2020 TRD Off-Road Battery Continually Dying Following Service

old thread bump...

Toyota truestart 84 month warranty or Walmart everstart 24f agm with an offgridengineering strap. Coupe makes some nice battery straps too...

https://www.tacomaworld.com/threads/3rd-gen-trd-battery-hold-downs.574494/

 

Same here with some folk. I’m still on the original OEM battery. And the truck was parked for nearly two years with both a covid working at home and a fucking cancer fight back to back. I never tended to the battery. I finally cleaned the terminals for the first time not too long ago. But I’m presently searching for a replacement even though the cranking is in good condition.

 

4 wheelin’ in the mornin’!

Us vampires don’t get much sleep

 

Wife has a Subaru Outback that was killing batteries. Turns out the source of high current drain (a.k.a. Parasitic or Dark Current draw) when the vehicle is not being driven is the DCM used to communicate with "Mother". Some are getting replacement DCMs. I read on an Outback forum that others had found a way to implement a "fix" whereby the DCM is unpowered when the ignition is off. Simple, simple modification using two "add a circuit" fuse taps. (basically the fuse for the DCM is pulled, and then that circuit is fed by a spare tap in the engine compartment that is switched with the ignition). Two add-a-circuit fuse taps are wired together. The fuse from the DCM is placed in the add-a-circuit tap that is inserted back into the DCM fuse's location. The other add-a-circuit tap (with the same or higher rated fuse) is inserted into the fuse location that is known to be switched with the ignition. A genius solution IMHO. That cleaned up my issue with the wife's car.

While it's most likely not the same issue in the Toyota, the way to identify a large high current draw is to perform some "Dark Current" (aka "Parasitic Current") testing.
You disconnect one of the battery terminals, and you put a multi-meter in series with the battery post and the battery terminal that was disconnected, and set it up to measure DC current.
You note the current draw with all fuses installed.
Then one by one, you pull and re-install each fuse, writing down the current draw when the fuse is pulled.
The "Dark Current" heavy-hitters are the ones who's fuse being pulled resulted in the largest drop in the reading on the multi-meter.
There should be an outlier that is most likely at root cause.

I'm sure the process is documented on the web, specially YouTube, but that is the basic method.

With the car ignition off, if you have more than a 60mA - 80mA draw, that's suspicious.
Make sure when you are doing this testing that the FOB is not on your person. You want the test to be done without the FOB in range.

Here's another Tacoma thread on the topic:
https://www.tacomaworld.com/threads/ma-draw-w-truck-turned-off.644085/

HTH.