? on charging system

[Batman]

Hopefully someone out there can tell me if this is normal or not.



Started the truck this morning (about 40 deg. F). didn't plug it in last night. let the oil pressure go up to normal the slowly brought rpm's up to about 1300. voltmeter (stock) was reading around 14 at idle, I brought the rpm's up and voltmeter dropped to about 10-12 (half-way between the first line and 14).



After about 5 minutes of running at idle I brought the rpm's up to 1300 again and the voltmemter didn't drop more than one thickness of the needle.



I had the defroster on the whole time.

I did notice the cab interior lights dim when I raised the rpm's.



What gives?? Any ideas?



TIA

 

[Shovelhead]

Grid heater cycling?



It's a MAJOR amp draw.

 

[Batman]

Shovelhead

Thanks for the quick response.

Does the grid heater cycle while the engine is running?? I thought it only cycled prior to start-up. Although I really don't know.

Thanks

 

[Big White Beast]

Sure does......

Couldn't figure out why my wipers would slow down and speed up on those dewy mornings. Turns out that's what it is.



Garrett

 

[illflem]

Not sure on the newer rigs but on the older ones the heater will continue to cycle for up to three minutes after starting, but will shut down if you exceed 16 mph.

 

[Batman]

Thanks guys, guess that would make the difference. At least I know its nothing to worry about.

 

[wtrenholm]

On my 2001, the grids cycle a lot now that the weather is colder up here, block heater use mellows it out some. They can be on for rather long periods of time. If the lights and blower are on, the volt guage is down around 8-9 volts. They do shut down at 19 mph as illflem mentioned.



Wayne

 

[dresslered]

Some of us have grid heater LED indicators telling us when and which heater is on. As already mentioned, the grid heaters can cycle for several minutes after starting the engine.



Assuming that it is cold enough, prior to starting the engine, both heater grids come on simultaneously (maximum current draw). Once the engine is started, the individual heater grids will toggle back and forth (only half of maximum current draw) until adequate intake air temperature is achieved.

 

[Batman]

Okay, grid heaterS?? I was only aware of the one grid heater at the base of the air intake. Where is the other one??

Thanks

 

[wtrenholm]

There are two grids that are controlled independently, but can come on together. You can watch the operation with a DRB III if you have access to one, just look in the Cummins ECM not the JTEC controller.



As long as were on the heater subject. Does anyone run the products that limit cycling on warmer restarts? Just wondering if there is enough failures to justify purchase / installation.



Thanks

Wayne

 

[dresslered]

Wayne-

I am not familiar with the products that you are referring to, however, I do notice that my grids NEVER come on in the summer time. It sounds like the feature is already built in unless you are looking for even colder conditions to disengage.