1FZ alternator overdrive pulley source (5 Viewers)

[spensert5]

Looking at options to increase amperage at low (trail speed) RPM. A 140-150A alternator will help at higher RPM, but still doesn’t accomplish much more than the stock 80 alternator at idle or low revs. It’s getting hot here in the south already and I want to run my lights, blower in hi, aux fan, etc while moving slow on the trails.

I missed the chance to pick up the Wit’s End overdrive pulley and haven’t seen them come back in stock. Is there another source or do I need to look at machining my own? Is there another solution for increasing amps on the trail or in traffic, etc?

 

[landtank]

So I pulled the data sheet from the alternators in my upgrade kit and they state that at 1600 rpm (alt) the output is 88 amps. I took some hasty measurements of the crank and alt pulley and it would seem that an engine RPM of around 915 would spin the alternator at that speed. I have to believe if the truck is moving you are at least at that RPM.

I don't see an undersized pulley getting a stock alternator to that output at that RPM.

 

[spensert5]

@landtank ok, so maybe we are better off bumping up all together rather than overdriving the stock alternator. With your math and what the upgraded alternator will do, we would be getting over the max stock alternator's amperage at "trail speed", which is what I am looking for.

I know much of this would be dependent on wear, etc., but I wonder what the amperage/rpm curve looks like on the stock 1FZ alternator. I did a lot of low speed poking around yesterday with my low beams, fan on hi, aux fan, and radio going and my voltage dropped into the 10-11V range and stayed there until I was back on the highway. Maybe that's not a huge concern but I want to be covered if when I add additional demand or heaven forbid have to use my winch on one battery....

 

[BILT4ME]

@landtank ok, so maybe we are better off bumping up all together rather than overdriving the stock alternator. With your math and what the upgraded alternator will do, we would be getting over the max stock alternator's amperage at "trail speed", which is what I am looking for.

I know much of this would be dependent on wear, etc., but I wonder what the amperage/rpm curve looks like on the stock 1FZ alternator. I did a lot of low speed poking around yesterday with my low beams, fan on hi, aux fan, and radio going and my voltage dropped into the 10-11V range and stayed there until I was back on the highway. Maybe that's not a huge concern but I want to be covered if when I add additional demand or heaven forbid have to use my winch on one battery....

If you're going to do a winch, install a hand throttle.

Hand Throttle installation 96 LC

Possibly for the FAQ: This week I installed the Toyota Hand Throttle in my 96 LC so I can keep the RPM up for winching, jump-starting, and in my immediate need, keeping the RPM up while allowing my LC to warm up and circulate distilled water for a coolant flush sitting in the driveway. I...

forum.ih8mud.com

 

[baldilocks]

Looking at options to increase amperage at low (trail speed) RPM. A 140-150A alternator will help at higher RPM, but still doesn’t accomplish much more than the stock 80 alternator at idle or low revs. It’s getting hot here in the south already and I want to run my lights, blower in hi, aux fan, etc while moving slow on the trails.

I missed the chance to pick up the Wit’s End overdrive pulley and haven’t seen them come back in stock. Is there another source or do I need to look at machining my own? Is there another solution for increasing amps on the trail or in traffic, etc?

What indications have manifested which tell you that you need to alter your charging system?

 

[spensert5]

What indications have manifested which tell you that you need to alter your charging system?

Lower than 12V with high electrical demand while moving slowly and/or at low RPM. Slow windows after new runs and motors. Pull the window switch and watch the meter drop 2-3V.

Maybe I’m being too picky?

 

[Fosters]

Try the gm diode on the charging circuit…
A search on mud will reveal all

 

[LC4LIFE]

If you haven't yet, swap the alternator brushes. Its and easy maintenance item and many see an improvement from simply doing that.

 

[spensert5]

If you haven't yet, swap the alternator brushes. Its and easy maintenance item and many see an improvement from simply doing that.

Just did that actually and hoped it would help, but still the same.

 

[baldilocks]

This subject has come up many times in the ten years I’ve been on Mud so several years ago I did an internet search and found a table that listed the typical electrical demands of the equipment/accessories installed on automobiles.

All typical accessories turned on to include the fuel injection and ignition system added up to 62 amps. This does not include a million amp stereo or all passengers running windows up and down nonstop and simultaneously.

My personal experience winter wheeling, for instance, with defroster/heater on, lights on, wipers on, puny not crazy stereo going and a winching operation or three sprinkled in through out the day, is zero issues with a battery discharged too low to restart the engine which is our main concern. As for slow windows, they do get slower when the exterior of vehicle is wet, that’s just how it is.

As stated before, a hand throttle solves a couple issues. Always use it during winching and jump starting ops. When coming to a stop to break for a while use the hand throttle to bump rpm’s up to charge that battery for a bit before shutting down if there are concerns about restarting.

I’ve been at this game since the late 80’s and the 80 amp (conservatively rated) alternator on the 80 series is the most powerful alternator I’ve ever had in a vehicle that I’ve used off road and never have I had problems or been left stranded with a dead battery.

Also stated before is the fact that the alternator is putting out at capacity at an rpm we will reach on most off road conditions.

 

[BILT4ME]

Just did that actually and hoped it would help, but still the same.

I have an UltraGauge that I use to watch my voltage on the alternator for that reason.

If I pull up to a stop light with my (4) 100W driving lights on, headlights on with hi-beams, the heater fan on high, the rear hear fan on, and the rear window defroster, I can watch the voltage output at idle decline to as low as 11.2VDC if I allow it to get that far before I shut off something. That has to be a really long light (about 3 minutes) for it to get that low. My turn signal will start to chatter about 12.2VDC.
How often does this happen? About once per year, for 3 minutes.

If I'm wheeling and I have all those accessories on, I need to adjust the load. Turn off something. If you're wheeling, you don't need the stereo blaring, if on at all. If all your windows are down, maybe turn off the AC.

If you have a fridge and other accessories, maybe consider a second battery and solar for keeping that one up to charge and having it as a back-up battery for the truck.

Is it so hard to be slightly inconvenienced without your electric hot-dog cooker and deep fry air oven while out wheeling?

 

[spensert5]

I appreciate all the suggestions and ideas here. I could probably continue to “get by” with the stock alt, but went ahead and ordered a 150a kit from @landtank

Hand throttle is on order as well.

This way the kids can play with the window switches and we can run the AC all day while moving slow in the dirt. And I won’t have to watch the meter move up and down when I turn on the blinker.

 

[LongDuck]

Something else to consider is that overdriving your alternator so that it's spinning faster at idle will cause more wear and tear on bearings and belts when you're back on the freeway running 2400rpm on the engine to drive 75mph for hours on end. Your alternator is going to get hot, and your bearings will take a beating over time.

Case in point, my other ride is a Mazda Rx7 with a rotary engine that redlines at 7k RPM, so for spirited driving, it's common to underdrive the alternator so you don't burn it up. For cars that get tracked or just driven hard at higher RPM, it makes a difference, and this is paired with going to a more powerful alternator (*70amp vs 55amp - these are small cars, remember).

As an interesting aside, the retrofit pulley also offers 2 belts, replicating what the Toyota FZJ80 gets from the factory. Normally, its only one alternator / waterpump / eccentric shaft belt.

 

[landtank]

With what you are doing I'd add a new Ground cable. Worn and corroded it can have an adverse effect on supplying voltage to devices and the alternators ability to do it's job.