# [EVDL] 12V questions



## EVDL List (Jul 27, 2007)

Hi Ben,

I have an Elcon DC-DC converter in my conversion, but I've elected to keep
the 12v battery and switch the converter on with the ignition. Even without
significant power draw, I wasn't sure how much power the converter would
draw with the ignition off. I also wasn't sure if it was rated to run all
the time. Things I would recommend looking into more than I did. I didn't
need to understand that behavior since I was switching the converter.

Inrush limiters are very simple. They have higher resistance when cold than
hot. They are also sized to dissipate some serious power. I got some 5 ohm
(cold) 12A rated inrush limiters from eBay. I have one wired on the
positive battery input to the DC-DC converter. It is wired in series with
the input. Battery positive connected to one leg of the inrush limiter.
The other leg of the inrush limiter is connected to the positive input of
the DC-DC. The negative input is just wired normally from the battery to
the converter.

They do need to be placed in a physical location where their heat output
won't cause problems. They get hot.

The resistance is chosen to limit the current spike to something the
converter can take. I purposely got one that could take 12A when I knew the
normal draw of the converter would be 2-3 amps. Some things just work
better if they are oversized. I can tell by the lights and other
accessories that the converter takes 2 seconds or so getting to full output.
That is a pretty soft start.

I could probably provide 3 or 4 of these to people if useful. I bought 8
and only used 1 so far. Let me know. They were cheap. A little over $1
each.

One other thing: If the DC-DC is permanently wired to the pack (except for
an emergency disconnect), it will always be on. In that case, you don't
need a precharge resistor for it so much. However, if you are switching the
power to the DC-DC, you don't want it being precharged. I did that in my
original installation. The precharge resistor would charge up the converter
input until it hit about 100v. At that point, the converter would switch on
and drain the input node. It was cycling on and off every few seconds. I
don't think that was good for it. You do still want your controller
precharged, though. =


I took my power for the DC-DC just after the safety disconnect and before
the main contactor (and precharge resistor). Through a solid-state relay
and then the inrush limiter to the converter. I have a schematic I could
provide.

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Ben Jarrett
> Sent: Wednesday, January 11, 2012 8:20 PM
> To: Electric Discussion List
> Subject: [EVDL] 12V questions
> =

> =

> =

> =

> Hey guys,
> =

> My 84 jeep conversion is coming along pretty well and I'm trying to figure
out
> how I want to do something.
> I've gone back and forth on this, but here's my current plan. I'd like=
to
not
> have a 12V auxiliary battery, but have my dc/dc converter always on. I=
'm
> planning to purchase an elcon dc/dc converter. I'm guessing that the
current
> draw when everything is off except my bms and soc meter will be very
small.
> As long as I'm routinely charging my traction pack (160V, 130 Ah), I
should be
> fine I think.
> =

> Any thoughts on this?
> =

> One other question. Can anyone point me to some good documentation on
> inrush limiters? I'd like to see the circuit with details. One thin=
g I
wonder....
> If I just push a resistor (maybe 1k) in parallel with my main circuit
breaker, will
> this resistor allow things to precharge (like the dc/dc convert before=
I
turn
> the breaker on and enable my high voltage pack?
> =

> thanks for all your continued help!
> =

> -ben
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL:
> http://lists.sjsu.edu/mailman/private/ev/attachments/20120111/0cc746e1/a
> ttachment.html
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere. Thanks.
> |
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev


_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

From: Ben Jarrett
>> I'd like to not have a 12V auxiliary battery, but have my dc/dc
>> converter always on. I'm planning to purchase an elcon dc/dc
>> converter. I'm guessing that the current draw when everything is
>> off except my bms and soc meter will be very small. As long as I'm
>> routinely charging my traction pack (160V, 130 Ah), I should be
>> fine I think. Any thoughts on this?

The idea can be made to work, but it's not easy. There are a lot of 
details that need to be checked. The consequences of failure can be 
extreme -- anything from having to walk home, to destroying your pack!

First, you need to *confirm* by actual measurement how much current your 
DC/DC draws from the pack with the car off. Modern cars have lots of 
"vampire" loads that draw 12v current all the time, like the clock, 
radio presets, trip odometer, keyless entry, security system, etc.

A big DC/DC converter is efficient at full load; but very *inefficient* 
at light loads. For example, if your car draws 50ma at 12v, you might 
expect the DC/DC to draw 5ma at 120vdc. But by actual measurement, I've 
seen DC/DC's (like the Iotas) draw 50ma! That would kill your pack in a 
few months.

You might think, "I'll never leave my EV that long without charging." 
Unfortunately, it happens. The charger fails and it takes a few months 
to get it fixed or replaced, or the car's in the shop that long to be 
painted, or you go away on vacation and the person you tell to charge it 
occasionally never gets around to it.

Second, you need to know what the *peak* load of your 12v system is. It 
will be surprisingly high. Light bulbs, motors, and similar loads will 
draw 5 or 10 times their normal current when starting. Sometimes you can 
include a monster multi-farad capacitor to supply this peak load so the 
DC/DC won't have to provide it.

And, you need to know what your DC/DC will do if it sees a peak load in 
excess of its ratings. Its voltage might momentarily sag toward zero. Or 
it might shut off, so you have to disconnect and reconnect power to 
restart it. Or, it may keep trying until it dies! It would be very bad 
to lose all power while driving because you switched on some 12v load 
that pushed the DC/DC over its limit.

Third, make sure that DC/DC is actually rated for continuous duty 
operation. Many inexpensive consumer items are designed to assume you 
won't use them very often. For example, they'll use electrolytic 
capacitors that only have a 2000 hour rated life. That's 100,000 miles 
if it's only on while driving; but less than 3 months if you leave it on 
all the time.

Based on all this, my advice would be:

1. Install *two* DC/DC converters, wired so you can drive as long
as either one of them works.

2. Include a very large filter capacitor, to handle the peak
currents when lights or motors are first turned on.

3. Install an automatic shutoff device, so the pack gets
completely discononect from everything if its voltage gets
dangerously close to dead.

>> One other question. Can anyone point me to some good
>> documentation on inrush limiters? I'd like to see the circuit with
>> details.

Mike Nickerson provided a pretty good description. I've also written 
quite a bit on this topic in the past, and so have many others. A little 
reading of earlier posts should cover this just fine for you.

>> If I just push a resistor (maybe 1k) in parallel with my main
>> circuit breaker, will this resistor allow things to precharge?
>> (like the dc/dc convert before I turn the breaker on and enable
>> my high voltage pack?

That's the principle all right, but 1k is likely to be too big for most 
DC/DC converters. Typical precharge resistors are in the 10's to 100's 
of ohms.

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

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Ben Jarrett wrote
> 
> ...I'd like to not have a 12V auxiliary battery...
> 

What does it say about that in the manual for your motor controller?

We, for one example, certainly recommend you use a 12V battery along with
some means of keeping it charged (either a dc-dc converter or an alternator
driven by the tailshaft). Failure to do so will almost certainly result in
the controller shutting off whenever you turn on, say, the headlights or
windshield wipers. Even with a big, bad, 1kW dc-dc converter.



--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/12V-questions-tp4287783p4288901.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Hey Mike and Lee,

Thanks for all the details. I'll need time to digest.

Some notes on vampire loads. I've completely rebuilt my 84 jeep from scr=
atch and I know
exactly what things are on when the car is off. There's no clock. Th=
e radio only get
the ACC power (it's analog, so nothing to store). The only thing I have =
on is my BMS
stuff. That said, your point about DC/DC converters not being effici=
ent at low loads is a very good point.

One question. Does anyone know where I can get something that automatica=
lly shuts
off my system if voltage gets too low (to save traction pack)?

thanks!

-ben


________________________________
From: Lee Hart <[email protected]>
To: Electric Vehicle Discussion List <[email protected]> =

Sent: Thursday, January 12, 2012 12:28 AM
Subject: Re: [EVDL] 12V questions
=

From: Ben Jarrett
>> I'd like to not have a 12V auxiliary battery, but have my dc/dc
>> converter always on. I'm planning to purchase an elcon dc/dc
>> converter. I'm guessing that the current draw when everything is
>> off except my bms and soc meter will be very small. As long as I'm
>> routinely charging my traction pack (160V, 130 Ah), I should be
>> fine I think. Any thoughts on this?

The idea can be made to work, but it's not easy. There are a lot of =

details that need to be checked. The consequences of failure can be =

extreme -- anything from having to walk home, to destroying your pack!

First, you need to *confirm* by actual measurement how much current your =

DC/DC draws from the pack with the car off. Modern cars have lots of =

"vampire" loads that draw 12v current all the time, like the clock, =

radio presets, trip odometer, keyless entry, security system, etc.

A big DC/DC converter is efficient at full load; but very *inefficient* =

at light loads. For example, if your car draws 50ma at 12v, you might =

expect the DC/DC to draw 5ma at 120vdc. But by actual measurement, I've =

seen DC/DC's (like the Iotas) draw 50ma! That would kill your pack in a =

few months.

You might think, "I'll never leave my EV that long without charging." =

Unfortunately, it happens. The charger fails and it takes a few months =

to get it fixed or replaced, or the car's in the shop that long to be =

painted, or you go away on vacation and the person you tell to charge it =

occasionally never gets around to it.

Second, you need to know what the *peak* load of your 12v system is. It =

will be surprisingly high. Light bulbs, motors, and similar loads will =

draw 5 or 10 times their normal current when starting. Sometimes you can =

include a monster multi-farad capacitor to supply this peak load so the =

DC/DC won't have to provide it.

And, you need to know what your DC/DC will do if it sees a peak load in =

excess of its ratings. Its voltage might momentarily sag toward zero. Or =

it might shut off, so you have to disconnect and reconnect power to =

restart it. Or, it may keep trying until it dies! It would be very bad =

to lose all power while driving because you switched on some 12v load =

that pushed the DC/DC over its limit.

Third, make sure that DC/DC is actually rated for continuous duty =

operation. Many inexpensive consumer items are designed to assume you =

won't use them very often. For example, they'll use electrolytic =

capacitors that only have a 2000 hour rated life. That's 100,000 miles =

if it's only on while driving; but less than 3 months if you leave it on =

all the time.

Based on all this, my advice would be:

1. Install *two* DC/DC converters, wired so you can drive as long
as either one of them works.

2. Include a very large filter capacitor, to handle the peak
currents when lights or motors are first turned on.

3. Install an automatic shutoff device, so the pack gets
completely discononect from everything if its voltage gets
dangerously close to dead.

>> One other question. Can anyone point me to some good
>> documentation on inrush limiters? I'd like to see the circuit with
>> details.

Mike Nickerson provided a pretty good description. I've also written =

quite a bit on this topic in the past, and so have many others. A little =

reading of earlier posts should cover this just fine for you.

>> If I just push a resistor (maybe 1k) in parallel with my main
>> circuit breaker, will this resistor allow things to precharge?
>> (like the dc/dc convert before I turn the breaker on and enable
>> my high voltage pack?

That's the principle all right, but 1k is likely to be too big for most =

DC/DC converters. Typical precharge resistors are in the 10's to 100's =

of ohms.

-- =

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

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20120112/68d59a2b=
/attachment.html =

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Dang, sounds like I need to read the manual again. I missed that point.
Sometimes I like to make bold statements to find out what I'm missing.
I perform an impulse function to the EVDL and observe the output.
You can learn lots from a system with an impulse function 

thanks,
-ben


________________________________
From: Jeffrey Jenkins <[email protected]>
To: [email protected] =

Sent: Thursday, January 12, 2012 7:13 AM
Subject: Re: [EVDL] 12V questions
=


Ben Jarrett wrote
> =

> ...I'd like to not have a 12V auxiliary battery...
> =


What does it say about that in the manual for your motor controller?

We, for one example, certainly recommend you use a 12V battery along with
some means of keeping it charged (either a dc-dc converter or an alternator
driven by the tailshaft). Failure to do so will almost certainly result in
the controller shutting off whenever you turn on, say, the headlights or
windshield wipers. Even with a big, bad, 1kW dc-dc converter.



--
View this message in context: http://electric-vehicle-discussion-list.41352=
9.n4.nabble.com/12V-questions-tp4287783p4288901.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabb=
le.com.

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20120112/49332c79=
/attachment.html =

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Most converters prefer the safety margin of having a battery to keep things 
working if the DCC converter fails. Solectria dispensed with a battery in 
their Force and E10 EVs, probably to save weight, but they're one of the few 
commercial converters who have. 

FWIW, even Toyota uses a small 12v aux battery in the Prius. Their DCC is 
shut down when the vehicle is off.

David Roden - Akron, Ohio, USA
EVDL Administrator

= = = = = = = = = = = = = = = = = = = = = = = = = = = = =
EVDL Information: http://www.evdl.org/help/
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = 
Note: mail sent to "evpost" and "etpost" addresses will not 
reach me. To send a private message, please obtain my 
email address from the webpage http://www.evdl.org/help/ .
= = = = = = = = = = = = = = = = = = = = = = = = = = = = =


_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Why does the BMS have to be on when nothing is going on?

Shouldn't you only need it when you are actively charging/discharging?



> On 12-01-12 01:29 PM, Lee Hart wrote:
> > On 1/12/2012 11:24 AM, Ben Jarrett wrote:
> >> > ...on vampire loads. There's no clock. The radio only get the ACC
> >> > power (analog, nothing to store). The only thing I have on
> ...


----------



## EVDL List (Jul 27, 2007)

If I don't have a battery (which I've changed my mind and will have), I nee=
d 12V
to run the BMS (so it can shut off the charger if necessary) and to run my =
SOC meter
(so it doesn't loose track of my pack's used Ah's).

-ben


________________________________
From: Paul Wujek <[email protected]>
To: [email protected] =

Sent: Thursday, January 12, 2012 12:35 PM
Subject: Re: [EVDL] 12V questions
=

Why does the BMS have to be on when nothing is going on?

Shouldn't you only need it when you are actively charging/discharging?



> On 12-01-12 01:29 PM, Lee Hart wrote:
> > On 1/12/2012 11:24 AM, Ben Jarrett wrote:
> >> > ...on vampire loads. There's no clock. The radio only get the ACC
> >> > power (analog, nothing to store). The only thing I have on
> ...


----------



## EVDL List (Jul 27, 2007)

After reading thru this string of discussion about how to use up to three
or four DC/DC units just to avoid including an $18.99 gerden tractor 12V
battery and only one DC/DC seems to me a "NO-Brainer" the battery 12V aux,
is far more economical even if you replace the battery every year and skip
the preventive maintenence that would let it live for two or three years
(Several major retailers put the garden tractor/riding lawnmower starting
batteries on sale every spring.) And the auto parts stores sell a Lithium
12V for replacement in ICE autos which should give a long life with a DC/DC
for charging it. And you won't see any headlight dimming at traffic
slowdowns or red-lights.
Regards,
*Dennis Lee Miles* (Founder)
*"**Electric Car Service Shop"*
*[ the Forgotten Infrastructure ]*
-----------------------------------------------------------------------------------------------------------


> Ben Jarrett <[email protected]>wrote:
> 
> >
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Heck, you can even make it simpler:

Use a cheap, small 12v battery, attach a battery-minder that is active 
when the car is plugged in, and a DC-DC converter that is active when 
the keyed +12v is on.

Easy. 

Cheers,
Peter

On 1/12/12 11:22 AM, Dennis Miles wrote:
> After reading thru this string of discussion about how to use up to three
> or four DC/DC units just to avoid including an $18.99 gerden tractor 12V
> battery and only one DC/DC seems to me a "NO-Brainer" the battery 12V aux,
> is far more economical even if you replace the battery every year and skip
> the preventive maintenence that would let it live for two or three years
> (Several major retailers put the garden tractor/riding lawnmower starting
> batteries on sale every spring.) And the auto parts stores sell a Lithium
> 12V for replacement in ICE autos which should give a long life with a DC/DC
> for charging it. And you won't see any headlight dimming at traffic
> slowdowns or red-lights.
> Regards,
> *Dennis Lee Miles* (Founder)
> *"**Electric Car Service Shop"*
> *[ the Forgotten Infrastructure ]*
> -----------------------------------------------------------------------------------------------------------
>


> Ben Jarrett<[email protected]>wrote:
> >
> >>
> >>
> ...


----------



## EVDL List (Jul 27, 2007)

I have an IOTA DC/DC convertor, and a 17WH gel-cell to take out the bumps (=
turn signals - brake lights). I have a power steering pump, and vacuum p=
ump. I drive to work with headlights on. The Iota can't keep up -- no=
t the fault of the device -- I just have high 12v demands.

Replacing the 17AH with a 50AH battery, and adding an onboard 12v charger h=
as made cold weather/dark morning worries a thing of the past. I hop in,=
and everything is charged, and the undersized Iota just maintains the use.=
I even have extra power to run a finger warmer heater -- but it is real=
ly designed to just keep the windshield clear.



________________________________
From: Ben Jarrett <[email protected]>
To: Electric Discussion List <[email protected]> =

Sent: Wednesday, January 11, 2012 8:20 PM
Subject: [EVDL] 12V questions
=




Hey guys,

My 84 jeep conversion is coming along pretty well and I'm trying to figure =
out how I want to do something.
I've gone back and forth on this, but here's my current plan. I'd like t=
o not have a 12V auxiliary battery, but
have my dc/dc converter always on. I'm planning to purchase an elcon dc/=
dc converter. I'm guessing
that the current draw when everything is off except my bms and soc meter wi=
ll be very small.
As long as I'm routinely charging my traction pack (160V, 130 Ah), I should=
be fine I think.

Any thoughts on this?

One other question. Can anyone point me to some good documentation on in=
rush limiters? I'd like to see
the circuit with details. One thing I wonder.... If I just push a resist=
or (maybe 1k) in parallel with my main
circuit breaker, will this resistor allow things to precharge (like the =
dc/dc convert before I turn the breaker on and enable
my high voltage pack?

thanks for all your continued help!

-ben
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20120111/0cc746e1=
/attachment.html =

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20120112/b4d65b5d=
/attachment.html =

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

> Ben Jarrett <[email protected]>wrote:
> 
> >
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Ok, then have a diode from a tap on the traction battery at around 12V,
DC-Dc supplies 14V so no current flows unless the DC-Dc fails.... I know it
is a bad idea to use a tap but this is different as it's only for
emergencies.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Chris Tromley
Sent: Saturday, 14 January 2012 4:04 p.m.
To: Ben Jarrett; Electric Vehicle Discussion List
Subject: Re: [EVDL] 12V questions

On Wed, Jan 11, 2012 at 10:20 PM, Ben Jarrett


> <[email protected]>wrote:
> 
> >
> >
> ...


----------



## EVDL List (Jul 27, 2007)

> Tom Keenan <[email protected]> wrote:
> 
> > If it needed to be done temporarily in an emergency situation as George
> > mentions, just make sure nothing that can be touched (switches, meters,
> ...


----------



## EVDL List (Jul 27, 2007)

> Chris Tromley <[email protected]> wrote:
> > On Sat, Jan 14, 2012 at 9:23 PM, Tom Keenan <[email protected]> wrote:
> >
> >> If it needed to be done temporarily in an emergency situation as George
> ...


----------



## EVDL List (Jul 27, 2007)

> David Nelson <[email protected]> wrote:
> 
> > Or was it you who missed the point about safety?
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Dennis;

More money, but I used an Odyssey 16Ah PC680, and it's been going now for 2=
.5 years.
The only issue I had was my E-meter dragging it down if the truck sat for ~=
10 days.
(Lee Hart mentioned this in a previous E-Mail)
I solved that by putting in a separate kill switch.
If I know the truck will be sitting for a while, I switch off the E-Meter a=
fter charging.
No problems since.


Dennis=
=

Elsberry, MO=
=

http://www.evalbum.com/1366
http://www.evalbum.com/3715=
=
=





-----Original Message-----
From: Dennis Miles [mailto:[email protected]] =

Sent: Thursday, January 12, 2012 1:23 PM
To: Ben Jarrett; Electric Vehicle Discussion List
Subject: Re: [EVDL] 12V questions

After reading thru this string of discussion about how to use up to three
or four DC/DC units just to avoid including an $18.99 gerden tractor 12V
battery and only one DC/DC seems to me a "NO-Brainer" the battery 12V aux,
is far more economical even if you replace the battery every year and skip
the preventive maintenence that would let it live for two or three years
(Several major retailers put the garden tractor/riding lawnmower starting
batteries on sale every spring.) And the auto parts stores sell a Lithium
12V for replacement in ICE autos which should give a long life with a DC/DC
for charging it. And you won't see any headlight dimming at traffic
slowdowns or red-lights.
Regards,
*Dennis Lee Miles* (Founder)
*"**Electric Car Service Shop"*
*[ the Forgotten Infrastructure ]*
---------------------------------------------------------------------------=
--------------------------------


> Ben Jarrett <[email protected]>wrote:
> 
> >
> >
> ...


----------



## EVDL List (Jul 27, 2007)

> Dennis Pestka wrote:
> > The only issue I had was my E-meter dragging it down if the truck sat for ~ 10 days.
> > (Lee Hart mentioned this in a previous E-Mail)
> > I solved that by putting in a separate kill switch.
> ...


----------



## EVDL List (Jul 27, 2007)

Definitely use a trimpot or very accurate resistors,
else you won't get 12.25V
(Using standard 5% resistors as suggested by the
values 390k and 100k will give you a shut-off
anywhere between:
390k*1.05 and 95k => 13.27V
390k*0.95 and 105k => 11.32V
In other words: totally useless.
If you want better than 0.1V accuracy
then make sure to get 0.5% accurate fixed resistors
or use the standard 1% accurate resistors and a pot
to calibrate where exactly it will disconnect.
Success,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Lee Hart
Sent: Monday, January 16, 2012 11:15 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] 12V questions



> Dennis Pestka wrote:
> > The only issue I had was my E-meter dragging it down if the truck sat
> for ~ 10 days.
> > (Lee Hart mentioned this in a previous E-Mail) I solved that by
> ...


----------

