DC Boost Converter, XH-M411 DC 3-35V to 5-45V Output Voltage, Adjustable Step Up Voltage Regulator Module for Solar Panels

Used this with a laptop charger to bring back a dead Ryobi 40v battery. It worked perfectly and saved me a ton of money on buying a new battery.

Works as expected. Quality build

Arrived damaged, the Heatsink was knocked off the circuit board. Other than that it worked fine, just needed to be repaired.

These work great. I've boosted 25.6v to to 36 volts without any issue. Order with confidence.

I bought it to use it as a manual charger for defective Ryobi 40v batteries. Some of them refuse to be charged by Ryobi charger due to control board error or because of being discharged below a certain voltage. This DC to DC converter just pumps out required voltage from the output end without running any checks or asking any questions. This simplicity is a beauty! I had to use my old laptop's 19V 5A charger to provide an input that was successfully boosted by this converter to 42V to make it compatible with Ryobi batteries. It worked like a charm!

Copper square mount fell off due to poor heat sink. Product didn’t work as intended and 5v fan overheated within 1 min.

This seems well made but mine arrived in very minimal packing and the heat sink had gotten knocked off. If you have some heatsink paste/glue that's not a big deal (unfortunately I don't). More importantly, in testing it out I find it has a very dangerous behavior: if the input voltage falls to the range of 3.0 - 3.5 volts, the output jumps way up to 30 or even 50 volts! A moderate load (100 mA) seems to prevent this. I know it's not designed for that input voltage range but one hopes that if the input is too low it stops working in a benign way. I can imagine lots of situations with a light load and a battery running low where this behavior would be unexpected and disastrous. I read many reviews of another similar device with the same kind of behavior so I don't think this is my mistake or a faulty device. I think this is a design error.

I bought this to run 48 V lights on my 36 V golf cart. It worked perfect. Very easy to install and the lights went from down to bright. Would buy it again if I had to. Love the low good price as well.