EREV - A Horsepower Math Problem?

[chriserx]

I am going to find it hilarious when an EREV towing a camper exits the interstate, gets to the stoplight and the engine runs full throttle to try and catch up. I figure it's unlikely, but still.

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[ZeusDriver]

Maybe. I think the hybrid Atkinson cycle engines are going to have a tough time supplying the truck in edge case conditions which is kind of why ford is in the situation it is in- the Lightning “failed” in fords eyes due to range collapse towing and in the cold.

if the go with a smallish hybrid engine then you will have a situation where you will be in a derated condition when towing grades. Edge case but important to theoretical buyers. I think if ford wants this to be a true towing machine then they have to have an engine able to supply the vast majority of power at peak demand.

if they actually build it- the genset will have to be substantial and will likely have multiple modes - standard output and a max output. To supply max output it may be better for a tuned turbo generator where it can produce massive power for heavy loads for short periods and standard output, likely somewhere out of boost, to just recharge the battery- out of boost. 2.7 would be perfect for this but packaging and price would be a nightmare. And at that point why not just build a traditional hybrid or small battery PHEV 2.7 that could have 40 miles or all electric range?

I don’t know if the economics work out but would be happily surprised to find out otherwise

On the back of an envelope, I looked at 14,000lb, 12% grade, 100 FPS = 305 hp for just the grade. So given aero, something around 500 hp should do the trick. A diligent driver (or an automated GPS- based system) would allow one to arrive at the base of the Rockies with a full charge (given a 130kW generator) . Hmmm: 100kWh pack, 400,000 Watts: 15 minutes range. Might want all the HV wiring to be water cooled, and you'd want to keep the generator running.

On the way back down wouldn't it be great if there were a way of using the drive motors to generate electricity!!?? Of course there is that darn aero drag -- works against you going uphill, and then works against you going downhill, putting energy into stirring air, that might be better put into your batteries... using my system, which I might call AgainGeneration, or BackAtYaGeneration... or how about RecuperationGeneration?

These edge cases certainly drive up costs. And in the current practical sense, the vehicles that will "solve" these cases (the RAM and Ford) are going to be incredibly expensive. A decade ago, I drove across the country in a minivan, towing a boat. I went quite slowly up long hills, with my eye on the temp gauge. Worked fine at 30 mph. The van, (which was solar-powered for its house batteries) was fun and reliable, and the slow speed towing was .0001 percent of its time on the road.

I think I will be looking at the RAM and new Ford from afar. My Volt was cheap to buy (slightly used) , cheap to drive, and very reliable. I even used it to tow part of my boat (about 800 lb trailering weight), and it did well, in spite of the fact that its tow rating was 0 lbs. If I find the need to tow my boat (the heavier part) for long distances, or if fast chargers become less reliable and harder to find (both minor annoyances now) the Silverado's range would work very well for me. Until then, even my SR lightning works really well. Could have been such an easy path into another Ford, if the range were like the Silverado.

 

[ZeusDriver]

I am going to find it hilarious when an EREV towing a camper exits the interstate, gets to the stoplight and the engine runs full throttle to try and catch up. I figure it's unlikely, but still.

My old Volt would occasionally do that. When commuting, the engine never started. If it did under normal circumstances passengers would not even notice -- it ran very quietly at low load. But for a long uphill pull, the engine was audible, and would continue to run fast for a while after.

 

[chriserx]

My old Volt would occasionally do that. When commuting, the engine never started. If it did under normal circumstances passengers would not even notice -- it ran very quietly at low load. But for a long uphill pull, the engine was audible, and would continue to run fast for a while after.

I figure exactly 2 people are going to be putting a loud aftermarket exhaust on a volt, one to see what's possible, and one for the lulz. The truck market though???

 

[ZeusDriver]

I figure exactly 2 people are going to be putting a loud aftermarket exhaust on a volt, one to see what's possible, and one for the lulz. The truck market though???

I'm thinking straight through (we don't need no stinkin mufflers) and two 4" chromed vertical slash cut stacks at the front of the bed. 6' from bed to tip seems right.

EDIT:

I'm tooling up to make the kit now! I'll send you half the profits.

 

[Mal106]

My PHEV Niros were '19 and are '23 obnoxiously loud when cold but when warmed or at speed, I have to look at the tach to know the engine is running. Transitions are seamless. My '23 Powerboost was not nearly as smooth or quiet.

Software can overcome a lot but if you HAVE TO have ICE power up a hill, your regen will be limited coming down. Even now with my truck, I wonder if it disables trailer brakes downhill so that regen is maximized. The YouTube towing videos don't seem to address that.

 

[chriserx]

I'm tooling up to make the kit now! I'll send you half the profits.

Bet.

 

[ZeusDriver]

My PHEV Niros were '19 and are '23 obnoxiously loud when cold but when warmed or at speed, I have to look at the tach to know the engine is running. Transitions are seamless. My '23 Powerboost was not nearly as smooth or quiet.

Software can overcome a lot but if you HAVE TO have ICE power up a hill, your regen will be limited coming down. Even now with my truck, I wonder if it disables trailer brakes downhill so that regen is maximized. The YouTube towing videos don't seem to address that.

Long before I bought the volt, I'd designed and built a prototype micro car PHEV, which gave me a lot of appreciation for NVH engineers. Even when only the electric motor was running, it was loud. The only noise deadening feature were the Lord mounts that the engine/motor subframe was on. It was like riding inside a cello. When the engine was running, earplugs were prudent, unless you were OK with not having a conversation for about a day afterwards.

 

[RickKeen]

The ICE engine in an EREV will have a differing load profile. Unlike an engine used directly for driving which has to handle peak HP demands AND steady state efficiency, the ICE engine in an EREV does not have to handle peak HP demands. It can be sized smaller, but it needs to be designed to run at whatever its full power rating is on a sustained basis.
Also, as mentioned, it might be the case that its not designed to keep up with the worse case headwind/uphill/total weight scenario. It could be that you can do short climbs at some peak HP from the electrics until the batteries are depleted. Then you would be constrained to the power available from the ICE engine flowing through the generator and drive motors. Might have to slow down on that uphill mountain slog, or take a break and let the battery charging catch up.

I also worry about the weight and resulting puny payload. Seems like worse of both worlds to have a larger, heavy battery AND a V6 engine to lug around. Plus you likely lose cargo space somewhere (goodbye frunk?)

 

[Mal106]

It makes you wonder how much do you reduce battery size to compensate for the weight and cost of the ICE and all it's necessary systems like gas, coolant, oil, generator etc. If Ram is using a 90 or so KWH battery I suspect it's going to be fairly porkey.

 

[sysop1]

Then you would be constrained to the power available from the ICE engine flowing through the generator and drive motors.

Once the battery is depleted the EREV will not continue to propel the vehicle. You will need to stop and let it charge for TBD minutes.

Once the usable battery reserve is gone, there’s nothing to absorb power spikes or respond instantly to load changes. The generator can’t ramp fast enough, isn’t powerful enough, and isn’t mechanically connected to the wheels. That’s why the vehicle has to stop and rebuild a minimum battery buffer before it can move again.

EREV isn't the answer to Ford's issues selling EV's, their legacy dealers and not improving and optimizing the sales model and service IS the issue. Lighting would have been OK if legacy dealers were not involved in the purchase / service process.

 

[Mal106]

I don't really know how it will work but, though it likely wouldn't need to, certainly the engine could power the truck without the battery. The ICE ioutput is throttlable, the generator or alternator is variable and the motor's output is variable. Software can do the decisions as to what does what and when.

It's going to be interesting if it's going 700 miles and you have to watch your gas and battery. My bet is that it will be like my Niro. 1000 to 1500 miles on a tank of gas and just hauling a big hunk of maintenance pain around 90% of the time.

 

[sysop1]

I don't really know how it will work

Well, your right about something!!

 

[P-38]

Once the battery is depleted the EREV will not continue to propel the vehicle. You will need to stop and let it charge for TBD minutes.

This makes no sense.

Easily programmed around, have a limit on the battery depletion, when that is reached limit the power output (just like my truck does as it gets low or cold) to what the generator can produce.

Volt owners don't have the issue you describe.

 

[Deleted member 21405]

This makes no sense.

Easily programmed around, have a limit on the battery depletion, when that is reached limit the power output (just like my truck does as it gets low or cold) to what the generator can produce.

Volt owners don't have the issue you describe.

Cuz a Volt generator can probably replenish the battery faster than the car is using the power. A truck towing a heavy load will likely be a very different story.

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