Buddy, Do you have a Lithium pack? If so, you are being way too conservative limiting regent to only when your pack is below 80% SOC. You would be better served to limit regen based on battery terminal voltage than on SOC.
On Thu, Mar 20, 2014 at 12:04 AM, Buddy Mills <[email protected]> wrote: > So much math...it hurts my head. Regen good. It kicks in, the amp gauge > goes positive. > As for the setup; I have a switch on the dash. Position 1, it only works > when the brake is applied. Second position. it work when I let off the > accelerator. Third position it is turned off. I also have a disengage > switch on the clutch to keep the motor from coming to a dead stop when it is > working off the accelerator and trying to shift gears. And last but not > least my BMS turns off regen if my SOC is above 80% as to not overcharge the > battery pack. > > Buddy Mills > [email protected] > > Look mom, no gas. http://www.evalbum.com/2887 > > Disclaimer: No animals were harmed or killed in the process of writing this > email. Any stories to the contrary are, for the most part, either fictional > or greatly exaggerated. > > > Cor van de Water wrote: > >> you have a total efficiency of: >> 90%(batt) x 95%(controller) x 85%(motor) x 90%(drivetrain) = 65% > > Excluding the battery efficiency for simplicity and considering the > situation from the point of view of energy provided by or received by the > battery: > > Consider a 1000kg (approx. 2200lb) vehicle travelling 50km/h (approx. > 30mph); it has a kinetic energy of 96450.6J. > > Using your numbers above, 96450.6J/(0.95 x 0.85 x 0.90) = 132715J were > provided by the battery to achieve this. > > Regenning to a complete stop provides 96450.6J * (0.95 x 0.85 x 0.90) = > 70095.5J to the battery. > > So, (0.95 x 0.85 x0.90) = 72.7% of the available kinetic energy is provided > to the battery, however only 70095.5J returned / 132715J consumed = 0.528, > or 52.8% of the battery energy consumed in achieving that kinetic energy > level is recovered. > > Joules aren't a unit that means a lot to some of us (though SI units are > easy to work this example in ;^), so let's convert it to something more > familiar: > > 1J = 1W-second, so 70095.5J = 19.47Wh. > > If we assume that you accelerate to 50km/h and then regen to a stop every > 500m (so you start from a stop at 0m and are again stopped at 500m), then > out of every 500m travelled you recover 19.47Wh. > > So, how much does this extend your range? > > If your vehicle consumes 200Wh/mi (=200Wh/1609m) at 50km/h, then every 500m > you recover enough energy to travel a further 156.6m: 156.6m/500m = 31% > increase in range. > > Another way to look at it is that accelerating to speed after the stop > consumes 132715J from the battery; this is 36.86Wh, or enough energy to > travel 296.6m at constant speed. > > So, regenning to a stop allows you to recover enough energy to travel > another 156.6m, but avoiding the stop in the first place saves you enough > energy to travel 296.6m further. > > Obviously, the shorter the distance between each start and stop, the greater > the % range increase appears. How high can we push it? Let's assume it > takes us 5s to accelerate to 30mph (50km/h) and 5s to regen back to a stop. > Let's assume that we accelerate to speed and then immediately regen to a > stop, and continuously repeat this pattern. > > During each acceleration we travel 34.7m and during each deceleration we > travel another 34.7m. So, for every 69.4m travelled, we consume 132715J to > accelerate, plus about 31055J (69.4m @ 200Wh/mi) = 163770J. We recover > 70095.5J, which is enough to travel (70095.5/163770) = 42.8% further in this > inefficient driving pattern. > > > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA > (http://groups.yahoo.com/group/NEDRA) > -- David D. Nelson http://evalbum.com/1328 http://www.levforum.com _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
