regulated-output dc-dc converter

[Dave]

I've got an electronic device which operates, at least it used to operate,
using a car battery as a power source. Over time it has begun to complain
about low battery voltage which causes the unit to shut down. The battery
voltage is fine... when I hook it up to the battery in my car and leave the
car running (~14.4VDC while charging) the device will run indefinitely.
So... it would appear that whatever is sensing the input voltage is sensing
the voltage incorrectly.

So... my options are to open up this device (it's a sealed, ruggedized,
evacuated of air, computerized survey total station so this would be my 2nd
choice) to have a look at the (no doubt) SMT microcircuitry within, or to
find a device which will give me a regulated, say, 13.8VDC from my 12V wet
cell.

Can anyone point me at a retailer who sells 12V-12V converters with
regulated boosted voltage? I've only found one at
http://www.electroparts.com.au/volatge_boosters.htm but a) they are in
Australia and I am in Canada and b) these units are 8A and up whereas I only
require maybe 1A max. Otherwise the description of this device is EXACTLY
what I want.

Somebody must make these things, maybe for RV's or sailboats or so
solar-powered survivalists can write their manifestos on laptop computers...

Any help greatly appreciated.

Sorry about cross-posting to the repair group but there's no
sci.electronics.workaround group.

Dave

 

[Joerg]

I've got an electronic device which operates, at least it used to operate,
using a car battery as a power source. Over time it has begun to complain
about low battery voltage which causes the unit to shut down. The battery
voltage is fine... when I hook it up to the battery in my car and leave the
car running (~14.4VDC while charging) the device will run indefinitely.
So... it would appear that whatever is sensing the input voltage is sensing
the voltage incorrectly.

So... my options are to open up this device (it's a sealed, ruggedized,
evacuated of air, computerized survey total station so this would be my 2nd
choice) to have a look at the (no doubt) SMT microcircuitry within, or to
find a device which will give me a regulated, say, 13.8VDC from my 12V wet
cell.

Can anyone point me at a retailer who sells 12V-12V converters with
regulated boosted voltage? I've only found one at
http://www.electroparts.com.au/volatge_boosters.htm but a) they are in
Australia and I am in Canada and b) these units are 8A and up whereas I only
require maybe 1A max. Otherwise the description of this device is EXACTLY
what I want.

Somebody must make these things, maybe for RV's or sailboats or so
solar-powered survivalists can write their manifestos on laptop computers...

Any help greatly appreciated.

Sorry about cross-posting to the repair group but there's no
sci.electronics.workaround group.

See if something like this could work:

http://www.v-infinity.com/pdffiles/PTK15 Series.pdf

The PTK15-Q24-S12 from Cui is around $50 at Digikey, in stock and the
Digikey P/N is 102-1078-ND.

I believe TI has numerous modules as well.

 

[John Fields]

I've got an electronic device which operates, at least it used to operate,
using a car battery as a power source. Over time it has begun to complain
about low battery voltage which causes the unit to shut down. The battery
voltage is fine... when I hook it up to the battery in my car and leave the
car running (~14.4VDC while charging) the device will run indefinitely.
So... it would appear that whatever is sensing the input voltage is sensing
the voltage incorrectly.

---
Another possibility is that your battery is coming to the end of its
useful life and its capacity has been diminished.

To find out, connect a voltmeter across the load without the engine
running and track it until your device shuts down. Track it,
because as soon as the load shuts down the battery voltage will rise
and you want to know where it was when shutdown occurred.

 

[Dave]

Another possibility is that your battery is coming to the end of its
useful life and its capacity has been diminished.

To find out, connect a voltmeter across the load without the engine
running and track it until your device shuts down. Track it,
because as soon as the load shuts down the battery voltage will rise
and you want to know where it was when shutdown occurred.

Thanks, John, but that was my first hunch too... I tried several
fully-charged different batteries and got the same results.

Given all the other projects I've got on the go right now, I'd as soon buy
one as my employer will pay for it, but if I've got to build one, so be it.

Thanks for the link.

Dave

 

[Fred McKenzie]

So... my options are to open up this device (it's a sealed, ruggedized,
evacuated of air, computerized survey total station so this would be my 2nd
choice) to have a look at the (no doubt) SMT microcircuitry within, or to
find a device which will give me a regulated, say, 13.8VDC from my 12V wet
cell.

Dave -

Yours is a common problem faced by Ham Radio Operators, as some
transceivers are voltage-critical. There was an article published a few
years back in the QST magazine, on how to build a DC-DC converter to
convert a range of input voltages to a steady 13.8 Volts. I believe it
was also offered in both kit and finished form. However, I don't recall
the company.

I searched Google for 13.8 dc-dc and came up with several hits. One of
the first was
http://www.powerstream.com/dc2.htm
which had two models, PST-DU500 and PST-DU700, that appear to do what
you need.

Fred

 

[Rich Grise]

I've got an electronic device which operates, at least it used to operate,
using a car battery as a power source. Over time it has begun to complain
about low battery voltage which causes the unit to shut down. The battery
voltage is fine... when I hook it up to the battery in my car and leave the
car running (~14.4VDC while charging) the device will run indefinitely.
So... it would appear that whatever is sensing the input voltage is sensing
the voltage incorrectly.

Leave the car battery in the car, and get a deep-cycle (marine, golf-cart,
etc.) battery for your device, and a proper charger.

Car batteries are for starting car engines, and don't like long-term
"moderate" loads, and discharging them very much shortens their life.

A deep-cycle battery would be seriously overloaded if you tried to
start a car with it, but they can provide a few amps for a surprisingly
long time, and they're not damaged by a deep discharge. (well, within
reason - the point is, they tolerate it better than a motor-starting
battery.)

Good Luck!
Rich

 

[Dave]

Leave the car battery in the car, and get a deep-cycle (marine, golf-cart,
etc.) battery for your device, and a proper charger.

The device only draws a few hundred milliamps, and I've tried deep cycle,
gel cel, and AGM over the years.

the drain on the battery isn't the problem.

I've got several smart-chargers for the different types of batteries and
generally get several years out of a battery.

 

[ehsjr]

I've got an electronic device which operates, at least it used to operate,
using a car battery as a power source. Over time it has begun to complain
about low battery voltage which causes the unit to shut down. The battery
voltage is fine... when I hook it up to the battery in my car and leave the
car running (~14.4VDC while charging) the device will run indefinitely.
So... it would appear that whatever is sensing the input voltage is sensing
the voltage incorrectly.

So... my options are to open up this device (it's a sealed, ruggedized,
evacuated of air, computerized survey total station so this would be my 2nd
choice) to have a look at the (no doubt) SMT microcircuitry within, or to
find a device which will give me a regulated, say, 13.8VDC from my 12V wet
cell.

Can anyone point me at a retailer who sells 12V-12V converters with
regulated boosted voltage? I've only found one at
http://www.electroparts.com.au/volatge_boosters.htm but a) they are in
Australia and I am in Canada and b) these units are 8A and up whereas I only
require maybe 1A max. Otherwise the description of this device is EXACTLY
what I want.

Somebody must make these things, maybe for RV's or sailboats or so
solar-powered survivalists can write their manifestos on laptop computers...

Any help greatly appreciated.

Sorry about cross-posting to the repair group but there's no
sci.electronics.workaround group.

Dave

How about a simple "Rube Goldberg" solution -
add a 1.5 volt battery in series. That will
at least buy you some time until you find
or build the DC-DC converter.

Ed

 

[kell]

I've got an electronic device which operates, at least it used to operate,
using a car battery as a power source. Over time it has begun to complain
about low battery voltage which causes the unit to shut down. The battery
voltage is fine... when I hook it up to the battery in my car and leave the
car running (~14.4VDC while charging) the device will run indefinitely.
So... it would appear that whatever is sensing the input voltage is sensing
the voltage incorrectly.

So... my options are to open up this device (it's a sealed, ruggedized,
evacuated of air, computerized survey total station so this would be my 2nd
choice) to have a look at the (no doubt) SMT microcircuitry within, or to
find a device which will give me a regulated, say, 13.8VDC from my 12V wet
cell.

Can anyone point me at a retailer who sells 12V-12V converters with
regulated boosted voltage? I've only found one athttp://www.electroparts.com.au/volatge_boosters.htmbut a) they are in
Australia and I am in Canada and b) these units are 8A and up whereas I only
require maybe 1A max. Otherwise the description of this device is EXACTLY
what I want.

Somebody must make these things, maybe for RV's or sailboats or so
solar-powered survivalists can write their manifestos on laptop computers...

Any help greatly appreciated.

Sorry about cross-posting to the repair group but there's no
sci.electronics.workaround group.

Dave

Go to bgmicro.com and search for PWR1245
here is a link if it works:
http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=12297

The device puts out 1A positive and negative 15 volts (for driving op
amps), obviously you will only use the positive.
Only costs $9, surplus. It would cost a chitload more than that if
you bought it retail.

 

[Rich Grise]

The device only draws a few hundred milliamps, and I've tried deep cycle,
gel cel, and AGM over the years.

the drain on the battery isn't the problem.

I've got several smart-chargers for the different types of batteries and
generally get several years out of a battery.

OK, so, then, what was the question? ?:-/

Thanks,
Rich

 

[neon]

the devu\ce care about voltage if it is wthin specs it cares about current more.

 

[Dave]

On Thu, 19 Jul 2007 20:15:05 +0000, Dave wrote:


OK, so, then, what was the question? ?:-/

Thanks,
Rich

Where might I procure a voltage boosting device to feed >13V to my device
from a 12.6V (or less) source? There were a couple of suggestions, I
ordered one yesterday.

thx

Dave

 

[Dave]

Dave -

Yours is a common problem faced by Ham Radio Operators, as some
transceivers are voltage-critical. There was an article published a few
years back in the QST magazine, on how to build a DC-DC converter to
convert a range of input voltages to a steady 13.8 Volts. I believe it
was also offered in both kit and finished form. However, I don't recall
the company.

I searched Google for 13.8 dc-dc and came up with several hits. One of
the first was
http://www.powerstream.com/dc2.htm
which had two models, PST-DU500 and PST-DU700, that appear to do what
you need.

Thanks, Fred, that's just the ticket. Overkill with 36A continuous ability,
but I ordered up the 500W model yesterday.

Dave