The idea is valid, but what really makes series hybrid worth it, is not a small amount of batteries but a large amount. Those days with expensive and heavy NiMH cells are over. Now it makes economically and technically sense to have 30-50 km of full electric range, and all hybrids should be made plug-in.I'm wanting to build a series hybrid vehicle. Where I'll have gas engine running a generator to power the electric drive motor. In addition I want a small amout of batteries to handle the short bursts ...
This also has the point most people forget to mention: if you buy a larger battery pack, you can get more power out of cheaper low-power cells. For example, if you built a pack that can run 2 km electric, you would need to buy special power cells that are more expensive. If you build a 10x larger pack with the same cells, you get not only 20 km electric range (actually a bit more!) but also 10x higher output power (for higher speeds & acceleration). In practice, if you don't need all that power, you can then switch to a cheaper cell -- from so called "power cells" to so called "energy cell", latter of which is optimized for low weight and low cost (EV use). Larger pack = better battery efficiency, more power (= better acceleration at higher speeds), less need for cooling, and what goes without saying, more range.
Also, the energy recoverable from regenerative braking and the benefit running the ICE at optimum RPM (traditional points of having a hybrid drive with a small battery pack) is not so much; you may lose it in the series hybrid losses. The large battery pack changes the game by making your car a plug-in car. Then you mostly drive with electricity from the wall and only need gasoline for longer trips, and even then only for a part of the trip.
Expect to spend $2000-$3000 in lithium battery cells and you'll get decent electric range and power. You'll get this investment back in about 5 years in saved gas. A proper lithium pack lasts for at least 10 years.
Well, to be really usable, your range extender would need at least 10 kW (13 hp) of electrical power. With your truck, that would probably have you go at maybe 60-70 km/h on average with gasoline. With a largish battery, this would truly be average speed; for example, it would charge the batteries while you stop for a break. (You could also charge from a public charging point at the same time.)gas engine,the truck would have enough room for the electric motor and a small motorcycle engine(hoping 125-250cc would be ample) to run the generator and hopefully enough batteries for what I'm needing.
So I guess a 125-250cc motorcycle engine ain't enough, unless it's only for emergencies and you are fine with a "limp mode" or extending the range only a bit. I think you need to go up to around 500cc or more. The engine and the generator will weigh more than 100 kg.
Most seem to be, but I'm also thinking about converting a pickup to a plug-in series hybrid with a 10..15 kW generator and full electric range of about 50 km.Thanks for any help and/or information, and I hope you all aren't strictly electric.