Charging Problems? (1 Viewer)

[70 FJ40]

I'm trying to make sure my charging system is working as it is supposed to. I've just replaced my batteries. The old ones lasted nearly nine years. I have 2 batteries connected together as one. Everything else in the system is stock. I took the alternator off and took it down to be tested at an auto electric shop. The guy told me all was up to par. Reinstalled it with new batteries and with the truck running and even revved up a little all can get is 13.16 volts at the battery terminals. Seems like this is too low. It should be closer to 14 volts or higher. Correct? Do I possibly have a failing voltage regulator? I did clean all the connections very well, so I don't think that's my problem.

I have what I'm sure is not original connectors at the alternator but they seem to connect tightly. This could be where the problem is. ???

 

[70 FJ40]

Also is this my voltage regulator?

 

[DeskJock]

That relay next to the coil is for the horn.

I can’t see enough of the alternator - it’s orientation doesn’t look factory.

In a factory setup, the voltage regulator is under the master brake cylinder.

With the duality battery setup, I suspect you have an alternator that puts out much more than the 45/50 amps that a stock setup could do. Note - that you can’t run much more than 55 to 65 amps thru your dashboard or fuse box.

Voltage to the battery changes as the voltage regulator dictates - depending on what voltage the regulator see from the battery.

My stock configuration will push 14.2ish voltage when it in its max charge rate.

There are several write ups in this forum on this specific topic.

I suggest using the the search function and read thru the threads and find on that comes close to your setup.

13.1 volts sounds like the voltage regulator is in a float mode

 

[70 FJ40]

Thanks for the tips and voltage regulator location. It is a stock alternator. I have a vintage air conditioner. That moves the alternator from it original orientation

 

[charliemeyer007]

So with everything off test the voltage at the battery terminals. Then fire it up and test again using the same meter at a good fast idle. Now turn on the headlights, heater fans and test again.

If you have an external voltage regulator, they can often be adjusted - procedure in the manuals. at least clean the contacts.

 

[Grayscale]

Check the 'engine' fuse - it turns on the voltage regulator. Remove the corrosion at the terminals.

Does this harness have a fusible link?

 

[70 FJ40]

Check the 'engine' fuse - it turns on the voltage regulator. Remove the corrosion at the terminals.

Does this harness have a fusible link?

I don't know if there is a fusible link. I've been seeing lots of talk about them and have wondered if I should probably add one. But then I comfort myself with the fact that the truck has been fine the way it is for nearly 48 years. So unless there was one from the factory I doubt I have one. How/where would look for one. I have added an aftermarket fuse panel and 50 amp breaker with some extra 12 volt outlets and a hot wire at the trailer plug coming off the panel. Also i switched to the Koito headlights and a set of off road lights. There was the vintage air add on a couple years before I bought it. Otherwise the rig is pretty well stock.

I will do the test that @charliemeyer007 suggested here in just a bit.

 

[Grayscale]

A fusible link is just a section of wire that is smaller in gauge, and it has insulation that melts before it burns. The advantage over an inline fuse is that it doesn't burn up and ignite flammable hydrogen that your battery(ies) might be out-gassing during heavy use, or a short. You can find them everywhere, but, finding the correct size might be a hurdle. Any wire connected to the positive terminal, that isn't the cable for the starter, can use them.

 

[70 FJ40]

Forgot to say, I checked the "engine" fuse. It appears to be fine.

 

[charliemeyer007]

Always a good plan to test the volt meter calibration, some times they go out of adjustment and lie.

 

[timmyisinthewell]

You might try to get in touch with coolerman here on the forum. I believe he has fusible links as well as wire, connectors and such for these trucks.

 

[DeskJock]

You might try to get in touch with coolerman here on the forum. I believe he has fusible links as well as wire, connectors and such for these trucks.

Second this. He also made me a backup.

Without a usable link - you run the risk of the power cable to the battery melting and shorting to ground - which then - the battery boils and possibly explodes/ catches fire.

In my 75 rig - what was there kinda looked like it might have been a fuse-able link - it won’t risk a maybe on that power supply- personally.

Coleman is super awesome and fast.

 

[peesalot]

X2, sounds like your batts are at voltage. the regulator is working and in float, do what Charlie mentioned and it will draw a load on the batts, regultor should kick into charge mode and you should see a charge voltage at batt. pics of your batt + side going to starter wires will show a fuseable link , usually just off batt +.

 

[JohnnyC]

I love when the car parts guys tests the alternator and says its all good... ëven the regulator?¨ .... they say yes its fine lol

I say... funny because its an external regulator

x3 sounds like your fine IMHO

 

[70 FJ40]

OK. So the guy at the auto electric place told me that I have an external voltage regulator, so he couldn't say if that was causing problems but the alternator tested out good and "very consistent".

Did some testing this morning.
Cold before starting batteries were at 12.71
Pulled choke, started it
13.65 slow but steady increase to 14.35
Warmed up a bit and amp gauge returned to center pushed choke in
13.55
Turned on headlights
12.95
Turned on headlights and off road lights
12.75
Turned off all lights
13.02
Revved motor
14.28
Turned truck off.
13.06

All this seems good to me except shouldn't it be putting out more volts when the lights are on?
Again, batteries are are brand new(installed last night) group 24 Interstate and wired together as one large battery.

 

[DeskJock]

It’s likely to pull more voltage with the lights on - but - it boils down to what voltage the regulator see on the battery.

Note - the regulator only tells the alternator which of the 3 levels of voltage supply the alternator needs to send. The regulator is a very - very simple device.

Amperage is handled by the alternator- and I think that that is a resistance issue in the battery - I think.

 

[peesalot]

Sounds like proper operation to me. If you are concerned, go for a 20 min drive with all elec acc on, test when get home, if its at voltage your alt & system are performing.

 

[70 FJ40]

What voltage should the batteries be after a drive like that?

 

[70 FJ40]

Also is this a fusible link?

 

[JohnnyC]

Yes that’s the fusible link