electric vehicle and ultracapacitors

[michaeljayclark]

in florida we get 5 sun hours a day. if you have a 144 vdc battery pack with 200 Ah batteries you have 28.8 Kilowatt hours in your battery pack.

typically you would only drive half your range so youd only need to replace 14 kilowatt hours.

Id say youd need about a 6 kilowatt system on your house and that costs about $15,000. 30 200 watt solar panels. that cost is WOW but consider you are charging your car PLUS running your house on solar. a double win. free energy for your car AND house.

 

[shortbus=]

All this about EV's is great at this moment. Wait till the Government figures out how to charge the 'Road Use Tax' for them. That tax is figured into the price of gasoline and diesel and it will eventually be figured in on EV's.

 

[tcmtech]

the ac systems have been improved but are not within reach of the ev builder unless you want to spend $50,000

If you are looking for a off the shelf AC drive system that is not all that pricey and can in many cases be found used look for commercial VFD units.
Although they are rated as needing a three phase AC input they in fact rectify that three phase into a high voltage DC before converting it to a variable frequency and voltage AC.
Which means they work just fine off off a high voltage DC source just as well once the input rectifiers are bypassed.

Typically the ones in the higher horsepower range also have dynamic braking by means of a load dump output that usually just goes to a big resistor. That output could likely also dump that regenerative power into other things including a bank of ultra capacitors or back to the battery bank.


Just something to look into.

 

[michaeljayclark]

the best AC system for the ev builder is made by ac propulsion. the system costs $50,000.

there are those in eastern europe that have made their own ac system but they wont make it for anyone else. companies that make dc systems are looking at ac but are waiting to see if the auto makers follow through with their promises or not.

as far as road tax, I believe that EVers should pay for road tax. But the amount will be under debate. In my previous post I calculated that a prius uses $1000 a year in gas with about 300 gallons. Florida adds 16 cents to every gallon for taxes. That would be $48! But thats if you drive 15000 miles. I can see them just use a flat tax for EVs thats added to the registration cost.

Washington is trying to impose a $100 tax on EVs to pay for road tax and I think that's fair. washington tacks on 37.5 cents per gallon with 6.5 cents for sales tax. a prius that drives 15000 miles pays $112 in road use tax and pays $19.50 in sales tax.

 

[tcmtech]

I checked out the AC propulsion site and to be honest there isn't anything about what they are claiming that cant be done with off the shelf commercial VFD units and other common industrial power management hardware for far less cost that $50K.

To me it looks like nothing more than a rich dumb tree huggers feel good toy. At $50K plus the cost of the vehicle it would go into its so far outside of the practical intent and purpose of EV tech its sad.

Ev's are intended to be practical, cheap to own, operate and justify it on their outstanding cost per mile numbers offsetting their purchase price in the long run.

Comparing just that controllers cost alone to $4 a gallon gas used by a mid sized car that gets 25 MPG average it would have to travel some 312,000 miles just to offset the cost of the controller in fuel savings assuming the electricity was free the whole time.

 

[peufeu]

Ev's are intended to be practical, cheap to own, operate and justify it on their outstanding cost per mile numbers offsetting their purchase price in the long run.

If the main purpose of the vehicle is for commuting (which is a common case) you'll get a much better and cheaper EV by dropping the requirement to haul around 2 useless tons of car.

Like <**broken link removed**> for your highway commute .

Or the <city version>.

Those two are not that cheap, due to small production runs. More sales would fix that.

Both solve the traffic jam problem, and the parking problem.

I've tried the Kalkhoff, it's pretty good due to the strain gauge torque sensor, you don't feel the assist at all, but the hills are magically flattened. Since the electric motor goes through the gears, it can haul a lot of weight up a steep slope.

 

[michaeljayclark]

the AC propulsion scion XB is a really nice car. as fas as the cost, a gas car total ownership of say a ferrari is way past the cost of the E-Box, the name given to the electric scion.

you get what you pay for. if you buy a tesla electric rocket, lol, you get really fast and 200 miles electric range. if you pay $10,000 you get an electric chevy S-10 with 60 miles range and the take off like a 4 cylinder.

I think that considering cost savings isnt really the way to think of electric cars. If you cost compare anything you will make anything look cheaper than something else.

I just think OIL is a polluting, murderous, geo political nightmare. watch shows telling the history of oil. its amazing we didnt kill ourselves over it!

oil got us where we are. like most resources we use it up till its gone. when oil gets more and more scarce our world will change for the worse. Lets do something now to mitigate it.

wow this thread went WAY off the original topic!

i drew up a precharge circuit that i think can precharge the capacitors safely, see attached.

 

[wannaBinventor]

Don't capacitors in series lead to a lower capacitance than any one capacitor in that series? In other words, putting them in series will give far less than the 156,000F expected by multiplying 56 x 3000.

I'm right here..... right?

 

[michaeljayclark]

correct. the capacitance is the same for all these caps. 6 in series is

1/C = 1/C1 + 1/C2 + 1/C3 + 1/C4 + 1/C5 + 1/C6

voltage is added together. each cap is 2.7 volts so 6 * 2.7

 

[peufeu]

> I just think OIL is a polluting, murderous, geo political nightmare.

Not to mention we're past the peak.
I wonder if it is really such a good idea to replace oil cars with electric cars which use about the same amount of energy, said energy coming from electricity generated mostly from coal and natural gas...

Additionnally, the world"s biggest lithium reserves are below ... afghanistan. I guess we haven't seen the end of murderous, geo political nightmares...

PS : if we model the 75W bulb with a 6 ohm resistor (rough estimation since its nonlinear), the RC time constant will be close to 1 hour...

 

[michaeljayclark]

lithium is only one technology for batteries, more are being discovered.

lithium will be found everywhere, even in the rockies and salt flats, etc...

ill charge up the caps with the lightbulb, whats the worst that can happen? the lightbulb explode? LOL

 

[tcmtech]

I don't think the light bulb will have any troubles but the resulting low input current could give you a tremendously long charge time!

If it was me and I wanted to charge them quickly without over current concerns I would be dumping them through a high wattage low resistance device like several space heater elements. 2 ohms at 144 volts would give you a peak current of 72 amps which is not much as far as a big deep cycle battery is concerned with.

Given a 1500 watt space heater is roughly 9.6 ohms four of them would give you 2.4 ohms and a peak current of 60 amps that rapidly tapers off as the capacitor voltage rises.

In regards to capacitor over voltage protection that has to be done on every single one. Over current is not an issue really. Over voltage due to imbalances in the true capacity of each individual one is the problem.
They may all be rated a 3000 F but the actual variance between the highest and lowest of the group could be that one is 2900 F and one or more is 3100 F. the higher capacity ones in the series will get less voltage built up across them but the lowest one will be getting over charged to the point of destruction.

 

[michaeljayclark]

the nice protection circuit that maxwell makes for their caps I will be investing in. With those circuits which are boards that go between two caps in series and so on are used on an electric vehicle I just found out about. They have been regenerating 400 plus amps into the cap pack with no issues.

I asked maxwell about the current limits and so forth and they replies the caps can handle 150 amps continuous, max surge current for 1 full second is 4000 amps. the caps be used to zero moving an electric vehicle with no damages.

I am not worried about the length of time to recharge the caps now... as long as its done safe with no explosions LOL

 

[adamey]

^ OK, if you're not worried about the time to recharge the capacitors, then what's the point of even having them? You need to be able to dump a lot of energy into them in a short period of time if you want to recover energy from braking. Otherwise, they aren't providing any benefits.

You're using lead acid batteries, so it's not like they aren't able to provide high current to your motor for accelerating. If you were using lithium or some battery that can't provide high current, then when you want to accelerate you're at the whim of your capacitor charging circuit and the time it takes to top them back up to get you going again.

 

[michaeljayclark]

that was only for this one time precharge. not for full time use. I am just learning so start out slow and go up from there. Ill look at faster charging when I get the caps installed into a full pack, all 52 or them.. Ill be buying more this month. Id like to get it close to 200 volts.

ok, the lightbulb handled the current no problem and you were right, took almost an hour to precharge one volt!

I moved to using a 12 volt turn signal lightbulb from the truck itself. it charges faster and the bulb is lit up but not really bright so it handles the current with ease.

Ive read that the 75 watt lightbulb is a 6 ohm resister, the lightbulb maybe a 4 ohm. Ill need a lower ohm resistor to charge faster...

 

[tcmtech]

Ive read that the 75 watt lightbulb is a 6 ohm resister, the lightbulb maybe a 4 ohm. Ill need a lower ohm resistor to charge faster...

Huh?

don't you even know the electrical basics of ohms law?

At 120 volts a 75 watt light would need to be, 75 watts / 120 volts = .625 amps.
To get .625 amps current flow at 120 volts you need a resistance of 120 / .625 = 192 ohms.

If it was a 75 watt 12 volt light it would be, 75 / 12 = 6.25 amps.
To get 6.25 amps current flow at 12 volts you need a resistance of 12 / 6.25 = 1.92 ohms.

 

[michaeljayclark]

didnt know the 12 volt lightbulb watts. math isnt my forte, but i understand what your doing

 

[peufeu]

What is the purpose of pre-charging those supercaps btw ? If you want to use regen braking, you need to have enough storage left in the caps to absorb the braking energy...

 

[michaeljayclark]

just precharging to see how they act and such. this configuration with 6 for 16.2 volts is to see how they act in place of the car starter battery. looking to so how many cranks they have in them.

 

[peufeu]

OK, that makes sense.

You live in a place with very cold winters ?