I'm doing a bit of an overhaul on my 2000 Limited 4Runner. I have a 1 year old Duralast Platinum 60Ah Battery (considering going classic dual battery soon, but somewhat unrelated).

I just ordered a 320A alternator and want to protect it and my AGM battery, any way I can.

Are these voltage boosters required for 3rd Gen 4runners with "dumb" alternators? I'm already reading 14.4V to my battery with my ScanGauge II and also on my hardwired radar detector.

There are ways to bump up the voltage. One is with a gm alt diode, though without some tricky wiring you'll loose the fuse protection on the sense wire.

I did this a few months back on my cs144 alternator. Didn't like all the whacky wiring or the way it performed, so I just bought a preset voltage regulator and swapped it out inside the alternator. It's now charging at 14.8v cold and 14.6v hot, can't complain about that. I have an Odyssey 27f agm.

I designed a voltage booster diode PCB that plugs right into the stock fuse panel. I have not tested the system though.

I bought a HKB adjustable voltage booster from Oz to use with the standard 80A Toyota Denso alternator. MK4 Adjustable Alternator Voltage Booster | HKB ElectronicsI've had it in for about 2 years. Seems to work fine. Experimented with +.4 vs +.6 V boost; Results inconclusive, either is better than the feeble stock voltage outputted by the stock alternator.

Interesting what Interstate has to say about charging an agm batt. Now I get it that they're talking about a stand alone charger yet I think the same guiding principles apply. More current not so much extra voltage. Here's why.

Here’s How to Charge an AGM Battery and Why It’s Different | Interstate Batteries

Interesting read for sure. But stand alone charging is different then use charging. Requiring different cycles and voltage/amperage.

Best bet is to check what your manufacturer says or call/email them to find out for sure.

I was liquored-up one night and bought the Australian plug n play fixed-voltage unit. I have not had a chance to install it and observe the results yet.

7.5A MK3 Mini Blade (Electronic fuse version) Micro Blade/Low Profile compatible) | HKB Electronics

A warning about counterfeiters/functionality may be of interest to some: Warning | HKB Electronics

I have a 2019 so my needs were different. But i got the arclight voltage booster which has OEM voltage, a .5 boost and 1.0v boost which was a great decision because the full 1v was too much in the winter. Its also fused which is nice, but only for pre 2020 models.

AGM batteries though look great on paper, but you have to drive more than an hour a day to charge up enough over time. This was my problem with only 30min a day driving most of the time.

The sweet spot for charging my AGM as 13.6v over time, so i have my voltage booster set to +.5a. But in your case it looks like you are charging at 14.4 so you probably won't need a voltage booster at all and just trickle charge now and then depending on how big of an AGM you have.

I have a CS144 that usually reports good voltage but I think it's regulator is messed up because sometimes when I'm in gear and the RPM's drop below 1K (at a stop light) the voltage drops to 13 volts until I get moving again. It doesn't happen all the time, but I noticed it happening more often in summer where the voltage is already downregulated. Can you link to the regulator you used and how you performed the swap?

Sure I can, here it is:

Regulator

It requires taking the whole alternator apart, some soldering and reassembly. Here's a few vids

https://youtu.be/riYZssdSmXY?si=si5jHnwPGgbhpj3d
https://youtu.be/vKbX7mezuFM?si=FrD6TZKzKURLWqyU

Your voltage dropping at idle might mean your pulley on the cs144 is to big. Not spinning at the proper ram's. I changed mine to this:

Pulley

But only do that at your own risk. It can break your alt due to over reving the alternator.

Keep in mind that 13V is not discharging the battery - it just isn't CHARGING the battery. The truck is still running off the alternator - if things got down to 12.7V or lower, then you are running at least partially off the battery. 13V in some operating conditions (say, HVAC on full, all lights+brake lights on at idle) is not the end of the world.

-Charlie

In my 97 build and repair thread I show how I made VR booster using the GM diode and a fuse circuit doubler to use the diode and keep the fuse protection.

That happened to me as well and it turned out to be a dirty positive cable connection. I took off the cables, cleaned them good with rubbing alcohol and put them back on securely and back to 14V+. It was an observed drop as when I installed them it was fine then it slowly started to drop.