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Damien is planning to use a BMW i3 REx in an upcoming project... great way to get a cheap ~20kW (iirc) generator with ICE attachedAny input would be of great interest!
Some info in this video (start at 13:14);
Damien is planning to use a BMW i3 REx in an upcoming project... great way to get a cheap ~20kW (iirc) generator with ICE attachedAny input would be of great interest!
It seems that series hybrid systems are often discussed and rarely built. I think the realities of the series hybrid configuration dawn on potential builders before they get very far.Just wondering if anyone has done a DIY hybrid project? What I mean would be a series hybrid not a parallel hybrid.
If you don't need much power, a commercially produced consumer generator set is the obvious way to get a generator set. Of course they are set up to produce 120 V AC single phase power (or up to 240 V is a larger unit). The old-style constant-speed designs are not very efficient or compact, so an "inverter" type would likely be preferable. You might look at intercepting the power before the built-in inverter, then using a DC-to-DC charger to regulate power to the battery.1. household portable generator
A typical automotive alternator is not likely a highly efficient generator. I had to search for a what a "HF predator motor" might be, and it turns out to be a basic small gasoline engine from Harbor Freight. I can pretty well guarantee that's about the least efficient and most noisy thing you can get to burn gasoline and turn a shaft.2. High powered Aumobile Alternator driven by a HF predator motor.
Okay, although not highly efficient... but with what engine driving it?3. Brushed sepex DC Motor used as a generator.
Yes, 3-phase permanent magnet motors make good efficient 3-phase generators, but you need to be able to control it. It may be sufficient to just rectify the output and manage the engine to control out voltage. And there's still the question of what engine to drive it.4. Large heavy duty PM motor.
I think this fits in the same category of "it's not very good but it's what I can get cheap" category as forklift motors to drive EVs... except that those old aircraft units are probably no longer cheap or even readily available.5. WW2 aircraft generator used on older EVs
Just as the most effective components for a DIY EV conversion come from production EVs, it makes sense that the most effective engine and generator set for a DIY series hybrid conversion would come from a production series hybrid. The only pure series hybrid car (rather than truck or bus) currently available in most of the world is the BMW i3 REX, although Nissan now sells them (the e-POWER Note and Serena) in Japan, and some production hybrids have a series mode (a current Honda Accord runs as a series hybrid at all but highway speeds).Damien is planning to use a BMW i3 REx in an upcoming project...
It will be easier to select components when you have a more clear idea of the required power and operating voltage.
If you don't need much power, a commercially produced consumer generator set is the obvious way to get a generator set. Of course they are set up to produce 120 V AC single phase power (or up to 240 V is a larger unit). The old-style constant-speed designs are not very efficient or compact, so an "inverter" type would likely be preferable. You might look at intercepting the power before the built-in inverter, then using a DC-to-DC charger to regulate power to the battery.1. household portable generator
A typical automotive alternator is not likely a highly efficient generator. I had to search for a what a "HF predator motor" might be, and it turns out to be a basic small gasoline engine from Harbor Freight. I can pretty well guarantee that's about the least efficient and most noisy thing you can get to burn gasoline and turn a shaft.2. High powered Aumobile Alternator driven by a HF predator motor.
I can only guess that the reason to consider this combination is that you want DC power at some voltage over 12 volts, so off-the-shelf engine-generator sets are not directly usable.
Okay, although not highly efficient... but with what engine driving it?3. Brushed sepex DC Motor used as a generator.
Yes, 3-phase permanent magnet motors make good efficient 3-phase generators, but you need to be able to control it. It may be sufficient to just rectify the output and manage the engine to control out voltage. And there's still the question of what engine to drive it.4. Large heavy duty PM motor.
The generator included in a modern inverter-type portable engine-generator is a three-phase PM machine.
I think this fits in the same category of "it's not very good but it's what I can get cheap" category as forklift motors to drive EVs... except that those old aircraft units are probably no longer cheap or even readily available.5. WW2 aircraft generator used on older EVs
I don't understand why older EVs would use these. They're EVs, so their only need for a generator would be to produce low-voltage power from the high-voltage battery, inefficiently (because modern DC-to-DC converters were not available)... but aircraft typically have 24-volt systems and a car would want 12-volt power.
They work well, but compared to modern EV equipment I doubt they're efficient - maybe fine for what is essentially an educational project.2. The alternator——
Now I have done a lot of experiments with this. One of the keys is which one you use. The large case GM alternators work the best. You take all the regulators and diodes out of the the unit where you have only the three phases and field exposed. Then run the three phases to a three phase bridge and you can control the current output through the field. It quit remarkable because this three phase synchous machine works like a current source and not like a voltage source! It really seems rather efficient !
Ah, I was thinking of the 3-phase synchronous PM motors typically used in EVs, not realizing that permanent magnets were common in large brushed motors. I don't know what a typical application would be for a PM motor - brushed or AC - of that size.The PM DC—- now I was thinking of using a big 45lb 4 pole low RPM brushed motor like the imperial 36v motors they have for Sale on eBay from floor burnishers. But a 3 phase dc Motor seem interesting... where would I get one that could handle 6KW of power?
That's the start of the discussion of the i3's motor, which is not specific to the REX version. Try starting at 15:25 for about one minute about the engine-generator set (no internal details, but he mentions that the generator is used as the starter motor) and then Damien's plan to build a BMW E39 as a series hybrid with it (no other details).Damien is planning to use a BMW i3 REx in an upcoming project... great way to get a cheap ~20kW (iirc) generator with ICE attached
Some info in this video (start at 13:14);
Wow this is extremely informative! I did Not realize these things were this inefficient. I typically get 3600 watts with a predator 212 with is close to what this engine is rated as...usually the alternator does not get that hot.. but this white paper Is eye opening!They work well, but compared to modern EV equipment I doubt they're efficient - maybe fine for what is essentially an educational project.2. The alternator——
Now I have done a lot of experiments with this. One of the keys is which one you use. The large case GM alternators work the best. You take all the regulators and diodes out of the the unit where you have only the three phases and field exposed. Then run the three phases to a three phase bridge and you can control the current output through the field. It quit remarkable because this three phase synchous machine works like a current source and not like a voltage source! It really seems rather efficient !
Delco Remy promotes their higher-efficiency alternators, publishing a white paper on the subject (Improving Alternator Efficiency Measurably Reduces Fuel Costs), yet the specs for one of those high-efficiency units claims only 72% efficiency.
Why remove the stock diodes? They just form a rectifier, which is what you want, right? Yes, the regulator controls the field current, and for better control you might want to use your own regulator.
I would plead with you to keep us updated on your project on this thread I really would like to see how you do this!I have the VW 1.9TDI for my REX and it will be coupled to another Leaf motor to directly charge the batteries. I just have to get a speed increaser set up so I can run the TDI at less than 2000 rpm (within its best torque range) and the generator at perhaps 6000 RPM. It is a bit of an experiment of course. I am very curious how Damien controls all this. It is helpful that he has a complete unit so that wheel does not need to be re-invented.