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Discussion Starter #1
I had a though on a way to set up the auxiliary battery . My goal is
to have the auxiliary battery and dc to dc completely unhooked when
the car is off . Here's how I'm thinking of doing it . I will hook
the auxiliary battery B+ to the wire that went to energize the starter
motor solenoid . So when you turn on the key and turn to the start
position the aux battery energies ( back feeds) to the 12v system in
the car . Next we have a relay who's coil is hooked to the 12v key on
and its points will connect the aux batteries 12+ to the always on 12
v system giving you power to all systems . When you turn off the car
this relay opens and now there is no connection to the aux battery (
and he won't get drained when sitting ).
Now the dc to dc converter . I just blow one , a model that I had
been using on over 200v cars , the first time I hooked to to the 300v
car I ran it in series with a load , and it worked ,, but without the
in rush limiter it didn't hold up on the next turn on so having
something to slowly turn this on ( next and last one I have) would
be good . I don't want the dc to dc on all the time either. I am
thinking of a mos Fet that would connect the hi voltage side . I will
turn him on with a relay from the keyed 12v system . His source pin
will be on the traction neg On his gate I'll have a 7v zenor and a
100k pull down resistor to keep gate from going to hi , I'll also
have a capacitor from b- to gate to slow the turn on time . The points
of the relay will connect another 100 k resistor from the traction b+
to the gate. As the capacitor charges up the dc to dc will come on
slowly . When the key is off the relay open and fet turns off . Am I
missing any thing here ?
Steve Clunn

A fool and a wise man went walking
the fool did all the talking
at the end of the trip
the wise man let slip
thanks for the enlightenment.



--
Tomorrows Ride TODAY !
Visit our shop web page at: www.Greenshedconversions.com

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Discussion Starter #2
If there is no 12 volt aux power on you will loose you clock & radio presets
settings every time you turn your car off.
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Discussion Starter #3
From: shred

>If there is no 12 volt aux power on you will loose you clock & radio presets
settings every time you turn your car off.<

and your e meter won't keep track of the ah put back in by the
charger . Yep my idea is not perfect , one could add a small dc to dc
like what the lap top computers use and just power those loads. I've
though about this whole thing for a while
Here are some of the problems I see''
If the dc to dc is on all the time , it drains the traction pack , it
can also cook the auxiliary battery shorting its live . Also wast
power form traction pack and can even run it down over enough time .
If its on only when the car is on auxiliary battery might not get
charged all the way as car is not on for many hours and has its own
loads. No aux battery has its own problems , brown outs from low
traction batteries or when heavy acceleration , load surges when many
thing come on at once. The car's aux 12v system my work fine with
daily use but go away for a week or month and you have problems .
Switches that might turn on or off converters or batteries get left on
by accident. In some ways getting the 12v aux to really work right is
harder than any of the other parts of an EV. Maybe we need to think
out side the box. :-( I wonder how the leaf will deal with this . If
somebody doesn't drive there car for 6 months and kills there 24kwh
pack and wants there money back "cas it died and I didn't even drive
it" -
Steve Clunn
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Tomorrows Ride TODAY !
Visit our shop web page at: www.Greenshedconversions.com

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Discussion Starter #4
Steve Clunn <[email protected]> wrote:
> From: shred
>
>>If there is no 12 volt aux power on you will loose you clock & radio pres=
ets
> settings every time you turn your car off.<
>
> and your e meter won't keep track of the ah put back in by the
> charger .

I recently put a CycleAnalyst in my Gizmo. I got around the meter
being off while charging by using the two relays in my Zivan NG1
charger. I hook the traction + through the NO contacts of the AC
presence relay and the NC contacts of the charge finished relay. When
I plug in the charger the AC presence relay closes the circuit to the
meter and turns it on. It dutifully counts down until the charge cycle
is done when the charge finished relay opens and turns it off. It
works just fine and the voltage and current draw is still within the
ratings of the relays in the charger. A different relay turns on the
CA when I turn on the key. Also, I have a SurePower DC-DC with an
always on side. I wish they made one for more than a 36/48V and 72/96V
nominal DC-DC. It has very low current draw when nothing is hooked up
to it (<=3D10mA).

-- =

David D. Nelson
http://evalbum.com/1328

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Discussion Starter #5
Lee Hart wrote:

> You could rewire or redesign the car's various 12v systems to
> be completely off, or at least vastly reduce their "vampire"
> power consumption.

A little tidbit I gleaned in conversation with an ex-auto industry engineer recently is that reasonably modern cars don't require any large-scale re-wiring or redesign to achieve this.

Check your fuse block for a fuse marked "IOD"; pull it out half way and you will eliminate *all* of the "vampire" power consumption. "IOD" = "Ignition Off Draw". All of those key-off loads are already wired and fed through this single circuit (at least when the key is off); pull the fuse and the parasitic loads are eliminated, but the vehicle will still start and operate normally. It should be reasonably simple to pull the IOD fuse and connect a small DC/DC to power those loads from the pack when the key is off.

(How this came up was in a discussion of parasitic loads on the battery pack of an EV, and the ex-auto engineer explained that the term they were familiar with for this sort of thing was IOD...)

Cheers,

Roger.

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Discussion Starter #6
Roger Stockton wrote:
> Check your fuse block for a fuse marked "IOD"; pull it out half way
> and you will eliminate *all* of the "vampire" power consumption.
> "IOD" = "Ignition Off Draw".

Cool! Thanks Roger; I'll look for it. My 2001 Prius and 2002 VW Eurovan
(my newest gassers) don't have this fuse, so they must have started
doing this sometime later (or in different makes or models).

--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

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Discussion Starter #7
Lee Hart wrote:

> Cool! Thanks Roger; I'll look for it. My 2001 Prius and 2002
> VW Eurovan (my newest gassers) don't have this fuse, so they
> must have started doing this sometime later (or in different
> makes or models).

Well, the engineer was ex-US auto industry; it may be that the IOD fuse will only be found on domestic NA OEM models. If something similar is present on imports, it may have a different (and similarly uninformative ;^) label. I'd be a bit surprised if the imports don't have something similar since they have the same issues that domestic makes do (the vehicles may sit on lots or in transit for long enough that the 12V battery will go flat without some way to disable the parasitic loads).

I'll have to doublecheck, but I'm pretty sure that I recall seeing an IOD fuse in either my '95 Aerostar or 2000 Windstar, htough I didn't know what it was for at the time.

Cheers,

Roger.

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