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I bought a new 2022 Tucson Hybrid Limited 3 months ago. I have not had any problems. The gas mileage has been fairly
descent. I just came back from a vacation after 10 days. I got an email from Hyundai Blue Link during my vacation stating that my battery was low. This morning I tried to get into the car, but all systems were dead. With help from the YouTube and friends I was able to get the cap off the handle on the drivers side. Once that was off I was able to enter the car and start up the car by pushing the 12 volt recharge button followed by the power button. The car started right up. What is drawing power from the 12 volt battery? I am wondering every time I go on vacation without the car will the battery need to be recharged? It seems like everything is off.
 

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2022 Tucson Hybrid Blue Trim
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There are lots of things that draw small amounts of power but if your car is parked outside in cold weather it will self-discharge at a rate commensurate with the cold. The hybrid's 12-v lithium polymer battery capacity is only 15ah, so there's not a lot of capacity for long periods of not charging, esp. in cold weather.
 

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Limited PHEV, Quartz White with grey interior
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This happens with (Gen2, at least) Priuses. (Prii?) The main culprit is the sensor system for the keyless entry. There is a button on the bottom of the dash to disable that system if the car isn't going to be driven for a week or two. Some Prius owners have a little solar panel that they put on the dash and plug into the 12-volt outlet to keep the battery trickle charged.
 

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2022Tucson "Blue" Titanium White/ Black
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You answered your own question (in part) with your first sentence. The Blue Link system requires battery power from the car to operate and probably more monitoring systems also, like remote start / lock communication, computer memory functions etc. There is even a warning in the manual not to leave the car unused for an extended period. That 12 volt system isn't very big, because it doesn't start the engine, it basically boots up the computer that starts the car and runs lights, infotainment and other 12 volt systems. The 12 volt system does not completely discharge, it just gets disconnected from the traction battery (which maintains the 12 volt system) after a certain discharge point so that the traction system doesn't get too low. If the traction battery got too low, the car would have to be towed to the dealer in order to recharge the traction battery. You could probably extend the storage time by running your car in Sport mode until the traction battery gets to it's maximum charge just before you take a trip. (about 10 minutes of around town driving with the hvac off would do it). There is a connector for jump starting in the fuse box under the hood. I wonder if you could hook up a battery maintainer to it to avoid this problem. The PHEV has a similar problem, (although the plug in has it's own, separate traditional 12 volt battery) which could be solved by incorporating a 12 volt trickle function to the charger plug.
 

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2022Tucson "Blue" Titanium White/ Black
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I found this in the manual. "NOTICE : The hybrid system contains many electronic components. High voltage components, such as cables and other parts, may emit electromagnetic waves. Even when the electromagnetic cover blocks electromagnetic emissions, electromagnetic waves may have an effect on electronic devices. When your vehicle is not used for a long period of time, the hybrid system will discharge. You need to drive the vehicle several times a month. We recommend driving at least for 1 hour or 10 miles. When the hybrid battery is discharged, or when it is impossible to jump start the vehicle, we recommend that you contact your authorized HYUNDAI dealer ". It also says this about the 12 volt system - "Battery : The vehicle is composed of a high voltage battery that drives the motor and air conditioner, and an integrated 12V lead battery with the HEV battery that drives the lamps, wipers, and audio system. • The integrated 12V battery is automatically charged when the vehicle is in the "ready" mode." If this is accurate, the 12 volt battery is only maintained when the car is powered on, so my suggestion about charging up the traction battery may not be helpful.
 

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'22, Tucson hybrid, SEL convenience
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FWIW, trying to maintain the 12v system with a solar charger plugged into the 12v accessory plug won't work. That plug is only powered when the ignition is on.

Suggest becoming familiar with how to get into the car with the key, if things won't open, and how to hit the jump start switch (on the HEV, the PHEV may have other options). If that fails, then the only option is call roadside assist.

Kind of crazy that Hyundai doesn't have some sort of disconnect switch to prevent a discharge when the car is left for a vacation. I guess the low voltage cutoff for the 12v system accomplishes this, though. On my previous non hybrid cars I just pulled the battery leads off when I left it for a long trip.
 

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Limited PHEV, Quartz White with grey interior
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FWIW, trying to maintain the 12v system with a solar charger plugged into the 12v accessory plug won't work. That plug is only powered when the ignition is on.

Suggest becoming familiar with how to get into the car with the key, if things won't open, and how to hit the jump start switch (on the HEV, the PHEV may have other options). If that fails, then the only option is call roadside assist.

Kind of crazy that Hyundai doesn't have some sort of disconnect switch to prevent a discharge when the car is left for a vacation. I guess the low voltage cutoff for the 12v system accomplishes this, though. On my previous non hybrid cars I just pulled the battery leads off when I left it for a long trip.
Good catch. Can vary by vehicle, however. Accessory plug is always on in my wife's car. Is it on or off in the Tucson? (I don't have my Tucson yet.)
 

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2022Tucson "Blue" Titanium White/ Black
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FWIW, trying to maintain the 12v system with a solar charger plugged into the 12v accessory plug won't work. That plug is only powered when the ignition is on.

Suggest becoming familiar with how to get into the car with the key, if things won't open, and how to hit the jump start switch (on the HEV, the PHEV may have other options). If that fails, then the only option is call roadside assist.

Kind of crazy that Hyundai doesn't have some sort of disconnect switch to prevent a discharge when the car is left for a vacation. I guess the low voltage cutoff for the 12v system accomplishes this, though. On my previous non hybrid cars I just pulled the battery leads off when I left it for a long trip.
There are instructions in the manual on hooking up a charger or jumper cables if the 12 volt battery won't power up the car. There is a terminal in the fuse box under the hood for the positive cable and you connect the negative to a bolt head on top of the strut tower. I don't know if that just allows for powering up or whether it will also charge the 12 volt system.
 

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Limited PHEV, Quartz White with grey interior
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There are instructions in the manual on hooking up a charger or jumper cables if the 12 volt battery won't power up the car. There is a terminal in the fuse box under the hood for the positive cable and you connect the negative to a bolt head on top of the strut tower. I don't know if that just allows for powering up or whether it will also charge the 12 volt system.
The solar trickle chargers will charge the battery. Some Prius owners rigged wires from the jumper points under the hood to their 12-volt solar trickle chargers (which were often put on the dashboard when in use). Some of the trickle chargers listed on Amazon come with ring cables to connect to battery posts. They also come with battery clamp connectors for temporary installation (i.e. during a vacation).
 

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2022Tucson "Blue" Titanium White/ Black
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Have you confirmed that a trickle charger will maintain the 12 volt system? I have not had good luck with solar chargers. If you get a poor quality one they can actually drain your battery. I bought two different products for my trolling motor battery and neither made a noticeable difference.
 

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I never needed to do it myself, but I've seen the solar trickle chargers mentioned on Prius forums as being successful over the 14 years I've owned my Prius. Maybe the failures didn't advertise themselves.

Is the 12-volt battery in the Tucson Lithium-ion? That could be a new factor.
 

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They call it "lithium polymer", which I imagine is similar. I just don't know for sure whether hooking up a charger to the system will allow the 12 volt system to be charged when the car is powered down. The manual only describes the terminal in the fuse box as a jump starting feature and doesn't say specifically whether you can trickle charge the integrated battery. The PHEG has it's own separate 12 volt battery in the rear of the car that has access to the actual battery terminals.
 
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