12v battery Replacement

I prefer removing the negative cable from the frame, too, which is how I did mine. Kept sparking further away from battery, and made it easier to for me to clean the post clamp up good while it was out of the car. I slather mine down with plain motor oil before reinstalling. Had a practice of doing this for many years, and never have a corrosion problem after doing so. I don't like idea of unclicking/reclicking positive wires first/last. You still get sparks -- they're just up inside the connectors and you don't see them. Burns little chunks out of your metallic connecting parts.

I also did a little trick to avoid having to reset my radio and window. I have a low current 12v power supply that I hooked up to the booster terminals under the hood, to maintain 12v during the swapout. It is only about 3 amps, and I didn't connect it until right before I disconnected the negative cable, and disconnected it as soon as I had the new battery connected. I figured that way I wouldn't fry a battery or produce much charging gas to ignite with the sparks. No resetting!

 

Click connector didn't spark, the connectors looked fine and car has been fine for the 2 years since.
Its an instant disconnect unlike the neg terminal that's bouncing and twisting around loose and sparking on the chassis till you get the bolt off.
No burnt chunks on he connector. You can keep your sparking away from the battery. I prefer no sparking at all.

Slathering the battery in motor oil is just plain ridiculous. Must be a nightmare to re-install. Really dangerous making the battery that slippery.
All you have to do is apply some grease to the terminals. Car probably stinks of motor oil. Just spray a little CSP on the terminals.
Its made specifically for that purpose.

And how does hooking up a 12 volt supply other than to keep alive the radio & window setting result in your quote:

"I figured that way I wouldn't fry a battery or produce much charging gas to ignite with the sparks".

 

I believe that 90miler's concept is that the 3A power supply, not being connected for a very long period prior to disconnection of the 12V battery, would not have a chance to overcharge the battery. Of course, 3A is not enough to cause such difficulties unless the charger was connected for days at a time and the charging voltage is well above 14.4V.

Also, 90 miler is applying engine oil only on the battery posts. I don't have a problem with that practice, but I also don't think that is necessary as long as the battery case is not leaking acid, which is really unlikely in the case of AGM.

 

Ed, I'm sure your connectors are still fine. But, I will assure you, if the battery was connected to any load at all, there was a spark. You just can't see it. The chances of blowing the battery up from a spark are small, but I have seen it happen, at least with conventional lead-acid batteries. I know that liquid acid in the face is no fun. I'm not sure what happens when/if an AGM blows up. No more frequently than you click/unclick these connectors, it is unlikely to do that much damage to the metal contacts. Pressing some dielectric grease into the connectors can help to supress the arcing/sparking somewhat. However, it is still my preference to disconnect the (-) cable first. Then you can unclick the (+) if you like.

I never thought about slathering the battery itself with oil. Maybe it would have fit down in the space in the rear of the car better if I had! Actually, slather was probably a bit of a strong word. You just need a fairly generous film of oil or grease over the metal. Oil is less messy to me. There was a little light oxidation on my (+) cable end. It may have had more to do with the presence of some water moisture (relating to a problem I won't go into on this thread) than with the proximity of acid. Nevertheless, the oil keeps the metal bright & shiny, and I feel better doing it. If you feel better using a product that is produced & marketed specifically for that purpose, great! I think I own a few shares of stock in a company that sells a couple of those products, so we should all be happy.

 

I did not see or hear any spark disconnecting the plug. Its a very quick positive disconnect. Sorry you cannot understand this. Unlike the neg cable first which involves metal wrenches and sparking to the chassis as you attempt to remove the eyelet. Yes I used dielectric grease in the plugs.

Motor oil is very poor choice to lubricate anything other than internal engine. It will not stay where you put it do to its viscosity. Anywhere you put motor oil on the battery will eventually end up in the trunk well not to mention the smell. Motor oil stinks.

Sand down both eyelets of the both cables. Lightly, and sand down both posts lightly. Till you see shiny metal. Sand down the contact area of the negative cable where it attaches to the chassis. Sand down the negative eyelet connector where it attaches to the chassis. Clean that all up. Use either synthetic axle grease (no smell, stays there) on both posts and the chassis sanded down area. After bolting up the neg cable cover that connection in axle grease. I prefer CSP as its a fantastic product with no smell and its intention is Corrosion Stop Protector.
While in there check trunk for any corrosion. Spray CSP on any bolt head. Lubricate the hatch lock assy and both hatch hinges with CSP. Don't forget the front hood latch assy and all door hinges and the rubber bellows in the door seams.


I don't like the standby power supply just to keep alive the radio. It takes all of 20 seconds to re-program the radio and do the windows. Quicker to do the radio programming than hook up the supply and then disconnect it and then put it all away.

Stand by supply injection means now there's 2 supply's I have to worry about in the trunk. One is the battery and after I disconnect the 12 volt hot lead now that's still hot too laying in the trunk. Given how easily it seems to be to damage the
Inverter in a Prius with sparks, and surges it seems foolish to induce another power supply on that 12 volt line.

 

I do similar, with a 0.5 amp motorcycle battery charger (basically a brick, 110 volt cord/plug and black & red alligator clips).

 

I do similar, with a 0.5 amp motorcycle battery charger (basically a brick, 110 volt cord/plug and black & red alligator clips).

 

Glad to hear you were able to the job yourself. Best of luck to you!

 

After I successfully replaced the HV battery for my 2007 Gen 2 Prius, I decided to replace the 12v battery since I have not replaced it even once during my 140k miles of driving. I looked up Amazon and found the battery from Optima (DS46B24R) that claims to fit to 2007 Prius (other reviewers also confirmed that).

After the battery was arrived, I found that the battery did not fit. It was an inch longer than the battery compartment and my factory-installed battery was a smaller than that. After I did some research, I also found that Prius without a smart key and a navigation option uses a smaller battery. Now I am looking for a battery that has the exact same size as the factory-installed one. My searches through few web sites only gave me Optima batteries and I was not sure which one really fits. Where can I find (buy) the 12v battery that has the exact same size as the one came with my Prius 2007? AutoZone stores in my area carry only Optima battery for Prius.

Thanks.

 

Dealership.

 

Or install the longer battery bracket intended for Smart 2G Prius. It certainly would not hurt your car to have a higher capacity battery installed.

Alternatives to Optima include Exide and of course the GS Yuasa battery sold by the Toyota dealer parts depts.

 

What Patrick said is the answer. Go to the dealer and get the alternative battery tray. Two trays are made for the Prius. The NON Smart Key Prius uses the smaller battery and the small tray. The battery you bought requires the larger tray. The hold down clamp is the same on both models. Only the tray changes. Easy fix, but you will have to pull the battery to change the tray.

FWIW, I think the TRUESTART battery found at Toyota is better than the Optima yellowtop. But that is just my opinion. It is based on numerous reports of recent yellow tops failing quickly and having very short life spans. You can find this information here on Prius Chat if you search using Google.



Best of luck to you,
Ron (dorunron)

 

Mendel, Patrick and runron,

Thank you very much for your comments. I did order the battery tray from the local dealership and installed the Optima battery successfully yesterday. For someone who might have a problem like me, the Toyota part number for a bigger battery tray is 74440-47020. I learn new thing every day and always appreciate the help that I get from here.

zelium

 

I agree, and one other thing, the OEM battery is rated at 45 Ah where as the Optima is rated at 39 Ah. If you don't want to go OEM, there are better batteries than the Optima.

This info is more for the people that come along later, not really of use to zellum as it is a fait accompli for them.

 

45 Amp/Hr it is. Plainly shows it in the photo above. And yes, the yellowtop documentation from the factory plainly states 39 Amp/Hr.

6 Amp/Hr does not seem like much, but these batteries are small to begin with. Why cut your throat even worse by buying a battery with less power to spare?

Ron (dorunron)

 

Without wanting to be seem picky or "teach grandma to suck eggs" Ron, but what you've written (Amp/Hr) means Amps per hour (Amps divided by hours) which is incorrect. The correct nomenclature is Amps multiplied by hours (Amps times hours) abbreviated to Ah.

How does this makes a difference? Taking the first metric quoted (45 Amp/Hr) would convey that the battery could supply 45 Amps for 1 hour, 90 Amps for 2 hours or 22.5 Amps for half an hour, etc but this is incorrect.

Amp * hours (or Ah) in relation to Lead/Acid batteries is usually quoted for either "@ 10 hours" (Starter batteries) or "@ 20 hours" (Deep cycle batteries). The OEM battery (and the Optima, too) are 20 hour metrics so 45 Ah means that it can supply 2.25 Amps for 20 hours. It doesn't necessarily mean that it can supply 4.5 Amps for 10 hours, though because of the Peukert effect (i.e., The faster a battery is drained, the less overall amperage is available). It is more likely to be under to 3 A. The Peukert effect means that if you discharge a battery over the course of 100 hours, the Ah rating looks higher than if you discharge that same battery over the course of 1 hour. Some battery manufacturers use the 20 hour rate because of this, i. e. the 20 rate is a larger number.

The above information is necessarily simplified in the interests of keeping this post short, lol.

I do, however, apologise for this post being as long as it is, but in the interests of accurate information it is necessary to use correct terminology. I hope also that this does not come across as "preachy". I truly am just trying to share knowledge.

If what I posted has piqued the general readership's interest and they are interested to find out more Mr Google is your friend.

 

That is news to me if correct. I was under the impression the 2.25 is an average discharge rate, higher at the start and lower at the tail.

 

That is spot on, SageBrush. I was keeping it simple. In reality the current supplied will drop off towards the end, so the Amps will be the average over the whole time.