1-hdt alternator issues

[coffeebean]

I have a Lexus lx450 with a swapped 1hdt with a single battery set up.

Had the stock oem alternator replaced a few years back with another oem, ran fine for a few years and just started seeing low voltage again (in the range of 12.1-13.2 on idle and throttle).

Had the alternator swapped again and truck was running fine, voltage at 14.1 on throttle for a few weeks but have again started seeing a drop in voltage in the past two days, back down to 12.3 at idle.

Ive peeked around the sub on the topic, outside of cleaning grounds, possible regulator issues, any other suggestions or possible culprits I should look out for?

 

[67azcruizr]

my initial thought, because its the simplest and possibly the most common variable to rule out, where is the alternator from (e.g. factory rebuilt, new OEM, Denso grouping or maybe ebay/Chinese knock off?

I have received 'not so good" information about aftermarket windings, rectifiers and internal regulators. if i were to guess, it sounds like you have either a bad regulator or rectifier or both.

2nd, and perhaps easier than my first suggestion would be to trace and clean ALL, major and smaller, grounds

 

[TheBussman]

a genuine Toyota 1hdt alternator is over $1k is that what was for sure installed? Is your idle speed correct? belts tight? Do you have a large load like charging up a big AUX battery or something else? are you watching the factory gauge or using a different instrument?

 

[TreadingLight]

Bad battery. Bad fusible link. Bad voltage regulator (they are replaceable).