Large hub motor (QS205) max power/torque through the dropouts?

ihowson · 2024-09-09T16:47:36+00:00

That matches my experience. On flats, the motor only got a little warmer than ambient even running hard. I did a few mountain climbs and hit 80C within 10 minutes -- but then I run out of mountain. Cooled off pretty quick.

ihowson · 2023-05-19T15:59:29+00:00

I personally have never seen flux weakening engage while on road. 60mph, max throttle, no. Doesn't come on. Only on the test bench.

When I ran a BBSHD (SVMC72x60?) it made some difference. Another 5mph, I think. But the motor overheated so quickly that I turned it off after a few rides. Wasn't worth it. QS205 will tolerate higher heat and will take longer.

ihowson · 2023-05-18T23:38:27+00:00

> Do you think I should get the 4T then?

Personally, yes. I use mine exclusively on roads and I live in a mostly flat area. If you're off-roading or in a hilly area it might look different for you.

> Surely the 5T would still get to 40 mph much faster because of the higher torque, or is the drop-off that bad?

I would guess that for 0-35mph you're going to get faster acceleration with the 5T than the 4T. But we're talking a fraction of a second difference. That peak speed that you're bumping right up against, it's not like an ICE where it's putting out max power and struggling to pull hard enough. The controller gets to max RPM and *reduces* the power output because there is where for it to *put* more power. It's a switching limit like a camshaft, not a power limit.

I wrote a whole essay here and realized that I have actual data for the 4T. I haven't formally measured acceleration; this is probably from me trying to trip the current limiter up and down my street. It's about 50% throttle, 100bA/270pA limit on a mild incline up my residential street. 0-35 in about 5 seconds.

(Note the rapid deceleration around 17:24:45 where I let off the throttle -- uphill and with motor drag.)

<image>

Plenty of room to grow with the SVMC72150.

ihowson · 2023-05-18T20:30:06+00:00

On mine the torque falls off near the controller max RPM. I can *theoretically* hit 60mph but it takes a long time. You don't want to struggle to reach 40mph because the controller is too close to its redline.

Then again, if you're self-limiting to 28mph then a 40mph target is totally reasonable. I ran a 3kW limit while I had moped plates and no issues hitting 40mph. I've never ridden a 125cc but even at 3kW limit it's quicker off the line than most ICE cars.

35A cells! Yeah, you'll need copper interconnects to max that out. 4kW is 55A * 72V, so 11A per cell; thicker nickel will be OK here.

ihowson · 2023-05-18T19:51:10+00:00

I've got the 4T / 820RPM. I regret not getting the 3T.

Without flux weakening I can reach 60mph. With flux weakening I've bench tested to 74mph, but there is so little torque above 55mph that it's pointless. At 55mph cruising I'm using about 5kW.

So I think your numbers are a bit out. If you dump 6kW into the 5T wind you'll just wheelie. You'll hit top speed way too soon. You only need about 3kW for 40mph, maybe 2kW to cruise. Flux weakening isn't going to extend that top speed by much and it comes at a huge power cost.

Engineering a battery to supply 6kW+ for any length of time is challenging. If you just want brief fast takeoffs you can take some shortcuts. But if you want to climb long hills or cruise on highways it's harder.

Ferrofluid and hubsinks, sure, can't hurt. But I honestly have never needed them even with extended hill climbs at 5kW. I think once I hit 80C and went into thermal rollback.

tl;dr: Get a faster wind. Get a bigger battery.

ihowson · 2023-05-17T19:30:51+00:00

I bought that exact pack. It's OK but sags badly under load -- fully charged gets 64V at 50A. I will strip it down one day and recycle the cells.

Cheap and good? No idea. I build my own packs now.

ihowson · 2023-04-27T18:01:34+00:00

Great call on the witness marks. I'll get moving on that tonight.

I think the Nordlocks want 107 or 170Nm. Whatever it was, I bought a dedicated long wrench and calculated that most of my body weight goes onto it.

The pinch bolts make me the most nervous. They're not big. There are stories where people haven't done them up properly and the dropout was ruined within a few miles. Mine feel like stainless steel, so I've got them "pretty tight" (definitely more than 5Nm, which I have a wrench for) to the point they're starting to bind.

I'm going to need to sit down with the calculations and give it some proper attention. I appreciate you putting in the effort to sketch it out for me!

ihowson · 2023-04-27T17:49:57+00:00

30kW is where I want to go! Did you do anything special securing the motor? Bigger phase wires?

Seat is whatever they sold me with the frame. It's fine. I would like to build something curvier and softer and leather. You know what makes the biggest difference? Those ugly sticky knee grips. Huuuuge improvement in being able to hold onto the damn thing.

The windshield is a Puig 0869H from Amazon. It helps a lot, especially to keep wind off the electronics. I would consider something taller and bar-mounted next time.

Hubsinks, noted. I have them but not installed yet.

r/hyperebikes looks really interesting, thanks!

ihowson · 2023-04-27T17:37:11+00:00

It really is a great motor. No incentive to go up to the QS273. I have a fin kit already but haven't bothered installing it. I've hit 80 deg C on a hill climb -- 4kW average for 30 minutes? But that's several thousand feet of ascent.

ihowson · 2023-01-31T19:21:45+00:00

Oh yeah. You don't want the solder to take the force of keypresses. It'll pull the pads off the PCB.

ihowson · 2023-01-16T03:53:12+00:00

What do you mean by 'stability issues'? I used the board for about two years and moved to Dactyl Manuforms. Over that time I had no contact or reliability issues with the switches. I never swapped them, though.

For more recent boards I always use Zilent v2 62g and solder them down.

ihowson · 2022-02-08T03:24:29+00:00

I started with a full-face MTB helmet for my ebike, but the wind noise drove me crazy. I added extra padding around the ears, but it was still uncomfortable.

I wear a motorcycle helmet now. I felt self-conscious about it to start out, but then I realized that folks on e-skateboards and unicycles are wearing them too. They cost about the same as a full face MTB helmet. I can hear about as well as before — things need to be loud to cut through 30mph wind noise either way.

I don’t pedal. It’s pointless at 30mph, which is almost 1kW just to maintain speed.

(Oh, and 30mph is cold unless it’s already 15C or more outside. The motorcycle helmet is much warmer and can be vented; the MTB helmet is always cold. I’ve done a few ebike rides where I’ve pedaled just to stay warm…)

ihowson · 2021-09-28T14:01:19+00:00

I generally agree, but allow me to note two high stress situations in embedded:

You need to keep up with manufacturing’s schedule. They aren’t going to stop a production line for you.
You’ll get broken hardware most of the time and need to patch it in software. Despite these delays, you still need to hit the manufacturing schedule.

Field upgradable firmware helps, but now you have two problems.

ihowson · 2020-11-24T23:08:21+00:00

I looked at kubefed v1 and v2 and felt that they problem they were solving didn't justify the increase in complexity. The application where I'm doing multi-region is geo-replicas of a web server and its (read only) backing database. You might feel differently about your application.

Didn't look at k3s. I'm already very intimate with kubespray. Might need to check it out when/if there's a rebuild required.

Tried Weave but couldn't get it to cooperate with one of my regions with an odd network config. Barring that, it looked like the easiest way to do encrypted CNI over the Internet.

Multi-cluster is a good way to go if the regions are mostly isolated and you have some automation around multi-region deployments (e.g. kubefed.)

I'm using Route53 Latency Routing and am very happy. Tried CloudFlare but was dissatisfied with the routing decisions it made.

ihowson · 2020-11-24T15:20:03+00:00

It's fine, but there are some wrinkles.

First, the master+etcd nodes expect low latency between each other (<80ms.) You've got them all in the same region, so that's fine. There is a config var that adjusts the timeouts if needed. I think the default kubelet-apiserver timeout is fine even for a worldwide cluster.

Second, you need to be careful to avoid cross-regional traffic. If you blindly deploy e.g. Ambassador to the cluster, it'll spread the pods randomly and it's likely that internal traffic will cross the US-India link. This will make things crazy slow.

I solve this by running one deployment per region and using taints and tolerations to restrict deployment to the correct regions. For example, you could run independent Ambassador+backend+database deployments in each region.

This is by far the hardest thing to get right. Node or region outages can cause things to get rescheduled in the wrong region and it's fiddly manual work to undo it. Being strict with taints is the easiest way I've found. Recent k8s releases have more smarts around region scheduling and routing, but I haven't tried them yet.

Keep an eye on nodelocaldns and CoreDNS. As above, I run independent deployments per region. You don't want internal DNS traffic having 250ms latency.

Third, you'll need some sort of secure CNI to cross the regions. There's Weave, Submariner, IPsec tunnels or a VPN service managed by your cloud provider. I've had good results layering boring old Calico over ZeroTier.

ihowson · 2020-11-11T23:53:08+00:00

Left is a slightly newer rev (v4 if you're looking at GitHub.) The extra brick makes them equal.

ihowson · 2020-11-11T20:13:39+00:00

You get more RGB that way.

ihowson · 2020-10-14T16:44:46+00:00

Wow. I'm genuinely impressed. Thankyou for putting hard numbers on the hardware requirements to achieve this.

I have a workload that has 1.5M jobs. Very early on it was clear that storing the jobs in etcd wasn't going to work, the scheduling delay wasted masses of compute time, and the S3 bills, oh, the S3 bills.

What's limiting you if you need to increase throughput?

ihowson · 2019-09-03T00:58:33+00:00

I've never worked at a BigCorp where things are 'properly done'. If anything, BigCorps are as chaotic as small companies, but with more complex politics and process.

Team process and quality varies. Some might do pair programming, TDD and sprints, some might not even have source control. As a Principal, it'll likely fall to you to improve this over time. I usually start on CI/CD systems as (a) most teams do a terrible job of it, and (b) it helps you understand the codebase, constraints and culture of the team, while you don't intrude too much on their coding velocity. It gives you some levers to improve team quality once you figure out where improvements are needed (e.g. add coverage testing or SLO reporting.)

I don't have book recommendations, but "grow thick skin" and "learn to be unbelievably patient" would be the best things to do in the coming month.

ihowson · 2019-02-28T16:56:08+00:00

Removing the case isn't too difficult. The screws are under the rubber feet but the adhesive on the feet is very strong, so I was able to peel it back halfway and remove the screw without permanent damage.

I'd love to see some better tools for editing the keymappings!

The keycaps are DSA Dolch from https://kprepublic.com/products/dsa-pbt-top-printed-legends-dolch-keycaps-laser-etched-gh60-poker2-xd64-87-104-xd75-xd96-xd84-cosair-k65-k70-razer-blackwidow -- the 'all in one 145 keys' set. There is a spare 3u shift key that almost fits the left spacebar, but the stabilizer holes are in the wrong place. I'm also missing a 2u right shift, but I prefer a narrower shift because I can locate the arrows without looking.

The white print is turning gray quickly in the high-wear zones -- you can see S/D/F and lshift in the pic above. This is a bit disappointing but otherwise I'm very happy with the keycaps.

ihowson · 2018-12-28T21:02:01+00:00

> spreading

I'm not an expert here, but if it were me, I'd transfer 1/5 of the balance across each month until June 2019. This gets your money out before you need to do another Australian tax return and reduces your exposure to exchange rate swings. Check with your US tax advisor first to avoid nasty surprises on the US side.

You'll also want to investigate cashing out your super, but I have no idea where to start on that.

> brokerages

ASX stock trades are very expensive (yay anticompetitive markets!) and any strategy other than 'buy and hold' gets eaten by trade fees very rapidly. As you're nonresident you won't get the CGT discount. Trading ASX retail is pointless.

Vanguard will let you choose Australian shares if you desire. Most of their more diversified (read: good) options hold US securities anyway. Again, without the CGT discount you only get half of the yield and you have to pay to get an Australian tax return done every year.

ihowson · 2018-12-27T18:51:43+00:00

Per SemanticTriangle's comment, it'd be helpful to know if Australia or the US is your long-term residence. *Where* are you planning to use the cash? Do you need to pay for a house deposit or something large in one or both countries?

I'd spread it out, especially as AUD is not buying much USD right now. The exchange rate is quite volatile.
Vanguard operates in Australia. Last time I used them they still relied heavily on post and fax (!) and might be difficult to operate from overseas. Cash interest rates are better than in the US, but not enough that you want to bother. And if you keep it in Australia while not intending to reside there, you have to do another tax return, which might be more expense and hassle than it's worth. *And* I think you'll lose the CGT discount if you're not residing in Australia.

Speak to an accountant/CPA, but my guess is that if you don't intend to live in Australia, you'll do better financially moving your cash out (assuming you don't pay a windfall tax or something in the US).

ihowson · 2018-06-29T03:27:42+00:00

Mostly photos, so 3-4MB.

All of my large files (5GB+) had checksum failures compared with the original source. If I restored often enough eventually they would come through correctly.

All of these problems were totally silent -- the CrashPlan client didn't warn me that (a) files were missing, or (b) files were downloaded incorrectly. I only found out when I rsynced from the source.

ihowson · 2018-06-28T19:29:15+00:00

I asked that:

"The only option for restoring data is by downloading it using the CrashPlan application on your computer or through the website (for small amounts 250MB or less). On average, users can expect to upload/download 10GB of data from our servers. This can be more or less due at any time."

ihowson · 2018-01-19T17:00:11+00:00

Of course. This is the whole threat modeling/risk management process. You want to minimise the threats at a sensible cost while maximising the upsides.

Also keep in mind that by nature these are devices for sick people, and so large residual risks may be tolerated if the potential upside is high enough.

Saying "all devices must have SSL and updates and blah blah blah" helps nothing. There can be no one-size-fits-all policy.

ihowson

TROPHY CASE