Ignoring the nonsense statements from Stumpy, a few topics came up worthy of discussion. I offer:
".....Given electric torque is available from 0 RPM they could have made it 400hp and had plenty of capability. Unless the generator and battery setup is adding a thousand pounds to the curb weight, in which case the extra power will be needed in order to have satisfactory performance."
I tend to agree. The lead engineer pretty much acknowledged they're reusing as much REV design as they can, so... And since less EV HP would have meant less battery, and thus less cost and weight... Still, that battery capacity ends up getting used when we do truck like things.
BTW, added to what baseline weight? I've modeled Ramcharger (RC) weight relative to REV and RC will pretty much match REV with the base battery. I'd have to go back and look, but as I recall we're talking around ~ 750lbs of battery weight over a similarly built ICE (Tried to give you two answers).
"How much hp do you expect it to take to generate enough electricity to keep this truck rolling?"
Great question, (and tactfully done) as it helps us understand what power we need and for how long. I've modeled a bit and come up with these rough power demands:
75-78mph unloaded:
50hp
75 mph moderate load:
100hp
65-70mph heavy:
100hp
Extended Towing - Steep Mountains:
300hp average, brief peaks to 350hp.
".....The generator in the Ramcharger is stated to be 131kW, that takes about 1.5 to 2 times that amount in an ICE engine HP to deliver the rated output."
I expect that to be on the high side. The standard HP to KW factor is ~1.34HP per KW, and while we don't know conversion losses I assume conversion losses will be within 5% of drivetrain losses of an ICE. That said, the sophistication they use in generation management could put the 5% either above or below. if we assume 15% loss we'd be 1.34/.85=1.58HP IRL per KW demanded. That said I use 1.34 knowing conversion losses are outstanding.
..I wonder what RPM the V6 will run at since they make very little power at 2k and below?
I mean sorta, for a few reasons, but for general modeling purpose we can say gas ICE engines make ~13hp/L/1K RPM. A bigger issue is full throttle demand at very low RPM creates a lot of cylinder pressure on gasoline engines, so they won't run too hard too low. Which as we'll see isn't gonna happen anyway (gimme a moment).
RC will certainly have a number of operating modes. EV only mode and a range extend mode are certainties. The latter implies some degree of battery discharge to some minimal state before it fires up and delivers power to the bus with drivetrain excess going to the batteries.
Before we can dig much into this we need to acknowledge RAM engineers will likely be looking for operation in at least few states, and at low BSFC. They will also want to minimize NVH (noise, vibration, harshness).
We could throw darts at that all day, but as SWAG's:
1) Let's assume they take something like 3500RPM as a target: 3.6*13*3.5= ~ 163HP, 122 KW. At full throttle. But will NVH be met at full throttle? It's likely to be where best BSFC is to be found, but...
2) OK, lets look at 3K rpm and 50% throttle: ~70hp and 52KW.
There is no way in hell they do #2, right? That's basically running the engine full time, and they not only won't want to they'll want to operate the engine in higher BSFC ranges.
So 3), 75% throttle, 3K RPM i~100HP, ~ 78.5KW
OK maybe, but that might still get noisy, likely in the ballpark though and if we back out conversion losses it's hard to see much lower RPM (NVH) or much less throttle (N and BSFC).
So what do I think they'll do?
I think we'll see algorithms electing, largely based on average load/battery state, somewhere along the lines of #3 as a driving minimum and #1 while under larger loads like towing at speed.
I also hope to see a mode enabling a manual recharge. Given same one could fully charge before a mountain. If so we can get a SWAG of around 40 minutes of constant 300HP delivery (likely more like 30-35) minutes, but still plenty).
Disclaimer: Conversion losses are hard to predict here, and some of above math is just using good rules of thumb for estimating power output (for NA engines, although it's easy to correct for boost). It would be prudent to assume a 10% loss to above!!
Anyway, this #1 through #3 part should give us some crude idea's of the operating range of the engine (to say nothing of ending the "the engines too big" nonsense).
Again I expect the algorithm to manage them and make then user transparent. In fact, I expect an infinite amount of said modes. (#1 and #3 are just so we've targets to consider what ranges we're operating within).
BTW, I also hope/sorta expect they will give us two other "modes" within the ranges:
A) "Silent", basically a mode for emulating a portable generator. Here I'd expect it to have a low RPM /low-load state. Lets take 30% load and 2kRPM and expect it to deliver ~21KW (thus meeting 120/240V output demand and putting some mild power back into the battery.
B) Manual "an over-ride" whereupon those with adequate understanding can select the generator output wanted/needed.
Finally, I've also wondered if there might be some form of option to allow engine start and warm-up before load. Goodness knows I'd rather not see it go to directly to #1 output from a -10F engine. Sure, some commercial generators do just that, but that don't make it good for the engine!
Above are mans opinions, but at least I've done some rough math first. Your thoughts?