Can you simply add a generator to your electric car for more range? Well, yes… and no.
If you’re talking about adding a wind generator, or some kind of power recovery system attached to a wheel to recover electricity while driving along – no. That just won’t work, no matter who tells you it will. Trust me, I’ve done the math and written the article.
If however, you’re thinking of installing a gasoline generator in the boot (or trunk as my American readers call it) then yes, you can boost your range when you’re idling or cruising at a low & constant speed.
What size gasoline generator will you need to achieve this? Well, that depends on how big your battery pack is. If you’re not in a hurry and your car is stopped while you’re shopping/at work etc, then we’ll run through some really simple figures.
First of all, let’s assume you have a small and cheap generator that puts out around 2000 watts. If your car is stopped for an hour, and your charger is plugged into your generator, then you’re going to generate 2000 watt-hours, or “2 kWh” in fancy speak (though in reality we’d probably lose about 15% of that power through inefficiencies).
If your battery pack is 20 kWh in size, and it’s at half-full (10 kWh) then that one hour of recharging will have brought it back up to 12 kWh capacity – or in really useful terms that we can all understand – you’ve replaced around 6 miles of range (assuming your EV used 0.3 kWh per mile, which is a fairly average economy for a home conversion).
Now, if you were actually driving at the time, would it be beneficial at all? Well, realistically, unfortunately not. This is because driving your home converted EV for about an hour would probably use around 15 kWh of electricity, and in that same hour, your little generator will have only replaced about 2 kWh.
So the secret to reliable range extension with a generator is to find the right output. I would recommend for a typical EV, somewhere around 10 kWh output. Unfortunately, this means a pretty large and heavy (and very expensive) generator which realistically will need to go on a trailer.
Then there’s the problem of matching the output voltage from the generator to the same voltage your car is using. For example, attaching a 24 volt DC generator to your 144 volt DC battery pack is not going to end well. The generator will probably sizzle its circuitry before you can say, “Where’s that smoke coming from?”.
If the cost isn’t an issue, and if you can adjust your generator’s voltage to match your EV’s pack – and if your car can handle towing a generator trailer – then it might just be an option for you. If done well, the positives to such a system are immense if long distance driving in your EV appeals to you.
There’s also the option of having the generator controllable from the comfort of the driver’s seat, so you can start, stop, and monitor what the generator’s doing (and shut it off in an emergency) without having to leave your seat.
Ultimately it comes down to practicality for your situation and cost. Let’s face it, when it comes to EVs it’s always about cost – that’s often the motivating factor behind breaking your “oil addiction” in the first place!