Battery Maintainer

[Benc2020]

Hi guys,
I am about to go on a vacation for 4 weeks. I am told that the 12v battery will likely go flat before I come back. I am getting a NOCO Genius5 battery maintainer.

On the car manual page 548, it says "Before recharging: If recharging with the 12-volt battery installed on the vehicle, be sure to disconnect the ground cable." What does it mean? If I am correct, the ground cable means the negative cable? I have to remove the negative cable? If so, what's the point of having the battery maintainer? I could just leave it disconnected for 4 weeks. I don't want to disconnect it because I don't want to lose the car's setting. That's what I got the battery maintainer for.

Has anyone done this before? Did you connect the battery maintainer without removing the negative cable? Does anyone know if Toyota permits an external charger to operate while the vehicle's electronics remain connected? Thank you

 

[bigcat]

Welcome to the a.... forum . I am not sure I know the answer to your question (battery newbie here too ), but I've been charging my 12v battery today with a NOCO genius5 as well, using the under the hood terminal, not the battery terminals directly. The charger is showing green light now so I guess it's done but I haven't removed it yet.

I did not remove the ground cable from the battery, perhaps I should have? It may be possible to disconnect the ground cable without fully removing the negative assembly from the battery? Below is a pic of the left terminal, maybe that 12mm nut (lower nut) can be loosened to release what I assume is the "ground" cable the manual is referring to. Just speculating here so don't do anything until the experts here chime in

I am now wondering if the interior of my car is full of explosive hydrogen gas (it's the reason the manual says ground should be removed )

 

[Bad1975]

On the Toyota OEM battery there is a vent tube that routes the gases external to the vehicle.

 

[Benc2020]

Thanks for sharing your experience. Yeah, I am so confused.

Google Gemini says that line on the manual is just a classic piece of legal boilerplate text written to cover all types of traditional old school battery charger. So it's OK to leave the negative cable on, just hook up the NOCO Genius5 under the hood terminal.

ChatGPT keeps emphasizing that line, saying Toyota manual specifically instructs owners to disconnect the ground cable before recharging. It has not confirmed whether Toyota makes an exception for maintenance charging. It says before leaving it unattended for a month, get Toyota's confirmation about disconnecting the ground cable. I don't think I have enough time to wait for Toyota to answer. LOL!

 

[GR8Santini]

Hi guys,
I am about to go on a vacation for 4 weeks. I am told that the 12v battery will likely go flat before I come back. I am getting a NOCO Genius5 battery maintainer.

On the car manual page 548, it says "Before recharging: If recharging with the 12-volt battery installed on the vehicle, be sure to disconnect the ground cable." What does it mean? If I am correct, the ground cable means the negative cable? I have to remove the negative cable? If so, what's the point of having the battery maintainer? I could just leave it disconnected for 4 weeks. I don't want to disconnect it because I don't want to lose the car's setting. That's what I got the battery maintainer for.

Has anyone done this before? Did you connect the battery maintainer without removing the negative cable? Does anyone know if Toyota permits an external charger to operate while the vehicle's electronics remain connected? Thank you

Who is saying your 12v battery will go dead, & without testing your battery how would they know? This isn’t a situation you should lean into Ai for advice. I’m sure some of the forum members can help provide good information.

My 2 cents- Unless you have a sick battery with low SoC, your battery’s condition, while w/ a maintainer connected, should be the same condition when you return.

Your situation is exactly what a maintainer is designed for & many of us use them for much longer periods of time without disconnecting the battery. A maintainer isn’t a ‘real’ charger (very low amps), & there is no need to disconnect the battery negative cable while you’re using a 5A NOCO maintainer.

Connect the maintainer correctly & go have a good trip.

 

[DubDub]

I’ve left my LC for 5 weeks three times for travel to Japan. Not a single issue to date with first time starts. No tender or maintainer used.

However, I just replaced my battery out of precaution, and to facilitate some planned mods. I also own a NOCO and would advise any owner of any vehicle to consider one for their arsenal all well. They aren’t mutually inclusive.

 

[EOD Guy]

Welcome to the Jungle!

Your AI is smoking crack and bad crack at that........lol There is no need to disconnect the neg cable to use a maintainer, My trickle charger has been connected to my battery for over a year with no ill effects. If your battery was completely dead (zero volts) and you were going to use a "reconditioner" type charger that's sends extremely high voltage in micro short bursts to shock the lead plates in the battery in order to "blast" the sulfate deposits off the plates....... then yes you should disconnect the neg cable.

 

[ultane]

Welcome to the asylum @Benc2020.