Z Source Inverter

Assuming that the portable pack is a standard Lead Acid cell type currently available, and that a typical public charging station outputting 30 amps charge current would provide about 32 kilometers (20 miles) extra range for a 1 hour charge time, and disregarding any inverter/charger losses, a portable pack providing the same charge rate would need to be at least 120Ah to allow it to maintain a minimum 50% cell state of charge for that 1 hour period.

Factor in losses, and the pack capacity would need to be closer to 150Ah.

That battery will weigh around 40Kg (18lbs) and starts to get beyond the realm of being reasonably considered portable, plus you also need to carry the inverter as well as the battery.

Whether the extra cost of purchasing the battery pack and inverter, and then carting it around in the vehicle on the off chance that you may need it to get a further 20 miles down the road, is an advantage or not would be up to individual perception.

It's a common misconception that an EV charging station/cord provides DC to charge the battery, it doesn't. The output of a charging cord is exactly the same as the input; same voltage, same current, same frequency.

An SAE-J1772 compliant plug provides AC to the vehicle, which is then run through the particular vehicle's onboard charging electronics package which communicates with the charging station things like battery state, readiness to accept charge, correct connection, and safety. Without that electronics module the cord is basically a glorified extension cord with a GFI specifically designed to detect that if you drop the J1772 into a puddle of water or if somehow the car chassis becomes energized, you don't get killed.

In the case of Tesla, Elon's Supercharger bypasses the AC side and goes directly to the battery at around 480V. Now there's something that is probably not meant for mere mortals, fooling with a 480V, 200A battery capable of delivering in excess of 100kW in short bursts!

what do you mean "bypasses THE AC side"?

Like this?

http://forums.aeva.asn.au/forums/new-to-the-forum-new-imiev_topic3714_post44469.html#44469

See Z_man (or maybe not).

When you say " business model" , it sounds like a portable mobile charging platform ( tow truck) .

Let's say the EV does conk out because the batteries are drained, so the service man hooks up charging cables and recharges the vehicle in the field because the batteries are in fact drained, but let's say that the vehicle conks out not because the batteries are drained when in fact there is another problem with the vehicles electronics package, would attempting a field charge cause damage and result in liability issues ? And wouldn't it be better to tow the vehicle to a service facility for a proper diagnosis ? Which brings us back to tow trucks, hmm ?

right now towing is the only option unless you happen to be really close to an outlet, which is rarely the case on the road or parking lot. tow trucks are not equipped with charging capabilities to charge a lithium battery pack like Tesla, remember their is no engine with an alternator so you don't just need a "jump" you need a charge of electrons, thousands of watts. the smallest Tesla holds a 60K charge, thats beyond a tow trucks ability to help, so currently you need to be towed home or to a charging facility. most Tesla's consume about 1K to travel about 3 miles, so any field charging would need to be a couple of KW's so they could drive another 5-6 miles to the nearest charging site.

What about a tow start??

Most of these cars already have regenerative systems that work whenever the driver's foot is off the accelerator, but not on the brake...

So...he says tongue in cheek.

You could always tow it and let the regenerative braking charge the battery.

Maybe the service truck just needs a tray with a rolling road on it.

I've been driving fully electric for 2 years every day now and haven't "conked out" yet. The remaining range displays on EVs are quite precise and get more accurate the closer you get to fully drained. "Range anxiety" appears to be a hangup of folk who have never owned an EV.

Sorry Fredski I'm not having a go at you but replying here seemed the right place.

it happens

Yes, I guess it does. It would be interesting to get hold of the stats on the ratio of electric to fossil fuel cars towed compared to the ratio of same on the road.

Would EVs be over represented?

Back to the topic. The e-jerry can (Battery pack and inverter) I linked to earlier is used by a couple of AEVA (Australian Electric Vehicle Association) members to give them slightly additional range if they are expecting to go beyond their normal maximum range. It's not used as a "ran out of energy" emergency device.

I must admit than when I started to drive the eVogue daily, I made sure I had the phone number of a flat bed tow truck as I didn't expect my debugging stage would be tow-free. I haven't bothered with an e-jerry can and in fact I don't even carry a charge cord with me as I always charge at home off-peak (low tarrif) and plan my trips - thanks google maps.

http://electricvogue.blogspot.com

Fredski, have you done any research on how much a charging vehicle might cost and if in the field charging can be done safely, timely and without creating warranty issues ? Is anyone else providing the same or similar services ?

I've been costing it out, yes. I don't see anyone doing it, just flatbed tow trucks making a small fortune, Tesla plans on cranking out 500k more cars

Hey, if you want to hire me for a part time gig, I can do that, I've got a class A license.

How about a welding truck, and make/install an adapter off the welding machine's 110 VAC outlet? I bet that might help. If I were you I would invest in the new Aluminum-graphite rechargeable batteries instead (research was done at Stanford U. if you wish to google).

In fact something like the Al-C battery might be better in the EV in the long run, since it cycles faster than Li+ ion, can cycle many, many more times, can be made flexible, and will not catch itself on fire. Something that could be charged up within 2-3 minutes out on the road is appealing. For that matter, one could rendezvous with a charging vehicle, where both have induction coils, and dock to the charging vehicle while still enroute!

110vac is charging at a snails pace.......hours, DC direct is minutes. the Stanford word is very interesting but I believe thats still at the laboratory stage, nowhere near commercially available just yet

OK, then re-work the welding truck's power out connections to match optimum rate of battery re-charging. Maybe the welding truck could even lower a recharging coil to work through a pick-up under the car, so that that no one has to stop to re-charge. Obviously, this would be less efficient than a hard connection. I am thinking the only way to do re-charge through a hard connection would be a required auto-pilot mode where the car on auto docks with the charging connector on the truck (also on auto-pilot), sudden stops might be chaotic?

While all these ideas are good, what really needs to be done is the creation of a standardized battery pack, one that can be slid in and out, just like they use in warehouse fork/lift trucks. Its done already on a smaller scale already, look at a cell phone, pop the cover, drop in a fresh cell look ma, no wires, pop the cover on, boom diddy boom, away you go.

The standardized battery pack with "load & go" is part of Musk's vision. Now let's pretend that you just took delivery of your brand new Tesla, drive a few hundred miles, and you pull up to a Tesla-authorized "battery swapper" who proceeds to put in an obviously older reconditioned battery pack.

So how are you going to feel watching your brand new factory fresh unit swapped out for one with who knows how many charge/discharge cycles on it? Gasoline is at least more or less fungible, a one-use commodity with some sort of government regulation as to its specifications, unlike the used battery pack you just got stuck with.

I think his battery swap option only comes with a "lease the pack" purchase. If you buy the pack with the car outright you wouldn't want to go swapping - as you say.

BTW Google "Better Place" and you will find that this has been tried before. Shai Agassi spruked enough of the battery swap hype to rake in 800 Million US$ of investment then went belly up (unsurprizingly). A project or two here in Australia with Better Place involvement were also stymied by their failure.

Maybe Musk can make it work but even he (or his minions) might realize that before he can get enough swap stations installed to make it viable, battery technology and fast charge stations will be (and have been) been faster, cheaper and easier to implement.