Lectrickery wrote:Isnt there some way to burn off the regen power even if the bateries are full so it is still used sa a brake support system without killing the batteries?
Ha ha and I dont mean a large row of 240V 100W globes on the back parcel shelf either....
That's the thing about EVs; you are dealing with significant amounts of energy and power. Suppose you are cruising at 80 km/hr, using say 5 kW. So 100% regen isn't the 5 kW what you are using now; that's just what it takes to keep you from slowing down to 79 km/hr. Full regen is like 50 kW, or whatever peak power your controller and motor are capable of. 50 kW is 500 100W bulbs; the guy behind you won't just get blinded, he'll get a sunburn!
I've come across a similar problem trying to load my motor at home without too much danger. I thought of lifting 100 kg loads a metre or two, but it's just not enough. I thought of winching White Suzi up my driveway; there is about a metre from the bottom to the top. So the potential energy is m.g.h ~= 1000.10.1 = 10 kJ. Sounds a lot. But just to put a nominal
load on my 7.5 kW motor means I'd have to raise the car in 10/7.5 ~= 1.3 seconds. I'd have to profile the acceleration so as not to snap the cable/chain, and to slow the thing to a halt at the end of it. Not sounding very safe, and I'd like to test it at up to 2xovervoltage (possibly 3) and 3x overcurrent. My mains supply is only up for 15A anyway, which is just 3.6 kW.
So maybe I need to put the motor and controller into White Suzi, such that I can still use the ICEage motor, but then I need to bring along a lot of batteries as well...
Significant power and energy levels.
Fortunately, you don't usually need to blow off regen energy due to a full battery for long, so you could maybe get away with a large brake resistor (think coils of glowing wire 6mm thick in the transmission tunnel or in the nose cone, where there is hopefully lots of cooling. But even then, if you happen to opportunity charge at the top of a long hill, you could exceed the capability of your system to dissipate regen energy.
You could say "well only charge to 80% if you happen to live at the top of a big hill", but you may have opportunity charging different to where you live. You might lend the car to your brother, who lives at the top of a hill when you don't. Etc etc.
So I'm thinking if the battery is full and regen is called for, do nothing. The user's foot will sink a few more mm to the mechanical brakes, and they are (pretty much) rated to take the vehicle's energy continuously. (Though some people do have problems with glowing brake components when descending long hills or mountains). But that's not an EV specific problem; you would have had the same problem with an ICEmobile.
For the maximum safety, it would be nice to make the amount of travel of the brake pedal in regen mode (where it could be ineffective if the batteries are full) as short as possible. Yet have a moderate range of regen, from very mild to about half. (Exactly how far depends on the vehicle; rear wheel drive should probably regen less than front wheel drive). And when the foot pressure exceeds that amount, it should "pass on" the pedal travel to the hydraulic system, in such a way that no possible failure could cause that not to happen.
Any mechanical types have a solution for that?
If we can make the regen happen in ~5mm of travel, is that safe enough?
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.