Topic: 6V vs. 9V vs. 12V

[gratefulphish]

This is a question for those electrical engineering types out there, as for the life of me, I have Never understood electricity.  My R-4 will run on 9-12V.  Is the current draw different at each voltage, i.e., would a 9V battery with the same amp hours last shorter, longer or the same as a 12V.  I am also considering a V3, and if I got a 12V model, would that allow me to run both the R-4 and the V3 from the same battery, assuming sufficent Mah, and amp handling?  I have also seen people running 6V V3s with the 9V Wally battery.   Will this cause issues in the long run, make it run hotter, fry electronics, etc?

[Fatah Ruark (aka MIKE B)]

I can't answer all of your questions but the number you need to look at for HOW LONG your device will last is mAH (milli Amp Hours).

If you device uses 500 mAH and your battery is rated at 2000 mAH you device would theoretically last 4 hours. This is not the case exactly. I think you need to devide by about .8 to get an accurate result. Not totally sure on that number but it's in the ballpark.

I don't think the amount of voltage has anything to do with how long your device will run. Could be wrong on that, but I think I'm right. I run my UA5 with a 12V battery and it call for 9V, but it works fine. I've never had a problem.

Someone else please chime in.

MIKE B

[Digital Quality]

Power drives your device, not volts. Multiply volts times current and they should all be the same.

[anhisr]

I talked to Jamie about using a 9V and he said no problem at all.  Make sure you have the jumper set for 6 volt.  If you set it for 12v the low battery light and automatic shut down will kick in to early. 

[Chuck]

I find that 9v DC will run a wide range of gear. I use the 9v Walmart Li-Ion batteries with my V3. Also, things run cooler at lower voltage, so I aim on the low scale of what the device will accept. Heat is bad for electronics.

The 6v and 12v V3's are exactly the same, except for a jumper setting that determines when it warns you you are running low on voltage. In the 12v setting using a 9v battery with the V3 isn't a good idea. Just have them set it at 6v and you'll be set.

[pigiron]

(snip)
i.e., would a 9V battery with the same amp hours last shorter, longer or the same as a 12V.
(snip)

In general, the answer to this one totally depends on the device's power supply circuit.

For instance, if the device is using a simple 7805 voltage regulator chip, the current draw from the battery would be about the same for both 9V and 12V... so the time would be roughly the same... but since DC power (Watts) is equal to Volts times Amps, the amount of Watts consumed would be greater for 12V... this "extra" power will be dissipated as more heat, but if the device states that it will run in this voltage range, it should handle this heat (i.e. use large enough heat sinks) to stay within the circuit specs.

If the device contained something like a complex DC-DC converter, I would expect all the above poop to be different.

[bluevolvo]

In general, the answer to this one totally depends on the device's power supply circuit.

good answer

If the device contained something like a complex DC-DC converter

which it would if it provides phantom power.  complexity would depend on the OEM i suppose.

i'd also add that if it does have a voltage regulator, a higher voltage may run longer depending on the discharge curve of the battery and current demand until it reaches the regulators dropout...plus i think you have to multiply by the speed of the earth's rotation divided by...never mind

[twatts (pants are so over-rated...)]

A 9v battery with 5500 mAh will run a 55mA device for 100 hours.  So will a 12v 5500mAh battery.

If the device calls for 9v, and you use 12v, the extra 3v will dissipate as heat.  This may or may not be a problem.

If a device calls for 12v and you use 9v, it won't receive enough power and not work correctly.

In your case, running an R4 (9v-12v) and a V3 (6v or 12v), I'd probably go with a 12v SLA battery and the 12v V3.  The 12v SLA can power everything.

Or you could go with a 6v V3 and use 9v batteries for everything.  The extra 3v to your V3 will make it run hotter (may be issue in enclosed bag). 

Terry

[gratefulphish]

This thread has revived itself.  It seems that the V3 will run on either 6, 9 or 12 without any issues.  It has been running without any problems with a 9V wally battery.  I decided, that since I was going to want serious backup power anyway, to go with a separate heavy duty 12V L ion for the R-4 Pro.  I would rather know that both pieces of equipment have their own batteries, that should run them for hours and hours, but if there is a problem, I can use the backup 9V on either one.

[kskreider]

one thing to keep in mind about running a 6v V3 off of a 9v battery is that the low battery indicator will not function normally.  I run my 6v V3 off of a 9v wallyworld battery and it works fine.  It just gets a little hot.

[T.J.]

This thread has revived itself.  It seems that the V3 will run on either 6, 9 or 12 without any issues.  It has been running without any problems with a 9V wally battery.  I decided, that since I was going to want serious backup power anyway, to go with a separate heavy duty 12V L ion for the R-4 Pro.  I would rather know that both pieces of equipment have their own batteries, that should run them for hours and hours, but if there is a problem, I can use the backup 9V on either one.

btw..NICE RIG! +T i am eager to hear some recordings with this setup. question: is your V3 jumpers set to 6Volts or 12Volts? by no means am I a circuitry wizard, in fact far from...I just remember a discussion somewhere on these boards about powering a a V3 6V vs. 12V using wallyworld 9V.

[Nick's Picks]

the V2/3 doesn't care what voltage it gets.  as long as its in between 6 and 12v.
the low battery light comes on when voltage drops below a certain ssetting.  this is for calibration  only, for a blinking light.
nothing else on the Grace is affected...so whatever you power it with is cool.  but have it setup for 6v.
the R4 will also rock out between 9-12v. 

drop the coin on a couple of power-runners.  you'll be golden.

[H₂O]

The amount of current a device will pull is totally dependent on the type of the DC-DC voltage regulator that is used in the device.

A Linear Voltage Regulator (as what is in the V3 - According to Grace) typically pulls the same current at any of the rated supplied voltages, so it operates less effeciently the bigger the difference between the output voltage and the voltage supplied.  If you supply a V3 12V the power conversion is less effiecent than if you supply it 6V.  I do not know the operating voltage (after the power curcuit) of the V3 but would guess it's no more than 5.5V (and there may be multiple outputs - i.e. 3V and 5V).

Assuming the V3's Voltage Regulator outputs 5.5V:
- if you pass a V3 12 Volts the power circuit will run at about 45% effeciency
- if you pass a V3 6 Volts the power circuit will running at about 91% effeciency.
These numbers are not exact as the circuit it self draws power.

The lost power is converted to heat - so a V3 running on a 12V will run hotter than a V3 on a 6V.

With a Linear Volatge Regulator, since the current draw is the same a batteries rated at the same mAH rating at different voltages should last the same amount of time. (i.e. a 7200 mAH 12V battery will last the same time as a 7200 mAH 6V battery - a V3 is rated at 1A so it will run about 7.2 hours on either a 7200mAH 12V or a 7200 mAH 6V)

A Switching Voltage Regulator - These are much more effecient than a Linear Voltage regulators as the effiency is typically the same no matter what the difference is between input and output voltages.   Switching regulators work by changing the energy stored in an inductor or transforer using a switch controllered by a very highspeed clock.  Due to this design Switching Voltage Regulators can introduce noise and EMI so they typically require filters and Shielding to prevent any possible noise and EMI from leaving the power circuit.  This is probably why Grace decided to use a Linear Regulator.

[gratefulphish]

This thread has revived itself.  It seems that the V3 will run on either 6, 9 or 12 without any issues.  It has been running without any problems with a 9V wally battery.  I decided, that since I was going to want serious backup power anyway, to go with a separate heavy duty 12V L ion for the R-4 Pro.  I would rather know that both pieces of equipment have their own batteries, that should run them for hours and hours, but if there is a problem, I can use the backup 9V on either one.

btw..NICE RIG! +T i am eager to hear some recordings with this setup. question: is your V3 jumpers set to 6Volts or 12Volts? by no means am I a circuitry wizard, in fact far from...I just remember a discussion somewhere on these boards about powering a a V3 6V vs. 12V using wallyworld 9V.

It's set at 6V.  I am not sure that it would run off a 9V if it was set at 12V.  Anyone?

[Brian Skalinder]

It's set at 6V.  I am not sure that it would run off a 9V if it was set at 12V.  Anyone?

The default auto-shutoff for a 12v-calibrated V3 is 10v.  So...probably not, unless the battery puts out > 10v when fully charged.

[bluevolvo]

Assuming the V3's Voltage Regulator outputs 5.5V:
- if you pass a V3 12 Volts the power circuit will run at about 45% effeciency
- if you pass a V3 6 Volts the power circuit will running at about 91% effeciency.
These numbers are not exact as the circuit it self draws power.

The lost power is converted to heat - so a V3 running on a 12V will run hotter than a V3 on a 6V.

Not entirely correct.  I can see where this could turn into some engineering topic...

ANY 78xx series Regulator (or other correctly engineered discrete transistor-resistor VR circuit) with "NO LOAD" is only going to draw whatever current is biasing the transistors in the circuit and some designed load (in the > ma range).  This is the effeciency and without knowing resistance you can't just divide ouput V by input V. There is not going to be [or if correctly engineered should not be] some enormous amount of energy or heat wasted here.  For sake of simplicity and further discussion let's accept this as nill at look specifically at 78xx series.

You can run 35V to these things.  Say I have the 2 700Ah batterys from my RAM 2500 Cummins powering a 7805 regulator.  Series "24V" at 700Ah or parallel "12V" at 1400Ah your pick (call me crazy and in reality it's more like 28.8 and 14.4).  If my load is OFF there is NO current so no waste and NO heat.  If I put a 5 Watt 5 Volt light bulb in the circuit I am going to draw 1 amp.  The 7805 is going to get hot and may thermally shutdown without some heatsinking, it is dissapating ONLY what the circuit is drawing, 1 Amp or 5 Watts.

1 Watt 5 Volt bulb = 200mA it's going to cruise along just fine for many many many days

sooo

The Zoom H4 runs on 2AA Batts.  2 NiMh batts put out about 2.4 volts.  The wally they give you says 9V but it puts out 14.4 at no load.  I run mine with a 7.2V RC pack.  The electrons are all happily going where they need to and the 414's get the same 45.7 volts phantom all 3 ways.  Life is good. 

Of course without looking at any particular OEM's circuit you never know what they did in there...

REFERENCE: http://www.national.com/ds/LM/LM7512C.pdf (plus OHMS LAW and 35 years of building do-dads and what-nots)