Typically, battery-powered devices tend to swoon down below their advertised voltage when the battery is placed under load which is an expected phenomenon but ends up feeding a dropping voltage into a device which might confuse upstream electronics that have a small input voltage specification. Small gadgets or small vehicles such as the Wizardry and Steamorks Remote-Operation Vehicle (ROV) use small step-up, step-down converters but large vehicles such as golf carts, scooters or electric motorcycles need a high current circuit.

A step-up, step-down buck converter is thus used to ensure that the output voltage is fixed to a user-requested value, no matter what the input voltage might be.

The following is a tear-down and analysis of a very popular buck converter that is used mainly for large vehicles such as golf carts or scooters.

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Be very careful when you purchase these devices because there is a very large selection range regarding the prices and the item that is purchased sometimes differs in the description just a little that can distinguish between a high quality device and a low quality device.

Many of these items, not the micro-electronics bucks but these high-current bucks, are sold as buck converters that go one way, mostly, step-up converters that go from a small voltage input range to a higher input range. More expensive devices, which is this device, take a large input voltage range, that can sometimes even exceed the output voltage and convert the input voltage regardless whether it is less or more than the desired output voltage. In that sense, also note that for these devices the lowest voltage that the buck accepts as an input becomes very significant in terms of pricing: a device that has a lowest acceptable voltage as is about USD20 less than a device that has the lowest acceptable voltage as ; the price difference is mostly fully justified because taking an input of and leading it up to, say, three times as much, whilst also providing a high amperage is truly heavy duty stuff. In terms of batteries, a voltage drop of , depending on the application, say, an electronic scooter can make the difference of a few kilometers of distance that a rider can travel.

Lastly, keep in mind that these are not micro-electronics, such that step-up and step-downs equivalents for micro-electronics or IoT are available at a much, much lower price because the current that they can provide is also much lower.

Regrettably, there is no elegant way to "open up" the buck converter because it is filled with a rubber-foam substance and opening it up is destructive, requiring the foam to be scooped out of the aluminum shell.

Scooping up just a little bit reveals some very bulky capacitors like cherries in chocolate and with a coil that is semi-revealed under one single layer of rubber foam.

Interestingly there are two separate layers of this substance, maybe fire retardant, that are placed one on top of each other. The next layer under literally encompasses the underlying PCB circuitry and the rest of the large components that just stick out right now.

If you ever had any high praise for this device it is time to drop it now because scooping further into the rubber marmalade reveals one screw and that is also the single screw that fastens the PCB to the aluminum chassis that is supposed to act as a radiator. Obviously, a single screw will not make a great contact regardless of the foam that the whole PCB has been drenched into.

This rubber foaming deal is very bad and something should be said about it. First, one single screw holding down the other side of the PCB which consists in a metal plate, just viced into the aluminum and, after inspection, also without any thermal paste compound to ensure a proper capillary transfer of heat between the PCB and the aluminum chassis, is terribly bad and ill not ensure a proper heat transfer. Second, this rubber-like material might be a fire retardant but putting some of this material onto the fire made the material release some smoke, yet worst of all, seemed to contain the heat within for quite a long while acting as a thermal store itself. The PCB does have some ICs that resist at higher temperatures and also some other components that should not mind the heat but the capacitors on the PCB are rather large and if this enclosure heats up, there is a risk of popping the capacitors. Similarly, in case of a short or other malfunction that would warm up the PCB unexpectedly, the whole gadget just becomes a self-contained fireball that will smolder itself to lava while destroying components without any ability to repair them. Also note that, as it was mentioned, these devices are typically to be found on the inside of the chassis of vehicles such that a beaming sun will not help its thermal design at all. It is understood that the device is supposed to pass but there is absolutely no reason to drench it with this stuff; quite on the contrary, placing a small fan on the inside and letting air in would have actually been much, much better in terms of heat.

For the former reason, the buck PCB was scooped out completely out of its aluminum box and will be cleaned thoroughly for its final application.

The PCB looks fairly good, with solid connectors and reasonable suggested leads (very thick wires). The solder job looks fine, a lot of the components being surface-mounted implying that the PCB was actually machined rather than sweat-shopped. Unfortunately, the protruding capacitors are annoying and their connection to the PCB is rather flimsy. You can observe in the former image that the black capacitor on the top right has its pins soldered to … the extremes of a pin header? No doubt that was done to save space but why use a pin header there in the first place is a good question. Maybe they thought to lift the capacitor off the board a little but even so, these capacitors have long pins such that they could have just been bent onto the PCB and soldered without using a header. The other capacitors are soldered the same way, two pairs, head-to-head indicating a circuit that would act as a filter to trim out ESL and ESR.

One issue to watch out for is that when the buck was delivered, it was measured and it would output a sharp yet its specification says that it outputs . The buck will be used to bump voltage to be used with a battery and a HAM radio such that some degree of precision is desired.

Fortunately, the PCB has a potentiometer on the inside that allows a very fine selection of the output voltage such that the voltage was pulled down to about . For the record, the potentiometer is a very-very fine control such that the buck converter can be made to output between and up to . Depending on the precision of measurement instrumentation available, it might be worth correcting the voltage.

The PCB will be thoroughly cleaned and then a more compact enclosure for the circuitry will be found. The heatsink is great for prolonged usage, for example, used within vehicles where the buck converter is engaged all the time but for HAM radio, the only consumption taking place is when the radio is keyed such that finding a more convenient heatsink, maybe smaller should do fine. Perhaps, a small fan can be added, just for the extra ventilation but even so, this planning should perform better than the original aluminum box to which the PCB was only pressed.

All-in-all the buck is impressive and it uses an IC board that is very tidy and pretty good quality components such that even purchasing the components individually would not have made the converter any less expensive. Buck converters are also most efficient when they act as shifters of very small levels and in this case, the radio equipment is powered at whereas the batter outputs something like , which is ideal.