Off the shelf "step up" voltage booster DC DC converters reliable?

[vanilla ice]

https://www.amazon.com/gp/product/B0DC6HSHQM

What do you guys figure the reliability and efficiency would be on these inexpensive off the shelf voltage boosters?

I'm assuming the ratings are two or three times what the real world continuous limits would be. At this cost, even if the rating is optimistic, it has got my interest. I can think of a few things I could them for.

Is there a better solution out there?

 

[sternwake]

I use Vboosters exclusiveky to charge, and do own and regularly use the one you linked, among some lesser wattage boosters as well.

The efficiency varies widely depending on input voltage, output voltage and output current. I'd estimate 82 to 93% efficiency depending on those variables in my inout and output voltage ranges.

They are limited to 40 amps input current and the 1800 watt rating is ONLY achievable if ones input voltage is very high.

Boosting from 12v nominal then 480 watts would be the maximum possible output, before losses, and it will be wasting 60-70 watts as heat, and the fan will be running continuous and the heatsink uncomfortable to touch

I would recommend using an XT90s antispark connector on the input side.
I use one on output side as well.

Mine will only limit current to a minimum 0.82 amps.

My first one I did not use antispark connectors, and it quit when hooking it to a battery about the 7th use. The ebay seller took it back and sent a new one and this second one seems to perform better, allowing higher outout amperage with a 12v nominal input.

My second one has performed well over at least 350 charge cycles, boosting from 12v nominal to 41 to 42 volts, from 0.82 amps to as high as 10 amps. though in general I charge at 2-3 amps 70% of the time into a 360wh battery twice a day.

 

[lnanek]

I bought one once when I had three 48V batteries but my controller could handle 60V and I was trying to get a bit more speed. Field weakening was really inefficient. Like I'd add 10A and only get 1-2 more MPH. So I decided to try boosting the voltage instead.

Anyway, didn't work out. Baserunner controller kept throwing faults even when I made sure I only had the boost set to 58V (via trim pot and multimeter). Especially going downhill even though my motor was geared. I think the controller was designed to feed surges back into the battery or something. Would need to add a regen clamp/brake resistor or something in front.

 

[vanilla ice]

Had a suspicion that issues such as that might rear their head with something like this.

There are some slicker looking units out there, but the pricing is on a different level to these cheapest of ones.

 

[harrisonpatm]

I also use them in various projects for charging, from my 48v nominal house battery, to my 72v nominal ebike/scooter/motorcycle battery, and they work reliably enough for that.

 

[sternwake]

I had not considered the OP might NOT be using them for charging, even though using it to boost 12v battery to 24v output was my first use of such a booster, 7 or 8 years ago.

This was for a 24v hedge clipper. The set up worked fine, until the blades hit the first thicker branch.

I had been using an inline wattmeter rated at 60vDC between 12v battery and 24 hedge clipper and it went dark the same time magic smoke escaped from booster.

These cheap boosters were never intended for dynamic loads.

I'd urge users when employing them for battery charging, to not spin the trim potentiometers too quickly, loaded or not, and never try and adjust output voltage with a battery attached on the output.

Also, do not use them without some way to monitor output voltage and amperage the whole time in use.
I use inline wattmeters on both input and output of 'big red 1800', and My input wattmeter has an audible alarm if I exceed 36 amps.

 

[vanilla ice]

Yes dynamic load. I was thinking half of the max rating is about the most I would need out of one of these "1800 watt" units. I would be using them to output 24 to 48 volts from a running vehicle's alternator, so 12 to 15v power input. That is my first reason anyway, for looking into them.

I had also considered Inanek's use case as a secondary. I recall back in the old times, adding one or two extra 5.0 lipo sticks in series with my sla pack in my pannier bags for more speed. This would have been much simpler.

 

[sternwake]

Yes dynamic load. I was thinking half of the max rating is about the most I would need out of one of these "1800 watt" units.

I thought I would be safe as the 24v hedge clipper at 25.6 volts was drawing only ~2.4 amps with no load iirc. I knew when loaded it would draw far more, but I had that beefy '1800 watt rating' and told myself that surely would be enough.

The set up worked fine until I hit that first thicker branch. Even though I had set output voltage to 24v, it had spiked to over 60v and blew up my wattmeter and smoked the booster too, but the brushed motor hedge clipper was fine.

If the battery on the output side of booster does not have any dynamic loads on it, it should work OK, but even with a small cycling load, like a small DC fridge compressor cycling at 2.7 amps, I would not trust it to not exceed 16v at which point Automotive/RV/marine 12v nominal systems might release magic smoke in protest, eventually, if not immediately.

My inline wattmeter does not have a high refresh rate, but If I pull the charge plug from the battery the wattmeter often shows a voltage spike 3-5v above what I set output voltage to. like 46 or 47v when I had it set to 41.80v, unloaded. This Big red 1800 is better than some other boosters I have in this regard, but the worst is the cheapest '400 watt' red booster. This '400' one will also have output voltage drift upwards, once it gets warm and I always set output voltage to more than half a volt below max charge voltage if I am forced to use it.

 

[lnanek]

Oh, that's an interesting point. The controller fault was over voltage, but I'd always assumed that was from the controller. It's possible the DC-DC output a different voltage under varying load ebike conditions compared to when I set the pot.

I did eventually buy a regen clamp for a different project, but it's one that is wired serially and triggers when the controller side is 2.5V over the supply side: ODrive Regen Clamp

If I ever wanted to try the DC-DC again, maybe I'd be better off with one that is wired in parallel like:

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There's always interesting industrial options on eBay too, but a bit tougher to figure out if they are appropriate for eBikes. E.g.:

https://ebay.io/m/fiLeds

 

[docw009]

I used the same model to boost a 36V12AH silverfish battery (10S-5P) to 48V, and later 54V and 60V. I didn't keep notes/ Posted about it here though. Recall that efficiency was around 70%.

Riding around at 60V, the fun ended when I blew the 30A output fuse on the Silverfish, and had to pedal a 20" fat tire bike home without power. The battery also went unbalanced shortly afterwards. Maybe a coincidence. Maybe too much of a load.

 

[vanilla ice]

These 100 amp units are 10x as expensive. Larger/heavier seems 10x too. Probably more what one should be spending for something like this.

www.ebay.com/itm/127956131765