Electric cars, unclean at any speed

[RedDevil]

If I had to pull a trailer with an EV, I would like it to have extra battery packs instead of an ICE. The combined charge has to be just enough for a days drive.
Charge time remains the same as you can charge both car and trailer at the same time, unless they have to share an outlet.

Would be bad to leave them unused between holidays, but maybe U-Haul or the likes could rent them out and swap them if you're running low.

[P-hack]

wow, talk about a quick change battery That would be a very nice thing to have waiting plugged in at gas stations for a trade in, if folks could agree on a standard voltage/ah battery/plug/hitch size.

[redpoint5]

I like the battery exchange idea. It's sounds feasible after an infrastructure were put into service.

I was wondering though, what about a generator that merely extends the range of an EV, but can't quite keep up with the energy demands. Here is a 7kW portable genset. It weighs 310 pounds and could be mounted to a hitch on the car instead of dragged on a trailer. Fuel consumption is 0.53GPH at 3/4 rated load.

Do factory EVs disable charging while the vehicle is in motion? I wonder how far the genset would extend the range of a fully charged Leaf if it continuously supplied the extra 7 kW of power? The genset could be left running to charge the vehicle during rest stops and meals.

Since it's portable, it could easily come on and off the vehicle and be used for other applications when not in use as a range extender.

[NachtRitter]

Great idea about the battery trailer! With modern battery technology (e.g. NOT lead acid), you could probably keep the trailer relatively small & light so that it's more acceptable to people that aren't used to towing. Make it aero shaped along with a little additional cargo space and you've got something that might even improve the default range of the EV and avoid the need for an aero-killing roof rack... (though obviously if it's used for cargo too, it reduces the "quick change" capability... unless it was designed in such a way that the depleted batt pack could be slipped out and a new one slipped in easily at the service station). Heck, if it could help you get ~250-300 miles with the EV, then you're at a point where you'd probably want to stop for lunch/dinner anyway, so if it takes 10 - 15 mins to do the swap, it wouldn't all that much of an inconvenience.

[NachtRitter]

Originally Posted by redpoint5

Do factory EVs disable charging while the vehicle is in motion? I wonder how far the genset would extend the range of a fully charged Leaf if it continuously supplied the extra 7 kW of power? The genset could be left running to charge the vehicle during rest stops and meals.

I was wondering the same thing... Since that isn't a normal usage, I wonder how the manufacturers decided to address that (if at all)...

[IamIan]

For steady state cruising the pusher trailer is more efficient ... but a generator trailer have other utility abilities to it that a pusher trailer does not ... power outages and such... and as speed changes to that which is outside the efficiency band of the pusher trailer ... the generator might be more efficient in those other conditions.

If I was going for a generator ... I like what AC propulsion did for the T-Zero.
20kw continuous ... all together the whole trailer came in at 300 lbs ... had a 9.5 gallon tank ... and they claimed to have a tank to battery efficiency of 22% ... which isn't great ... but it isn't horribly bad either ... compared to the 25% to 30% that most straight ICE cars get... and as was posted it would still have the EV range for shorter trips.

And a little 20kw generator like that should be able to handle an entire house load during a black out.

[P-hack]

Originally Posted by IamIan

... and they claimed to have a tank to battery efficiency of 22% ... which isn't great ... but it isn't horribly bad either ... compared to the 25% to 30% that most straight ICE cars get...

I don't know what that means except that maybe the T-zero can charge the battery at %78 efficiency (still have to get it out of the battery too), don't know what that translates to with a straight ICE?!?

But wikipedia says:
" they get about The trailer used a 500 cc Kawasaki engine with a 9.5 U.S. gallon (40 liter) fuel tank and achieved 30 to 35 mpg" with no mention of the state of charge before and after. can maintain 60-80mph w/20kw

and that is a rather small and light car with fairly optimized engine and generator vs a lead sled rabbit w/auto diesel pusher getting 25/30mpg.

The boxy old rabbit weighs 3100 lbs vs 1587 for the tzero also.

AC Propulsion tzero - Wikipedia, the free encyclopedia

now where is that dead horse gif?

[IamIan]

Originally Posted by P-hack

I don't know what that means except that maybe the T-zero can charge the battery at %78 efficiency (still have to get it out of the battery too), don't know what that translates to with a straight ICE?!?

Electricity doesn't work that way.
They don't have to get it out too.

At the battery terminals there are three devices connected electrically in parallel ... the generator , the batteries themselves , and the motor controller.

For example:
If the motor drive controller is pulling 20kw while the trailer generator is outputting 20kw ... than those 20kw can skip going through a battery cycle completely... pull = to push = net zero.

Their 3rd generation system is better ... but I don't have details at finger tips for it ... the 2nd generation AC Population system got from battery terminals to the road ( controller, motor, transmission , tires , etc ) at 86% efficiency ... that would mean 86% of 22% ... or ~19% efficiency from gasoline tank to road.

Again that is not great ... there are ICE vehicles with peaks above that ... but it is not horrible either ... there are conditions where a straight ICE vehicles will get down at or bellow those ~20% tank to road efficiencies... I've seen many BSFC charts that show the ICE itself bellow 20% even before the additional losses of going threw transmission and such.

- - - - - -

Modern Lithium batteries can have a round trip cycle efficiency of about ~98%.

So even if the motor controller only was pulling 15kwh directly ... ie no battery cycle loss ... while the trailer is putting out 20kwh ... the remaining 5kwh would get cycled through the batteries ... but at ~98% cycle efficiency ... that still would later get 4.9kwh of the 5kwh back out.

[oil pan 4]

Originally Posted by RedDevil

If I had to pull a trailer with an EV, I would like it to have extra battery packs instead of an ICE. The combined charge has to be just enough for a days drive.

Good to rent, not so good to own. I don't think you would want hundreds if not thousands of dollars worth of batteries wasting away just from sitting in your drive way.

[oil pan 4]

Originally Posted by P-hack

if folks could agree on a standard voltage/ah battery/plug/hitch size.

That's not going to happen. The OEMs don't even have a standardized voltage with in their own company.
The only thing standardized is the input voltage to the charger. Usually its single phase 220. I am sure 3-phase 220v chargers exist or can be built for most battery systems.