Yes I've done it a few times but not in the Sienna (yet). This is a very common mod in the motorcycle world. Just need to make sure: A) the posts are in the same location and connector style, B) cables have enough slack, and C) enough space to fit it.

B) is usually what matters most in the ones I've done.

GOOD LUCK!

 

Size is not an issue, more AMPS = more mmpphhh, since the battery lives inside the sienna just make sure your new battery fits.
I have done this before since its a very common practice when I was a Jeep person.... you start with the oem one, then it just does not do the job, you get a bigger one and a bigger one, next thing you know your rig has a bigger alternator and 4 batteries running what I can only define as an offroad lighthouse

 

Right, but I am not looking for bigger size per se, I just want more amps.

 

First question that needs to be answered is why? What's your goal? The 12v battery in a hybrid doesn't need more AMPS (or mmpphhh) as jareza put it, as it does not drive any starter motor. It is only used to power the computer and accessories. Just leave the van in READY mode (and not in neutral), and it will stay charged.

 

Hey I just answered the question, and justified it... I needed it for my jeep.
For my sienna though? I guess stock is the only battery Ill ever use. Maybe Templeton will do a camper conversion and thats the reason he needs the bigger battery

 

Actually if you drain the battery you cannot start the car. I've had this happen to me twice. Once while listening to the radio for 8 minutes or less and another time wiring the dash cam and having dome lights on. It does not take long before the battery is drained and then you will need to jump start the car. I will be upgrading my battery in the future with a larger capacity. I have to make sure if we are in the car that it is in ready mode or off.

 

Which is why you leave the van in READY mode. The engine will start to recharge the battery(ies) as needed. The amount of gas used is negligible, particularly compared to the inconvience/cost of a dead battery.

 

While not 100% necessary, it would be good to have some extra capacity to protect against using the ACC mode. I am concerned that my wife will not quickly adapt to some of the subtle differences between normal ICE and the the hybrid Sienna. Getting a battery with higher output is not the goal, a battery that can provide the same output for a longer amount of time is needed. This is the amp hour rating of a battery. Based on this discussion it sounds like there is no issue using a larger capacity battery that physically fits in the van. Maybe a deep cycle battery would work well.

 

Look at an agm battery. I have installed a trickle charger on the 12v battery that I hook up when the van sits longer than a few days.

 

This may be not related, but how about a solar trickle charger when you have it sitting for a while?

I have a pickup truck that I barley drive 1K miles a year*. It has been going thru a new battery every other year. The most recent battery tach recommended a solar trickle charger. I just bought one for about 25 bucks and hooked it up. Let's see if it helps any.

*I know I should sell it off, but I just can't. It's a stick shift 2006 Chevy Colorado. It is fun to drive whenever.

 

I don't think it's the battery issue, to me it's more like DC/DC charging behavier problem that make you think it's due to battery capacity too small.
I hard wired a 24H timelapse dash cam with low voltage protection. with OEM 12V battery, low voltage protection triggered within one minute when the car turned off.
Then I swap for a fresh fully charged AGM battery for it, dash cam timelapse only function 3-4 days (3 hour timelapse each day), then the same problem persists.

 

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 necessarily want to increase the size or the capacity of the 12V battery, but I do want to put in a better quality battery in (I am kind of getting a wind that stock 12V batteries in the Sienna are not the top dollar ones). As for trickle charging, solar or not, it's in general a good idea regardless of the battery age and quality, especially if the car sits for longer than a couple of days.

For emergencies I carry a cranking battery

 

I don't necessarily want to increase the size or the capacity of the 12V battery, but I do want to put in a better quality battery in (I am kind of getting a wind that stock 12V batteries in the Sienna are not the top dollar ones). As for trickle charging, solar or not, it's in general a good idea regardless of the battery age and quality, especially if the car sits for longer than a couple of days.

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?

 

If someone is able to find a suitable “upgrade” battery, please post the make/model that worked for your year Sienna. Thanks!

 

My comment will be to be sure that you have the space to fit a larger unit.

I don't know the gen4 Sienna, and have no clue where its located. But my experience with another toyota hybrid (2013 hihy)... is that sometimes the mounting spot is literally exactly as big as the battery thats in it already needs.

Turns out when our 13 HiHy battery died during early covid, I literally could not find an exact battery size match... even from a dealer. I had to get a different size, and while is was literally less than a half inch larger in 2 of the 3 dimensions, I had to modify the mounting straps/plates, and bend a few things to make it even come close to fitting. It was a pain in the ace.

 

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.

 

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

 

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

 

Lead acid seems to be standard.

 

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?

 

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.

 

I changed to AGM on my then new Subaru Outback as the battery would go dead just listening to the radio. It worked out well. I am following this thread and will upgrade to AGM, but am waiting until someone confirms a battery that fits.

 

I replaced with H5 AGM battery from costco, so far so good since last September.

 

If you don't correct the root cause of the parasitic power drain, then a battery replacement is only going to get you so far...

 

<32F Most BMS will not charge lithium to protect the battery. “Battery Management System - Prevents Damage to Battery in Extreme Situations and Balances the Battery Cells for a Longer Service Life”

 

I’m interested in this upgrade as well. A search of Group 48 battery yield this…

ACDelco Gold 48AGM 36 Month Warranty AGM BCI Group 48 Battery, Black https://a.co/d/6CKKnjg

 

@yonah

Edit: Awesome, thanks

 

OEM battery:

34.2 pounds
Length - 9 3/4”
Height - 7 3/8”
Width - 6 3/4”

Photos:

 

OEM battery bracket I referenced; you can see the, IMO flimsy, sheet metal bracket under it:

 

Gen4 Sienna batteries not searchable at this time.

Although 375LN2-MF is searchable, and are the same for 2019 RAV4 hybrids among other Toys.

 

Conventional Lead Acid (Flooded Cell) batteries don't like to be deep discharged. Once that's happened, they often suffer sufficient damage that they never deliver the original capacity again. And each subsequent event only increases the chance of being sucked dry as the total available capacity continues to drop. So they aren't a great choice in situations where deep discharge can occur. And after reading thru these threads, it seems that's just part of life with these hybrids.

So maybe the goal isn't to search for a replacement that's just physically larger or has higher amperage or reserve capacity. Even 25% greater might not prevent that one single deep discharge event that begins the cascade of failure.

A better goal might be to identify a battery technology that offers better deep discharge recovery, but doesn't:
1) Add significant extra weight (concerns about the hold-down brackets.
2) Change technology so drastically that charge maintenance becomes difficult (I'm thinking Lithium as low temp charging is typically gated).

So that leads us to either AGM or an EFB (enhanced flooded battery). Both of these will likely offer better moderate to deep discharge capacity recovery, higher CCA and Reserve, but higher weight.

But maybe you could balance this. The OEM battery isn't a champion on CCA (563 on the label above), although the total capacity as measured on the 20 hour discharge test is decent at 60 amp-hours.

Maybe there is an AGM in a slightly smaller size that would give equivalent electrical specs but being smaller weigh a bit less so that it's not significantly greater than the 35 lbs indicated above?

 

In search for a higher capacity replacement battery, it appears that the capacity of 60Ah is the norm. One 62Ah came up, the XS power D4700. It is spec’d for deep cycle, though at a cost of over $300+, nearly double Interstate.

For myself, I’m not in a hurry to perform this upgrade, I’ll wait until this one dies, then get a Costco AGM replacement, which essentially is the default upgrade. Weight-wise, the 2 Costco Interstate batteries, AGM is heavier than Lead acid.

 

I have a 2010 Toyota Sienna that has been converted to a wheelchair van. The equipment causes extra demand on the battery and I have had to replace it several times. Recently, I had the system that operates the lift disconnected when the car is not running. Since then, I have had to charge the battery twice because the power was too low to start the car. The guy who disconnected the wheelchair system suggested I could use a larger battery. Suggestions?