Last two times ive started my truck, my battery light stays on and my volts are in the low to mid 11s.

Within 30-60 seconds my volts jump up to the 14s where they normally are and the battery light goes off.

Both batterys are 6-7 months old.

I assume this is an alternator on its way out, but figured i would ask you fellas here if it may be something else to add to the list.

 

Volts may run low on initial start while the glow plugs are on, jumps back up when they shut off.

 

Its never done it before though, the battery light being on w the low volts concerns me. Its like the alternator isnt kicking in until its been on for a minute. I think i will go ahead and replace if it keeps acting up and hang on to my current alternator as an emergency spare.

Any higher output aftermarket alternatives i should look into?

 

Higher output alternatives are a waste of money unless you plan to use the higher output for something. If your truck is all stock in the electronics/sound department, you aren't even using the 110 amps you are currently capable of producing. If you are going to install sound system amps, a fridge, a compressor, or a hot tub in the back, then you would need to upgrade to a higher output alternator. If you are planning to stay all stock in these departments, save your money for something else.

 

Have the batteries AND charging system properly tested before just throwing expensive parts at it. If one or both batteries are bad, it could have damaged the alternator, and just slapping a new one in could also ruin the new replacement.

Its not normal for the system to be at 11v with the truck running, even if you just started it. You say it quickly gets to 14v, so the alternator is doing something. It sounds like either the battery(ies) are weak, or perhaps there is something wrong with the starter or solenoid, causing an excessive draw when starting.

I have a feeling you have something else going on besides a bad alternator.

However, if you need a new alternator, I would highly recommend getting an upgraded 140amp 6G large case, from Quick Start in Michigan. I recently put one on my truck. Its all American made new heavy duty parts. It was about the same price as a Chinese made piece of junk from any of the major parts stores. (comparing to new, not reman.) http://store.alternatorparts.com/825...lternator.aspx

 

EDIT: DOUBLE POST

 

Good call on getting things tested. Ya, its like the alternator has to go through 30 or so seconds of rotation before it begins putting power out. The only electric things i may add are an electric winch, some led lighting, and just upgrading sound system to better speaker's and a double din head unit. But nothing with subs or amps.

 

An electric winch, if big enough and actually used, could certainly warrant a bigger alternator when installed. Many here are going to the 6.0L 130 amp alternators. It is not a drop-in. You have to modify the case slightly or clock (turn) the alternator a bit internally.
I quick search will reveal many threads on that topic.

For the record, my alternator behaves the same way yours does. It kicks up the voltage after the glow plugs turn off, but stays at about 11.7-11.9 volts during that time.

 

Start with the basics like good connections at the batteries. I am betting your alternator is fine. I normally see 11.1 volts for a few seconds than voltage rises. Same for years, no problems. I think you are seeing glow plug draw at start-up as suggested in earlier post. Those things are power pigs.

 

If you are going to do that, you might as well just get the Quick Start I linked.
A.) Its 140 amp, not 130 (They also have 160amp, or more available)
B.) It uses a 6g LARGE case, whereas the 6.0L alt is still a small case. Large case = bigger fan, better cooling, etc..
C.) It uses a heavy duty rectifier, rated for 205 amp, whereas any "stock" replacement 6.0L alt will likely be only rated for slightly above its advertised output (less long term durability)
D.) The Quick Start is 100% American made vs most people doing the 6.0L alt getting a parts store chinese made unit.
E.) Cost is just about the same.
F.) As long as you give them your yr/mk/model when ordering, the Quick Start 6G large case IS a drop-in replacement. Yes, some trucks may need a couple washers/shims UNDER the alternator to clear the bracket, but they include them in the package. No re-clocking or other modifications needed.

While I will likely never need the full 140amps, what I like is the substantially increased output at idle, vs a stock alternator. This way, no worries about dimming lights if you are sitting in traffic, with the headlights on, wipers on, and heater/fan at full blast. The higher capacity may also allow the batts to recover quicker from a start. That may be important to someone who shuts off/start the truck frequently during the day. I may also add an electric cooling fan in the future, and I wanted the extra idle amperage.

I don't work for them or anything. I just think, after a bunch of research, that it makes more sense then any "stock" replacement, considering the benefits, and the minimal cost difference to a cheap chinese parts store unit.

 

The low voltage for the first 30-60 seconds is absolutely normal. Mine is 11.6 until the glow plugs shut off then it jumps to 13.5-14 volts.

The alternator is just heavily loaded during that time.

You do have something going on though, bad battery or alternator because the truck was designed to take the load of the glow plugs on start up without making the battery light come on.

 

I too was looking into an electric fan, but found alot of topics on the subject which showed the stock fan is better than the electric. Haven't looked much further into it but seems some guys are putting 6.0 fan blades on the 7.3 for even more cfm of air movement

 

Ya, you don't want an electric fan. Can't remember of the top of my head for the cfm, but the stock set up is more than sufficient.

 

I'm not a doctor but, I have most of the bolts you have including a 9k winch.. (used regularly) .


If your connections are good (and I recommend using the terminal paint) and your batteries are fresh, I guarantee your on a new alt.


I wouldn't go big. Just stay home with the stock. I buy all my electronics from a place in Tennessee called ???BD electric. Let me check. I'll repost. Standby............

 

Sorry for that, DB electrical. You can ebay it and they are awesome people to deal with. I've been with them for years and have NEVER had to warrant or return a thing. One other thing to check is the top of the alt connection. It sits danger close to the insulation and the stud lug is typical for bending and breaking off.




JS


Denny