AC vs DC

From EvTechWiki

This is an interesting article by an EV expert defending DC drives.

Before adding my thoughts, a disclosure...I consider both Otmar and Victor to be good friends.

Victor Tikhonov wrote:

> Practically for the driver this translates to covering all driving speeds on one gear, no need to shift. > > You ask me what you can do with high voltage and AC motor and this is the answer. You cannot do it with a DC motor.

I don't agree. My high voltage DC powered Datsun 1200 sedan with its Siamese 8 motor runs 0-120 mph in one gear. I cannot think one of Victor's AC drive packages that can even remotely match this car's 0-60 performance (3+ seconds), its 0-100 mph performance (11+ seconds), or its top speed for that matter (without shifting). Credit to Otmar for his over-engineered Z2K design!

My other more tame lower voltage (156V) EV, another Datsun 1200 sedan, can be left in third gear to give a no-shifting driving experience. Left in third gear it 'is' slower than if shifted from 2-3-4 (under that mode it runs 0-60 in ~ 6 seconds, probably runs 14.5 -14.8 in the 1/4 mile, and can top 120 mph), but still under the handicap of being left in one gear it runs 0-60 in ~ 8 seconds and tops out at ~ 90 mph...about the same as one of Victor's $10,000 AC drive systems (price includes a high voltage battery pack and BMS), but this car is able to do it for half the price at about $5000 with a 9 inch motor, a Z1K controller, a separate DC-DC, and a low voltage pack of just 13 Optimas, Orbitals, or Hawkers...credit again, to Otmar for his affordable Z1K line of controllers.

> I'm yet to hear anyone who tried an AC system and regret the decision and want to go back to DC one. This alone means to me AC is overall technically more superior

Hate to pop your bubble then.....I have vast experience in driving AC powered EVs, trust me. I've driven perhaps 20 EV1s, have had AC powered pickups to drive for months at a time, have driven Alan Cocconi's AC CRX, have driven quite a few Solectria vehicles including the Sunrise, the Force (Metro), and their twin drive AC pickups, have driven AC powered Ford Rangers, have driven factory made AC vehicles from Nissan's LiIon powered Altra wagon to Honda's NiMH powered EV +...oh, the list could go on and on. But the truth is, I still prefer DC powered cars in nearly all aspects. For the same money, the DC cars run off and hide from AC cars...heck, even at half the price, they still outperform the AC cars. DC cars give thrilling, adrenalin pumping off line torque, and have a much higher fun factor, period! It was always interesting to go from driving the EV1 to my DC powered Datsun 'Blue Meanie'. The EV1 was smooth and swift, could hit 80+ mph, and of course, had a higher tech, higher energy density pack of NiMh batteries that gave it outstanding range per charge, but my trusty lead acid powered, shorter range DC car could still kick its butt in the 0-60 run and really kick its butt in top end speed :-) For me, the driving experience in the EV1, hip and advanced as it was, was still not to the level of my backyard built DC car with its instantaneous torque and snappy 0-60 blast!

So, am I dissing AC? Certainly not. My Insight has an AC drive system, and some of my favorite EVs I have had the pleasure to sample have been AC powered. I loved GM's AC powered EV1 and have fondly written about it...I also loved Otmar's cooler than cool little Sprint with its low power Brusa AC drive. I spent many hours behind the wheel of that fun car. What it lacked in power, it made up for in stingy miles per charge, silky smooth rev-forever drive, killer regen, and oh yeah, that rock'n Wayland sound system it had! One evening Oat and I took it up into the hills near Palo Alto for a spirited drive up twisting mountain roads to the summit where it was getting low on SOC, only to regen all the way back down and return to the flatlands with a hefty charge put back in...what fun that was! I also have an EV grin producing memory of watching Victor do his capacitor powered AC burnout....way cool!

AC is cool, DC is cool. However, the thought that only AC can be used for single gear driving to cover 0-100 mph speeds, is not correct at all. In fact, I would say that for the same money, the DC single speed (direct drive) is superior to the AC single speed (direct drive) in terms of thrilling power, extreme torque, and higher top speed (while still retaining super quick 0-60). Now, as to regen and the highest overall efficiency (perhaps 3-5% better), the nod goes to AC.

While I've enjoyed the discussion between my two friends, in the end, all I can say is thank you to both for providing expert service, and for helping to shape the EV conversion market in a positive way.

See Ya......John Wayland