked at mine compared to the description I think it actually should be the 'standard' type with the positive terminal on the left when looking at the front of the battery, terminals at the front. I can't fully read the label on mine - the hold-down clamp is in the way and my tools are at home - but it appears to start S4 and end in R. (We don't have smart key but that doesn't necessarily mean we got the smaller battery, because we do have a standard alarm system.)

The new designation for NS40Z is a group B20 battery, and the new GS part number is 36B20R. Perhaps I have an S4xB20R? There's a slightly larger group B24, which has a size 46B24R but I'm not sure that would fit length-wise. On the other hand there could be different hold-downs depending on which type of battery was originally fitted.

The OE battery type appears to be a 'maintenance-free' wet (i.e. liquid, non-absorbed electrolyte) design. It isn't absorbed-glass-mat. I'm not actually sure that using an AGM replacement is warranted, nor a deep-cycle battery, though the float charge voltage (13.8V) is on the verge of causing out-gassing when charging with the wet battery.

The Optima kit certainly fits (well, just about), but you might get as good results from any other BCI Group 51 battery. All the other BCI sizes are just too big.

 

Yeah, it IS the battery. I am stuck, dead, awaiting AAA. Hopefully they will be able to help. Note: When battery is dead, you cannot open the rear door, where the BATTERY is. I assume jumper cables will allow the car to start, and I can limp home, and try charging thre battery overnight with a charger?

HELP!

 

Okay, I stand corrected. It's not a special size, it's only an uncommon size.

Tom

 

Well, at least you figured out what the problem was.

There should be an emergency manual release in the trunk I think. It may take some work to get to though - at least for the Gen2, I superficially remember having to take plastic panels off.

Your thread title invoked an interesting image:

You: Prius will now start.
Prius: You want me to do WHAT? Hell no!
You: Wth, Bro???

 

Either get enough of a charge on the battery or jump start it then drive to the dealer & have them replace it. If the battery won't hold a charge you can take some pleasure in pulling up to the service desk & shutting the car off. They'll have to work on the car to move it and won't be able to say "can't replicate the problem". When I replaced the battery it was about the same price as the aftermarket one that needs modifications.

 

Well, battery seems to take a bit of charge; hoping it will last me a day or two until I can get a replacement from Toyota. I suspect the shortness in lifespan has something to do with the amount I drive the car--most days its just a short commute morning and evening; probably not enough to really give it a good charge, and I have the smart key, so there is a small constant drain on it. However, a voltage readout on the dash would be nice so as to monitor the conditions.

Thanks everyone!
John

 

You can access the 12V battery from inside your car when you flatten rear seats. It is not very pleasant, but achievable.

 

On my 2005, you jump the car from a special terminal provided for that purpose in the fusebox to the extreme right under the hood. Once you open the fusebox, the jumper terminal has a red cover on it.

 

Maybe your brake light switch isn't registering the pedal push all the way (and you didn't have it down all the way) so it just went into ignition-on mode? I saw some other posts about people saying their brake lights don't come on until they push the pedal down about 1/4 of the way.

 

I agree that your driving habits shortened the battery's life. The 2nd 12V battery in my 2006 lasted about 6 weeks. The MFD has a diagnostic screen. Press the power button without pressing the brake. Hold down INFO button and flip headlights on/off 3 times. Poke around & you'll find the voltage readout. A search will find several references for this procedure.

 

Six weeks? Wow, hope I do better than that!

Voltage showed marginal, dropping below 12 with aux on, going up to 14.1 when "ready"; battery took a charge overnight, but is not holding it well; planning to replace it tomorrow.

Thanks,
John

 

No reason for the Prius original equipment 12V battery to be so mysterious. In the US, the 2G Prius with Smart Entry / Smart Start has the GS Nippon Denchi S46B24R battery. The base 2G Prius has the smaller S34B20R battery. The latter is the battery in Hobbit's car.

Classic Prius has S34B20L. Same physical size as 2G base model, but terminal polarity is reversed. This battery was replaced by the Panasonic S55D23L battery in a TSB. Since the Panasonic is much larger, a new battery bracket and cabling are also required. I understand that S34B20L is no longer available from US Toyota dealer parts depts.

The Prius original equipment battery is specified to be AGM. Some owners have found their batteries actually are liquid acid although the battery case markings appear to be the same as AGM batteries.

I looked at the batteries in my 2001 and 2004 and they are AGM. I even removed the rectangular vent cap on top of the 2001 battery to see the lead plates and the whitish fuzzy mats between the plates. Also tipped the battery over 90 degrees: no fluid inside.

The 2004 has a black case so you can't see inside but I held the battery and shook it, and did not hear any fluid.

Attached photos are of the S46B24R, S34B20L, and S55D23L.

Since this is supposed to be a 3G forum: when I looked at the 2010 vehicles on display in Detroit back in January 2009, it appeared that the 12V battery was S46B24R. Maybe someone owning a 2010 can confirm whether this is correct.

 

Gen III is the same, There is a metal "blade" for the positive in the engine bay fuse box and connect the negative to something unpainted.

Shame on the dealer for not showing you how the jump the car! You should never be stuck trying to access the battery unless the rear hatch release is broken. Just power up the car from another battery under the hood.