I do have a brake vacuum pump with a sizeable reservoir (holding vacuum)
and my truck can stop pretty well, though I often use the brakes so
little
and so gentle that from time to time I have to force myself to make a
harder stop, just to keep the brakes from getting stuck.

On my previous EV truck, the vacuum pump was drawing so much current on
12V
and my battery so weak (the DC/DC went out) that I disabled the vacuum
pump
and simply pushed harder on the pedal. I could still make an emergency
stop,
I just had to *stand* on the pedal, but it still worked and I never had
a collision in that vehicle. The problem the vacuum pump in that vehicle
had
was that there was no reservoir and the pump was not entirely up to
keeping the brakes fully powered, so when braking with the vacuum pump
the brakes first engaged too forceful, but then lost pressure and slowly
faded so you had to keep pushing harder during the stop, while the start
was too grabby.
I noticed that in one incident where it had just freshly rained, I was
driving on city streets doing maybe 35 and the light turned red close
before me. I started to brake, but all I got was locked up wheels from
the grabby brakes and I floated through the intersection, aquaplaning
with locked brakes. Luckily it was empty. After that I disabled the pump
and had no more "incidents".
I like the Prius braking and it is very similar to the Leaf - it gives
you
plenty of stopping power when planning ahead and only if a light
unexpectedly changes or another surprise happens, do you need the
friction brakes. Since regen can typically only give you around 50%
back, it is better to anticipate with your speed long before even using
the brakes.

Regards,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: cwa...@proxim.com Private: http://www.cvandewater.info
Skype: cor_van_de_water Tel: +1 408 383 7626


-----Original Message-----
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Willie2 via EV
Sent: Tuesday, August 12, 2014 10:29 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Regen : Conversion advice

On 08/12/2014 09:12 AM, brucedp5 via EV wrote:
> Regen is much more to me than just regaining some range. It is a
safety item
> that I would use for dynamic braking. Since my physical size is large,
I
> physically fit better in a larger heavier vehicle (why I chose to have
a
> S-10 Blazer converted). So, regen would be quite useful to me in a
heavier
> EV.
After driving my regenless conversion quite a distance, then driving a 
Leaf (with relatively poor regen) and then the Tesla (with really great 
regen), I can say that I MUCH prefer regen.  Regen makes it easier and 
more convenient to drive.  Aside from putting a little energy back in 
the battery.  I doubt that the Tesla will ever need any brake work.  
That's amusing because the Tesla has these enormous brakes visible 
through the wheels.  In my experience, one of the most common failures 
on conversions is the brake vacuum pump; my conversion spent perhaps 30%

of it's life being driven without power for brakes.  My wife refused to 
drive it in that condition. Reasonably so; it was quite exciting never 
knowing for sure that you could make an emergency stop.  Though I did 
mange to avoid rear end collisions.

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