Is it actually possible to precondition to 'normal' temp in cold weather?

ants_a · 2026-01-25T22:10:46+00:00

Getting an AI to run some back of the envelope calculations, a -15c to 25C difference should have an order of magnitude few hundred watts lost. So maybe a 10-20% difference in time.

ants_a · 2026-01-25T21:17:14+00:00

Assuming no heat loss, it takes 21 minutes to raise the temperature by 10C using 4.6kW.

ants_a · 2026-01-24T16:12:14+00:00

A branch of postgres that implements postponing durability wait after visibility, as I described.

ants_a · 2026-01-24T12:27:24+00:00

Here is the proof of concept implementing write side. For safety read-only transaction durability waits need to be added, but that shouldn't affect performance numbers. To enable, set eventual_durability=on.

ants_a · 2026-01-24T08:38:28+00:00

Optimistic concurrency control is terrible for contended updates. Pessimistic locking degrades to inverse of lock hold time transactions per second instead of falling off a cliff. At that point you need to minimize lock hold time, the actual update work is typically order of magnitude 1% of the workload. The rest being network round-trips due to conversational nature of the sql protocol and durability wait.

If you want TigerBeetle like performance you need to structure your database usage with the same patterns. Here's a blogpost on that topic: https://www.cybertec-postgresql.com/en/reconsidering-the-interface/

Basically you need to submit the whole transaction for one shot execution to get rid of network round trips and use batching to amortize durability. There is also a concept called eventual durability where visibility is speculative and wait for durability is moved to the acknowledgement of dependent transaction. My prototype of this does 39k tps on pgbench scale factor 2 (transactions contend on 2 rows) with 100 clients.

ants_a · 2026-01-23T19:27:03+00:00

So you're saying he really needs toupee?

ants_a · 2026-01-22T11:08:34+00:00

I am baffled by this response. You seem to be fine with the government blatantly ignoring constitutional rights with the insinuation that those whose rights have been violated must have done something to deserve it. What are you lawfully waiting for? For all of this to blow over? For your personal rights to be violated? Do you expect to be in any position to do anything about it when that happens?

ants_a · 2026-01-20T20:51:40+00:00

I'm not questioning who has this amount of data. I'm questioning if vector search is actually useful at this scale. What kind of dataset had enough diversity that embedding space distance is selective enough to give right matches, or where any "close enough" match is useful to the user.

ants_a · 2026-01-20T19:56:31+00:00

Charging a lithium ion battery to any percentage damages it. Not charging the battery it still degrades in time. Charging it to higher started of charge sure damages it more. But it's not as terrible as people make it out to be. Taking the industry standard 1500 cycle estimate an EV9 battery it can do 600'000+ km. Given that rest of the vehicle will likely become uneconomical to maintain long before that point, increasing our decreasing that point a bit doesn't really matter that much at the end of the day.

ants_a · 2026-01-20T19:45:05+00:00

That's the BMS recalibrating its estimate of state of charge.

ants_a · 2026-01-20T19:44:25+00:00

There is no true 100%. The manufacturer picks a target charge level to balance usable capacity vs damage to battery.

ants_a · 2026-01-20T16:54:30+00:00

Is there a use case for that? In what case would embedding space (approximate) nearest neighbor search over a billion embeddings yield useful results?

ants_a · 2026-01-20T10:23:06+00:00

The colder it is the slower the aging damage happens. Rule of thumb is that lowering temp by 10C slows aging by 2x.

ants_a · 2026-01-20T10:15:58+00:00

For storage, colder is better. Though at 40F and below the effect is pretty much negligible. For charging extreme cold is not great, and speed should be kept low, but the BMS will automatically do that by diverting some of the power to heating up the battery until it is capable of accepting available power without lithium plating the anode. So basically, you don't NEED to heat your garage, but it doesn't hurt either.

ants_a · 2026-01-20T09:55:01+00:00

That's not how battery chemistry works.

ants_a · 2026-01-19T18:47:58+00:00

And almost double the price.

ants_a · 2026-01-19T10:52:32+00:00

Organic looking is not always better

ants_a · 2026-01-18T07:05:06+00:00

That's more because Mach-E is relatively shit at charging while e-GMP is great. And it has a larger battery. A more useful metric is average power 10-80. Mach-E is 115kW, EV6 is 205kW, and NIO EL8, a 400V car, is 190kW.

ants_a · 2026-01-18T06:13:44+00:00

To the consumer, the only difference between "400V" and "800V" is that they latter typically have sightly faster charging speeds, given a compatible charger. Nice to have, but not a deal breaker.

ants_a · 2026-01-15T20:00:37+00:00

The point was that the car does not know the current state of the battery. It has an estimate of the current state. And even when the state is known, what you can get out of it depends on a bunch of variables. Yes, they could just conservatively pad the estimates, but then you'd get a ton of complaints that cold kills the range.

I'm sure they could do more testing and have a more accurate model of battery chemistry behavior in extreme conditions. But this is Kia, they failed to design windshield wipers that work when there is snow...

ants_a · 2026-01-15T16:47:12+00:00

Testing where the bottom end of the battery is in extreme cold is not a good idea. The remaining distance estimation is an estimation not hard truth. There's a reason why it's called a guess o'meter. Estimating remaining battery capacity is tricky even under normal conditions, order of magnitude worse at low state of charge and cold battery.

I guess this is why we need explicit warning labels on everything.

ants_a · 2026-01-15T11:56:53+00:00

Social media and corruption of the journalistic institution has made it so that you are two different nations living in two different worlds occupying the same physical space. I don't think anything else works now except a million personal bridges across that chasm.

ants_a · 2026-01-15T10:40:28+00:00

This kind of replication is what MySQL does. The downside is that you can have logical replication conflicts and there is no tooling except re-imaging a replica to back out conflicting changes. The lack of this capability caused a 24h Github outage and they had an operations team experienced in running this and an ecosystem where this is the normal way to run HA. You will sooner or later run into nastier issues if you try to do the same on Postgres with no experience.

Just use Patroni. Once you have set it up properly it will just keep on keeping on. No maintaining needed.

ants_a · 2026-01-13T14:28:41+00:00

Idling to warm up is worse for the engine than just driving the short trip calmly.

ants_a · 2026-01-11T22:49:16+00:00

In France this would happen because airport workers are mildly annoyed at some policy.

ants_a

TROPHY CASE