[AT] Cummins scan tool was OT Buck-Boost convertor for charging auxiliary battery

[Dennis Johnson]

I used to do that all the time with the oilfield trucks we had. I even had a CAT service adapter and program where I could set parameters from my work PC. Most trucks we had then were Peterbilt with CAT engines. Also have done similar things with a few other chassis/engine combinations.
Many years back we designed an auxiliary throttle system much like the real old cruise controls that connected to the mechanical throttle linkage to run older mechanical throttle engines at a higher speed for driving pumps, etc.

Dennis


Sent from my iPad

> On Sep 29, 2019, at 9:09 AM, James Peck <jamesgpeck at hotmail.com> wrote:
> 
> That vocational truck was a Navistar with a Cummins engine. We had been told that we could use the cruise control setting to regulate PTO speed when stationary. The engine load was going to a shiftable transfer box that had pumps bolted to it. The Navistar dealer brought over a Cummins rep with a laptop type diagnostic tool.  We ended up adding a potentiometer that provided a voltage speed command to the engine in place of the fly by wire type accelerator pedal when the truck was stationary.
> 
> [James Peck] I worked on a 12 volt battery vocational truck that used voltage converters to get 24 vdc to run a plc and  electrohydraulic valves.
> 
> I personally would try to determine if the problem is just a poorly performing voltage converter. I would avoid modification if the problem can be rectified by replacing a poorly performing component.
> 
> ]Cecil Bearden] To update the VC problem, after measuring the voltages and looking at diagrams again I am beginning to understand the system, but I don't understand the reasoning behind it.   In a nutshell, the alternator charges the main battery, at the same time the VC charges both batteries in series at 24V.  Definitely something lost in translation in their engineering. All I can think is What the H*#L ?!?!?!?
> I have found a 24V alternator of the same size and connections. 
> 
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