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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / August 2007

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How to make a mobile jump-box?

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Matt - 14 Aug 2007 02:40 GMT
I am a master auto technician, and I am seeking the opinion/advice of
other master technicians who work in the field.

We've all come to know (and love, in my opinion) battery jump-boxes in
the last 10 years or so. The days of jumper-cables are pretty much
over.

What would it take to make a jump-box part of an automobile?

Let me explain... a jump box can easily be connected to a battery, and
even left there if desired. A basic parallel circuit. It would then
take a charge from the alternator right along with the regular car
battery. Trouble is, if something were left on such as an interior
light, the jump-box would be drained right along with the car's
battery. Not the result I am looking for.

What device might be created that would allow a jump-box to be wired
into a vehicle were it would be charged during vehicle operation, but
not drained when the vehicle was turned off?

Example: vehicle drives from point A to point B. The battery and the
jump-box are charged along the way. Owner shuts the car off but
accidentally leaves the dome-light on, thus killing the battery.

How might it be possible for the jump-box to receive the alternator's
charge but not be drained by the forgotten dome-light?

Some sort of magnetic switch (a solenoid, perhaps) comes to my mind,
but how that configuration might be alludes me.

It has occured to me that constant charging of a battery (jump-box)
might not be a good thing, but I have also observed that a vehicle can
charge a battery for dozens of hours without said battery exploding. I
have also seen jump-boxes be left on a plug-in charger for weeks (even
a month) with no apparent negative effect.

The final product I seek: An jump-box stored in perhaps the trunk or
elsewhere that is kept charged by the alternator during vehicle
operation, but would not be drained if a device were accidentally left
on after the engine was shut off. Should the vehicle have a dead
battery, just take that jump-box out of the trunk and get going.

Is it possible? It must be. It has to just be a matter of power here,
switch there, relay here, jump-box there...

Calling on the best of the business, I know you're out there!

Matt
Nate Nagel - 14 Aug 2007 02:53 GMT
> I am a master auto technician, and I am seeking the opinion/advice of
> other master technicians who work in the field.
[quoted text clipped - 44 lines]
>
> Matt

I believe that you can buy a box that will cut off your battery before
it drains, thus leaving enough juice for one attempt at starting before
it goes dead flat.  I think you pop the hood and press a button to reset
it before starting or something like that.

The other option would be an extra full sized battery with one of those
electronic isolators like RV's use, with a switch to cut over the
auxiliary battery when the primary goes dead.  Space and weight are the
downsides of that setup.

nate

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Matt - 14 Aug 2007 03:11 GMT
"Electronic isolator" is what I am searching for. I can take care of
space, weight, long wires, etc... anyone out there who might be able
to elaborate? I think it should be possible to connect a jumper-box
*that could be used on any vehicle*.

Think how the towing business could profit!
Nate Nagel - 14 Aug 2007 03:46 GMT
> "Electronic isolator" is what I am searching for. I can take care of
> space, weight, long wires, etc... anyone out there who might be able
> to elaborate? I think it should be possible to connect a jumper-box
> *that could be used on any vehicle*.
>
> Think how the towing business could profit!

They already make mobile jump-starters...  and they do work on pretty
much any vehicle; you can indeed start a 6V vehicle from a 12V battery
if you a) know what you're doing and pay attention to polarity (the vast
majority of 6V vehicles were positive ground) and b) make sure that
*ALL* accessories are turned off until the 12V battery is removed.

nate

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http://members.cox.net/njnagel

Don Bruder - 14 Aug 2007 04:57 GMT
> "Electronic isolator" is what I am searching for. I can take care of
> space, weight, long wires, etc... anyone out there who might be able
> to elaborate? I think it should be possible to connect a jumper-box
> *that could be used on any vehicle*.
>
> Think how the towing business could profit!

All the tow-trucks I've seen lately have had simple plug-in cable
connections at the bumper. Grab the cables, cram 'em in the socket,
attach to "jumpee", proceed.

Why do they want to dink around with another battery?

Signature

Don Bruder - dakidd@sonic.net - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more info

Matt - 15 Aug 2007 02:00 GMT
> In article <1187057506.185334.165...@g4g2000hsf.googlegroups.com>,
>
[quoted text clipped - 16 lines]
> somewhere, any message sent to this address will go in the garbage without my
> ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more info

I am just trying to keep it light. If they already have it, then fine.
I don't work on tow trucks, so maybe I could gain from what people
have already figured out. That's the point of this post... *how* does
it work.
Bob M. - 16 Aug 2007 06:15 GMT
>> In article <1187057506.185334.165...@g4g2000hsf.googlegroups.com>,
>>
[quoted text clipped - 25 lines]
> have already figured out. That's the point of this post... *how* does
> it work.

These things are all over. You can buy a self-contained unit (battery, 2
foot long cables and an AC plug for charging the battery) at <insert car
parts place here>, *-Mart, and so on for not much.  Includes a handle too!
Weighs 5-10 pounds; cart not necessary.

Some have other features like a flashlight & cigarette lighter socket.
Ad absurdum per aspera - 15 Aug 2007 20:31 GMT
> Think how the towing business could profit!

Huh.  I'd guess that increasing the redundancy of vehicles' starting
power, and the self-reliance of drivers, would mean *less* business
for them. Of course, in big cities that might be a good thing, weeding
out the silly little "one minute's worth of problem at the end of half
an hour's trip" calls and letting them work on the backlog of accident
and serious failures.

One might envision a slightly evolved version of the now familiar and
pretty cheap jump-start box that can trickle-charge off the car's
circuit (suitably isolated) and sit in a well in the engine
compartment -- sounds like what you're talking about. However, that's
space and weight that a lot of people begrudge in the already tight
engine compartment; and the environmental factors in there are not
kind.

Several years ago there was a brand of car battery that had a small
auxiliary built in.  After a few minutes of coulda-shoulda-woulda
regarding the headlight switch, you opened the hood, flipped a lever
or something, and (unless the car was really balky or the system
wasn't working properly) started off this reserve of power.  I haven't
seen those in a long time, though, and seem to recall them as having a
premium price, which might have been the reason.

> The days of jumper-cables are pretty much over.

I see them in use quite often, and have them in every vehicle.  The
days of people willing to pull over and help a stranger may not be
what they used to in some places, of course.  For sure, jumper cables
don't do you much good in situations where no one is likely to come by
for some time (a suitably stored -- and reasonably charged! -- jump
box might be your only friend there!)  And people can be goosey about
doing it wrong and frying some electronics.  But a great many people,
at least where I live, haven't gotten word that their days pretty much
over...

Cheers,
--Joe
Comboverfish - 15 Aug 2007 21:30 GMT
On Aug 15, 2:31 pm, Ad absurdum per aspera <jtc...@california.com>
wrote:

> Several years ago there was a brand of car battery that had a small
> auxiliary built in.  After a few minutes of coulda-shoulda-woulda
[quoted text clipped - 3 lines]
> seen those in a long time, though, and seem to recall them as having a
> premium price, which might have been the reason.

Didn't the first wave of these have the Champion brand name?  I
haven't seen them in years either.

> > The days of jumper-cables are pretty much over.

Really small jump boxes are becoming popular now.  I bought one back
when they were a bit newer and no reviews existed for such a product.
Luckily it has been absolutely great.  I see no reason to carry around
the larger portable type units (almost the size of a car battery), let
alone a roll around monstrosity, when these mini jump units work so
well.  I wouldn't bring it to start a diesel though...

Toyota MDT in MO
Ad absurdum per aspera - 15 Aug 2007 22:24 GMT
> Really small jump boxes are becoming popular now.

I haven't taken one apart, but wouldn't be surprised to discover a row
of lithium-ion laptop-computer batteries or at least the  cells used
therein.  A lot of those batteries happen to have output of 14-ish V,
and the economies of scale must be sizable.

--Joe
Comboverfish - 16 Aug 2007 12:37 GMT
On Aug 15, 4:24 pm, Ad absurdum per aspera <jtc...@california.com>
wrote:
> > Really small jump boxes are becoming popular now.
>
[quoted text clipped - 4 lines]
>
> --Joe

I'll be taking mine apart when it fails -- hopefully not for 10 years
though.

Toyota MDT in MO
Tegger - 14 Aug 2007 03:16 GMT
Matt <matthewmpower@gmail.com> wrote in news:1187055612.315562.322410@
19g2000hsx.googlegroups.com:

> How might it be possible for the jump-box to receive the alternator's
> charge but not be drained by the forgotten dome-light?

A diode?

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Tegger

Matt - 14 Aug 2007 03:46 GMT
"A diode?"

Thank you, Tegger.

Yes, I agree that a  one-way gate is the trick here...

But how to make it happen in a real-life situation?

Where exactly might that diode be positioned? That where I am asking
for some help.

Matt
qslim - 14 Aug 2007 13:08 GMT
Diode?

On the positive connection to the 'on board jump box' (OBJB). Then have a
separate circuit for 'jump starting' the main battery with a relay jumping
the "DIODE" controlled from inside the car whose power supply would run off
the OBJB, providing a direct connection between the car battery and the
OBJB. How many ASEs do you have?
Kevin Bottorff - 14 Aug 2007 14:38 GMT
> Diode?
>
[quoted text clipped - 3 lines]
> supply would run off the OBJB, providing a direct connection between
> the car battery and the OBJB. How many ASEs do you have?

it is very simple, limos have been doing it for years. you use a solenoid
to isolate the 2nd batt. and it charges and everything normally when key
is on but is isolated when the key is off. also providing a built in
boost when cranking.  KB

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Matt - 15 Aug 2007 02:02 GMT
> > Diode?
>
[quoted text clipped - 12 lines]
> Thunder Snake #9
> "Protect" your rights or "lose" them.

Thanks, that makes perfect sense. I haven't seen one because I rarely
service limos. Great response, thanks again for helping me to solve
this little puzzle.
Matt - 15 Aug 2007 01:50 GMT
> Diode?
>
[quoted text clipped - 3 lines]
> the OBJB, providing a direct connection between the car battery and the
> OBJB. How many ASEs do you have?

It is besides the point, but I have 9.
qslim - 15 Aug 2007 03:24 GMT
Scott Dorsey - 14 Aug 2007 15:25 GMT
>What device might be created that would allow a jump-box to be wired
>into a vehicle were it would be charged during vehicle operation, but
>not drained when the vehicle was turned off?

A diode block that goes between the alternator and the two batteries.
You can buy such a thing at an RV store... lots of RVs and vans are
set up with dual-battery systems so the RV appliances run off a deep
cycle battery that is charged by the alternator, but which cannot
discharge the starting battery for the vehicle.  Same thing.
--scott
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Mike Romain - 14 Aug 2007 16:20 GMT
> I am a master auto technician, and I am seeking the opinion/advice of
> other master technicians who work in the field.

Wow!!!!

They have had dual battery setups for 4x4's and RV's for many many Many
years with various types of isolators available.

Tow trucks are also set up with front 'plug in' booster cables and have
also been this way for years!

How can someone 'claim' to be a 'master auto tech' and not know this?

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos:  Non members can still view!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)
cuhulin@webtv.net - 14 Aug 2007 20:06 GMT
One battery, in your vehicle, and jumper cables.What more could you
want?
cuhulin
qslim - 15 Aug 2007 00:37 GMT
Sorta the same thought I had...
Matt - 15 Aug 2007 01:57 GMT
On Aug 14, 3:06 pm, cuhu...@webtv.net wrote:
> One battery, in your vehicle, and jumper cables.What more could you
> want?
> cuhulin

Sometimes there is not another vehicle to jump off of. Another poster
gave me a response that helped me think of the solution, so thanks.
cuhulin@webtv.net - 14 Aug 2007 20:10 GMT
I used to drive a Deuce and a half truck (ammo truck) in Vietnam.It had
two 12 volt batteries.I own a 1960's Mercedes Benz four cylinder diesel
engine.It requires two 12 volt batteries.
cuhulin
Matt - 15 Aug 2007 01:55 GMT
> > I am a master auto technician, and I am seeking the opinion/advice of
> > other master technicians who work in the field.
[quoted text clipped - 15 lines]
> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590
> (More Off Road album links at bottom of the view page)

Thanks for the "Wow!", but I don't work on RVs or tow trucks. That's
why I am asking for other technicians who might know. Thanks for the
rhetoric, though. I am not interested in character attacks. Bye!
Mike Romain - 15 Aug 2007 14:55 GMT
>>> I am a master auto technician, and I am seeking the opinion/advice of
>>> other master technicians who work in the field.
[quoted text clipped - 18 lines]
> why I am asking for other technicians who might know. Thanks for the
> rhetoric, though. I am not interested in character attacks. Bye!

If you are a 'master auto tech', then it is no wonder the state of auto
repair these days, sorry man but 'wow'...

Here you go then:

Back int he 60's when I started working in garages, we used a 'portable
jump box' in the various garages I worked in.

It was simply a battery on a two wheeled 'suitcase' dolly with welding
cable clamped onto the battery posts and ground clamps on the cable
ends.  This got charged up as needed.

It worked well.

Mike
tippybob@yahoo.com - 15 Aug 2007 02:44 GMT
Matt,

http://bluesea.com/category/2/productline/236

This may be what you have in mind.

-Bob
 
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