Toyota Sienna hybrid electrical system

[WNCGUY]

Posting this here in hopes that others have investigated or completed an electrical system on a Toyota hybrid sienna. I've searched this forum and coming up with no conversations about adding an electrical system to the sienna hybrid. I did find some info on another forum but very limited.

The hybrid van relies on a gas engine and 1.9kWh nickel metal hydride battery, there is also a very small 12-volt battery located in the rear of the van that I understand its purpose is to provide power to start up computers and keep everything running like memory, clock, as well as anything else that needs power while the van is turned off.

I am interested on doing a camper conversion and would like a to build an electrical system that would include a DC to DC charger connected to the small sienna 12v battery to power 100-200 amps of house battery and then continue to build the system to include solar and shore power.

I'm a newbie with the most rudimentary electrical skills so I am very reluctant to tap into the van system without learning of proven systems.

 

[sunshine_eggo]

Your stated understanding is correct. Note that 1.9kWh is not its usable capacity. In normal operation, it only uses 40% of that, and it's very rare to use that much. It's possible to use about 55% of the total capacity, but it will be disruptive to unattended operation.

You should essentially treat the vehicle no differently than a non-hybrid designing within limits. I don't know the HV DC-DC converter max current, but it's probably north of 70A, i.e., you can pull 70A from the 12V with the vehicle on and in ready mode and have the vehicle HV system providing the current. This is about 1000W. Toyota HV 12V charging systems peak at 14.0-14.4V and tend to float at 13.6-13.8 in a very traditional fashion.

I assume that you're looking to tap into the vehicle 12V system to charge the house system. If you intend to use the vehicle system as a direct power source, limit it to 1000W.

 

[daemorhedron]

I have a sister vehicle to OP, a 2003 hybrid toyota alphard.

IMHO, don't mess around with these systems. The HV battery has an inverter that you can plug into if you really need, but you are far better off just leaving as is and investing in a battery system that is in addition to as opposed to replacement of. At most, I could see replacing the 12v battery with a LiFEPO4 project as that's been documented many times on youtube and such.

There are projects coming out (such as https://projectlithium.com/) that offer direct replacements for the NIMH batteries with lithium, and while I'm tempted by this myself with all the benefits (much lighter, runs cooler, much more power, more responsive, etc) I'm just going to wait for something like a Canoo EV that I will sink my money into instead.

And if you sank your money into a separate battery system, you can just move that over to the new vehicle when the time comes =)

 

[sunshine_eggo]

Concerning project lithium:

Zero change to battery management system.
NiMH requires temperature compensation and BCM allows higher voltage at lower temperatures.
5S LFP per block
ROUTINELY subjected to 3.8-4.0V/cell at 15C current.
ROUTINELY subjected to < 3.0V/cell at about 25C.
Routine deep cycling due to flatness of LFP curve vs. NiMH.
Marginal cooling system. Far worse on newer model than Gen2 Prius.

Outcomes:

1) LFP performance will be superior with a far greater EV range and improved mpg.
2) battery life will be severely shorter. Very common to see 12-17 year old original NiMH packs with > 200K miles. LFP will not last nearly as long. I would estimate 3-5 years in extreme climates and 5-10 in moderate climates.

Had they done their homework and overlayed a LFP control system to spoof the NiMH BCM to properly manage the LFP cells, they could have had the best of both worlds. This last bit is what makes the "homebuilt" conversions work.

 

[WNCGUY]

Your stated understanding is correct. Note that 1.9kWh is not its usable capacity. In normal operation, it only uses 40% of that, and it's very rare to use that much. It's possible to use about 55% of the total capacity, but it will be disruptive to unattended operation.

You should essentially treat the vehicle no differently than a non-hybrid designing within limits. I don't know the HV DC-DC converter max current, but it's probably north of 70A, i.e., you can pull 70A from the 12V with the vehicle on and in ready mode and have the vehicle HV system providing the current. This is about 1000W. Toyota HV 12V charging systems peak at 14.0-14.4V and tend to float at 13.6-13.8 in a very traditional fashion.

I assume that you're looking to tap into the vehicle 12V system to charge the house system. If you intend to use the vehicle system as a direct power source, limit it to 1000W.

Correct. Tap into the 12v system same as would be cone on a gas vehicle by adding a fuse to the battery and connecting the DC-DC charger to the fuse. Assuming there is 70 amps going to the battery, I would measure current to confirm this, I should be able to use a Victron 12-12-30 smart charger to charge house about 200 amps of house battery.

I hadn't considered using the vehicle system battery as a power source, I am interested in knowing how this would be dome but this but may put me in well over my head.

 

[WNCGUY]

I have a sister vehicle to OP, a 2003 hybrid toyota alphard.

IMHO, don't mess around with these systems. The HV battery has an inverter that you can plug into if you really need, but you are far better off just leaving as is and investing in a battery system that is in addition to as opposed to replacement of. At most, I could see replacing the 12v battery with a LiFEPO4 project as that's been documented many times on youtube and such.

There are projects coming out (such as https://projectlithium.com/) that offer direct replacements for the NIMH batteries with lithium, and while I'm tempted by this myself with all the benefits (much lighter, runs cooler, much more power, more responsive, etc) I'm just going to wait for something like a Canoo EV that I will sink my money into instead.

And if you sank your money into a separate battery system, you can just move that over to the new vehicle when the time comes =)

Maybe a little over my head here, I believe your recommendation is to connect at the small12v battery and build a house battery system and not to attempt to connect to the 1.9kWh nickel metal hydride battery. Is this correct?

 

[circus]

There's no alternator, the 12v battery is charged from the high voltage traction batteries using electronics. Without knowing the capacity of the electronics your risking a huge repair bill. I think that's why Toyota offered a 1500w inverter option. So people don't install one.

 

[daemorhedron]

Maybe a little over my head here, I believe your recommendation is to connect at the small12v battery and build a house battery system and not to attempt to connect to the 1.9kWh nickel metal hydride battery. Is this correct?

I need to be clear here: I am nothing like most of the people on this forum. I am not skilled, experienced, knowledgeable, etc like all of them. Definitely encourage leaving the high voltage battery alone period and pretty firm that's the right answer.

I do fantasize about replacing the 12v house battery with a LiFEPO4 system instead which is why I'm here in the first place to hopefully attain that goal =)

 

[sunshine_eggo]

Correct. Tap into the 12v system same as would be cone on a gas vehicle by adding a fuse to the battery and connecting the DC-DC charger to the fuse. Assuming there is 70 amps going to the battery, I would measure current to confirm this, I should be able to use a Victron 12-12-30 smart charger to charge house about 200 amps of house battery.

That will work.

There's no alternator, the 12v battery is charged from the high voltage traction batteries using electronics. Without knowing the capacity of the electronics your risking a huge repair bill. I think that's why Toyota offered a 1500w inverter option. So people don't install one.

Per the above the DC-DC converter is 70A or greater. People have been doing this with the Prius for 15+ years.

I hadn't considered using the vehicle system battery as a power source, I am interested in knowing how this would be dome but this but may put me in well over my head.

Simply attach a 1000W inverter to the car 12V and use it directly. With car running, you have a perpetual 1000W generator.

 

[WNCGUY]

That will work.



Per the above the DC-DC converter is 70A or greater. People have been doing this with the Prius for 15+ years.



Simply attach a 1000W inverter to the car 12V and use it directly. With car running, you have a perpetual 1000W generator.

Understood but I think I would rather run a 1500 watt inverter off of the house batteries.

 

[daemorhedron]

Not sure if prius comes with an inverter but the alphard already has a 1000W one, would be nice to somehow 'upgrade it' rather than run a second one in tandem.

Assuming DC-DC controller to LIFEPO4 batteries to replace the existing 12v startup battery, how would one introduce solar charging into the mix?

 

[sunshine_eggo]

Not sure if prius comes with an inverter but the alphard already has a 1000W one, would be nice to somehow 'upgrade it' rather than run a second one in tandem.

Assuming DC-DC controller to LIFEPO4 batteries to replace the existing 12v startup battery, how would one introduce solar charging into the mix?

The fact that the car is in the mix doesn't matter. Just attach the solar to the battery as if the car wasn't there.

 

[daemorhedron]

The fact that the car is in the mix doesn't matter. Just attach the solar to the battery as if the car wasn't there.

Would a dc-dc mppt controller by the right choice then? Like the renogy 60a one?

 

[sunshine_eggo]

Would a dc-dc mppt controller by the right choice then? Like the renogy 60a one?

I dislike the renogy DC-DC that also includes MPPT solar as it's very limited. I'm of the opinion that they should be separate devices.

DC-DC charger between Sienna 12V and House battery and dedicated solar MPPT to house battery.

 

[daemorhedron]

I dislike the renogy DC-DC that also includes MPPT solar as it's very limited. I'm of the opinion that they should be separate devices.

DC-DC charger between Sienna 12V and House battery and dedicated solar MPPT to house battery.

I understand thank you for helping, really appreciated.

I obviously have a lot more research to do regarding the components, but this was a really nice start.

 

[Batvette]

You already own this van? If so what have you done about the second row seats?
Has anyone who figured out how to remove them AND tame the systems errors created, been able to actually calculate the real cargo capacity? Sienna now specs out at 110 cu ft vs odyssey at 149 or 158 depending on trim. Some claim thats all the second row seats. Others claim they lowered overhead clearance a bunch while raising the floor for batteries and its barely a minivan any more.

 

[WNCGUY]

I have not taken delivery of the sienna but have placed a deposit with a dealer for a factory order, they are telling me 3-4 months lead time.

My plan is to have a electrical design and materials before delivery.

 

[StormEagle537]

Having owned 2007 hybrid Camry for several year and kept it going for 260 K miles, about 170 K miles after the first, dreaded "check hybrid system" warning light came on, I'll offer these experiences:

By the time I gave up the car, I had taken the ~300 lbs "traction" battery out four separate times and replaced about 2 / 3 rds of the NiMH cells with less degraded ones from used Priuses bought from E-bay "refurbishers", rebalancing the battery each time. The NiMH cells steadily degrade because of Panasonic's crap forced air battery thermal management design. The cells in the center get the hottest and always were the ones that degraded below the specs the car needed (water loss via very slow pressure relief was the consensus from another forum). And this was under automotive conditions. From comments Will has made in his videos on thermal bulging issues with 3.2 V lithium iron phosphate cells, I agree with the above comments that LiFe cells will degrade even faster in cars both from thermal issues and mechanical abuse. Though they probably could perform electrically as well as NiMH cells, I'm sure there are reasons Tesla and cell phone application went the LiS chemistry route. The NiMH cells are smaller, more rugged, and are mechanically well secured. That is, the traction battery is royal pain to take apart and even more to reassemble.

 

[WNCGUY]

After a 3 month wait, I have taken delivery of a Sienna Hybrid so it is time to start taking the camper conversion seriously.

Since I didn't have a DC clamp on meter, I ordered a Kaiweets HT206D and today attempted to record the current at the small 12-volt battery.
Unless I am mistaken, the clamp meter should be clamped around the battery black ground wire? Setting the meter to 600 amps, zeroing it and setting to maximum I clamped onto the batter black ground wire then proceeded to drive around for 10 minutes. The meter recorded 28.4 amps.

The reason I drove around for 10 minutes is I am wondering if the current sent to the 12-volt battery is consistent or will fluctuate and I think I need to know the highest current provided? Did I measure the current sent to the 12-volt battery correctly? Do I need to gather additional data to determine how much current is available?

I’ll wait for your replies and then start asking the 100 other questions I know I will have.

 

[Batvette]

After a 3 month wait, I have taken delivery of a Sienna Hybrid so it is time to start taking the camper conversion seriously.

Since I didn't have a DC clamp on meter, I ordered a Kaiweets HT206D and today attempted to record the current at the small 12-volt battery.
Unless I am mistaken, the clamp meter should be clamped around the battery black ground wire? Setting the meter to 600 amps, zeroing it and setting to maximum I clamped onto the batter black ground wire then proceeded to drive around for 10 minutes. The meter recorded 28.4 amps.

The reason I drove around for 10 minutes is I am wondering if the current sent to the 12-volt battery is consistent or will fluctuate and I think I need to know the highest current provided? Did I measure the current sent to the 12-volt battery correctly? Do I need to gather additional data to determine how much current is available?

I’ll wait for your replies and then start asking the 100 other questions I know I will have.

I dont think it matters if the meter is on - or + wires, youll just see a - before the reading on one not the other. Youd want to be certain thats the only ground.
Your meter should have some kind of zeroing or trim adjustment, most do.

Without going too far off that topic, is this your first minivan? What are the interior dimensions like? As I mentioned previously, I heard some complaints that on its proportions Toyota was drifting away from the minivan format- less headroom, for one thing, and the raw specs reflect a significantly smaller interior (cargo capacity) volume.
Or is that volume loss solely the space occupied by second row seats?
On all previous generations, Siennas and Odysseys were as good as identical in interior dimensions.
I sure like the way the hybrid Sienna looks, saw a premium trim in that dark metallic blue it was just gorgeous. Had to be some compromises to get there. The only criticism I have seen of its driving manners is that there is a bit of throttle hesitation. Its a bit slower than the Odyssey but not to the point of being a deal breaker. (Not for 10 more mpg)

(I wont ask what you paid for it, but about a month ago a los angeles area dealer, who had apparently the only Limited Premium model immediately available in the whole region, had it advertised for I think $63,995. Bet they got it.)