EPU Questions

I just got a new truck which has an EPU. My last truck had an APU. The APU kept the truck cool even in this heat (not perfectly cool but cool nonetheless) it seems like the EPU doesn't do as good a job of cooling. Am I imagining this or do you have firsthand knowledge of this being a fact? I know the EPU runs off a separate battery pack on frame behind the cab, does this run till it shuts everything non essential down then die or does it start the truck to keep its batteries charged?

APU:

Auxiliary Power Unit

On tractor trailers, and APU is a small diesel engine that powers a heat and air conditioning unit while charging the truck's main batteries at the same time. This allows the driver to remain comfortable in the cab and have access to electric power without running the main truck engine.

Having an APU helps save money in fuel costs and saves wear and tear on the main engine, though they tend to be expensive to install and maintain. Therefore only a very small percentage of the trucks on the road today come equipped with an APU.

EPU:

Electric Auxiliary Power Units

Electric APUs have started gaining acceptance. These electric APUs use battery packs instead of the diesel engine on traditional APUs as a source of power. The APU's battery pack is charged when the truck is in motion. When the truck is idle, the stored energy in the battery pack is then used to power an air conditioner, heater, and other devices

There is a process you go through to set the truck to auto start when the voltage drops to a certain point. Once it charges up it will shut off. I think freighliner calls it opti idle. Each manufacturer is a bit different in their process to set it when you park.

There is a process you go through to set the truck to auto start when the voltage drops to a certain point. Once it charges up it will shut off. I think freighliner calls it opti idle. Each manufacturer is a bit different in their process to set it when you park.

Yep, noticed the option idle setup piece on the panel while flipping through, haven't set it up yet. Will have to in the next couple days, thanks.

Also, I'm curious which items are powered by the EPU and which are powered by the trucks main batteries. Inverter, fridge, TV, lights etc. any ideas?

What year is the truck? Manual or auto?

What year is the truck? Manual or auto?

2022 freightliner cascadia, automatic.

On my truck there is a screen on the dashboard display for the Optimized Idle. My process is with the engine running, turn on the A/C in the sleeper and in the cab, go to the Vehicle Settings, then the Optimized Idle Screen. Click "Enable-OK" on the steering wheel button. Click OK on the next screen. Final screen prompt asking for Cabin Comfort-click okay to enable that.

The engine should run as long as the A/C fan is on in the sleeper, but if the truck registers the temperature inside as cooler than the outdoors temperature, it will normally stop the engine.

What year is the truck? Manual or auto?

Any suggestions for a 2017 Peterbilt 579?

I'm debating a gas-powered generator on the catwalk with an Arduino controller as a backup to keep my batteries charged.

It depends.

I just found out there is an aftermarket copy of Freightliner’s system.

Guy asked me how it worked and he didn’t have an option for Interior Comfort. I went to look and his was an add on. The vents were on the back of the cab.

With mine when you enable Interior Comfort, it will start if the batteries are low OR if the AC can’t keep it cool enough using batteries.

I also have a factory inverter and Shore Power plug. When I go home I plug in, leave the key off and turn on the AC and it keeps the truck cool (or warm) and my fridge(s) doesn’t have to work so hard.

I meant to thank y'all for the help. I now use the Opti idle daily. I don't like leaving the key on but I can deal with it. I don't have the interior comfort setting so I start the truck, with front and rear A/C on I enable opti idle. The truck engine then shuts off with the EPU running until it drops to 12.2 volts then it starts up and runs for two hours then shuts off again. I haven't really paid attention to the idle when it starts up but I raise the idle to 900 rpm prior to turning it on. Hopefully it idles at 900 for the two hours but I'm usually asleep when it kicks on. Since I don't have the interior comfort mode I just adjust the front and rear settings to where it won't freeze me out when it starts. I like it cold though so I doubt it could do that.