Hooking Pelt up in Series

llarrythelizzar · 01-01-2005, 12:18 AM

Knowing just about enough about electricity to be dangerous, I would like to ask if anyone has tried powering thier pelts using this configuration. I would like to run 3 80 watt pelts in series using the positive 12 volt and negitive 12 volt line on my psu. The power supply is good for 20 amps on the + 12 volt line and 5 amps on the - 12 volt line.
So what would the current total be? 25 a or 20 a or 5 a. I figure that it will be at least 20 amps. Then I'm also wondering what the voltage drop will be across the three pelts.
So let me try some math here... If you take three 80 watt pelts in series you have a total wattage of 240 watts. If you take that total wattage and divide by the volts you would have a current of around 10 amps. Knowing total amperage and total power I figure each pelt will drop about 8 volts. Now because they are in series my psu will only need to put out 10 amps and 24 volts.
If anyone has tried this please let me know. If anyone dissagrees with my thinking, I look forward to hearing from you.

superart · 01-01-2005, 01:01 AM

hooking up to +12v and -12v will give you a 24V potential difference, no?

llarrythelizzar · 01-01-2005, 12:46 PM

Yes it will, but I worried about hooking them up to each rail and the avalible current from that configuration. Because each rails current ratting is based on max load to ground not to a negitive rail. Does that make sence.

dacooltech · 01-01-2005, 01:10 PM

Let's say the 80W TEC you have is rated Qmax = 80W , Imax = 8 Amps , Vmax = 16.1V

now you want to run this pelt @ 12V

EDIT : 5.96 Amps each x 3 = 17.88 A

You need a PSU with ~18 Amps on the 12V rail

MadHacker · 01-01-2005, 02:21 PM

If he wants to run them in series then it would be the 3 TEC's across 24 volts.
each one drawing 8 volts.
if @ 12volts there is 5.96 Amps(A)
then @ 8 volts there is 3.97 A across each TEC
since you have 3 of them you need a powersupply that can support 11.92 or 12A.
now would that be 6A from the positive and 6A from the negative?
only thing I'm not shure about is if the calculation to dertermin the initial Amps is correct... does it scale linerarly?
my 2¢

superart · 01-01-2005, 04:53 PM

each pelt would draw 8v assuming they all the same.

If the pelts are different, they will draw different voltages, but the total will still ad up to 24V.

Bigmack · 01-01-2005, 08:29 PM

to get the rated Qmax of 80 watts the chip consumes 8 amps at 16.1 volts or 128.8 watts. basic ohm's law: E=IxR (E=volts, I=amps, R=ohms) the resistance of each chip at rated voltage and current is 2 ohms (R=E/I) in a series circut, resistances add (2ohms +2 ohms + 2 ohms =6ohms) total applied voltage, 24 volts, total circut amprage 4amps(I=E/R). watts =volts x amps, total watts consumed by the three chips in series, 96 watts. this results in cooling performance less than a single pelter at rated voltage and current. as far as the power supply is concerned using the +12v and the -12v rails will produce 24 volts, however, only at a current equal to the -12v rail. trying to draw more will either damadge or shut down the power supply.

Butcher · 01-06-2005, 10:56 PM

Also note that TECs are semiconductors and thus don't follow ohm's law perfectly. In particular at low voltages you'll see some markedly different effects as you approach the semiconductor junction forward voltage.
Other than that caveat, Bigmack is correct (except voltage is generally V not E).

superart · 01-07-2005, 08:17 PM

Quote:

Originally Posted by Butcher

Also note that TECs are semiconductors and thus don't follow ohm's law perfectly. In particular at low voltages you'll see some markedly different effects as you approach the semiconductor junction forward voltage.
Other than that caveat, Bigmack is correct

really? i didnt know that.

Quote:

Originally Posted by Butcher

(except voltage is generally V not E).

I think physicists sometimes call it E.

redleader · 01-08-2005, 12:31 AM

E is the Electric field, V is Voltage, the electric potiential. They're different things; V is the distance integral of E.

Butcher · 01-10-2005, 11:20 AM

Ohm's law is voltage though not electric field...

superart · 01-10-2005, 01:02 PM

then it isnt E, but I know in physics electric potential is sometimes refered to by a letter other than V, I just cant remember what it is.

Butcher · 01-10-2005, 01:58 PM

I've seen it called p.d. (potential difference) and EMF (electromotive force).

superart · 01-10-2005, 04:07 PM

yea, EMF is what I was thinking of.

good call.

01-01-2005, 12:18 AM	#1
llarrythelizzar Cooling Neophyte Join Date: Nov 2002 Location: Everywhere Posts: 4	Hooking Pelt up in Series Knowing just about enough about electricity to be dangerous, I would like to ask if anyone has tried powering thier pelts using this configuration. I would like to run 3 80 watt pelts in series using the positive 12 volt and negitive 12 volt line on my psu. The power supply is good for 20 amps on the + 12 volt line and 5 amps on the - 12 volt line. So what would the current total be? 25 a or 20 a or 5 a. I figure that it will be at least 20 amps. Then I'm also wondering what the voltage drop will be across the three pelts. So let me try some math here... If you take three 80 watt pelts in series you have a total wattage of 240 watts. If you take that total wattage and divide by the volts you would have a current of around 10 amps. Knowing total amperage and total power I figure each pelt will drop about 8 volts. Now because they are in series my psu will only need to put out 10 amps and 24 volts. If anyone has tried this please let me know. If anyone dissagrees with my thinking, I look forward to hearing from you.

01-01-2005, 01:01 AM	#2
superart Cooling Savant Join Date: Mar 2002 Location: FL Posts: 787	hooking up to +12v and -12v will give you a 24V potential difference, no? __________________ When you do things right, people won't be sure youv'e done anything at all. Looking to buy/trade for used Deep Fryer and Vacume Pack Sealer.

01-01-2005, 01:10 PM	#4
dacooltech Pro/Vendor Join Date: Feb 2002 Location: NYC Posts: 267	Let's say the 80W TEC you have is rated Qmax = 80W , Imax = 8 Amps , Vmax = 16.1V now you want to run this pelt @ 12V EDIT : 5.96 Amps each x 3 = 17.88 A You need a PSU with ~18 Amps on the 12V rail __________________ www.cooltechnica.com Last edited by dacooltech; 01-01-2005 at 01:41 PM. Reason: bah shouldn't drink and try to make calculations @ the same time :)

01-01-2005, 02:21 PM	#5
MadHacker Cooling Savant Join Date: May 2003 Location: Okotoks, A.B. Canada Posts: 726	If he wants to run them in series then it would be the 3 TEC's across 24 volts. each one drawing 8 volts. if @ 12volts there is 5.96 Amps(A) then @ 8 volts there is 3.97 A across each TEC since you have 3 of them you need a powersupply that can support 11.92 or 12A. now would that be 6A from the positive and 6A from the negative? only thing I'm not shure about is if the calculation to dertermin the initial Amps is correct... does it scale linerarly? my 2¢ __________________ "Great spirits have always encountered violent opposition from mediocre minds" - (Einstein)

01-01-2005, 04:53 PM	#6
superart Cooling Savant Join Date: Mar 2002 Location: FL Posts: 787	each pelt would draw 8v assuming they all the same. If the pelts are different, they will draw different voltages, but the total will still ad up to 24V. __________________ When you do things right, people won't be sure youv'e done anything at all. Looking to buy/trade for used Deep Fryer and Vacume Pack Sealer.

01-01-2005, 12:46 PM	#3
llarrythelizzar Cooling Neophyte Join Date: Nov 2002 Location: Everywhere Posts: 4	Yes it will, but I worried about hooking them up to each rail and the avalible current from that configuration. Because each rails current ratting is based on max load to ground not to a negitive rail. Does that make sence.

01-01-2005, 08:29 PM	#7
Bigmack Cooling Neophyte Join Date: Jun 2004 Location: Miami Posts: 60	to get the rated Qmax of 80 watts the chip consumes 8 amps at 16.1 volts or 128.8 watts. basic ohm's law: E=IxR (E=volts, I=amps, R=ohms) the resistance of each chip at rated voltage and current is 2 ohms (R=E/I) in a series circut, resistances add (2ohms +2 ohms + 2 ohms =6ohms) total applied voltage, 24 volts, total circut amprage 4amps(I=E/R). watts =volts x amps, total watts consumed by the three chips in series, 96 watts. this results in cooling performance less than a single pelter at rated voltage and current. as far as the power supply is concerned using the +12v and the -12v rails will produce 24 volts, however, only at a current equal to the -12v rail. trying to draw more will either damadge or shut down the power supply. __________________ A smart man won't brag about what he knows, but listens to others that may know something he dosen't.

01-06-2005, 10:56 PM	#8
Butcher Thermophile Join Date: May 2001 Location: UK Posts: 1,064	Also note that TECs are semiconductors and thus don't follow ohm's law perfectly. In particular at low voltages you'll see some markedly different effects as you approach the semiconductor junction forward voltage. Other than that caveat, Bigmack is correct (except voltage is generally V not E). __________________ Once upon a time, in a land far far away...

01-08-2005, 12:31 AM	#10
redleader Thermophile Join Date: Jun 2001 Location: The deserts of Tucson, Az Posts: 1,264	E is the Electric field, V is Voltage, the electric potiential. They're different things; V is the distance integral of E.

01-10-2005, 11:20 AM	#11
Butcher Thermophile Join Date: May 2001 Location: UK Posts: 1,064	Ohm's law is voltage though not electric field... __________________ Once upon a time, in a land far far away...

01-10-2005, 01:02 PM	#12
superart Cooling Savant Join Date: Mar 2002 Location: FL Posts: 787	then it isnt E, but I know in physics electric potential is sometimes refered to by a letter other than V, I just cant remember what it is. __________________ When you do things right, people won't be sure youv'e done anything at all. Looking to buy/trade for used Deep Fryer and Vacume Pack Sealer.

01-10-2005, 01:58 PM	#13
Butcher Thermophile Join Date: May 2001 Location: UK Posts: 1,064	I've seen it called p.d. (potential difference) and EMF (electromotive force). __________________ Once upon a time, in a land far far away...

01-10-2005, 04:07 PM	#14
superart Cooling Savant Join Date: Mar 2002 Location: FL Posts: 787	yea, EMF is what I was thinking of. good call. __________________ When you do things right, people won't be sure youv'e done anything at all. Looking to buy/trade for used Deep Fryer and Vacume Pack Sealer.

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