Rumor ?

Battery life will depend on more than that. Weather, loads placed, type of batteries, etc etc

 

Also depends upon the accuracy of the gauge. Not uncommon at all for any or all of the gauges to be off. Ballpark and consistency. If the gauge starts reading differently, that's what you look for more than the exact readout of the gauge.

 

Just bought 2 new batteries in Scranton Freightliner Dealer - of all places?
Mine are perfectly fine currently, but for $84.00 each, how could I not?
Mine would fail in middle of this January, at 16 below, in a snowstorm, on the road - of course.
Looked online and all are over 100 bucks; so it's a good deal. I thought they must be old stock;
but they have refilled this stand twice since I noticed this. Asked - and it's a Distributor's "special price."

I thought dash gauges read the alternator output?
Yes - I know there are volt and amp gauges.
So, like the "Johann Sebastian Bach"- looking Gentleman in the above photo; Whaaat?

To flesh out your theorum - A Lower voltage charge to a lead-acid battery input prolongs longevity?
I won't give you the answer.
See for yourself:
Battery University.com
BU-804: How to Prolong Lead-acid Batteries

(There's a test after.)/sarc.

 

You are thinking things over hard. Let it go.

14 volts is good. I like mine at 15 if I can get them there at cruise. I always had the shop change all 4 batteires twice a year, before winter and after winter. They #####, but they change em for me. In addition to tires.

There have been a number of times that alternator quit working and failed, now you are on battery. You with a old air breathing truck with everything off except fuel pump and a couple other very small loads about 4 hours or 200 miles to get to a shop before the batteries drained below 8 volts and strand you. That full moon in the west virginia mountain sandstone came in handy once.... But being all dark with no lights was real interesting that night.

I once drove from roughly Matthews AR on 55 south about 40 miles on ice, salt and snowing etc without a battery cover. 3 months after those batteries essentially burned down. They were brand new. But ruined quickly by no cover. (I had to drive back and retrieve the stupid cover.... that was the last time I ever touched those #### things during Pretrips...)

Today's computer trucks require a range of 10 to 12 volts to stay booted. You have even less time on battery should you lose your altenator.

You generally don't even keep a tractor long enough to go through 5 years on a set of 4 batteries without changing the trucks or the batteries and a bunch of other stuff. (As a company driver...)

I went through three batteries so far in 20 months on my POS vehicle and my spouse's car is on it's 5th year we are fixing to replace it before it fails. (And they will.... due to a variety of very good basic reasons.)

 

There is a limit to how much voltage you charge those batteries at. You will cook them and shorten their life if you go much above I would guess 14.5 volts. More is not always better. I have never had an alternator charge at more than 14, but then again, I have never driven 130 mph in a big truck either ................

The expensive batteries are worth the money and replace all at same time for best results.

 

12 volt battery has 6 cells that make 2.1 volt each. Full charged battery should read 12.6. A system charging 1 volt over at 13.6 may not be strong enough to keep up with the loads that may be encountered and can be detrimental to the life of the battery. At 3 volts over you start to over heat and cook the battery. Ideal is 1.4 to 2 volts over so 14-14.6. That's at the battery with a known good DVOM. The gauge on the dash is just a reference to what is normal. They are not to be trusted.

 

Probably the best post I've seen today.