Stock vehicle electrical limits and when to upgrade

[SoCoRuss]

Has anyone seen or know of a vid or reference guide that would tell you at what point your vehicles stock electrical system must be upgraded due to extra lights, winches and other appliances you would add on? I looked at Michael's OB you tube channel but didnt see anything. Attn Michael, this might be a good video suggestion.

I have a 4Runner and my son is in the process of getting a 2023 Nissan Frontier Pro4x. We were talking about adding lights, winches etc as we go and the question came up, how do you know when at what point you have to upgrade your electrical system with a bigger alternator, terminal boxes maybe a more powerful battery or dual setup due to the current draw of extra items??

 

[smritte]

The limits are going to depend on the alternator design and what you actually want to do. Battery is easy but alternator can be difficult. There's two designs of alternator and you need more info then the stock output spec. I can tell you my 19 Tacoma has the better design alternator and your new Nissan "should".

An example is, you have the older design alternator and want quite a bit of power at an idle. The old design's output is low at idle, which means your pulling from battery. As long as your battery is big enough, your fine. Once the alternator hits about 1200 rpm it puts out well. As long as your moving your probably fine.
The newer design puts out three times as much at idle. If what you needed to do didn't take it all, your good and you wont exceed the battery and alternator limits.

As you can see, the answer cant be given unless you know the exact vehicle configuration. The odds of a new vehicle having the newer upgraded system is very good but not a given. You figure out what you need and see if what you have will work.
My Tacoma will never need anything upgraded but my Cruiser needed not only more over all power but more at idle. Now I needed to upgrade the charging system. Because I needed more while parked for several days, two battery's and solar. The Tacoma will never sit that long so no reason to upgrade the battery or add solar.

Odds are your stock battery isn't going to be happy running a winch more than a few mins. If you plan on doing winching the battery needs upgrading. Long time winching, now you need two.
The average battery will draw 40 amps when low. Two battery's is 80 amps. You add in two battery's and run them low. If your alternator is rated at 100 amp output, you would think your fine except, its night and raining. headlights, heater and wipers. Now the draw is 110 amp. you overheat your alternator.
Most stock alternators will run a bunch of off road lights. As long as you don't push past 70% of the alternators rating, your good.
When do you need to upgrade? It depends.

 

[rgallant]

@smritte hit the high points but also consider what your alternator output is on my Discovery II it is 130 now but the stock unit was 100. One advantage is that you can go LED for your off-road lights, which cuts your amp draw way down over halogen etc.

Battery condition cranking amps and quality matters a lot as well.

 

[4Funner]

I was having this same discussion with a couple buddies that are (relatively) new to modifying adventure rigs for trips longer than a couple days. Combining the fact that none of us are good with electrical it's super easy to get caught up in the excitement of other people's builds and that rabbit hole is deep and expensive!!

Based on your inputs @amritte and @rgallant I'll be checking my alternator output since having installed a 12k winch recently. I went off the advice of people more knowledgeable than me and thankfully I've only done a few short pulls with it, but now I'm curious.

 

[OTH Overland]

Today's lights and accessories are more efficient than the old 150 watt driving lights of the past, and our alternators much more reliable. You also need to consider how many of your accessories will you be using at one time, we seldom have more than a few lights on at a time and the overall load is pretty low. The winch is the biggest draw by far, and even that has a work/rest requirement from the manufacture so you do not damage the motor windings, on a hard pull I take enough breaks to rest the winch motor that the alternator and battery have not had an issue (a good quality battery goes a long way here, and will not live as long a life as one not used for winching) and I avoid shutting down the engine after a winching session to allow a full charge back into the battery. The other large load is my DCDC charger for the house battery at 30 amps, the factory alternator easily puts the full 30 amps into the house battery at idle. (I did have to connect a trigger wire to the charger to allow it to 'request' power from the alternator or else it would not initiate the charge)

 

[SoCoRuss]

@smritte, how do you know if you have an older alternator system or the new improved one? As I said, my 4runner is 2021. Son's Frontier will be a 2023.

 

[Longshot270]

I guess it depends on the automaker but to me idle restriction isn’t relevant anymore. My truck is a 2017 Ram with nothing innovative under the hood. When I put a heavy load from my 2000 watt inverter, the idle automatically rises to compensate until it hits 14v again.