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Howdy everyone. I spent a lot of time on the 7.3 forum, but I'm still new to the 6.0, so bear with me.
I've noticed that when I start my truck the battery voltage (as shown on SCT Livewire TS) often dips down to 11 or even 10.5 volts. The batteries are almost new, dated March 2016. When cruising down the highway voltage is about 12.7-13, sometimes a little higher. The alternator is also less than a year old.
For a stock electrical system that's pretty normal but a little low on the down the highway numbers, but that depends on what voltage reading your quoting. you should be in the 14.2 to 13.8v range. The glow plugs are just going to keep the voltage down since they most of the time exceed what the alternator can put out. You can help it out some by installing a smaller diameter pulley as many do to get the amps up earlier in the rpm band.
An early cold weather graph when volts go lower, and the pointing arrows for GP Initiated and Starter Engaged are off when it was converted to a jpg.
Howdy everyone. I spent a lot of time on the 7.3 forum, but I'm still new to the 6.0, so bear with me.
I've noticed that when I start my truck the battery voltage (as shown on SCT Livewire TS) often dips down to 11 or even 10.5 volts. The batteries are almost new, dated March 2016. When cruising down the highway voltage is about 12.7-13, sometimes a little higher. The alternator is also less than a year old.
Are these numbers normal?
The starting voltages you have reported are normal.
Not the running volts though. 12.7-13 is low IMO. The normal charging volts range should be 13.2-14.4 depending on the type of alternator.
For a stock electrical system that's pretty normal but a little low on the down the highway numbers, but that depends on what voltage reading your quoting. you should be in the 14.2 to 13.8v range. The glow plugs are just going to keep the voltage down since they most of the time exceed what the alternator can put out. You can help it out some by installing a smaller diameter pulley as many do to get the amps up earlier in the rpm band.
An early cold weather graph when volts go lower, and the pointing arrows for GP Initiated and Starter Engaged are off when it was converted to a jpg.
The starting voltages you have reported are normal.
Not the running volts though. 12.7-13 is low IMO. The normal charging volts range should be 13.2-14.4 depending on the type of alternator.
What type of alternator do you have?
I'm not sure what kind of alternator. The previous owner had a re-man alternator of some sort installed 30k miles ago, and then it went out and they put in another re-man alternator right before I bought it earlier this year. I'll take a closer look at it when I get a chance.
Originally Posted by akblackfoot
My tuner reports completely different voltage than checking the batteries with a meter, so you might want to check that out.
When I checked them with a meter after the truck sat overnight it showed 12 volts even.
Low temps have been around 50-55 degrees. Occasionally the truck cranks for a longer time than usual, and when it does so it seems like it is turning over slowly, which is why I'm looking at batter/alternator. Truck had new HPOP with updated STC fitting, head gaskets, studs, brand new heads, EGR delete, new OEM oil cooler, new Degas bottle, 8 new injectors, and SCT Livewire TS installed 30k miles ago.
When I checked them with a meter after the truck sat overnight it showed 12 volts even.
Low temps have been around 50-55 degrees. Occasionally the truck cranks for a longer time than usual, and when it does so it seems like it is turning over slowly, which is why I'm looking at batter/alternator. .
You need to address and fix this battery voltage issue NOW!!! Or your FICM will be toast.
Let the truck sit over night, take the alternator off, and go get it bench tested from a mechanic or parts store.
Also take the batteries off after sitting all night and get them LOAD tested from a mechanic.
You either have a bad alternator (which is what I think it is) or you have a parasitic drain.
After sitting overnight they should be at 12.5, preferably 12.6. I've seen 12.7 after a long days run. So you may have a drain, not full recharge, or an internal battery issue.
What I would do if after a day's normal driving disconnect the ground cable on one of the batteries. This will decouple each with loosing the electrical components memory. Then recheck each battery in the morning, rehook up each and go another day. Then repeat but disconnect the other batteries ground. Record in the morning again. The data will tell you then the charging, draining, and overnight battery conditions.
The other way is to pull the batteries and get them tested, along with the alternator. You still may need to do that, but the above gets you a general feel with the heavy lifting.
You may need to also clean all the grounds, and I've got a vid of what I've found for the major battery cables.
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