What battery [type/size/weight] holds most kWh for it's size?

Not as simple as even those 5 criteria unfortunately. Recharge and discharge rates must be considered, as well as lifetime, out gassing, charge memory and resistance to overcharging. I don't think there is one right answer.

Lithium. However, limber up your credit card.

There are other reasons for selecting Lithium. If you want to use regenerative braking (and you will need an AC drive motor to do this), Lithium offers the lowest internal electrical resistance, thus has the highest regen efficiency. Lithium also offers the higher number of recharges over other technology and they are the lightest for a given power density.

However, Lithium packs require their temperatures to be within a narrow range of operation and charging them requires each individual pack to be current monitored so that you don't blow one.

Why do you state that you need a AC motor for Regen Braking?

In the wheelchair controllers I used to build, we used Regen braking on the DC motors, and dumped the braking into a load resistor, dumping into the batteries made it more complex, and not as much braking force was created.

Regen works fine with brushed DC, brushless DC, and AC motors. I'm not sure what Anonymous Hero was trying to say.

My understanding is that the effectiveness of regen with a DC motor is not as good as and AC motor. If the DC motor is series wound I don't know how you would do it without injecting a current source into the coils.

Also, you have to reverse the motor's outputs to et the right polarity. So, it can be done, but I am guessing that it has to do more with economy of installation.

If the DC motor is series wound I don't know how you would do it without injecting a current source into the coils.

This used to be tricky, although now there are several controllers that handle the transitions without requiring contactor switching. In the old days it could be done as described in this article.

I think you are right re economy of installation. I think now, it makes sense to implement regen with most of the motor types, and the trend is to toward contactorless four quadrant controllers and AC and brushless DC motors. In a small vehicle like mine, the fairly small additional cost of implementing regen is paid back in 5 years or so -- although it depends on too many factors to predict accurately.

"Ideal is range and performance comperable[sic] to gasoline power."

No current battery technology comes close to the energy density of gasoline. Forget weight. Even if you just use volume, gasoline has more than 10-20 times the energy density of any battery.

I'm talking something in the size/weight/performance range of a Ford Crown Victoria/Lincoln Continental

For perspective, the Tesla uses about 900 lb of Li ion batteries. You'd need substantially more than that. You could figure on $60,000. The price makes lead acid batteries (at more than twice the weight) look attractive.

Check out this site for ideas -- it show hundreds of EV's with details on batteries, motors, etc.

As a former delaer of several battery makes and products, I can firmly state, that DELCO has the best power/wghi-size rate.

I suggest you to turn on personnally or by letter to the nearest dealer!

Should You be in Europe & I could give company, adresse & name.

eg.: A 14 kgs battery has 55 A/hour capacity.

good chance

Is this a deep cycle battery or a starting battery? Do you have a model number?

Your last information on DELCO is incorrect...

Odyssey is the leading lead acid battery bar none....

M-1 tank uses the battery, F-15, F-18 uses the battery...Nuke Subs use the battery (deep cycle)

400 cycles DOD @ 80% discharge

recharge acceptance amperage @ near 100%

8-10 service life

Could go on to say that Sonneschien are good too.... and Yasa, and whoever else someone likes the best..

I have been running Sonn in my Off Road buggy for a while, the punishment in airforce planes I doubt are quite as much as Off Road Racing, or even a tank.

But then again, you don't go jumping tanks off drop-off's as the idler wheels pop off, and not so good for the soft bodies inside either.