Alternator issues

[01DenaliHiker]

So my truck (01 Denali) has a DR44G alternator in it.

My dash gauge always reads just above 14v, but I'm running dual batteries and separate digital gauges to measure the output of both batteries which is slowly draining. They read 11.3 and slowly discharge from running my electric fans and headlights.

Dash gauge doesn't change 14+ volts when my truck is running. This is my second cluster and it seems to be a regular issue of showing higher than it actually is. Which it did when I had a single battery as well, it will fluctuate if my system hits hard, but it's not consistent with my digitals.

I took a long trip the other day and hit the mother of all dukes of Hazzard style highway bumps and they showed a constant 13.8 volts for the entirety of the trip like it shook something just right. I tapped around my alternator and that doesn't seem to be the case now.

I plan to purchase a 250amp high output next week to replace it, but don't care to kill my batteries in the meantime waiting on it to arrive.

Has anyone else had this issue?

 

[SnowDrifter]

Clusters can be pretty lackluster as far as accuracies go.

Where are you pulling voltage from for your meter? Where are they grounded to?

Done your big 3?

What's voltage at the alt?

Any improvement if you rev the engine to 1500 rpm?

 

[01DenaliHiker]

Well, finally got to a fluke and went to town on everything. My yellow top optima (second battery) seems to be a culprit right now, ran it at 11.3v with no load, what I'm not understanding is power to and from my battery isolator (only activated by my ignition) is a constant 14.6v when started. Yet at my battery I'm showing 11.5v, like in a short 34" section of 0g is losing it's charge somehow. 11.3 seems like a bad battery to me though, so maybe throw it on an AGM trickle and see if I can bring it back?

Could it be a possible bad ground on my second battery not allowing it to properly charge?

My starting battery is 13.1 no load and 14.6 engine running so no issues there.

Unless I have a bad connection on the battery..... Maybe a coating on there not allowing enough current?

Grounds and connections....

Sorry, scatterbrained thought. Seems to help me work through my issues typing on here. Haha. I'm guessing my dr44 has been built at some point as well, it does have an overdrive pulley on it, but at idle I was showing 108 amps, 1600rpm I was showing 194 amps. Always thought the guts looked different. So more than enough to work my batteries while they take the brunt of dual fans and 5000 watts of amps.

Definitely tearing out my stinger digital meters and looking into some SMD gauges.