6W 12V 5A peltier only drawing 1A, I am supplying more current but its only drawing 1A

Question

I just bought the peltier and its of 60W 12V 5A and its maximum capacity is of 90 watt power. I am using my Pc power supply which have ability to provide 12V and 15A maximum. I connect to that lead and check the current drawing using multimeter and my peltier only drawing 1.5A at start and then keep decreasing until 1A.
However peltier seems to be working because the colder side getting colder but not enaough because its only drawing 1 A. However it have capacity to draw maximum 6A.

To test it further, I connect it with my 12V 80Ah battery and same result. Not sure why it is doing that.

For further investigation I connect two peltiers (Connecting red wire to red and black wire to wire) by connecting red wire to the postive terminal of the power supply and black to the negative and then I check the current draw and its drawing 3A and then keep decreasing slowly slowly.

Answer 1

For current draw, the peltier just looks like a resistor. However, as it heats up that resistance increases. So in order to get maximum current draw you need to keep it as cool as possible.

1.5 Amps still seems a little low, but these things are notorious for being specified poorly. All it really does is move heat, the end result being a temperature difference between the two sides. So the colder you keep the hot side, the colder the cold side will get.

Thermoelectric Cooling

The current is linear with supply voltage. If you supply a higher voltage you will get a proportionally larger current and the temperature difference between the two sides will increase(not proportionally though). If you exceed 80C or so on the hot side, your device will start to degrade. These are just rules of thumb not knowing your exact specifications.

Answer 2

Sorry for resurrecting this old thread. But I had the exact similar situation few months back and this is what solved for me. Hope this might help someone in future.

1.A good quality high current 12V source i.e, what the OP has used here is good SMPS or Lead acid battery.

2. This is what solved my issue. A good quality Thermal paste with big heat sink and a good 12V 1A fan to drive heat out quickly. This one step brought my cold side temp from 5C to -4C and current draw was now like 4.5A initially, then quickly dropped till it reached 2.8A to 3A and stabilized.

Also never run the peltier above 12V for longevity of the module.

Answer 3

I had a similar issue and found a solution that worked for me.

Power connectors for typical computer psu's have multiple wires for the same voltage (e.g. multiple +12V ports). So even if the rail can draw 15A maximum, it won't through one wire connected to one +12V port. You'd have to wire multiple +12V wires together from the connector to get more amps. I found out about this here:

http://www.playtool.com/pages/psuconnectors/connectors.html

Manufacturers don't use just one beefy (think 10 gauge) wire for +12V to the connector because power losses would just be too high. Also, they don't want to run too much current through any one of the several +12V wires in the connector because they don't want to melt the wire (they're probably 18 gauge).

I'd try wiring two +12V ports from the same connector to a beefy (10 gauge) wire for power and then two of the GND ports to a beefy wire and give that a whirl (connect them to the peltier). If you use all three +12V ports, use three GND ports, etc., all with "beefy" wires to prevent things from melting.

(Your battery may also have a current limit of 3A. The current draw will depend on the load, but most constant voltage regulated power supplies have a current limit. Just google benchtop power supplies and you'll see a 0-30V adjustable voltage supply will only operate up to 5A. On the same note, a 0-30A adjustable current supply with only operate at/up to a given volage)

Granted, my solution really only works for testing. You'd be best getting a dedicated power supply for your peltier (like a Mean Well). If your psu is loaded up with other stuff, you might hit the 15A maximum sooner than you think.