How does it work... hybrid 12v + Alternator

[mjssss]

Hi All,

Curious to learn for the trucks that are both hybrid and have an alternator... how does feeding the 12v bus work?
- Seems like the output regulators of the alternator and the hybrid bus would fight each other(?)
- Or are they used one at a time? How to know when?

Thanks!

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[Dead Horse]

Following. I'm curious as well.

 

[Cranberry]

From my reading, The alternator is primarily charging the 1800 KW hybrid battery, the hybrid battery is what primarily charges the 12V battery.

I spend weeks in my rig when i go overlanding, im still waiting for my Gen 6 delivery but i researched the electrical system plenty to ensure the hybrid could handle our power needs.

When the truck is not in ACC or Ready mode all power is essentially off to all components of the vehicle unless they are directly wired to the 12V battery or to the 12V plug in socket in the back (only 2 points that maintain power when vehicle is off)

When the vehicle is then switched to ACC / Ready mode, it delivers power too all necessary ports, functions, heated seats, steering wheel fan blower lights etc... That power delivery from my understanding is all from the 12V battery.

When the 12V battery becomes low or the state hits anything close to remotely less then 90% - 80% capacity, the hybrid battery kicks in to start re charging the 12 V battery. This process continues on and on untill the hybrid battery gets down to somethign like 80% as well.

Once the hybrid battery hits that 80% capacity from constant on off recharging of the 12V battery, the engine kicks on by itself to begin charging the hybrid battery back up to 100%.

From user reports as well as manufacturer testing, the engine alternator can recharge the hybrid battery from 55% - 60% up to 100% in 15 - 25 minutes of engine idle time (depending on battery temperature at time or recharge).

In all of my research and what i am finding, the alternater does not charge the 12V battery, only the hybrid battery charges the 12V battery. HOWEVER, (i am still reviewing and details are still coming out) i have found some unconfirmed sources saying Toyota added redundancy connections JUST IN CASE the hybrid battery failed or the hybrid system in total failed, so that the alternator can switch on its own from only charging the hybrid battery to then switch over and divert the charge to the 12 V battery. Apparently this was a concern on reliability to the user should anything happen off grid or out overlanding, they still need to be able to get home safe.

If i can summarize my long winded opinion above it would be this:

"the entire toyota 4runner hybrid system is designed to run all electronics off the 12V battery. The hybrid battery is only used for 2 things, charging the 12V battery and delivering power to the hybrid motor assist. If the hybrid battery or total hybrid system fails for some reason, the 4Runner is designed to automatically switch over to pure gasoline function and still operate normally without the assisted hybrid horsepower."

Because of this view, i have prioritized a full solar set up and fridge system as well as power bank back up systems off the 12V starter battery. I am treating the new Gen 6 no differently then i treated my Gen 5. All accessories and function is off the 12V battery system and i dont even think about the hybrid battery in any of my applications.

i hope this helps.

*** EDIT ADDITION ***

I should mention there is no alternator on the 4Runner Hybris, when i say "alternator" i am referring to a DC to DC charging system toyota has developed. There is no belt driven system charging the batteries and all power generated for charging is from a more complex conversion set up pulling power directly off the engine itself (similar to how a generator makes power). From my understanding you can not install any aftermarket alternator on the hybrid model.

 

[mjssss]

From my reading, The alternator is primarily charging the 1800 KW hybrid battery, the hybrid battery is what primarily charges the 12V battery.

I spend weeks in my rig when i go overlanding, im still waiting for my Gen 6 delivery but i researched the electrical system plenty to ensure the hybrid could handle our power needs.

When the truck is not in ACC or Ready mode all power is essentially off to all components of the vehicle unless they are directly wired to the 12V battery or to the 12V plug in socket in the back (only 2 points that maintain power when vehicle is off)

When the vehicle is then switched to ACC / Ready mode, it delivers power too all necessary ports, functions, heated seats, steering wheel fan blower lights etc... That power delivery from my understanding is all from the 12V battery.

When the 12V battery becomes low or the state hits anything close to remotely less then 90% - 80% capacity, the hybrid battery kicks in to start re charging the 12 V battery. This process continues on and on untill the hybrid battery gets down to somethign like 80% as well.

Once the hybrid battery hits that 80% capacity from constant on off recharging of the 12V battery, the engine kicks on by itself to begin charging the hybrid battery back up to 100%.

From user reports as well as manufacturer testing, the engine alternator can recharge the hybrid battery from 55% - 60% up to 100% in 15 - 25 minutes of engine idle time (depending on battery temperature at time or recharge).

In all of my research and what i am finding, the alternater does not charge the 12V battery, only the hybrid battery charges the 12V battery. HOWEVER, (i am still reviewing and details are still coming out) i have found some unconfirmed sources saying Toyota added redundancy connections JUST IN CASE the hybrid battery failed or the hybrid system in total failed, so that the alternator can switch on its own from only charging the hybrid battery to then switch over and divert the charge to the 12 V battery. Apparently this was a concern on reliability to the user should anything happen off grid or out overlanding, they still need to be able to get home safe.

If i can summarize my long winded opinion above it would be this:

"the entire toyota 4runner hybrid system is designed to run all electronics off the 12V battery. The hybrid battery is only used for 2 things, charging the 12V battery and delivering power to the hybrid motor assist. If the hybrid battery or total hybrid system fails for some reason, the 4Runner is designed to automatically switch over to pure gasoline function and still operate normally without the assisted hybrid horsepower."

Because of this view, i have prioritized a full solar set up and fridge system as well as power bank back up systems off the 12V starter battery. I am treating the new Gen 6 no differently then i treated my Gen 5. All accessories and function is off the 12V battery system and i dont even think about the hybrid battery in any of my applications.

i hope this helps.

*** EDIT ADDITION ***

I should mention there is no alternator on the 4Runner Hybris, when i say "alternator" i am referring to a DC to DC charging system toyota has developed. There is no belt driven system charging the batteries and all power generated for charging is from a more complex conversion set up pulling power directly off the engine itself (similar to how a generator makes power). From my understanding you can not install any aftermarket alternator on the hybrid model.

No, I am specifically referring to the models with a physical alternator in addition to the hybrid:
https://www.4runner6g.com/forum/threads/hybrid-alternator-amperage.7059/

 

[Cranberry]

Wow, thank you for sharing this. It is news to me. From my research there was no alternator on the hybrid, if they have added one, i am very curious.

I will research more and come back to this thread with my finding.

 

[127.0.0.1]

I have (well, had) a 2022 rav4 hybrid and need to throw out
everything I learned about that system. 4runner hybrid is
not similar at all.

 

[Cranberry]

im absolutuly amazed at the changes i am seeing in the time i researched. Im still deep diving right now but it looks like the 4Runner platform is most definitely different from the standard hybrid platform they typically use. There is a DC charging system in the 4runner that does charge the hybrid battery, but there appears to also be a fully independent belt driven alternator as well (added a few months after the original 2025 release) that specifically charges the 12V battery & supplies top up to AUX switches up to 450 amps. I would assume this is how Toyota managed to get the vehicle to have redundancies incase the hybrid system ever failed.

Other reading (preliminary still) is showing me the alternator is only charging the 12V, so there is no in between of it hitting the hybrid battery with power. When the hybrid battery charges the 12V it knocks down the voltage to the same voltage as the 12V alternator, so weather your running off the alternator or the hybrid for charging the 12V, both remain the same voltage, thus causing no power struggles or conversion issues.

i sourced this info recently from this video at about 7:30 into the video.

Video here

 

[mjssss]

The manual notes the hybrid system powers things entirely when in ACC/READY (Eg. For car camping). The engine will occasionally fire up to charge back up. But the manual also doesn’t seem to note the alternator

12/14v, 450A seems unlikely from an alternator…

 

[shine]

Here's a video about it's big brother with the same hybrid system.

And another one where it is explained

 

[mjssss]

lol, nice music

It seems the alternator is only used with a hybrid malfunction… makes sense
(Side note: I’ve already had a hybrid malfunction on my 100mile TH… it did indeed hiccup and then start working again… not sure how much this played in)

 

[Cranberry]

The manual notes the hybrid system powers things entirely when in ACC/READY (Eg. For car camping). The engine will occasionally fire up to charge back up. But the manual also doesn’t seem to note the alternator

12/14v, 450A seems unlikely from an alternator…

the 450A is meant as powering things like winches directly off the 12V battery etc…. The under hood positive connection point will not handle 200-250 or more amps so the alternator can help kick in charging on the 12V system when such large draws are needed.

 

[Cranberry]

lol, nice music

It seems the alternator is only used with a hybrid malfunction… makes sense
(Side note: I’ve already had a hybrid malfunction on my 100mile TH… it did indeed hiccup and then start working again… not sure how much this played in)

I saw your other post on this in a previous thread. I hope your rig is ok. Im sure Toyota will fix this issue.

 

[Dead Horse]

I just need to know how big of an amplifier I can run off the 12v battery in my hybrid truck

 

[drchip]

This all makes sense. The V6 and I4 turbo hybrid systems for trucks is built with redundancy and durability. Think about it, the international Landcruiser is the base, Toyota had to build a system that is used the roughest environments in the world. It has a backup system to run in non-EV mode. And it puts the battery IN the CABIN, unlike all other EV/Hybrids, for maximum environmental isolation.. as in river forging, really bad weather, hot and cold.. I would say the 4Runner is benefiting from this system designed for the Landcruiser, the I4 and V6 systems are likely going to last just as long as any power plant Toyota has ever designed

 

[Nodak]

Wow, thank you for sharing this. It is news to me. From my research there was no alternator on the hybrid, if they have added one, i am very curious.

I will research more and come back to this thread with my finding.

only certain models with a very specific PIO will get an alternator in a hybrid.

from my understanding only the TH and PRO can add the aux switch option and get the alternator on the hybrid.

the aux dc to dc switch panel is standard on TH, TRD Pro and option package on TRD Off-Road Premium i-FORCE MAX.

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