If you have LiIon batteries and they are experiencing severe voltage
sag, you are discharging them too much, which will greatly shorten their
lifespan. You may get a few extra miles of range now, but your overall
range and total number of miles driven with the pack will be lowered
(quickly!).
Unless you have lots of money to buy new battery packs relatively
frequently, you probably shouldn't do that.
w.r.t. your observations: When you let up on the accelerator, it reduces
draw from the battery pack, allowing the cells to recover slightly and
give you another pulse of power before the voltage sag hits.
Jay
On 02/25/2016 10:08 AM, Craig M. via EV wrote:
I need some feedback for anyone who has seen the following effects.
I want the maximum possible range out of my EV but when the battery
is weak (58 miles or so,) acceleration can be a problem. If I hold
down the accelerator pedal too long the voltage drops low. The motor
pulls a lot of current, and the motor may slow down as the battery
rapidly discharges. I have also observed that if the motor stalls,
it draws very high current and the battery is soon fully discharged.
To get home on a weak battery I have had to accelerate in steps or
pulses. I would lift my foot off the pedal for about a second and
let the voltage on the battery come back up before pressing the pedal
down again to accelerate. There is an alarm that sounds if the
voltage on any cell is too low or too high. I have an AC-50 motor
and controller with the regenerative feature and LIFEPO4 cells. This
may be playing a role in this effect. I would appreciate hearing
from anyone who has pondered the effects of voltage sag on batteries
and motors. I have asked this same que stion elsewhere and I got
back shrieks of how I am breaking the laws of physics, motion or
thermodynamics. I can't break those laws so I frankly have stopped
worrying about it. I am making observations and trying to learn from
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