Lenovo Energy Provide: Dane Kouttron
Image the next:
Biking off to your distant work spot, with a scenic vista solely to be
caught with no choices to prime off your CAD laptop computer with out having to lug
round an influence inverter and an enormous pedestrian energy brick. Why not skip
the intermediary and convert a wide range of battery inputs to the usual
19-20V that the majority laptops crave. Lets check out DC/DC converters and make one thing compact, secure and PRODUCTIVE.
Some background, Lenovo slim-tip laptop computer energy provides are 20V, and
the interior pin resistance to return tells the laptop computer what the PSU ranking
is. The commonplace PSU rankings are 90, 135, 170, 230W. I do know from
testing that the Lenovo P53 will run off of a 170 / 230W provide. At
170W, that is ~8.5A. We do know that this energy stage is just not actually
steady, as thermally there’s not likely sufficient floor space to
radiate that a lot power. 20V is just not a ‘inventory’ DC/DC output voltage, so
we will search for one thing roughly 24V and discover one thing that
has an adjustable sense line for decreasing the output to 20V. We additionally
have some boundaries for enter voltage, my e-bike battery is 12S LiFePO4
/ 10S Li-Ion, or 36v nominal (42v max). We want it to help not less than
that working envelope and ideally manner outdoors of that envelope. So we
have our necessities, +100W, 30-42v in, 20v out.
One of many first choices was from Cincon, that they had a ‘brick’ that was
100W for 100$, with a considerably adjustable output. The datasheet
indicated that 20V operation was doable, however there can be some work
discovering a warmth sink and coupling every thing collectively. These are probably
chassis mounted or cover on a chilly plate in a server surroundings, so a
warmth sink may very well find yourself bigger than the footprint of the brick,
which once more, is just not that unhealthy. The CUI brick was pricier, at 180$, but it surely
was for probably the most half self contained. There have been loads of locations to
mount to, screw terminals are simply really easy, lets see if they’re
out there off-market at a cheaper price.
It seems these are pretty frequent on the excess market (comparable one
proven under), so I did a little bit of e-bay haggling and acquired myself an 18-75V
in 24V out brick. Proven under is an instance of the marginally extra frequent
12V variant, actually 6 for 65$. One other fascinating one is the smaller
100W variant, which is a bit undersized but additionally pretty frequent. This
could also be extra helpful for folk who’re inquisitive about making one thing
particular to their machine (IE; a 100W dell barrel-jack)
What’s considerably humorous is that this CUI brick does have a sibling that has a
9-36V enter, this could possibly be helpful in automotive purposes if
your car’s 12V aux port was rated for it. Most aux ports are 120W
max, or fairly, have a 10A in-line fuse. That is truly beginning to
make sense, there was dell automotive spherical barrel energy provides
which might hook up with a cigarette lighter outlet and provide you with a cell
90W on the street, however these considerably disappeared with the appearance of the
bigger desktop replacements.
A CAD Model Appears
This
is an interactive mannequin proven under, which ought to present a number of
viewpoints. The again cowl panel is eliminated on this render to considerably
show the inner area for reference. This mannequin makes use of the STEP recordsdata
offered from CUI together with a mcmaster-carr mannequin for the cable
glands. It took a bit however this also needs to work on cell, double faucet to
allow. Test it out!
This render was generated in Keyshot after making use of supplies properties
to the preliminary SolidWorks mannequin. For reference this ‘VR’ generates 30
horizontal and 30 vertical positions and renders all of the middleman
positions, or roughly 900 600px broad frames, the above iframe shows
them in a manner that is intuitive.
Let’s start buildingWith the 3d prints
full and the helps eliminated we’re prepared to start including thermal
inserts and the cable glands to the show holder half. I’ve gotta say
this got here out wonderful. In a considerably change of tempo I used an UP! Field 3d
printer which wanted a little bit of TLC. That is utilizing my favourite PLA,
‘Dremel’ model out there on mcmaster-carr https://transistor-man.com/lenovo_ebike_adapter.html It is rather repeatable,
prints from three years in the past are the very same hue, similar supplies
properties, general nice. UP! software program is extremely irritating however
even the ‘regular’ not hyper fantastic output seems to be wonderful.
Subsequent up is tapping the holes for the cable glands. I’ve tried
printed-in-place threads right here and it’s remarkably troublesome to get to
work, so I opted for numerous partitions with a excessive infill and a
regular machining faucet. On this case that is M12, the matching thread of
the cable glands.
Time so as to add the M2.5 thermal inserts. I used a lighter to
shortly warmth up the brass inserts whereas they had been hooked up to a screw
and inserted them into their respective small mounting holes. I believe on
a future print I could improve the wall thickness round these spots,
however they did work as is. These thermal inserts present a ‘door’ for the
remaining wiring to be tucked inside.
Tiny DC Watt Meter
This little watt meter is lovable, its comically tiny and out there from adafruit [link], its additionally out there on ail-express for half worth [link]. It’s very small
and has quite a lot of caveats, however thus far its type of my favourite little gadget. The
rankings are a bit exaggerated (150V DC, 20A), I might not run anyplace
close to that many volts into such a small machine however for laptop computer voltage
vary it is good. The oled show is hooked up by way of flat flex straight
soldered to the principle board and its sadly not likely constrained,
so its doable to have the show slip a bit behind the bezel.
The
again of the tiny watt meter is self-powered between 5-30v, so we solely
want to connect with the screw terminals to for energy in to energy out. I am
undecided what measurement small fork terminals match on this factor would
match, furthermore which of them would match and likewise have the ability to move 20A. To get
across the problems with the screws presumably falling out and the arduous to
discover fork terminals I opted to solder enter/output on to the
terminals. Filming soldering is awkward because of the digicam desirous to be
the place I would prefer to even be, so ignore among the goofy helpful work right here.
As it is a 24V nominal provide, we do have to set the output to be ~20V
nominal and to do that we truly solely want one suggestions resistor. I
did examine the inventory laptop computer energy provide and it got here in at 20.4V, which
was considerably curious. Provided that it is a 2-wire setup with out kelvin’d
sense factors, possibly they knew an 8A load would drop down a couple of hundred
mili-volt over the considerably skinny coaxial-ish cable and gave it some
additional volts to compensate. Unclear. Checking in opposition to the datasheet, I
got here up with ~12.7k to get to twenty.4V and the closest I had available was
13K, which might be nearer to twenty.8V, that is fairly cheap. The
voltage modify is a straightforward resistor jumper between trim and V+.
initially I used to be choosing the ‘presumably extra professional’ use of ring
terminals and small pressure aid jumper wires. That ended up being
extremely awkward, even when utilizing a little bit of RTV to supply some
mechanical help inside the warmth shrink.
It is fairly apparent how a lot better the resistor simply soldered to a
single ring terminal is versus making a resistor-in-heat-shrink wire
meeting, as proven under. The left picture exhibits a black warmth shrink loop
with an embedded resistor, whereas the appropriate exhibits the resistor sitting
in-place with manner much less chance of coming un-done.
With the sense resistor set, lets end up the output and show,
proven under is an out of focus accomplished show module earlier than attaching
it to the DC/DC after which the remaining wiring up of the remaining
wires. Talking of, lets do a fast overview of that meeting course of:
Using the existing mount-pointsThe
{hardware} used to carry down the covers and base plate of the DC/DC is
simply regular M3 screws, the great half about them not being some odd
self-tapping screw is we will take away the inventory screws and simply add in a
longer screw to compensate the distinction in size because of the printed
half. The one shortcoming right here is verifying the screw size that
enters into the case is preserved in case it interacts with something
inside. On this case I used flat head M3 x 10mm screws on the bottom and
sides. Whereas it was doable to simply use the facet going through screws,
grabbing from two axes actually helped in making this extra structural
whereas additionally decreasing area for particles to search out there manner in to the screw
terminal space.
The final bit was to tie up the inner wiring, and connect the again cowl. I opted for orange right here for the duvet each for distinction and likewise as a result of it was what I had queued up within the printer.
Size ComparisonWith the DC/DC
prototype full, lets take a fast comparability vs the ‘inventory’ charger,
whereas they don’t seem to be similar energy ranking, they each run the P53
with none throttling. Its mechanically smaller, however the warmth sink does
stick above the inventory charger top. After constructing this there’s a couple of
issues I might change. It might be a bit extra compact if I used recessed
XT90 / XT model panel mount connectors as an alternative of cable glands. The
chassis-mount sides of the DC/DC additionally do not likely have any profit and
can get caught in a backpack and many others, I ought to discover a method to mill these off
with out getting warmth sink chips into the dc/dc converter mainboard. Additionally
proven under is the availability sitting subsequent to a 4AH DeWalt 20V battery
pack. Once more this isn’t that massive.
How does it handle thermally?With the availability
sitting considerably subsequent to the laptop computer thermal exhaust, each charging the
laptop computer battery and operating with full brightness we see ~32C [89F] because the
case temperature on the gadget. Admittedly the ambient temperature was
~16C [60F], however realistically that’s phenomenal. Sure, i dragged out a
thermal digicam particularly to take a look at how nicely this was working, its
truly actually humorous how the plastic covers don’t even seem within the
thermal picture. The e-bike battery is
~400wh, so I’ve a couple of hours of steady use to check with. After an
hour of use 32C is admittedly cheap. The show will most likely endure
at greater temperatures / in excessive solar, however it’s very nice to know what
it’s doing. I discover it extremely dumb that each considered one of Lenovo’s laptop computer bricks don’t have any indication of performance. Have you ever
tried a 135W / 230W brick on an airplane? You are allotted ~75 watts
and the one indication you’ve got of your charger working is the mains
outlet indicator most likely hiding awkwardly beneath your seat. Seeing 20V,
and present draw is overkill but additionally superior, you get a manner higher really feel
for what your laptop computer is doing.
CAD & Supporting FilesWe now have a couple of printed
elements, and some bought elements, so lets begin with a diagram and
supporting recordsdata. Models proven under are imperial.
And eventually, the venture as a SolidWorks pack and go [link]
Concluding Thoughts
This
got here collectively in just a little over a day which is admittedly wonderful. The
prints all
match, I had the appropriate measurement screws on-hand and the appropriate measurement faucet for the
cable glands. It might be fascinating
to shrink the design a bit, both utilizing the smaller bricks outlined
earlier or altering how the cables hook up with the DC/DC. I’ve combined
opinions about nixing the cable
glands and going for panel mount connectors. One of many advantages to the
flush-mounted XT connectors is measurement, it removes the cable gland nubs
protruding, but it surely does consequence within the ‘ah dang I forgot the
corresponding cable’. Having a polycarbonate cowl on prime of the
watt-meter may be a good suggestion to maintain mud / outside from sneaking
its manner into the show. I believe this might work with some small
recessed thermal inserts and possibly a sq. o-ring.
Have you ever seen that there aren’t any
commercials or ridiculous pop ups? No cookie banner or publication?
I am attempting to make a greater internet, be happy to help it.
Need extra?
Here is a behind the scenes have a look at my work area and among the pictures
that didn’t make the reduce to be included within the write-up:
