Best way to build a hybrid truck?

[S Keith]

Originally Posted by Hersbird

Well if you have say a 10kwh battery you don't pull just 2000watts out of a generator. You pull as much as possible and charge the battery, then shut off the ICE and use the battery, repeat. Normally you would want to size the generator to the load, but with the battery you can make that the big load and then bleed that with the usage.

It depends on the goal. If the goal is to use the least amount of gas per kWh, then using the ICE for any charging is folly. Generators are designed for power production at constant rpm in mind. They have a near linear efficiency to power relationship. They are MORE efficient at 100% than they are at 50%. Propulsion ICE aren't. They are designed for efficiency while propelling a vehicle, and they have a variable mass/fuel flow, rpm and power relationship.

The ONLY way this would be viable is if you made the charging occur AT the peak efficiency point for power and rpm of the ICE. Under all conditions, the ICE would NEVER beat the generator in terms of fuel burned per kWh due to the larger mass and increase inefficiencies. Additionally, the battery would need to be VERY robust to handle this charge current as you'd likely be charging the 10kWh battery in under an hour.

The only place the propulsion ICE would beat the generator is in pollutants. Generators are dirty.

[S Keith]

Originally Posted by ksa8907

In the way the OP wants to create a "hybrid" probably so, but an engine designed for hybrid use is much better designed and tuned to work as a generator because that's what it is for.

You are mistaken on two counts:

1) "hybrid engines" are only marginally more efficient than comparable non-hybrid high efficiency engines. Small HX and HF Hondas and Geo Metros have been pushing 50mpg since the 80s.

2) "hybrid engines" are not designed to be generators AT ALL. They are designed as part of an integrative propulsion system for maximum mpg, and this does NOT include acting as a generator. It is used as a generator in very limited ways, but that is the exception, not the rule.

Take a look at the gen1 Volt. It literally had an on-board generator... arguably designed purely to act as a generator. What was its gas-only economy? About 30mpg.

Hybrids are efficient because they use different propulsion systems for different phases of operation and SHIFT energy consumption to times when it's more efficient rather than the exact moment it's needed.

Use stored energy for torque and accel to offset the horrible efficiency of the ICE during acceleration. Consumed energy is replenished by low power charging when the ICE is much more efficient and/or by regenerative braking.

Power the vehicle via battery when stopped at a light rather than run the gas engine - replenish this energy when moving by low power charging when the ICE is more efficient.

I've recorded many of my daily commutes to work in my Prius - about 15 miles. WITHOUT FAIL my battery CONSUMES 0.5-1.0kWh MORE energy THAN IT PROVIDES - EVERY time. That's provided by additional fuel burn, i.e., that energy comes from burning extra gas; HOWEVER, the WAY the battery is used to offset the ICE inefficiency has a substantial NET benefit to overall economy.

Hybrids are just about the trade off - recover kinetic energy rather than burn it off - release energy when the ICE is horribly inefficient - recover that energy when the ICE is at peak efficiency.

[cRiPpLe_rOoStEr]

Originally Posted by S Keith

The only place the propulsion ICE would beat the generator is in pollutants. Generators are dirty.

Comparing to a stationary genset, which is either unregulated or subjected to a less stringent regulation, a propulsion ICE will most likely be cleaner overall. But if we consider an ICE built into a hybrid car, while it drives the generator it won't be allowed to be as dirty as a stationary genset not even if it's providing stationary power to the household during an emergency.

[ksa8907]

Without some known quantities, this is an irrelevant argument. Is a small generator better suited to run sub-3000w loads? Yeah, probably. Is it better to keep one in the bed of your hybrid truck instead of using the already equipped hybrid system? I would say absolutely not.

Single cylinder gas generators are very inefficient, a 6500 watt Generac branded unit I found at lowes burns 6.9 gallons in 10.5 hours at half load. ...4.95kwh/gallon converts to roughly 15% efficient.

[freebeard]

...for some values of 'single cylinder'.

duckduckgo.com/?q=linear+electric+compressor+two+pistons+in+one+c ylinder

Granted this is producing compressed air instead of from electricity, but ICE could run on compressed air using the Scuderi Split-Cycle patent (when expired). Nevermind.

[Isaac Zachary]

In theory a single cylinder anything has the potential of being more efficient because 1) there's less friction and 2) there's less surface area to absorb heat from the combustion mix. In other words, if you need a 1, 3, 5 or 7 liter engine, just make one 1, 3, 5 or 7 liter cylinder.

Although I know it's not that easy.

[freebeard]

You can theory in one hand and practice in the other and see which one fills up first.

Cylinder arrangements on internal combustion piston engines
https://idahospudsblog.blogspot.com/...angements.html
The simplest configuration for a piston engine of course is a single cylinder. It has the advantage of simplicity and low cost. Disadvantages are intermittent power, low power compared to multi-cylinder engines of the same displacement, and vibration due to inherently imbalanced rotating parts.

Motorcycle Engine - Single Cylinder VS Double Cylinder ...
https://www.bikebd.com/motorcycle-en...linder-engine/
Single cylinder engines are less durable than the double cylinder engine. Construction of single cylinder engine is easier but it needs stronger parts than the double cylinder engine like the heavier crankshaft, connecting rod, piston etc. Those parts literary tackle more stress and pressure of engine stroke through single connecting rod.

thekneeslider.com/3000cc-single-cylinder-motorcycle/

[Isaac Zachary]

Originally Posted by freebeard

You can theory in one hand and practice in the other and see which one fills up first.

There's been plenty of practice. An inline 6 is about as good as it gets with durability and vibration. But car manufacturers keep using 4 and even sometimes 3 cylinder engines despite the drawbacks. A 1 cylinder enigne would be another step in that direction.

Of course I said single cylinder. An opposed piston, single cylinder, 2-stroke engine would be better than an inline 3 or 4 cylinder 4-stroke engine in some respects.

[freebeard]

It's an old joke, wish in one hand and poop in the other.

[Piotrsko]

Originally Posted by Isaac Zachary

Of course I said single cylinder. An opposed piston, single cylinder, 2-stroke engine would be better than an inline 3 or 4 cylinder 4-stroke engine in some respects.

Huh? What you talking about, Willis? Nict verstehe.