[wscan]

Another (related) tech question: why exactly does the Sienna (and prius and hybrid rav4) have the 12V battery placed so far to the rear of the vehicle? I know that the 12V battery does not start the car by cranking the engine, but what is the big advantage to putting the 12V battery in the aft part of the vehicle(s)? Vs putting it in the engine compartment which has plenty of room?

For one thing, the battery lasts longer without the heat of the engine compartment.

 

[Templeton]

For one thing, the battery lasts longer without the heat of the engine compartment.

Ok, makes sense. But are there other cars that do this as well? It is hard to believe that toyota cares so much for how long the 12v lasts for its hybrid customers that they moved the battery for this reason alone?

 

[bullfrog23414]

But are there other cars that do this as well?

Many cars, including ICE models, have the battery in the trunk. It is not new at all. BMW, Mercedes, Chrysler (300/Charger etc.), and the list goes on and on. Just google, "battery in the trunk."

 

[dunhamjr]

Ok, makes sense. But are there other cars that do this as well? It is hard to believe that toyota cares so much for how long the 12v lasts for its hybrid customers that they moved the battery for this reason alone?

Lots of other cars, especially Germans do this.

My old 92 audi s4 had the battery under the rear seat bottom.

 

[fotomoto]

Relocating the 12v to the back near a rear wheel for better weight distribution and traction has been a drag racing trick for a long, long time.

 

[happycamper]

My old 92 audi s4 had the battery under the rear seat bottom.

I used to own a Dodge Stratus. The engineers decided the best location was inside the front fender, and was only accessible through the wheel well. Supposedly, it was possible to replace the battery without removing the wheel, but I never tried it.

 

[Templeton]

I used to own a Dodge Stratus. The engineers decided the best location was inside the front fender, and was only accessible through the wheel well. Supposedly, it was possible to replace the battery without removing the wheel, but I never tried it.

All very interesting. The first (and only) car I had with a "rear located" 12v battery was our 08 prius. I thought this was just a hybrid thing. But, clearly not so.

 

[DKH]

I don’t know too much about battery chemistry, but the stock battery vents to the outside through a little breather valve. So if you’re replacing with a new battery remember to think about the off-gassing or whatever it does. Might not want to breathe whatever comes out

 

[jseyfert3]

Interestingly, this could be consistent with another datapoint: I did the mod to add a 12V outlet in the rear of the van. When I run my portable freezer off of that outlet, I can connect to it via bluetooth and it displays the input voltage. While driving, I frequently see this voltage in the 11.X range, I think typically it's around 12.5 and I've rarely seen it at 13+ (I don't sit there and watch it, so this is far from scientific).

That compares to what most of us are used to on alternator-equipped cars of seeing 14V+ while the engine is running.

I guess I'm just pointing out that the DC-DC charging is a very different animal from what most of us have become accustomed to.

I don't think you're measuring true battery voltage. The outlet you installed appears to have small gauge wires and you'll get voltage drop through then and the wires into your portable fridge. 11 volts is a dead lead acid battery. Lead acid needs 13.5 volts to float charge at 77 °F. I think you're seeing a lot of voltage drop and not true lead acid battery voltage.

If you want to check your battery voltage you need to get a voltmeter on the battery itself to check it.

I don’t know too much about battery chemistry, but the stock battery vents to the outside through a little breather valve. So if you’re replacing with a new battery remember to think about the off-gassing or whatever it does. Might not want to breathe whatever comes out

It's not toxic (though there will be some small amount of sulfuric acid fumes), but explosive. When charging, lead acid batteries make hydrogen and oxygen. This is what is getting vented outside. If an AGM battery is used though, those do not vent unless seriously overcharged, do not have vent ports, and are safe to install inside a living compartment without a vent.

 

[Templeton]

Do gen4 siennas come with AGM or with lead acid 12v batteries as original equipment?

 

[yonah]

For a number of reasons, I would be interested in slightly/somewhat increasing the electrical capacity of the gen4 Sienna 12V battery with a different, likely slightly larger, 12V battery. Anyone else consider this? Anyone else successfully do it? Any issues or limitations to be aware of, given the limited size of the battery space/compartment? I am not looking to double the capacity, just to increase it maybe 10-30% plus/minus.

From my research, it appears a H6-sized AGM should shoehorn into the OEM battery tray.

https://www.batteriesplus.com/productdetails/sli48agmdp?variationCode=VI840434

Check out the specs. This may work for your application.

 

[yonah]

Do gen4 siennas come with AGM or with lead acid 12v batteries as original equipment?

Lead acid seems to be standard.

 

[Templeton]

From my research, it appears a H6-sized AGM should shoehorn into the OEM battery tray.

https://www.batteriesplus.com/productdetails/sli48agmdp?variationCode=VI840434

Check out the specs. This may work for your application.

Thanks for the info. Is a size H6 battery what comes stock on the gen4 sienna?

 

[yonah]

Thanks for the info. Is a size H6 battery what comes stock on the gen4 sienna?

I believe H5 is the standard, OEM size for the 4th Gen Sienna.

H6 is the next stepped-up size. IIRC, H6 = Group 48 size.

This is the unit I’m considering:

https://www.batteriesplus.com/productdetails/sli48agmdp?variationCode=VI840434

 

[Subieyoda]

There’s a brand called Ohmmu and they sell 12v batteries for EV and Hybrid vehicles. For Toyota they sell one for the Prius, but I wonder if that will also work for RAV4 or Sienna?

Toyota | ohmmu.com

www.ohmmu.com

 

[Templeton]

I believe H5 is the standard, OEM size for the 4th Gen Sienna.

H6 is the next stepped-up size. IIRC, H6 = Group 48 size.

This is the unit I’m considering:

https://www.batteriesplus.com/productdetails/sli48agmdp?variationCode=VI840434

Thanks for the replies.

Random question: if one wants to upgrade the 12v battery, what does one do with a perfectly good, almost new lead-acid H5 battery?

 

[Vanfam12345]

Random question: if one wants to upgrade the 12v battery, what does one do with a perfectly good, almost new lead-acid H5 battery?

Sellers will generally credit you for bringing it back in for recycling. They accept it much like they do for used motor oil.

 

[yonah]

There’s a brand called Ohmmu and they sell 12v batteries for EV and Hybrid vehicles. For Toyota they sell one for the Prius, but I wonder if that will also work for RAV4 or Sienna?

Toyota | ohmmu.com

www.ohmmu.com

It all comes down to the size (will it fit in the OEM tray?) and the post (positive / negative) orientation (will your OEM cable/hook-ups match the location of each on the battery?).

IMO, if it’s a regular lead acid battery, probably not worth the effort. An AGM dual purpose/deep cycle battery of the same or greater size and specs to the OEM battery is preferred and more of an upgrade. AGMs usually have outstanding 3-4+ warranties.

Thanks for the replies.

Random question: if one wants to upgrade the 12v battery, what does one do with a perfectly good, almost new lead-acid H5 battery?

You can trade in the core to the vendor after you purchase the new battery. You’ll likely get a core charge refund around $10-30. Not much. Most vendors actually advertise battery prices with the core charge/refund factored in (read the fine print). If a battery is listed at say, $200, that is likely with the core charge/refund. In reality, you’d pay $220, or so, before taxes and get the refund when you bring back your old battery.

If the battery is not old and near new. You may be able to sell secondhand via Facebook marketplace or similar and fetch a price closer to it’s newer, actual value. The battery build date should be printed somewhere on the battery casing to prove its age. Keep it on a battery charger/monitor periodically to keep the battery’s health in good condition - you do not want it to deplete its charge (doing so will damage the unit).

Sellers will generally credit you for bringing it back in for recycling. They accept it much like they do for used motor oil.

Yes. I believe they are mandated to do this via regulation, just like the motor oil example you mentioned; i.e., if your storefront sells batteries, you must in turn accept used batteries for recycling.

 

[Templeton]

It all comes down to the size (will it fit in the OEM tray?) and the post (positive / negative) orientation (will your OEM cable/hook-ups match the location of each on the battery?).

IMO, if it’s a regular lead acid battery, probably not worth the effort. An AGM dual purpose/deep cycle battery of the same or greater size and specs to the OEM battery is preferred and more of an upgrade. AGMs usually have outstanding 3-4+ warranties.



You can trade in the core to the vendor after you purchase the new battery. You’ll likely get a core charge refund around $10-30. Not much. Most vendors actually advertise battery prices with the core charge/refund factored in (read the fine print). If a battery is listed at say, $200, that is likely with the core charge/refund. In reality, you’d pay $220, or so, before taxes and get the refund when you bring back your old battery.

If the battery is not old and near new. You may be able to sell secondhand via Facebook marketplace or similar and fetch a price closer to it’s newer, actual value. The battery build date should be printed somewhere on the battery casing to prove its age. Keep it on a battery charger/monitor periodically to keep the battery’s health in good condition - you do not want it to deplete its charge (doing so will damage the unit).



Yes. I believe they are mandated to do this via regulation, just like the motor oil example you mentioned; i.e., if your storefront sells batteries, you must in turn accept used batteries for recycling.

Exactly, yes, I have turned in old (dead) lead acid batteries for that $15 credit.

But I was more wondering how to sell a nearly new battery, if I choose to upgrade. Because many car parts one can sell (and ship) for decent money. Not so a for 50 lb battery ...

 

[yonah]

Exactly, yes, I have turned in old (dead) lead acid batteries for that $15 credit.

But I was more wondering how to sell a nearly new battery, if I choose to upgrade. Because many car parts one can sell (and ship) for decent money. Not so a for 50 lb battery ...

If it were me, I’d try to sell locally via classified (Facebook marketplace, OfferUp, Craigslist, etc.). Label it as a near new Toyota OEM battery for the applicable model(s) it fits. It should sell quickly.