Trouble shooting Low Voltage

[JoshFulk]

Ok so I just replaced 2 batteries in the truck last month. The old ones were completely dead. So I have been running just fine I go to return truck and it wouldn't do it due to low voltage. I took the batteries to be testes and they tested good. Pre startup the voltage is 11.5 then once going it will gradually reach 13.0-13.4 volts just takes a couple minutes but once I shut it down and let it sit 15-30 or try to tune it jumps back down to 11.5. Took the truck by autozone for a quick check and that guy hooked it up and done a alternator check and he thought it could be a voltage Regulator going bad or is it an Alternator?
Thanks for the help an if its the voltage Regulator where is it from the Alternator?

 

[Atsah]

Ok so I just replaced 2 batteries in the truck last month. The old ones were completely dead. So I have been running just fine I go to return truck and it wouldn't do it due to low voltage. I took the batteries to be testes and they tested good. Pre startup the voltage is 11.5 then once going it will gradually reach 13.0-13.4 volts just takes a couple minutes but once I shut it down and let it sit 15-30 or try to tune it jumps back down to 11.5. Took the truck by autozone for a quick check and that guy hooked it up and done a alternator check and he thought it could be a voltage Regulator going bad or is it an Alternator?
Thanks for the help an if its the voltage Regulator where is it from the Alternator?

I would say Alternator.. When the truck is running, checking across the battery you should see at least 14V, normally 14.5 or so when the alternator is working correctly..

 

[JoshFulk]

but wouldn't the regulator going out cause a Low voltage also?

 

[Atsah]

The regulator is internal and yes, it could be causeing the problem, a new alternator is the answer.. Check all your grounds and make sure nothing is rusted and that everything is making good contact..

 

[JoshFulk]

What is the advantage to a higher output Amps on an Alternator? Im looking at DC Engineering

 

[Atsah]

I have alllways had a 200 amp, I plow snow and power a winch, never needed anything more..

 

[GreenMachine]

I'm having somewhat of a similar issue. My livewire is telling me my batteries are in the 11.5 range with the key turned on. As soon as I crank the truck over they drop into the 9 volt range. As soon as it starts and runs she fires back up to 13 volts on the livewire. I'm not sure if I'm having a battery issue or if my alternator is doing screwy things.

 

[JoshFulk]

Mine drops into the 10v range when cranking and im getting the 110d5 error code but the Livewire TS wont tune unless its at or around 13v. So I just took to Autozone had battery tested and then they hooked up and tested the Alternator and they thought it was regulator cause it kept balance then jumped up quick but was only high of 13.4

 

[Snake]

The regulator is internal and yes, it could be causeing the problem, a new alternator is the answer.. Check all your grounds and make sure nothing is rusted and that everything is making good contact..

This

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[JoshFulk]

I have alllways had a 200 amp, I plow snow and power a winch, never needed anything more..

Ive been looking at the 180 amp from dc engineering.

 

[Atsah]

Ive been looking at the 180 amp from dc engineering.

I have read some threads about them but I don't know anything about them, any Motorcraft one I have changed lasted at least five years so I just replaced them with OEM..

I would suggest not buying one from an auto parts store, most of them are junk and don't last worth a damn..

 

[Snake]

DC Power makes great alternators (I'm running one). Just check on the delivery times before placing your order. I heard things are getting better, but they had a back order for a while.

.

 

[Fordguy100]

Sounds more like a draw problem than anything. If you let it sit for a week or two, will the batteries be dead?

With one battery unhooked, leave the positive cable attached to the other battery. Now take a multimeter and check the amperage draw between the negative post and negative battery cable.

If your batteries are getting drawn down, it will take some time driving, idling, etc for the alternator to charge them back up to where they should be.

I'm fighting a draw issue on mine. The alternator is fine, as are the batteries and cables. If I drive it for half an hour, the batteries get their whole charge back. Cant let is sit more than a week without it dying. I did end up finding the factory radio was pulling nearly half an amp, which tells me something is up with that. Pulled that fuse, batteries have been fine for the last couple weeks without starting.

Just check for a draw with a multimeter, it literally will only take you two minutes to unhook those three posts (leaving that one positive on), and another couple minutes to let it sit and the truck to power down, then test it.

 

[JoshFulk]

What should the amperage be if there is a draw or isn't a draw?

 

[Fordguy100]

I think the spec says no more than 200 miliamps when powered down. It can take up to 20 minutes for everything to power down. I found my power draw, it happened to be the stock 6 disc head unit. Bought a used one, put it in, and I'm good to go now. Heck it even sat for 4 weeks and started right up!

 

[HeavyAssault]

Clean up all the major OEM grounding points including the alternator mount on the manifold. There's even a threaded hole on the back of the alternator case to run an additional ground wire. There's one on the motor to the passenger side, one under the cold side IC pipe, one near the trans cross member on the passenger side. Consider running some additional grounding wires/cables.

I had to add a ground wire between the bed and frame when I added some LED bed lights.