high voltage

So my trucks voltmeter seems to read pretty high all of the time. I had issues last night where the truck wouldn't start, started fine with a jump and got me home but it wasn't smooth. I had had issues with the battery terminals in the past so I replaced those and bought a new battery. Starts good now. I'm worried I'm frying the new battery. Alternator is relatively new, I have a new voltage regulator to install. Anyone have a map of the ground to the alternator for me to check or other ideas?

 

That's not high at all. You meter scale is 0-18, which means the mid is 9. The needle is sitting approximately in the middle of 9 and 18, so estimate that at about 14-15 volts. Which is pretty normal. While my Tundra is a 2014 Gen 2.5, my battery voltmeter is usually sitting at around 14 volts.

 

That voltmeter looks fine for when the truck is up and running making 13.5-14 volts. Measure the battery with an actual voltmeter to be certain.

 

That's a dummy gauge. Get a proper multi-meter and check the voltage at the battery terminals then report back. Check the battery voltage before you start the engine, and after a good long drive to make sure everything is charged.

Most importantly check the voltage at the battery when it's running. Acceptable range when it's running is anywhere between 13.2V and 14.8V, but 14.2-14.8V readings are going to be less common, especially if you're running an AGM without a proper AGM diode fuse/ voltage regulator.

Anything higher than 14.8V with the engine running, take the battery to get tested ASAP.

If you have an AGM battery, the battery will read 13.0-13.4V when the engine is off and the battery is fully charged. You won't fully charge an AGM off your truck's alternator without a proper AGM diode fuse/ voltage regulator.

If you have a standard sealed/ maintenance free lead battery, it should read 12.5V-12.9V when the engine is off and the battery is fully charged.

If you have a battery where you add water, I recommend checking the water level before looking at the voltage. YouTube can teach you how to check the water levels in a non-sealed battery.

 

This is the correct answer. I’m glad someone else said it so I didn’t need to explain it for the 50th time.

 

My bad. I tried not to be that guy but the search brought up damn near the entire forum and I'm impatient. Thanks everyone! Will check with the multi-meter when I get to it to confirm. Y'all do not disappoint.

 

I swear it’s also in the 2000-2004 Owner’s Manual. I know it’s not sexy to read an owners manual or anything, but it’s really helpful with something as generally complex as a vehicle.

 

I don't remember if it's in the manual, but I checked my numbers in the FSM:

 

I don’t think the FSM shows gauges. Toyota has a copy of year every owners manual online, but I’m on mobile so it’d be painful to try and check it for gauge cluster reading. Here’s the link: https://assets.sia.toyota.com/publications/en/om-s/OM34417U/pdf/OM34417U.pdf

Anyone can grab an owners manual for their vehicle for free by hitting Google with TUNDRA OWNERS MANUAL YYYY

(where YYYY is your year)

 

Hot damn there it is.

 

But if it were me, I’d be more worried about that check engine light, unless the engine was off at the time of the 1st pic.

 

O2 sensors. And aiight, loud and clear.

 

If upstream, best get on that ASAP. Bad upstreams cause several other issues.

 

18 volts is acceptable? That doesn’t seem right. It’s practically acknowledging how crappy the voltmeter was designed.

 

I thought that was weird also.

 

Consistently 18 volts, that's bad. Lead acid batteries have a tendency of going into thermal runaway at that point. That leads to a battery going boom

 

Strangely that’s not what the owner’s manual is stating. But then again, 2 quarts for transmission fluid replacement isn’t exactly accurate either.

 

It's an extreme case, not something I'd expect them to put in an owner's manual. wouldn't be a good selling point

 

Did the OP actually measure it with a decent voltmeter?