01-04-2020, 11:50 PM
The newest 5a xl4015 based voltage buckers i recently ordered, come with 50K ohm trimpots. These tiny blue trimpots are something like 20 turns to go through their full resistance range. meaning that dialing in voltage to a hundredth of a volt requires half the amount of turning as a ten turn potentiometer.
This precision is only really helpful at very low fan speeds, and I was and still am using 10 turn pots on a few fans for dialing in these very low speeds.noise/ampdraw.
I have cheapo 3/4 turn 50K ohm pots and in multiple other values, as well as 10 turn pots in 5 10 and 50K ohm.
Most buckers when fed battery to battery charging voltages, half the upper range of the potentometers does not add any more speed.
So I have been wiring up the new buckers to all three intake fans, the SSfm181 whose internal speed controller failed, the new 140mm fan that does not slow enough, and the 1212 Delta EHE. The 140mm fan is quite difficult to its minimum speed before it shuts off. I am still doing the trick of the tiny trimpot inline with larger finger twist potentiometer which keeps the fan from stopping. i was using 10K ohm trimpots inline with a 50k ohm pot, I noticed that I could get the fan to slow way way down before it shut off completely, with the 20 turn trimpot inline and the other pot turned all the way down. However it made a rhythmic clicking noise down this low.
The 10 turn 10K ohm trimpot, seemed to be at the upper end of its range with fan dialed to enough speed it did not make the clicking sound. The cheapo 50k ohm 270 degree pot still had much of its range unused, the fan speed was already maxed out with perhaps 100 degrees of that 270 degree sweep left in the knob. I tried a 20K ohm pot and it still has the full speed range and perhaps 30 degrees of sweep left when getting about 12.17v reaching the bucker over my test leads from my 18Ah agm battery. With a nearly 14.7v input reaching the bucker, when charging, perhaps the full sweep of the 270 degree trimpot will be used for the full range of fan speed. No 10 turn pots needed anymore, and i can use well under the 10K or 50K ohm pots the buckers themselves came with at these voltages for this duty. Perhaps if I were running 24v system and fans I would need the full 10K or 50K ohm pots for full speed range.
I am a bit perplexed with the max ouput voltage leaving the bucker, Ipreviously measured just under 0.3v, 12.0v in max and 11.71 out max, but tonight with more direct wiring with 12.17v reaching the bucker I was getting 11.98v out for a 0.19 overhead loss. Seems the higher the input voltage, the more efficient the buckers are in terms of voltage loss across the unit.
The new 140mm fan was drawing 1.47 amps when bucker was delivering 11.98v. It and the 120mm Delta fan move an extremely impressive amount of air, even well below their maximum speed/noise/ampdraw. I though the Noctuas at full speed were impressive but the new fans dwarf their airflow. The single Jaro in this shroud seemed to double the flow of the 140mm noctua df ss fm181 combined, andthe delta is as powerful if not more so and the 140mm fan seems to move 2x as much as the 140mm Noctua.
I wonder how much longer the Silverstone fm181 will last. When it goes, a 24v Papst fan will likely replace it, even though it is not quite as Quiet at minimum speed, which is a factor.
I've not yet wired up the individual switches for each bucker/fan as I am not sure the most ergonomic location to mount them or the potentiometers. I've just just using test clips hooked to the buckers to power them whcih can be a bit dangerous if they slide off the solder pads and dig though the insulation and short out the bucker.
This precision is only really helpful at very low fan speeds, and I was and still am using 10 turn pots on a few fans for dialing in these very low speeds.noise/ampdraw.
I have cheapo 3/4 turn 50K ohm pots and in multiple other values, as well as 10 turn pots in 5 10 and 50K ohm.
Most buckers when fed battery to battery charging voltages, half the upper range of the potentometers does not add any more speed.
So I have been wiring up the new buckers to all three intake fans, the SSfm181 whose internal speed controller failed, the new 140mm fan that does not slow enough, and the 1212 Delta EHE. The 140mm fan is quite difficult to its minimum speed before it shuts off. I am still doing the trick of the tiny trimpot inline with larger finger twist potentiometer which keeps the fan from stopping. i was using 10K ohm trimpots inline with a 50k ohm pot, I noticed that I could get the fan to slow way way down before it shut off completely, with the 20 turn trimpot inline and the other pot turned all the way down. However it made a rhythmic clicking noise down this low.
The 10 turn 10K ohm trimpot, seemed to be at the upper end of its range with fan dialed to enough speed it did not make the clicking sound. The cheapo 50k ohm 270 degree pot still had much of its range unused, the fan speed was already maxed out with perhaps 100 degrees of that 270 degree sweep left in the knob. I tried a 20K ohm pot and it still has the full speed range and perhaps 30 degrees of sweep left when getting about 12.17v reaching the bucker over my test leads from my 18Ah agm battery. With a nearly 14.7v input reaching the bucker, when charging, perhaps the full sweep of the 270 degree trimpot will be used for the full range of fan speed. No 10 turn pots needed anymore, and i can use well under the 10K or 50K ohm pots the buckers themselves came with at these voltages for this duty. Perhaps if I were running 24v system and fans I would need the full 10K or 50K ohm pots for full speed range.
I am a bit perplexed with the max ouput voltage leaving the bucker, Ipreviously measured just under 0.3v, 12.0v in max and 11.71 out max, but tonight with more direct wiring with 12.17v reaching the bucker I was getting 11.98v out for a 0.19 overhead loss. Seems the higher the input voltage, the more efficient the buckers are in terms of voltage loss across the unit.
The new 140mm fan was drawing 1.47 amps when bucker was delivering 11.98v. It and the 120mm Delta fan move an extremely impressive amount of air, even well below their maximum speed/noise/ampdraw. I though the Noctuas at full speed were impressive but the new fans dwarf their airflow. The single Jaro in this shroud seemed to double the flow of the 140mm noctua df ss fm181 combined, andthe delta is as powerful if not more so and the 140mm fan seems to move 2x as much as the 140mm Noctua.
I wonder how much longer the Silverstone fm181 will last. When it goes, a 24v Papst fan will likely replace it, even though it is not quite as Quiet at minimum speed, which is a factor.
I've not yet wired up the individual switches for each bucker/fan as I am not sure the most ergonomic location to mount them or the potentiometers. I've just just using test clips hooked to the buckers to power them whcih can be a bit dangerous if they slide off the solder pads and dig though the insulation and short out the bucker.
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