GTGallop 60 Posted January 28, 2024 With just 9,400 miles on the OEM battery that came with the truck, I started noticing odd electrical issues. Then one day it wouldn't start. I turned my ham radio on because it has a volt meter on it and the battery was sitting at 8.4v. Did as much diagnosing and trouble shooting as possible. No lights or accessories left on, unhooked the dash cam, unhooked the ham radio, all of it. Hooked up a trickle charger and it couldn't get it to take a full charge. Bell Road Toyota serviced it today and confirmed the battery was bad and replaced it. Quite literally the shortest lifespan of a car battery I have ever had. Noco Jump Pack is on order and will be keeping that bit of kit in the truck from now on. New battery has an 84 month prorated warranty but I don't want to start using that warranty on top of a mesa somewhere that's 30 miles from pavement. Good news is that I haven't had a battery last much more than 2 years in AZ, so the next one might be free too, at most 50% off. But if I have to pay anything, I'll probably let Toyota off the hook and just upgrade. Would like to get an AGM battery and this gives me time to figure out what I need to do so the Toyota alternator will charge it effectively. So check your batteries! And if you are running an AGM, let me know what you had to do to make it work. Share this post Link to post Share on other sites
os1rfw 7 Posted March 10, 2024 (edited) I never had an issue with a short life span of a battery (2 years is a short life span) when I lived in Arizona. I am running an Optima Yellow Top in my 13 Taco with no mods. On other AGM's I have heard of using an item (need to do some looking to find the proper name) that replaces the fuse in the engine compartment fuse box. Boosts the alternator's output to 14.6-14.7 volts which keeps an AGM charged. There are a few Youtube videos on it. I will look it up and give the name but it is literally just replacing the alternator fuse with it. Ron W. Edited March 10, 2024 by os1rfw 1 Share this post Link to post Share on other sites
theksmith 5,778 Posted March 10, 2024 (edited) i guess there is a simple diode mod that fools the smart alternator into outputting the higher voltage needed to fully charge AGM batteries. check youtube for the cheapest DIY methods, or have a look at these guys products: https://voltageboosterpro.com/ EDIT - apparently that diode mod doesn't work for the new Tacos like yours @GTGallop, instead people are using tuner software to adjust the charging profile: https://www.tacomaworld.com/threads/vf-tuner-for-the-3-5l-tacoma-agm-tuning.689652/ Edited March 10, 2024 by theksmith 2 Share this post Link to post Share on other sites
Lichen 215 Posted November 20, 2024 I just got 3 years and 9 months out an Autozone battery. I never got more than 2 years with Optima. 1 Share this post Link to post Share on other sites
GTGallop 60 Posted December 14, 2024 On 3/9/2024 at 8:45 PM, theksmith said: i guess there is a simple diode mod that fools the smart alternator into outputting the higher voltage needed to fully charge AGM batteries. check youtube for the cheapest DIY methods, or have a look at these guys products: https://voltageboosterpro.com/ EDIT - apparently that diode mod doesn't work for the new Tacos like yours @GTGallop, instead people are using tuner software to adjust the charging profile: https://www.tacomaworld.com/threads/vf-tuner-for-the-3-5l-tacoma-agm-tuning.689652/ As Toyota drivers are all too familiar Toyota did a lousy job of mapping the transmission shift points. So a tune is a pretty standard mod for a lot of people and I'd argue that you probably can't get a better performance lift out of $450 than something like the Overland Taylor Tune or Overland Torque Tune as some call it. I was going to see if they could adjust the charging at the same time they do the rest of the tune. Then the truck died in traffic the other day. Mild acceleration pulling onto a street, it shuddered, sputtered, died. Dash lit up like a Christmas tree. I restarted it, truck went into limp mode, and I drove it 15mph back home with a flashing CEL. Took it to Toyota and they said two codes - rough idle and two cylinders misfiring. Soooo glad I hadn't got the tune yet. Toyota cleared the codes, drove it 7 miles (they said 10 but the odometer doesn't lie). No codes came back and they called it good to go and fixed. Now I'm holding off on the tune and battery upgrade waiting for the other shoe to drop. Truck is a 23 with 15K miles. Fuel economy in the toilet was one of the reasons I was looking at the tune. Now I'm suspecting a sparkplug / coil pack issue or as some have pointed out the plenum actuator. Either way I have to get past this hurdle before considering anything else. I'm not even putting new rubber on it until this gets sorted out. 1 1 Share this post Link to post Share on other sites
Cypher 19 Posted August 3, 2025 Hey @GTGallop! Good to see you on here... How did things turn out with the Taco? Share this post Link to post Share on other sites
GTGallop 60 Posted August 22, 2025 Quote How did things turn out with the Taco? Hey @Cypher! Good to see you on the forum. OOF! It has been a comedy of issues. Battery was no biggie. Matter of fact I'm now coming up on 2 years with it and looking at replacing it (on my terms not its terms) with an AGM battery. I hear that the increased charging can be handled through a new relay or through programming via an Overland Taylor Tune. Looking at the tune for other reason (transmission shift points). The real issue was the Fuel Injectors on #2 apparently were bad from the factory. Toyota refused to even diagnose the truck because it had a ham radio on it. I pulled the radio out completely and it still died - in traffic. Ended up taking it to YotaPros down near Ikea in south south Phoenix on my dime. They kept it for two weeks, found the errant injectors, replaced them, and it got it running like a top again. I fought Toyota and eventually they cut me a check for the repairs - IIRC it was $1,300 or something. Not too bad for the amount of time they put into it. They cut me a deal because they weren't sure Toyota was going to reimburse and I let them have it with an open ended timeline since I had alternative transportation. That way they could work on it between jobs. There's a full length feature film, extended dance re-mix thread over on TacomaWorld that goes some crazy 27 pages of correspondence between me and Toyota. You got the TLDR above so no need to read unless you are having insomnia issues. Now that we have that fixed, I'm back in love with the truck and wheeling it. In the process of adding an AuxBeam Panel to separate the radio a little further from Toyota Electronics so they can't use that BS Excuse again. I'll still never go to Bell Road Toyota for service or buy another Toyota from the experience but I'm going to drive this one until the wheels fall off (hopefully around 400,000 miles or longer) 2 Share this post Link to post Share on other sites
GTGallop 60 Posted September 17, 2025 On 3/9/2024 at 5:28 PM, os1rfw said: I never had an issue with a short life span of a battery (2 years is a short life span) when I lived in Arizona. I am running an Optima Yellow Top in my 13 Taco with no mods. On other AGM's I have heard of using an item (need to do some looking to find the proper name) that replaces the fuse in the engine compartment fuse box. Boosts the alternator's output to 14.6-14.7 volts which keeps an AGM charged. There are a few Youtube videos on it. I will look it up and give the name but it is literally just replacing the alternator fuse with it. Ron W. Done a bit of research on the AGM and that fuse device. Looks like the OTT (Overland Taylor Tune) will correct it. So I'll toss an AGM in it in January and then the tune will follow. 1 Share this post Link to post Share on other sites