Hi there,

I am looking to buy your “DROK® Mini Electric Buck Voltage Converter DC to DC Step-down Transformer High Power 15A Volt Regulator Board Synchronous Inverter Module 4-32V to 1.2V-32V for 12V 24V Adjustable LED Driver Car Laptop Power Supply”.

I would like to use this with 200W of solar panels. They output 11.3A at 17.7V, and I would like to use this to step down the voltage to about 13.4V and boost the excess watts to higher current. If it was perfect, this would result in about 15A. I don’t expect the panels to ever be perfect though, so it is more likely that it would only ever get to 12-13A, which is still above your rating of 10A for long-term work. Could you please clarify what “long-term work” means? They would likely be running above 10A for 5-8 hours each day – is that too long?

Another question that I have is regarding a comment I saw in a review on Amazon for this product. The person said that when using your product with a current-limited charging source, it has trouble when the charging source cannot supply more current. He said that seems to enter a “bypass mode” and the voltage then matches the battery voltage and current drops. You can see the review here (https://www.amazon.com/review/R1VG3MTCQBHE3N/ref=cm_cr_dp_cmt?ie=UTF8&ASIN=B00C9UUFHC&channel=detail-glance&nodeID=172282&store=electronics#wasThisHelpful) or pasted at the end of this message.

Could you please confirm this device’s behavior as well as if it would be dangerous to run more than 10A for many hours?

Thanks!

Nick

UPDATE: After some experimenting this evening I have discovered they don’t like current limited sources of which a solar panel is an example (or could be if you are using all of its available current). It appears not to be harmful but not particularly effective either. What happens in proper or normal mode is that the converter is “transforming” the output, doubling the current and halving the voltage (for instance), until the source hits its current limit and starts dropping voltage. That causes the regulator to increase its PWM (pulse width modulation) duty cycle further increasing current demand from the source. But as there is no more current, the voltage can only go down on the input; it cannot maintain 25 volts (for instance). So the regulator goes into what seems to be a bypass mode and the source and the load settle on a voltage determined either by Ohm’s Law or by the battery you are charging. What you see on the voltmeter is it “snaps” from 25 volts input to 14 volts input, the output stays at 14 volts but current goes from 160 milliamps to 80 milliamps and the positive rail pulses stop suggesting that it is one big positive pulse. So it is a sudden drop in efficiency but at least the regulator is not dissipating the wasted energy (the source is).

The unit is compact with good design and layout. It is the big brother to the 12 amp version nearly identical but this has two power MOSFETS and the controller chip is surface mounted on the bottom.

It behaves like a variable transformer even though it has no transformer. It’s more of a magnetic charge pump. There’s a 7 microsecond cycle (150 kilohertz), with a variable width pulse and variable pauses between pulse trains. At 25 volts and 80 milliamps input there is 14 volts and 150 milliamps output, with two pulses followed by 400 microseconds of no pulses. As load increases the pause decreases. At even lower loads the pause lengthens and the pulse train becomes a single positive and negative transition spanning 7 microseconds.

With no input connected and the output connected to an AGM battery, it bleeds backwards 5 milliamps of current. If the source has no reverse protection it can bleed backwards all the way to the source.