Alternator upgrade (1 Viewer)

[000000000048]

hey everyone. I'm a Beginner when it comes to electrical equipment in my fj60. Anyway I'm looking to upgrade my alternator in my 85 fj60 for a possible dual battery set up. The dual battery will only be used for lights and winch. So my question is, would I really need a new alternator for dual battery setup? And if I do what alternator would work well?

 

[lovetoski]

you don't "need" an upgraded alternator for a dual battery setup. but if you want to upgrade, the 80 amp fj62 alternator is a good route. there are some posts on this, it's pretty simple.

 

[87CRUSR]

There are many rigs with systems running lights and winch with one battery and two batteries using stock and aftermarket alternator options and every combination therof. Two batteries is a redundancy solution for peace of mind and more options (fridge?) if nothing else. Personally, I am moving forward with 2 batteries and a mean green alternator.

 

[Output Shaft]

The stock 55 amp FJ60 alternator (when operating to spec) is perfectly matched to a big winch. It's not alternator output that's the bottleneck, it's heat dissipation of the winch. By the time the winch cools enough to run another short pull, the stock alternator will already be tapering its output.

Winches run on batteries. Lights run on alternators. The stock (properly working) 55A alternator has plenty of power to drive the car all night long with 80/100 headlamps, fan on, and dual 130 watt off-road lights.
At idle though, its output is decreased.

The higher output alternators will/should last longer as they are not being run near their limit, and they usually have higher output at idle, which is noticeable when driving at night in stop & go traffic. Lights dim a bit at stops with the stock alt.

 

[NookShneer]

Alternator altering

Probably the simplest step-up in amps with the least amount of work/cost.

 

[000000000048]

Awesome! Thanks a lot for the great replies all! You just saved me some dough! My brother in law has a fj62 with the 80amp alt that he's parting out so hopefully he hasn't gotten rid of that yet. This was lots of help to noob thanks!

 

[Landpimp]

If you want a little piece of mind and don't want to do dual batteries, get one good quality battery and get one of those small backup battery jumpers/booster, under $100. Yeah, it won't run a winch or fridge but it will get you started if you drain you battery.

 

[RBA]

Let me preface by saying I suck at electrical work.

I have a voltage gauge plugged into my cigarette lighter to monitor my battery. With the stock alternator on my '89 62 my battery voltage at idle with the AC on and using power windows, the voltage would drop to low 12. If I had the stereo on and the AC on position 2 or higher, the voltage would drop under 12 to 11.8 or so. When I upgraded my headlights to higher output bulbs the situation got worse. I ordered a high output alternator and while the situation is better, I've learned that my grounds are not good enough and I need to upgrade them to raise the voltage (according to the vendor). Since I have a winch also, I'm concerned that when I need it most, things will not work.

Are you guys really sure a stock alternator is enough??

 

[60Works]

Yes.

 

[Output Shaft]

The stock radio power source is shared on the same line as the cig lighter.

If your stereo is on that line, then there will be a voltage drop at the cig socket when the radio is on. But this drop will not accurately reflect the actual volts at the battery.

Check the voltage at the battery terminals to be sure.

 

[RBA]

Ah....thank you. I need to check on that.

 

[Cruiserdrew]

Yes-you are reading the voltage drop, not the true voltage of the battery.

In my opinion, the stock alternator is plenty for most people. Winches do not run from the alternator. There is no alternator big enough to supply that kind of power. A dual battery system is far more useful than an upgraded alternator.

Upgrade the alternator if you have large continuous loads on your electrical system. If it's just headlights, blower fan and normal stuff, the stock alternator is built to handle that. If you run Klieg lights, maybe you need more electrical power.

And one other thing-there is no reason that running dual batteries means you need a higher capacity alternator. And running a higher capacity alternator, means upgrading the wiring, figuring out a mount, etc. Not needed if you stick with the stock alternator. If your ongoing need for power is say 20 amps (and that's plenty for any amount of normal lighting), things are not better because your alternator can supply 150 amps.

 

[RBA]

So after reading this thread I decided to do some additional testing.

I did upgrade my alternator and here's what I'm seeing. On a cold start up, my dash gauge (which is connected through the lighter) showed 14.10 V. I turned on the radio, AC (2nd position) headlights (100W bulbs), hazard lights. As soon as the truck warmed up and the rpm dropped below 800rpm (Usually around 600rpm), my voltage plummeted. At the battery it showed 12.2V. Inside the truck on my gauge it showed 11.2V. I would expect (and I'm not an expert) that the voltage at the battery with the engine running shouldn't dip below 13V and be closer to 13.5. My modern truck keeps it above 14V.

Any thoughts on causes or remedy?

 

[60Works]

You will find that at your 14.1 'modern' volts, bulbs will fail sooner, lenses will melt, and you are risking gauge components which were designed to operate with 13.4 'old wimpy' volts.

Every modification has unintended consequences. Your test scenario, while interesting, isn't what you will tax your system with in normal operation. Most alternators, even new ones, perform poorly at idle. If you begin draining your battery above 1200 rpm, then it would be time to second guess Toyota engineers.

 

[lovetoski]

It's an old truck, and the wiring may be accumulating corrosion, which is resistance, which leads to voltage drop.
That's one reason people run a higher wattage bulb via a relay. Do you have a separate headlight harness? If not, I'd suggest it.
Also, you can add an 8 ga wire directly from the + on the alternator to the + on the battery (include a fuse in it). This will minimize voltage drop as well.
For my climate (pac NW) I believe the stock alternator has too few amps for our wet/dark/winter driving. Lights + two heaters + rear window defrost + wipers + radio is too much at low rpm. Fine on the highway, but getting to the highway will be a pia.

 

[John McVicker]

I've also done the 8 gauge wire w/fuse from the alt to the battery. Did the trick for me also.

John

 

[RBA]

What size fuse would you guys recommend?

 

[RockDoc]

Something between the output of the alternator and infinity.

 

[John McVicker]

RBA,

I used a big honkin 60 amp fuse. Have to get a larger holder, but they're easy enough to find.

John

 

[Cruiserdrew]

Regarding fuse size, the only thing you need to know is the size of the wire. That's what the fuse is there to protect. 8 ga wire = 60 amp fuse. 10 ga wire = 30 amp fuse. Be careful about this, because you don't want to burn down your truck.