[remy_martian]

What is a "battery"?

 

[remy_martian]

I doubt you'll get 1000 amps out of that setup.

500A peak, 300A continuous on a good day, imo.

Enough to maybe run a 60kW motor for 20 minutes...

 

[remy_martian]

Copper prices are irrelevant.

 

[remy_martian]

kW/kWh is a kW/kWhanadian term, apparently

Everybody but Brian writes his kW/kWh as "C"

Fires start and pack life gets totally trashed when you "hope".

For Lithium, COOLED batteries can generally do 3C continuous, 5C peak. Meticulous engineering using a compute farm of over 1000 GPUs, like the kids at Tesla and SpaceX have, get you that 8C, maybe 10C.

There's no magic. Hope gets you nothing in engineering. Ever cross a bridge, thinking the cable was designed for bicycles but you're hoping it wouldn't snap with a car going over it if you go quick enough? That's some Wile E Coyote thinking going on, dude.

Live within the current limit or buy the second pack by force to act again as one limited pack. You don't get Tesla amps (or even 1000 of them) just because you wrote it on the internet after buying half the battery and a "1000 amp" controller.

 

[remy_martian]

"Proper" air cooling CANNOT give you better pulse performance than published. It's a limitation you're stuck with.

Busbar has nothing to do with what the battery can deliver, only with what the busbar can deliver, unless it was deliberately undersized in its original application. The 5C rule of thumb applies, regardless, as a cell limitation.

 

[remy_martian]

In summary...no free lunch

 

[remy_martian]

You need to be able to shut off all voltages coming out of the front pack and the rear pack for safety reasons.

That precludes running 96 wires willy nilly all over the car to a single BMS, since those wires always have voltage on them and are usually not fused. So, you'll need a BMS master in one box connected with galvanically isolated communications to a satellite BMS in the second box.

You also need two contactors inside each battery box. One for plus, one for minus of its HV battery connection.

Interbox HV cables should be run separated, so a responder with a chop saw does not melt the sawblade with 2000 amps running through it. Ideally protected from road debris damage (including innocent-looking rocks, gravel, dropped car parts, and traction grit).

HV charge port cables need to run to a box with 2 more contactors applying voltage to the HV battery in the proper sequence if you are planning DC charging.

Depending where you live, you likely will need a coolant heater in the loop for the batteries as well.

Any heat source connected in series will heat the downstream heat source. So, no, you will not be equalizing the temperatures.

You can run the rear battery box's coolant loop through the motor (not the other way around) if you want to be frugal about number of loops.

 

[remy_martian]

Seems awfully thin, imo, unless you know your way around putting in dimples, doublers, and stiffening ribs with a bead roller in the right places - even then, seat of the pants says 18 is at least half the thickness you'd want.

I'll defer to our hands-on sheet metal expert, @Functional Artist

 

[remy_martian]

I'd point out that structural portions of a car body use doublers and triplers and that car body sheet metal that is holding the appreciable weight of a battery module could either tear out a fastener or buckle under load and sudden loads like potholes and trees. The car bodies of today use high strength steel to withstand wind loads...the real structure is under the skin.