12v battery (hybrid) runs low after sitting for a week

[Cordoc]

Adding an alternator won't have any benefit unless you're drawing more power than the hybrid motor/generator can supply.

Also given other threads it's not clear that all 2025's are getting the alternator.



12.2VDC after a 30 minute drive is a bad battery (or bad charging system) regardless of AGM or lead-acid. Given the amount of self-discharge in two days it's likely the battery unless there's some significant parasitic draw.

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[Cordoc]

I have a 24 Trailhunter with no alternator, I have never had a battery problem.
In Jan I left the country for 2 1/4 months and went to the garage, and it started in 1 sec flat.
Any problem with starting after a few weeks should be investigated since it is not supposed to happen

 

[SnowmanJPS]

This is also the battery that is in my '24 OR hybrid. I carpool every other week and travel, so my truck sits for a few days and intermittently a week or so. Knocking on wood, I have yet to see an issue.

Same battery as my 25 pro

 

[max911]

Just a follow up to my truck getting a new (12v) battery from the Toyota dealership.

Was away for about ten days on a roadtrip in my convertible.
Returned home and the truck fired up perfectly when i tried it this morning.
Voltmeter stays at midpoint (14v) Whereas before it would drop down to 12v after 5 or 10 minutes of driving with the original battery.

I'm thinking there is probably enough of a sample size by now that Toyota must be aware that there was a bad batch of batteries that are failing in the first months/year.

 

[MustardTiger]

So I had the truck sitting for a good 10 days…I left a 1.5 amp maintainer on a WiFi switch, and had run it on two occasions for about 8 hours. Then left it off for five days…the voltage of the battery when I got back was 12.4v. So I then decided to put a 7.2amp Noco charger on it, and set it to the agm setting, left it overnight. The next day the battery had got up to 12.9v…so that’s good. I drove the truck and the voltage gauge will always remain mid way for a good amount of time (I’m assuming midway is between 14-15v). However it will still drop low after a while, like the system stops charging the battery completely. See picture.

idk…I don’t think anything is wrong with the truck or battery…but it’s the most bizarre voltage readings and behaviour. I’m going to stop worrying about it, maybe keep a small jump pack with me, and just drive it lol. As you can see I need to do that more

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