FJ60 Alternator HOT (1 Viewer)

[ChaserFJ60]

1984 FJ60 Dual battery's.

After a few min of driving my alternator gets too hot to touch. Even before I had the two battery's it would do this. Is this normal? I cant find anything else about this on MUD or the FSM.
Thanks!

 

[Seth S]

What is the voltage it is outputting. How are your batteries wired up?

 

[ChaserFJ60]

14V according to my USB charger from my 2nd battery. Battery's are temporarily connected directly positive to positive.
I soldered on new brushes a while ago and its been working fine in terms of charging ever since

 

[Seth S]

I’m not sure what you mean by temporarily connected. Positive to positive tells me they are wired in parallel. If wired in parallel your voltage stays the same but your current adds. It’s possible you are overloading the alternator as it tries to recover twice as much battery. Better to install some sort of battery isolation system so you are only ever running off of or charging one battery at a time

 

[Seth S]

Keep in mind that we often just read the voltage out of the alternator...but really this is only part of the story because there is a loading component and the alternator can output 14v at 10amps or 14v at 60 amps. If you are at max current output on your alternator all the time then the unit is going to get hot and likely experience a shorter lifespan.

 

[OSS]

I never thought of touching my alternator after driving. Of course it's going to be hot as hell

 

[gbogh]

^^^^This.
Keeping another battery at 14v with no other REAL electrical loads should not significantly change the demand on the alternator. On the other hand, if there is a problem with the alternator, one of your batteries has an issue, or they are unequally discharged you could be taxing the alternator significantly. I haven't played with dual battery setups in these rigs, but in other situations I've seen with multiple battteries/cells, charging balance/cell balance is important.

 

[ChaserFJ60]

My alternator did this before I had my dual battery setup, Im addressing it now because two batteries are harder on a system than one and I dont want to over load it.

When I say my battery's are temporarily directly connected im implying that Ive yet to install an isolater which Im going to do. and yes they're in parallel.

My 2nd battery at this time only powers my radio, Air compressor, winch, and USB charger. Its only been powering my radio 99% of the time.


@gbogh Wouldn't the battery's equalize over time?
Thanks for the replys guys.

 

[gbogh]

They should, but killywiggles do weird things sometimes.
I'm probably overthinking/analyzing it.
Are the batteries different ages?
If your batteries are connected in parallel with no disconnect/isolation, both of your batteries are powering everything.
If you're really concerned- take your alternator to your LAPS or a mechanic and have them test it for output. You can also run check battery health with a load test & electrolyte (if lead acid).

 

[Seth S]

When you directly connect two batteries in parallel they will try to reach equilibrium together. In other words the stronger battery will basically try to charge the weaker battery. So you can have some strange things happen if both batteries are not in top shape. The alternator will get warm/hot depending on how its loaded...or if it doesn't have the cooling fan on the pulley. But I've also had plenty of alternators that stayed cool during operation.....its all dependent on how much electrical load you are putting on the alternator. lots of lights, a big stereo, heavy winching, other accessories etc can boost demand.

 

[ChaserFJ60]

@Seth S Just a computer for my 2fe, the AC, and the radio is all its charging. It held a steady 14v on a longer drive today. I was really just worried that it would overheat and shorten its lifespan. Both batterys were purchased relatively close in time to each other.

 

[Seth S]

@Seth S Just a computer for my 2fe, the AC, and the radio is all its charging. It held a steady 14v on a longer drive today. I was really just worried that it would overheat and shorten its lifespan. Both batterys were purchased relatively close in time to each other.

Other things to check are:

1. are your battery terminals all clean
2. are all of your battery cables in good condition
3. are all of your ground wires clean and in good condition
4. is your fusible link in good condition

A hot alternator isnt a worry point. if its getting so hot that you risk a serious burn by brushing against it there might be a issue. I'd go check mine but I cant run my engine right now.

 

[ChaserFJ60]

Other things to check are:

1. are your battery terminals all clean
2. are all of your battery cables in good condition
3. are all of your ground wires clean and in good condition
4. is your fusible link in good condition

A hot alternator isnt a worry point. if its getting so hot that you risk a serious burn by brushing against it there might be a issue. I'd go check mine but I cant run my engine right now.

Ill brush the terminals off but I would call them to be in a favorable condtion. I added 2 New ground cables a while ago, One to the starter(frame) and another to the engine block. When I painted the engine I pourposly left the faces of the engine mounts / accessory mounts bare to avoid a grounding issue. Ill test the fusable link with my ohmmeter tonight. Excellent suggestions!

 

[ToyotaMatt]

Chase

Are you running the stock fj60 unit ?

The one with the voltage regulator saddled to the side a bit size of a. Pack of cigarettes?

This unit here 27060-61071


If so , you should consider doing the field tests on the regulator and see if your main unit is FULL-Fielding

Or simply pumping out 55+Amps 24/7 ?

I don’t know much about a dual
Batteries set up but I can only conclude maybe its too much stress on the system

Grounds

And all connections must be checked

Esoecially the ring terminal at the back of unit it self for a solid clean contact and current flow Accross the board



I have a case. Of NoS regulators like the one picture shows example

Let me know if you have this unit ?

I will include one in your parcel being shipped out tommorow first thing