12V Battery Backup

[Marinna]

LC is going to be the first car I own that had 12V battery sitting in the cargo. I am thinking about some improvement plan for that 12V battery, potentially replace or extend the 12V battery to another Lithium battery in the cargo.

Has anybody done this kind of work before on similar vehicle? I wonder whether we should use this battery to power future extension like lightbar/offroad light/winch/tire inflator.... etc. I think I can improvise a connection to the 12V battery but not sure if it is even ok to connect both Lithium and Lead-Acid batteries together. Anybody who has experience on this before? Also the car is going to get very hot in the summer so placing a lithium battery in the car feels like a bad idea.

 

[EOD Guy]

I can not answer your question, but I do know that my Li batteries take a different charger than lead acid.

 

[Marinna]

I can not answer your question, but I do know that my Li batteries take a different charger than lead acid.

Yes I expect that. I was hoping that we can find a purposefully designed power extension unit given there are more and more hybrid chose to place the 12V battery in the cargo. I don't think I can place a marine battery inside the cargo in a close space. Just curious how should we wire all the accessories to this 12V battery in the future? (and have the harness capable of higher amperage)

BTW I have been using a few Bluetti units in the car but never figure a good method to power these high power accessories yet

 

[BigMF]

Check out @EOD Guy 's build thread. He's already got the "how should we wire all the accessories to this 12V battery" figured out using the positive 12V terminal under the hood up front.

Regarding the mixing of Lead and Lithium batteries, you may want to check out REDARC'S line of devices. This one in particular mentions Lithium and Lead as well as Gel and AGM. No idea if it could serve you purposes but it was the first thing I found that mentioned both of the battery types you mentioned.

 

[Don]

Wiring the vehicle like its not a hybrid with a generator, large inverter and a 1.8 kwh battery doesn't make a lot of sense. Leverage the expensive tech already purchased.

 

[BigMF]

Wiring the vehicle like its not a hybrid with a generator, large inverter and a 1.8 kwh battery doesn't make a lot of sense. Leverage the expensive tech already purchased.

Any suggestions on how to leverage the new expensive tech you mention to power 12V accessories?

I use a portable power station similar to the Bluetti the OP mentions to run my fridge 24 hours a day. The power station has traditionally (in my older vehicle) been plugged into a power source that is only energized while the truck is running. However, that 12V source powers up AUTOMATICALLY every time I started the truck.

Yes, I could plug the portable power station via the 120V plug in the back but then I'd have to remember to hit the button on the dash EVERY time I started the truck or I risk my portable power station running down and the food in the fridge going bad. I'd love to know how to keep the portable power station charged up using something OTHER than a 12V source similar to what I've done in the past.

BTW, I'm in and out of my truck many times during the day when I'm on an overlapping road trip and I guarantee that I will forget to turn the power on for the plug in the back at some point. I'm sure that someone will figure out how to "hack" the system so that the 120V outlet will be powered whenever the truck is running and bypass the switch on the dash but no one (that I know of) has done that yet.

What say you @EOD Guy ? Could we possibly pop that plug out of the dash and do a little rewiring so the switch is bypassed completely and activated via a relay?

 

[EOD Guy]

I have that panel out right now, I'll take a look. If it's a simple switch firing a latching relay...... should be easy to parallel the circuit for an "ACCY on" or "always on" or "off".

It would depend on what Toyota integrated into the circuit ie....... low traction battery low voltage safety / starting the engine etc.......

(edit) While sitting in the car rider line, waiting to pick up my G-baby........ I had the AC on about 76 degrees....... AC ran on battery for about 10-15 minutes, then the engine started and ran about 10 minutes............ cycled through this about 6 times. Not sure how much power it takes to run the 120v inverter or how much power you fridge uses etc.......

 

[Don]

@BigMF Seems like you are all set plugging the Bluetti into the 12v. I don't see a reason to maintain power to the Bluetti when the vehicle is off.

What I like about the Bluetti is that even the small ones have high output USB-C and recharge quickly on 120V. So beyond fridge use Bluetti do other things well. Also, they are LFP, and the new ones even work well at home as a computer UPS.

Considering the large inverter in the LC, the $300 Bluetti should be enough for most people that need to run the refrigerator all night. Even the $200 one would be good enough for my efficient Engle ice box.

 

[Marinna]

I don't think that hybrid battery is going to do any good for what I am trying to achieve.

My understanding is that all accessories should be powered by the 12V battery while we should keep hybrid battery to be for driving only. For simplicity or safety I don't want to tape accessories power uses into hybrid battery even if Toyota allows me to (and they usually don't)

A dual 12V battery system is no different from the traditional spare power circuitry offroad community uses. We expect continue low voltage power to continue even when engine is off. I simply think that now it is inside the cargo so wiring and placement should be simplifier, comparing to back in the days we are struggling to find space in the engine bay for the redundant battery.

I remember it used to be people install a manual switch or relay to flip the source of power when the engine is off. But these days everything is computerized so unless I know perfectly well the power switching logic is I would worry breaking stuff.

 

[Don]

The vehicle is on for high power use like a winch or more powerful air compressor.

The modern high power connector for electronics is USB-C, but the LC is only 15W and probably just 12V. The Bluetti and others are multi-voltage and high watt capable (either 65W or 100W).

The point of the hybrid is not to leave it on for long term low wattage usage, but to always have a source to easily recharge a power station or the starter battery. If I'm remebering correctly the LC does have a low voltage shutoff for the 12V system when the vehicle has the ignition in ACC.

So the choice is between adding a conventional battery in parallel with the existing starter battery or purchasing one of two small power stations. I think most people will find small power stations more useful. Not only do they provide high power USB-C but can be moved around camp.

The upside of a traditional house battery could be powering fixed vehicle mounted camp lights. Although traditionally one reason to have vehicle mounted camp lights was to access the energy in the vehicle battery systems.

We don't yet know winch requirements, but I find it unlikely that Toyota didn't design a 12V system that could not run a front winch. A high end ARB tire inflator uses about 800W which the vehicle can easily support with the engine in the on position.

Unlike conventional vehicles we completely avoid needing special alternator additions, portable generators or solar to keep up with higher power needs in camp. The reason solar is so often now paired with power stations is that the 12V/120-300w energy typically available in vehicles is not enough to recharge batteries in a reasonable time.

 

[Marinna]

The vehicle is on for high power use like a winch or more powerful air compressor.

The modern high power connector for electronics is USB-C, but the LC is only 15W and probably just 12V. The Bluetti and others are multi-voltage and high watt capable (either 65W or 100W).

The point of the hybrid is not to leave it on for long term low wattage usage, but to always have a source to easily recharge a power station or the starter battery. If I'm remebering correctly the LC does have a low voltage shutoff for the 12V system when the vehicle has the ignition in ACC.

So the choice is between adding a conventional battery in parallel with the existing starter battery or purchasing one of two small power stations. I think most people will find small power stations more useful. Not only do they provide high power USB-C but can be moved around camp.

The upside of a traditional house battery could be powering fixed vehicle mounted camp lights. Although traditionally one reason to have vehicle mounted camp lights was to access the energy in the vehicle battery systems.

We don't yet know winch requirements, but I find it unlikely that Toyota didn't design a 12V system that could not run a front winch. A high end ARB tire inflator uses about 800W which the vehicle can easily support with the engine in the on position.

Unlike conventional vehicles we completely avoid needing special alternator additions, portable generators or solar to keep up with higher power needs in camp. The reason solar is so often now paired with power stations is that the 12V/120-300w energy typically available in vehicles is not enough to recharge batteries in a reasonable time.

This is my impression for the accessory power wattage, correct me if I am wrong:

Cooler: 30-60W on 120V AC/DC
Laptop: 60-140W on USB-C
Offroad Light: 50-400W on 12DC direct wiring
Stereo: Not sure but I’ll say the same level or less of the offroad lighting, 12V direct wiring
Winch: 50- 200A on 12DC direct wiring so 600-2400W for a less than 10000lbs winch

For cooler, laptop there is no doubt 12V starter battery or power station should handle it.
For offroad light bar and stereo shorter term 12V battery should be fine, but long term the starter battery will need some support, this is where the power station or backup battery could help
For winch I am not sure. Ideally if traction battery can handle it would be great. But DC-DC conversion from 288V to 12V at thousands of watt is very taxing, loads of heat will be generated. This is also the area the stock alternator can’t catch up the discharge rate. For EV like Tesla Cyberatruvk or F-150 EV it wouldn’t really be an issue. But LC is not designed to be operated by hybrid battery, that is why I said until we fully understand the capability and control logic of the traction battery I will leave it untouched

In addition, one thing I worried about my Bluetti is that the cabin temperature during summer is very hot. Even if it is safe enough not to catch fire, the battery life might get some real impact. So there is going to be high wear to keep the power station I side the car during summer if we don’t do other thing to help.

 

[Don]

This is my impression for the accessory power wattage, correct me if I am wrong:

Cooler: 30-60W on 120V AC/DC
Laptop: 60-140W on USB-C
Offroad Light: 50-400W on 12DC direct wiring
Stereo: Not sure but I’ll say the same level or less of the offroad lighting, 12V direct wiring
Winch: 50- 200A on 12DC direct wiring so 600-2400W for a less than 10000lbs winch

For cooler, laptop there is no doubt 12V starter battery or power station should handle it.
For offroad light bar and stereo shorter term 12V battery should be fine, but long term the starter battery will need some support, this is where the power station or backup battery could help
For winch I am not sure. Ideally if traction battery can handle it would be great. But DC-DC conversion from 288V to 12V at thousands of watt is very taxing, loads of heat will be generated. This is also the area the stock alternator can’t catch up the discharge rate. For EV like Tesla Cyberatruvk or F-150 EV it wouldn’t really be an issue. But LC is not designed to be operated by hybrid battery, that is why I said until we fully understand the capability and control logic of the traction battery I will leave it untouched

In addition, one thing I worried about my Bluetti is that the cabin temperature during summer is very hot. Even if it is safe enough not to catch fire, the battery life might get some real impact. So there is going to be high wear to keep the power station I side the car during summer if we don’t do other thing to help.

Even small van builds no longer use conventional second batteries. The LC is much less suitable for living inside than a small van. I can't imagine planning to sit in a front seat night after night listening to the stereo. So I don't understand your electrical plan. I would put the interior of the LC as a living space a step above Turkish prison.

You can't safely run even a cooler overnight on the stater battery, which makes me believe you are inexperienced in practice.

As I've pointed out, you will not be using high powered devices with the vehicle off.

 

[Marinna]

Even small van builds no longer use conventional second batteries. The LC is much less suitable for living inside than a small van. I can't imagine planning to sit in a front seat night after night listening to the stereo. So I don't understand your electrical plan. I would put the interior of the LC as a living space a step above Turkish prison.

You can't safely run even a cooler overnight on the stater battery, which makes me believe you are inexperienced in practice.

As I've pointed out, you will not be using high powered devices with the vehicle off.

The electrical planning is for after I switch off the car. If you keep the offroad light on and stereo, especially some of the aftermarket system on for even an hour or two you will have issue. I have never do that but I have seen so many camper uses their car that way and they want to have this freedom. or how about I want to sleep in my car when I get to the camp too late and too tired, or just in the middle of nowhere when it snows outside and I do not want to drive? Even for just one or two night per year, should I be jedged by you and not be allowed to do so?

For cooler, it is easily expected. running a bigger cooler for 10 hours will consume about 500Wh, even for a bigger 12V AGM battery you are still getting close to not being able to turn on the car, let alone that tiny 12V in LC, which is why I was thinking about a spare battery. What is the problem with that?

Adding a spare battery is just for adding more general freedom how I can use the car, whatever that makes sense to anybody or not. Will you also criticize these Wrangler driver who install the second battery in their engine bay just because they want to use the car in the way you don't agree? Are things make sense only when you agree with it? I can't remember how many nights I am sitting in my car in the complete darkness at Banff, Jasper, Yellowstone, Grand Teton, Arches, Escalante, Yosemite, Crater Lake, Rocky Mountains... etc either waiting for stars and sunrise, stalking wildlife, or simply just get too tired to find a hotel that is 50 miles away from me. Apparently I am, in your standard, still a newbie. Fine whatever you want to say...

 

[Don]

First, It should be obvious that I have no interest in what you do personally. Second, to add a second battery to a system that isn't well understood in its charging behavior is the opposite of de-risking the potential of battery failure. You conflating my interest in good design with telling you what to do is weird.

You

 

[Marinna]

First, It should be obvious that I have no interest in what you do personally. Second, to add a second battery to a system that isn't well understood in its charging behavior is the opposite of de-risking the potential of battery failure. You conflating my interest in good design with telling you what to do is weird.

You

If you want to show yourself being reasonable, then show some more respect and stop talking in the condescending tone. Some might also comment that sleeping in tent outside is barbaric and people modifying car out of spec are people who has nothing better to do but wasting money. Do not project your own standard and stereotype other with something you don't like do be portraited. You don't know where other people is coming from or want they are experiencing.

Back to the subject, the 12V battery is the least of the risk if one want to modify the electrical system on LC, actually particular in LC since it is only responsible to boot up various sub-systems rather than start the engine or drive hybrid battery. I could be wrong in this but with all the information I read as long as the battery can provide power with the right voltage and support shorter burst of 30~50A output that is all it does. Adding accessories will de-stable it sure but so does every modification people in the community does. Just the standard temperature range for testing -40C ~ 80+C rarely any aftermarket modification has gone through these tests so everybody here is just hacking

 

[EOD Guy]

If you want to show yourself being reasonable, then show some more respect and stop talking in the condescending tone. Some might also comment that sleeping in tent outside is barbaric and people modifying car out of spec are people who has nothing better to do but wasting money. Do not project your own standard and stereotype other with something you don't like do be portraited. You don't know where other people is coming from or want they are experiencing.

Back to the subject, the 12V battery is the least of the risk if one want to modify the electrical system on LC, actually particular in LC since it is only responsible to boot up various sub-systems rather than start the engine or drive hybrid battery. I could be wrong in this but with all the information I read as long as the battery can provide power with the right voltage and support shorter burst of 30~50A output that is all it does. Adding accessories will de-stable it sure but so does every modification people in the community does. Just the standard temperature range for testing -40C ~ 80+C rarely any aftermarket modification has gone through these tests so everybody here is just hacking

I don't disagree with anything you've stated.... except it's informed hacking........ LOL

 

[Don]

Tone is your perception.

ACC mode has a 20 minute timer and then the vehicle switches to off. Providing more watt hours doesn't change the timer. There are literally over 100 warnings in the manual about only using 12V for short duration. The car is designed for long duration electrical usage only in the on/hybrid mode.

Even if restarting the ACC mode every 20 minutes was acceptable, there is still only one 12V connector in the interior and the six or so USB-C ports are only 15w.

There are good workarounds for all the low voltage limitations because the 2400w inverter can charge batteries and power stations fast.

A $70 12V jump starter backs up the 12V starting battery and fits in the underfloor compartments.

 

[EOD Guy]

No offense intended........ let it go.

 

[JordanJ]

Well all yall obviously know more about electrical than I, but given my mistakes I feel important to stress that the traction battery under the hood can only take 350amps, and if exceeded it will kill the truck. Anything light wise, I’d say is more than fine being tied into the traction battery under the hood without any issue, but anything larger needs its own 12v or tied into the existing 12v in the trunk. I tied my winch directly onto that and routing it wasn’t all that hard actually. There’s a grommet behind the drivers side wheel well, just FYI. And as far as fridges and what not, on my Tacoma I always used a Jackery 1,000, and that kept my things cold for 3-4 days, and 2 if it was really hot out. I wired a switch to a 12v outlet which I kept the fridge plugged into, so when driving I can push the switch and know it’s charging. I thought it was a very efficient way… just food for thought.

 

[Area 51]

Do not use lithium. the electrolyte is flammable.
There are many other good options.