Alternator Voltage

So, this condition, if you will, only was brought to my attention because I have Drone Mobile and it was warning me about a low battery. It was often 12.1 to 12.2. The battery was replaced about a year and a half ago and O'Reilly's honored their warranty and now I have a brand new battery.

Both batteries (I suppose the alternator, really) would often never reach a voltage more than 13.9v with the truck running. Often 13.7v, with no large accessories running.

I know from other threads ( https://www.tundras.com/threads/best-battery.101105/page-3 ) that one observation is that our stock alternator does not go much higher than 14v.

With that said, general alternator research suggests my alternator voltage is technically low, and would be better to get above 14v.

While some here are mechanics, I am also interested in hearing from owners.


Question: During normal driving, where does your alternator voltage gauge hang out? Is my "14, less than 14" average for Tundras? I can tell you that I took a meter to mine, and it is consistent with the reported voltage in Drone. It is also consistent with the dash in the truck.

 

Around 14 or under is normal for stock. Search for voltage booster. There’s a lot of threads about it. There’s 2 options, hkbelect makes one or get a gm diode for $5. Both replace the ALT-S fuse under the hood. I’ve been using the gm diode for a year with no issues. My truck usually starts around 14.4-14.7 then settles down to 14-14.2 after driving awhile.

I got the gm diode off Amazon.

https://www.hkbelect.com/products/toyota?model=tundra&year=2015

Edit: I should’ve clarified that I have an agm battery.

 

The voltage you're getting for your 2016 is correct for the type of battery that you have - or the type of battery it's supposed to have. If you had an AGM battery (which is not the type that came with a 2016) , then you would need it to be in the 14.5v range.

 

Any risk of putting the diode in without AGM battery?

 

Mine runs at 13.7 on my Scanguage. I'll look to see what my other indicators show.

 

Google says:

 

Totally get the risk of overcharging. I suppose I should have asked if 14.5v is too high.

 

@NHPig your alternator is in the normal range for a Tundra.

If you are running a standard lead acid battery there is only a small advantage with taking the voltage up (to about 14.2) and only if you have accessories like a winch that deep discharge your battery. If you aren’t running any deep accessories just leave it as is.

A GM diode with a lead acid battery takes the voltage too high and could damage the battery.