Harvester Selection -- use the gas engine to keep the batteries close to fully charged?

[iggy913]

Good morning all,

I'm incredibly excited about these Scouts, not only due to their anticipated off-road worthiness but the way the hybrid system will hopefully operate, giving an unlimited range.

My question is will the Harvester generator/engine operate at the discretion of the driver? For instance if I was taking a longer road trip could I use the Harvester to keep the batteries close to fully charged and essentially utilize gasoline to cover the first portion of my trip? In this way if I could stop for fuel and keep the batteries charged to cover the return leg of my trip?

 

[mcm4ss]

check Jay Leno's garage on youtube. Answer is yes. 500 mile range on a single tank of fuel and full batteries. Add gas, keep going all day, every day.

 

[colinnwn]

Unless there are restrictions about where gas would be available on your trip which doesn't seem likely, I think the better strategy is to leave the Harvester in the optimal setting to decide when to recharge on its own.

Batteries don't like to be charged up to 100% or held there. 80-90% is generally considered best for longevity, and don't discharge below 10% .

So the optimizer would probably let it discharge down to around 20% and then start recharging slowly as you drive. You'd have around 350 miles of gas range plus 30 miles of electric range from the point it turns on.

Based on what Scott has said this should work fine as far as power output unless you were towing, and if that's the case you should have the Harvester in tow mode and it would be much more aggressive.

I'm sure there will always be a display available of all electric and electric plus gas range for you to make good decisions around when you need to fill with gas or charge with electricity earlier in your trip.

 

[Bkenyon53]

check Jay Leno's garage on youtube. Answer is yes. 500 mile range on a single tank of fuel and full batteries. Add gas, keep going all day, every day.

This is the question I had.
It's 500 miles of range from a single fill-up and charge.

The generator kicks in and slows down the depletion rate of the battery. If the battery is depleted after the generator tank is empty, will each fill-up get you an additional 350 miles or will it only be something like 100-150?

I don't really understand how this works.
Does the generator produce enough power to create equal or more than the battery is depleting? If the generator is just slowing down the depletion rate, how can you keep going all day by just putting more gas in if you never drive strictly off of the gas engine?

 

[PMurphy]

My general understanding is that that the generator kicks in when the battery (Harvester model has a smaller battery than the full EV) reaches some level of discharge. 70% for example as determined by the software. The generator then runs to provide a base level of electricity to maintain vehicle speed and possibly slowly recharge the battery (generator likely won’t have a high enough output to quickly recharge the battery at highway speed but should prevent rapid battery discharge). Balancing charging vs. discharge will depend on the speed you are driving and hills/wind/ temp etc.

The range estimater will give you and idea of when you need to stop for gas OR a battery recharge. Since the Harvester has a smaller battery a recharge without refueling the generator will offer limited additional driving range. Don’t know if the generator will have sufficient cooling capacity to charge a depleted battery while parked or it the vehicle must be moving to increase airflow to the radiator/oil tank et. al. This is ALL speculative since none of us has seen the exact details.

 

[iggy913]

I realize a lot of this is speculation, but like I said above, with the language Scout is using I’m hoping so long as you can stop for fuel, you have an indefinite range, under normal driving conditions, albeit in short 150 mile increments.

We travel a lot during hockey season, typically it involves driving about 200-250 miles on a Saturday afternoon to play a game that evening, hotel stay, play a game Sunday morning, then the same 200-250 mile drive home.

Under ideal conditions this is the max range of a Harvester model, and that doesn’t necessarily factor in traffic, our family, and all our stuff, so figure we can maybe make it 425 miles total?

My hope would be to leave our house on a full charge, drive 100 miles or so, that should be 25% of the battery? then engage the Harvester to help cover the next 100 miles, which should have me arriving at the hockey rink with roughly a 75% charge and a fuel tank at about 1/8?

Sunday morning after our game I could top off the fuel tank and drive home on whatever method the truck feels is best?

 

[PMurphy]

Vehicle software will likely engage the Harvester to maximize vehicle range and performance without the driver making that decision. As long as you started with fuel in the gas tank and a reasonable level of charge you should make your trip with only a possible stop to top off the gas tank (range estimation gauge will advise you if a stop is necessary). One of the recent dash photos showed what the range estimate display looks like. That was the first time I had seen it.

 

[colinnwn]

We have some very good ideas of how this will work based on Scott (the CEO) and other Scout Rep statements and interviews of what their intentions are and this is based on engineering studies and POCs of what they can accomplish realistically. Of course this could change as development continues, but it isn't just speculation.

The intent is that Harvester models have a battery with about 150 miles range, and there will be enough gasoline for the engine to provide 350 more miles.

Scott has said the Harvester will be a "no compromises gas and go" experience. While I don't believe that means you could tow 5,000 lbs up a Colorado mountain pass with a depleted battery and only the Harvester (as that defies the capabilities of the 2.0 non-turbo engine they say the Harvester will use) - that does mean you should be able to drive 70 mph on flat land and a moderate headwind with a full vehicle load (which doesn't add much to power requirements anyway) right after gassing up with a depleted battery for 350 more miles.

This also means for it to meet that colloquial definition with reasonable headroom, it should be able to slowly charge the battery while providing traction power on a normal trip. Now if you go up a mountain pass with a strong headwind, you would likely need to use some battery power in addition to the Harvester.

There is little chance that the Harvester would turn on with 70% battery power under an Optimize setting. I can't remember what they said they planned to call this mode exactly. That's too close to the normal limit that a battery should be charged to and stored at. In Tow mode I would expect the Harvester to come on that early. In the Optimal mode I would expect it to come on no earlier than 30%.

There is also a Camp mode that will allow the Harvester to run when parked, so there should be plenty of cooling to allow it to recharge the battery parked. I expect to use the Harvester to recharge the battery while parked you need to put it in Camp mode to affirmatively tell the vehicle you want it to do this and that it's safe to do. Obviously there will need to be lots of automatic interlocks and safety sensors for this feature too. But you wouldn't want it randomly turning on in your garage when you plan to charge it later, even if it could eventually sense the buildup of fumes and turn off automatically.

 

[mcm4ss]

This is the question I had.
It's 500 miles of range from a single fill-up and charge.

The generator kicks in and slows down the depletion rate of the battery. If the battery is depleted after the generator tank is empty, will each fill-up get you an additional 350 miles or will it only be something like 100-150?

I don't really understand how this works.
Does the generator produce enough power to create equal or more than the battery is depleting? If the generator is just slowing down the depletion rate, how can you keep going all day by just putting more gas in if you never drive strictly off of the gas engine?

It does,,, but limited to 5k towing as that is max it can keep up with. You can just keep filling and rolling and as soon as the gas is out, fill and roll but that ,,, would be a very long day.

 

[PMurphy]

Quoting colnnwn “There is little chance that the Harvester would turn on with 70% battery power under an Optimize setting. I can't remember what they said they planned to call this mode exactly. That's too close to the normal limit that a battery should be charged to and stored at. In Tow mode I would expect the Harvester to come on that early. In the Optimal mode I would expect it to come on no earlier than 30%.”

Harvester energy management will be one of the most interesting issues to watch evolve. I “assume” the Harvester engine will be optimized for at least 2 scenarios:1) Low amp draw cruising and 2) Full load charging.

A low amp draw on an optimized engine would likely need low rpm’s and optimal fuel mileage with enough battery reserve to fill in intermittent hard current draws ( hills, passing etc.). I am betting that “Camp” mode will operate at this low rpm minimal power mode.

Full charge is the other obvious need and as mentioned heat management will be the challenge. I guess the Harvester 4 cylinder engine/battery size is roughly proportional to what was proposed for the Ram REV 1500 pick up trucks 6 cylinder/battery capacity.

Have to bet that engineering mules are already running around somewhere testing solutions to these issues. Sure would like to see some “spy” photos!

 

[colinnwn]

RAM has been publishing their specs more quickly than Scout, however clearly it's subject to change until order sheets come out too.

The Ram 1500 REV | Range-Extended Electric Truck

RAM says they'll have a 92kwh battery and a 130kw generator. They don't give specific mileage to efficiency specs, but I'd estimate they will get about 0.5 mi per kw meaning a 184 mi range, a little higher than I think Scout will land at.

I too am very interested in how they will manage the generator. I think your 2 speed idea is likely accurate. Though running engines too slowly actually lowers efficiency. I believe most of the time max engine torque is also at the highest efficiency.

I think they'll design around 2 speeds - most efficient which will provide a substantial amount of total possible power, probably close to 75% of the max power rating, then "max power" that will run the engine at max horsepower around 5k rpm. The powertrain management system would only engage this when it detects the combined power draw is lowering battery level significantly faster than optimal generator speed can replenish it, and would probably more aggressively turn on in tow mode.

I don't think heat management will be too big of an issue. There is a general rule of 1/3rds - a third of engine heat leaves by exhaust, radiator, and off the block. You should be able to increase the amount removed by radiator by providing more flow around the block. I think they will likely have the radiator far away from the generator capsule and assisted by electric fans to manage this instead of having the heat of the radiator just blow back on the engine like most vehicles.

 

[bpdougd]

This version of the new Scout (and the analogous Ram) are of the most interest to me. I have always wondered why no vehicle manufacturers had built hybrid EV's on the diesel-electric model.
Seems a no brainer. The battery can be smaller and lighter (you have a battery charger "on board"). There is no ICE drive train (vehicle is even lighter) and range anxiety disappears. VW seem to gotten the size and capability of the ICE-driven charger right. Ram's decision to go with an off-the-shelf 3.6L v6 is.... puzzling.

 

[colinnwn]

This version of the new Scout (and the analogous Ram) are of the most interest to me. I have always wondered why no vehicle manufacturers had built hybrid EV's on the diesel-electric model.
Seems a no brainer. The battery can be smaller and lighter (you have a battery charger "on board"). There is no ICE drive train (vehicle is even lighter) and range anxiety disappears. VW seem to gotten the size and capability of the ICE-driven charger right. Ram's decision to go with an off-the-shelf 3.6L v6 is.... puzzling.

I don't think it's too surprising given that they have room to package it. They probably had available capacity of that engine, they may decide to run it on a different engine cycle than Otto for better efficiency and low stress but lower power output. And they were wanting this to be a complete full size truck equivalent so they are still shooting for a 14,000 lb gas and go tow rating. They will need an engine that big to meet the SAE tow requirements for in the mountains.