Stock electrical system excess capacity?
 

With the stock alternator (and pretty much everything else stock), how much spare capacity is available from the alternator in an 2021 ORP assuming everything else (that makes sense) is on? The main loads would be headlights and running lights, starter battery charging, audio system playing, and either a cold weather situation (heat on, seat heaters on, rear defrosters on) or a warm weather one (A/C on max). Any other big loads I missed there?

Trying to size a charger for a second battery bank, and I don't want to nuisance blow the alternator fuse or keep the starter battery from charging.

Thanks!

The fuse box covers will tell you by the amp rating of the fuses. Big ones off the top of my head are going to be the PTC heater and any other heat strips, the brake booster, but that is a short duration draw, and the inverter

Hi scfw0x0f,

It's like Jeremy556 said: You likely have a 130A Stock Alternator! Size-up your loads; based on BOTH of your fuse-boxes: (Main [ENG RM]) and (D/S fuse-box covers). Once you calculate your standard-(Typical-loads), you subtract that# from the alternator's capacity (or 130A); I did it with my 4Runner and calculated using about 80% of the stock alternator's full output... (Not considering the fuel-injection/IGN Systems, and 27 compu's in operation!)

NOT GOOD for any sizable "Add-On's!"
So I went with the Power Engineering 270-XP to handle ANYTHING that I might; or already had added to my truck! Never have had a problem... "Loadwise!" ...and it charges the ODYSSEY EXTREME 1500T AGM @14.64V and 200A curb-side idle!

~rig~ Best to you!

Keep in mind that the alternator ratings are at rpm and not at idle.

Hi seatia,

That's true, but that doesn't change the alternator's "FULL OUTPUT CAP!" On the other hand... the "Power Engineering 270-XP puts out 200A @Curb-side idle, (compared to Denso 130A full output); more than enough for add-on's e.g., LED lighting, a fridge, BIG Sub-woofer system...etc, ask me how I know! LOL!:whoo:

~rig~ Best to you!

Thanks for the replies.

I think I'm stuck with the stock alternator, unless Power Engineering's 270-XP can fit on a 2021 ORP (it's not their list). Does anyone know what changed between the 2017 (last year listed for the 270-XP) and and 2020? It's weird because Toyota Parts says that the stock alternator (270603126084) fits a wide range of 4Runner, way back to 2015 and before.

An interesting data point: these folks claim to have a 250A alternator that fits 2014-2022 4Runners. Any experience with them (Power Bastards)?
250A High Output Alternator for Toyota 4Runner, 2014 - 2022 4.0L V6 (241c.i.) - 11764-250-HD1-1 | PowerBastards.com | PowerBastards.com

Thanks!

Nothing has changed since 2010. Maybe even back to 2003.

"Trying to size a charger for a second battery bank"
Can you expand on what it is you are doing? A second battery bank for what? An alternator is a pretty good battery charger by itself.

That's what I thought, so I don't understand why DC doesn't list newer years on their fitment list.

I'm sending a request to Singer as well; he seems to have a good rep. Power Bastards, not so much from reviews I'm seeing elsewhere. Could just be the usual problem of if you sell enough of a thing, some will be bad, so if you sell a lot you get more negative reviews. But still a caution flag.

How about Mechman? They have a part they claim is direct-fit.

I'm putting in a 3kW LiFeP04 battery bank in the second row area, 24V@125Ah (2nd row of seats removed; the packs go in the footwells). The charger part is straight-forward, two Victron Orion 12/24-15 chargers in parallel (yes they are designed to do that). If you want the math:

29V (absorption voltage) * 25A (preferred charge rate) = 725W
725Wh/0.88 (charger efficiency) = 823W (load at alternator)
823W/13.2V ~= 63A new load on the alternator

Those are all vendor spec numbers for the battery and charger. Yes I'm ignoring cable losses for now. 15 feet of 6 AWG would be about 0.8V drop, so really closer to 66A at the alternator.

It's 24V because the wiring, fuses, etc. all get funky big at 3kW. I'd rather do 48V but I can't get the packs that fit the space in 48V, and the 24V packs I can get can't be run serial, only parallel.

Thanks again!

...does your Denso 130A Alternator have STANDARD 4-pin harness, or (1) single pin in the harness cavity? If it has 4-pins, you're just like the rest of us [5'th Gen 4Runner] BTW: They're a little slow about keeping-up on their catalog products; mine wasn't in there for months when I 1'st bought it either! You can call-em: (888) 441-0144 (Pacific time)! Or use this link:

Product Result
– DC Power Inc.


~rig~ Best scfw0x0f!

Interesting and useful data, thanks! I'll have to check.

Oh,

Be careful about using Mechman; High Output (hair-pin) Alternators are NOT just built by squeezing more windings & capacitors in the End-frames... They're (Basically) High Efficiency Heat-Sinks that are able to remove tremendous amounts of Heat from the windings, and X-fer it to where it's NOT Objectionable! ...Something to keep in mind when choosing an alternator; they're Not All Built the same way!

rig

Okay so this is fascinating. Tagging @rigtec and @AMLOR on this, and @DCPower_Anthony .

Just spoke with Anthony @ DC Power. Apparently the main problem with more recent 4Runners is that Toyota moved the alternator slightly, and he hasn't been able to get a newer truck in his shop to work out the fitment kinks. Might just be some spacers.

I'm no where near Orange County but maybe some other reader would be willing to have their truck be a test subject?

He's offered to send out a unit to someone who can wrench it themselves (that's not me, I stick to weird electrical stuff :) ) and take it back if it doesn't fit.

Any takers? Or anyone near OC who is willing to be install #1?

Hello again everyone!

As mentioned above something has changed after 2017. I either need a 4Runner here or I can send one to someone who's willing to give it a go.

Nice to see this forum is still thriving!

If the 270-XP's End-frames are the very same, and just the mounting brackets are a lil' different, why not go to the dealership and compare the differences btwn the older and newer part; you're not buying the part, just gonna see how/what needs to be adjusted, bent, tweaked...etc!

Ask Anthony what he suggests... maybe you can find out what changes are needed, and tell @DCPower_Anthony " :noidea:

~rig~ Best scfw0x0f!

The parts call for the same alternator between the years. I had two customers have issues with installation. They weren't doin the work themselves so it was hard getting their mechanic to work with us.