Battery Saving Mode

[kthaxton]

We know that amperage is proportional to voltage according to Ohms law.

Man, you're making me work for it today......but technically, you are incorrect. One could say that wattage is proportional to amperage and voltage and be mostly correct, However...

In a properly working charging system, the voltage will remain the same regardless of amperage (within the alternators rated capacity). Theoretical example, cruising along like normal....lets say the system is drawing 60 amps, the alternator will still produce roughly 14 volts. Full load from whatever electrical components are capable of drawing the full amperage potential of 220 amps..... the alternator is still only producing roughly 14 volts. So again, they are not directly "proportional".

 

[SnoKing]

Think of Voltage as a pump to move amps. Increase the load and the pump works harder to keep the voltage at that same 14V creating more amps out its output.

 

[Newsa]

I don't think short AGM battery life in these trucks is a voltage regulation problem. I think voltage is correctly maintained at 14 (and change)-14.5V.

However, maybe the ISB smart battery module is allowing the voltage to maintian a 14 V charge on a battery that is already fully charged. This could lead to "ovetcharging". I also read that AGM batteries are susceptible to quicker failure in high heat conditions. The article i read recommended that AGM batteries not be stored in the engine compartment.

For the operatir who drives long hours (continuously charging the battery) & tows heavy creating alot of heat up front, that might cause reduced AGM battery life. That's why i was making comments in support of the long lasting, high quality batteries that Ram apparently used as OEM in the past.

AGM battery life can be reduced by "leaving it on the charger too long". (Or driving too many miles while it is being charged by the alternator). AGM battery life can also be reduced by being asked to operate or be stored in hot environments.

That was why I called them delicate.

 

[Newsa]

Man, you're making me work for it today......but technically, you are incorrect. One could say that wattage is proportional to amperage and voltage and be mostly correct, However...

In a properly working charging system, the voltage will remain the same regardless of amperage (within the alternators rated capacity). Theoretical example, cruising along like normal....lets say the system is drawing 60 amps, the alternator will still produce roughly 14 volts. Full load from whatever electrical components are capable of drawing the full amperage potential of 220 amps..... the alternator is still only producing roughly 14 volts. So again, they are not directly "proportional".

I didn’t want to bring wattage into the discussion. But you would be correct to say wattage is proportional to amperage in a relatively constant voltage situation. Where voltage is the constant of proportionality. In an unregulated electric circuit, (not a vehicle because all.of them have a regulated system) Voltage is proportional to amperage with resistance (wire gauge) being the constant (of proportionality). When the voltage in an unregulated (again, not our trucks) circuit gets too high, it drives a higher amp current through the wire.(causing excess heat and possibly buring up the wire). If voltage is not being regulated in a veh8cle, then it is not a properly operating charging/electrical system. Voltage regulation has been in vehicles for longer than i have been alive. I don't expect a problem with voltage regulation in the Rams. ( Although there appears to be something shortening the life of the AGM battery that didn't happen with the old lead acids)

I never suggested that high voltage was killing the batteries. I think you mentioned that above? But i was thinking there might be something in the charging system that is shortening the life of AGM's in the Rams. I think it is ISB related and possibly heat related. And that was why I posted that i dislike the AGM's in the Rams that have been reported on multiple forums that they have less than 5 years life. I would prefer an OEM battery with 6-10.years life. And i would like.to be able to replace it with another battery that has 6-10 years life. But you can't put a lead acid battery in a truck that is designed for an AGM. So you might hear me whine about this in the future.:-laf

 

[kthaxton]

However, maybe the ISB smart battery module is allowing the voltage to maintian a 14 V charge on a battery that is already fully charged. This could lead to "ovetcharging". I also read that AGM batteries are susceptible to quicker failure in high heat conditions. The article i read recommended that AGM batteries not be stored in the engine compartment.

For the operatir who drives long hours (continuously charging the battery) & tows heavy creating alot of heat up front, that might cause reduced AGM battery life. That's why i was making comments in support of the long lasting, high quality batteries that Ram apparently used as OEM in the past.

AGM battery life can be reduced by "leaving it on the charger too long". (Or driving too many miles while it is being charged by the alternator). AGM battery life can also be reduced by being asked to operate or be stored in hot environments.

That was why I called them delicate.

I think I read the same article.....the first one that popped up on a Google search, but I must say.....the above not only does not coincide with my experience, but the recommendation to not store them under the hood is ridiculous and gives me pause.....unless someone is running an aftermarket regulator that has no temperature compensation. Even the old non-computer era Dodge regulators based charging voltage on underhood temperatures and later used a sensor under the battery. The hotter it got, the lower the charge voltage. I think the author of that article is basing his information either on theory alone, or limited experience. I can't imagine someone developing (much less an OEM providing) and car battery that should not be in an engine compartment.

With both vehicles I mentioned above, they both had different scenarios of high engine compartment temperatures. On the 2000, I towed a small trailer for up to 8 hrs at a time.....multiple times. On the 86 Ramcharger, it even had a slight overheating problem during highway use so much so that I drilled five two-inch holes in the upper rear of the front fender (it was my off-road rig) to help let hot air out. I also did a lot of hard 4wheeling in it, some trips doing as much as 8 hours a day on the trail. Never did I have a problem with my AGM batteries, and as said, they lasted 3-4 times longer in these situations than wet cell batteries.

 

[kthaxton]

Think of Voltage as a pump to move amps. Increase the load and the pump works harder to keep the voltage at that same 14V creating more amps out its output.

I can understand what you are getting at, but I think it would be more accurate to equate voltage as the "pressure" created by the "pump", in this case the pump would be the alternator.

I think a better analogy that is easier for most people to understand is to equate a electrical system as a compressed air system more so than a liquid/pump system.

Voltage = air psi
Amperage/current = cfm
Alternator/generator = compressor
Battery = storage tank
Wires = air lines
Load = filling a tire/running air tools

Mostly, I find air pressure as voltage easier to visualize than liquid pressure. And most of us have seen how when an air compressor cannot keep up with the load, psi (voltage) drops, just like in a vehicle's electrical circuit.

 

[kcv67]

My truck was in battery saver mode. It is one month old and 500 miles. It was cold outside and I had been playing with the nav and air suspension and dash settings with out it running. I attributed the BSM to just the batteries being drawn down while the truck was not running and playing with all the new gadgets.

 

[Manchester]

My truck was in battery saver mode. It is one month old and 500 miles. It was cold outside and I had been playing with the nav and air suspension and dash settings with out it running. I attributed the BSM to just the batteries being drawn down while the truck was not running and playing with all the new gadgets.

Did the BSM message go out once you started driving? Mine stays on all the time.

 

[gsbrockman]

Did the BSM message go out once you started driving? Mine stays on all the time.

On the ONE occasion mine came on..........an approximate 1.5 hour continuous drive made mine disappear. It never reappeared. IIRC......it was single digit temps coupled with the truck not being driven for a few days.

 

[Manchester]

It has been negative temps here this week. Dealer just told me they are putting in a new alternator.

 

[kcv67]

The BSM went out as soon as I started the truck.

 

[Manchester]

The BSM went out as soon as I started the truck.

Its my understanding that is the way it's supposed to work. That it goes out once the vehicle is started or shortly thereafter.

 

[LandShark]

Warming up the truck this morning. Turned on the exhaust brake. Pressed the cruise control several times with nothing happening. Pressed cruise control again and "Battery Saving Mode" showed up on the EVIC. Pressed cruise control several more times and the Battery Saving Mode went away and the cruise control symbol finally came on the EVIC and I could do the fast idle. Any one know what the Battery Saving message is all about?

A few more details on my BSM episode: The truck had been sitting for a month, except for a 20 mile trip, the week prior. Temps were in the low 20's. Headlight are set to be always on (I have a bottle cap over the sensor). Defrost was set to ON. Radio, of course is always ON, and I expect the grid heaters were cycling. Haven't had the BSM again, even with a start at 17 degrees.

Now that I know a bit more about this problem, I try to remember to at least turn the headlights off prior to a below freezing start. I long for the simplicity of my old '95, but would not give up the power and comfort of the new truck!