Well, I'm trying to do a cooler using a peltier cell and it should be controlled by an arduino motor shield (it has H bridge). This motor shield provide 2A per channel, and it has 2 channels. Could I connect the 2 channels in pararel to supply the peltier cell? It would give me 4A, but the problem, I think, is that the H bridge only support 2A. Will it work fine? The other question is, could I control the voltage on peltier using PWM? Thanks.
Give us the part number of the bridge.
Weedpharma
weedpharma:
Give us the part number of the bridge.Weedpharma
I'll use a motor shield similar to that https://www.arduino.cc/en/Main/ArduinoMotorShieldR3 which uses L298P H bridge L298P pdf, L298P Description, L298P Datasheet, L298P view ::: ALLDATASHEET :::
yes you can output PWM to the peltier.
You have to check first the peltier module datasheet to see how much current it sinks at desired voltage. Better provide a link to its datasheet here.
If you can't find the datasheet.. use an ammeter to measure its current directly to VCC but that might break it, you have to be sure it accepts that voltage.
4A will be upper limit for the bridge (both ports in paralel), so start with analogWrite(63) for 25% duty cycle or less, but not before you verify the peltier module max amps. If it's higher than 4A I would avoid using that h-bridge.
blimpyway:
yes you can output PWM to the peltier.
You have to check first the peltier module datasheet to see how much current it sinks at desired voltage. Better provide a link to its datasheet here.
If you can't find the datasheet.. use an ammeter to measure its current directly to VCC but that might break it, you have to be sure it accepts that voltage.4A will be upper limit for the bridge (both ports in paralel), so start with analogWrite(63) for 25% duty cycle or less, but not before you verify the peltier module max amps. If it's higher than 4A I would avoid using that h-bridge.
I think it'll work fine for 12V and 4A.
I'll use this kit Thermoelectric Peltier Refrigeration Cooling Cooler Fan System Heatsink Kit SS for sale online | eBay
So, should I start to prove it with duty cycle of PWM over 25% ?
L298-based H-bridges will NOT provide 2 amperes per channel continuously. They overheat and go into thermal shutdown. Sadly, the manufacturers of these chips have been enthusiastically overrating them for about 30 years.
Just use a 50-100 amp LOGIC LEVEL MOSFET.
jremington:
L298-based H-bridges will NOT provide 2 amperes per channel continuously. They overheat and go into thermal shutdown. Sadly, the manufacturers of these chips have been enthusiastically overrating them for about 30 years.Just use a 50-100 amp LOGIC LEVEL MOSFET.
But could I use it for at least 5 minutes? I read that it could work for 10 minutes, y need only 10ºC change more or less... I'll try using the PWM at 25%, 50%, 75% (1A 2A and 3A, theorics).
are you trying to use the peltier device just cool - or heat AND cool.
if just using it as a cooler a logic level power MOSFET would be better than the H-bridge
and PWM woiuld be OK
regards Allan.
allanhurst:
are you trying to use the peltier device just cool - or heat AND cool.if just using it as a cooler a logic level power MOSFET would be better than the H-bridge
and PWM woiuld be OK
regards Allan.
Im trying to make a PID control system, so when I reach a determinate temperature, I want to keep it constant
Soi could you use the peltier as just a cooler, and rely upon external heat leaks for heating?
Or could you use a seperate resistive heater..?
In either case you avoid the H-bridge and things are simpler..
regards
Allan
allanhurst:
Soi could you use the peltier as just a cooler, and rely upon external heat leaks for heating?Or could you use a seperate resistive heater..?
In either case you avoid the H-bridge and things are simpler..
regards
Allan
I supose that I could do some holes on the box, and use only the peltier as cooler. But I need to use the motor shield,it's a requirement
if the motor shield won't handle the current, what's the point? - you'll just burn it out
regards
Allan
allanhurst:
if the motor shield won't handle the current, what's the point? - you'll just burn it outregards
Allan
But, the description says that motor shield can drive 2 motor, one for each channel, and 2A for channel. It's supossed that they must survive!!
But, the description says that motor shield can drive 2 motor, one for each channel, and 2A for channel. It's supossed that they must survive!!
The description is wrong. Here are the test results: The Motor Driver Myth — Rugged CircuitsRugged Industrial Arduino Microcontrollers
But don't believe us! Build the circuit and let us know what happens.
jremington:
The description is wrong. Here are the test results: The Motor Driver Myth — Rugged CircuitsRugged Industrial Arduino MicrocontrollersBut don't believe us! Build the circuit and let us know what happens.
I believe you, but a "professional" said me it would work. Thank so much for the information!
Another solution, if I reduce the voltage to 5 or 6 V, with 1.6A the peltier should work too!
Last question, COuld I supply the motor shield with 12V 0.82A?
Generally, a power supply provides voltage, and the circuit consumes current, in accord with its design.