[ejbleendreeble]

I recently installed a 12-volt splitter/charger in my 2008 Element - plugs into the cigarette lighter and gives me three 12-volt and two USB outlets.

It also has a voltage display, and the way it behaves has me puzzled.

Upon starting, the display reads between 13.9 and 14.3 volts. After driving for ten minutes or so, this will drop suddenly to somewhere between 12.5 to 12.7 volts. It will then occasionally jump back to 13.9-14.3 and then back again to 12.5-12.7.

If I turn on the headlights, it will immediately jump to 14+volts and stay there for a while. Then back to 12.5+

The battery is not new, but it doesn't seem to exhibit any problems. The engine turns over rapidly and starts immediately.

I was always under the impression that an alternator-based charging system might register 14+volts or so upon starting, and the voltage would then drop gradually over a short time to a base level. However, I have checked with Dr. Google, who seems to think there are many different ways that the charging process may vary.

When dinosaurs roamed the earth and I was a young man, we had dynamos rather than alternators. Alternators are mysterious to me ....

Is this charging pattern normal? Or may it be that my splitter/charger isn't accurately reading voltage?

Any help is much appreciated.

Regards,
EJB

 

[srteach]

That charging system behavior is normal.
Any electrical system has an inrush current when first turned on. The charging system senses this inrush and immediately turns the alternator up to compensate. When the demand is not there, the system lowers the alternator output. This is a digital control system, so there is not a gradual slope to meet demand.

Older systems used analog control and ramped up the alternator with a gradual slope.

 

[Fleetw00d]

I had the same question after installing a voltmeter. As srteach indicated, normal behavior. Charges when it needs to, doesn't when it doesn't. It is a little odd to me that it drops immediately to 12.6 when running (I guess because there is a constant current draw), but when you shut the E off, it decays gradually from 13+ to ~12.6.

 

[07lmnt]

Elements have an ELD module. Controls the charge system for fuel economy reasons. I installed a switch to by-pass the system. I only drive 2 miles to work, and the winter months it's not enough drive time to keep the battery fully charged, so I switch it to full charge. In the warmer months I've seen battery voltage go down to 11.9 while idling. Here is more info...

https://opensiuc.lib.siu.edu/cgi/viewcontent.cgi?article=1011&context=auto_pres

 

[ejbleendreeble]

Many thanks to you all!

Regards,
EJB

 

[Gutless]

Elements have an ELD module. Controls the charge system for fuel economy reasons. I installed a switch to by-pass the system. I only drive 2 miles to work, and the winter months it's not enough drive time to keep the battery fully charged, so I switch it to full charge. In the warmer months I've seen battery voltage go down to 11.9 while idling. Here is more info...

https://opensiuc.lib.siu.edu/cgi/viewcontent.cgi?article=1011&context=auto_pres

Great info!
Can you elaborate more on the ELD bypass-switch install or even a rough schematic on the hack?
And any risk on having the switch?
TIA

 

[srteach]

... And any risk on having the switch?
TIA

If you leave it on continuously, there is a chance of battery burn out. Used intermittently, no issues.

 

[Gutless]

^^^ got it. Thanks

 

[07lmnt]

If you leave it on continuously, there is a chance of battery burn out. Used intermittently, no issues.

No chance of battery burn out (what ever that means) The ELD system lowers charging voltage only when idling, and only for minutes at a time. If you think that having the alt charge full time will burn up the battery your mistaken. The system is used for fuel economy, not to prevent overcharging due to high voltage.

 

[07lmnt]

Great info!
Can you elaborate more on the ELD bypass-switch install or even a rough schematic on the hack?
And any risk on having the switch?
TIA

Install switch in the circuit between ELD and PCM. Connector 451 terminal 1. Connector is inside next to HVAC control, on my 2007.

 

[Gutless]

2007.

Great! Thank you..