Manual forced autostop - Battery issues

batteries

#1

Forced autostop involves accelerating to a good enough speed and then shifting to Neutral (to keep coasting) and killing the engine simultaneously. I did this aggressively - about 300 m of acceleration followed by 700 m of coasting with engine off - and had about 40% better fuel efficiency. My question is whether this technique would starve my battery of charge? Will I land up in a position where I have drained it so much that it will fail to crank my engine up in the morning? How long does it take to replenish the charge required for starting the engine? In the night time would the battery-supported headlamps hurt it beyond redemption…? I am being torn between this new found love (hypermiling) and commonsense worries about getting stuckk… Please help!


#2

You don’t want to get complicated on the answer, do you? In short, unless you are trying to run every electric item on the vehicle at once, it will be fine.
When you put the transmission in neutral, the engine goes to idle rpm (about 700 rpm), and the alternator is still charging the battery…albeit, at a reduced rate. So, keep the electrical load low. Leave the headlights ON.

Oh! CSA, I missed the part about turning the engine off.
Still, Humming bird, keep the lights ON. Since, it’s a manual transmission, you can shift into 2nd gear for a re-start when the car slows (naturally) to the points where you want to accelerate, again. This will save on your battery charge, because some charge is lost when the battery cranks the engine.


#3

Humming Birdie, Just Have The Battery Replaced Every Time The Body Shop Replaces The Sheet Metal On The Front Of Your Car.

This is a definite “no brainer”!

You will be using other cars for brakes and maybe steering, if you need either one in a hurry and can’t get your engine fired up quickly enough to power on your brakes and steering!


#4

hellokit: I don’t mind a bit more complicated answer - I KILL the engine, so the alternator and everything else is quiet - 0 rpm. I wanted to know if the 3-ON:7-OFF dutycycle is enough to bring back the lost charge in the battery… and at that duty cycle, how much time / distance would be required to put back charge in the battery worth 1 start.


#5

I do use bump start, in fact that is the way I start normally, but still I have to occasionally use self-start (at a signal, mostly). Worry is a couple of those, and the one when starting from parking, and I could be in trouble if treading on thin charge…


#6

Humming Birdie, Now That Your Charging Issue Is Resolved, Do Us A Favor …
Humming Birdies Sometimes Fly Into Windows.
Since driving cars is not exactly the same as playing a video game, would you please list the roads (and their locations) that you drive and a typical schedule of when you are likely to be on them? Thank you in advance and many of us can now adjust our routes and schedules.


#7

I think that the kind of information you seek is only researched, and charted, by battery manufacturers.
If you want to be the surest that the battery is maintaining adequate charge, the LOAD (cabin cooling fan, mega stereo amp, wipers, other electric motors) should be kept to a minimum. A warm engine needs much less battery power to restart.
In toto, I don’t think there is a problem.