How to Set Current Limit for Volteq Variable DC Power Supply?

Anything pertaining to the application, maintenance, and repair of Volteq Variable DC Power Supplies. You can post technical questions here, and our staff or other knowledgeable members will answer the question for you.
sean
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Joined: Sat Jan 10, 2015 5:23 pm

How to Set Current Limit for Volteq Variable DC Power Supply?

Postby sean » Sat Jan 10, 2015 6:11 pm

Setting the current limit is a little bit more complicated compared to setting the voltage limit, especially if you have one of the following situations:

1) your load has internal source of EMF, this includes battery, DC motors, RC cars and trains, any electrochemical systems including plating, etching, and electrolysis, etc.

2) your load might be sensitive or damaged by over voltage, e.g., LED

In the first scenario, you need to make sure to set the voltage to slightly above the maximum EMF from your load, say 0.5V to 1.2V above, and set the current to minimum before connecting the load. Once you connect the load, you can slowly increase the current limit by adjusting the current knob to the desired value. we recommend you to use only the "EX" models for this kind of load. if you are using a power supply without over-voltage protection, it is highly recommended to have a diode put in line with your load (connecting to the positive terminal of the power supply) to prevent the current flowing in the wrong direction and causing damage to the power supply.

In the second scenario, you should turn the power supply on, set the voltage to the correct value, and set the current to minimum. Next, use an appropriate sized wire to short the + and - terminals, you can then slowly turn up the current limit by adjusting the current knob to the desired value (Caution: the wire might be very hot if you are passing large current). Once you are done with setting the current limit, turn the voltage down to minimum, disconnect your short wire, then connect you actual load. you can now slowly increase the voltage while leaving the current setting unchanged, just remember to always stop before you raise the voltage too high for your load. If your calculation is correct, then you should be able to stop the voltage knob before actually damaging your load.

It sounds complicated, but when you are actually doing it, it only takes minutes to set it.

I should also mention that, for the first category of applications, you can use our switching power supplies: http://www.volteq.com/switching-power-supply.html

for LED applications, you should consider using our linear power supplies with output less than 10A, which have over-voltage protection and is less noisy: http://www.volteq.com/linear-dc-power-supply.html

sean
Site Admin
Posts: 11
Joined: Sat Jan 10, 2015 5:23 pm

Re: How to Set Current Limit for Volteq Variable DC Power Supply?

Postby sean » Thu Dec 03, 2015 6:38 pm

A bit of testing, set the voltage 15.1V and .18A assuming that the pack in in 1.8Ah-2.0Ah range. When the battery voltage reaches 15.1V the current drops to or close to zero. Of course this is what I don't want. Turn the voltage to max, connect the battery and set the current to .18A.

Some hours later, I find the voltage at 17.7V which is max(not 18V) and the current down to .06A. Disconnect the battery and it reads 15.6V. I'm wondering why? - this is normal, when you charge the battery at 17.7V, the battery is temporarily showing 17.7V because it's acting like a capacitor and your power supply charges it to that voltage. as soon as the power supply is disconnected, that extra voltage will go away due to leakage current, and what you will see is the normal voltage of the battery, which in your case is 15.6V I guess.

I was considering the HY3006D for 18V packs but just trying this old PS first. BTW: Your "selection chart" shows the HY300D as "not" having over voltage protection but its description does. - the Volteq HY3006D does have over-voltage protection.


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