Never Buy a Tesla

I just got my Tesla Model 3 delivered last week and I’ve added a few hundreds of KMs to its odometer. Frankly it’s largely a disappointment and I’ll state my reasons here.

First, it doesn’t have a ‘start engine’ or ‘ignition’ button at all! More to that, it doesn’t have an engine either, only electric motors. So I sit on my driver seat and shift the gear to ‘D’ with the right lever, and stepped on the acceleration pedal and it just went forward quietly. Also during acceleration there’s no delay, the instant torque is true, and there’s no gaps between gears normally with an auto-transmission car. Quite strange.

And when I said ‘quietly’ it’s really quiet, like awfully quiet. Imagine going through a parking place, the pedestrian in front of my car won’t notice given good hearing ability. I might need to roll down my window and yell ‘Excuse me’ out loud. This won’t be a problem with a normal car at all, not to mention the cars with mufflers removed.

All the buttons and dials on a car’s dash are replaced by a big tablet mounted at the center. This proved to be hard to use during driving because I need to look at the screen to see where to touch. As an alternative there are voice commands like “take me to work”, but who would talk to his car?

As the engine is replaced by motors, there’s no need for turbo, gear box, clutch, etc., so there’s no need to go to a mechanic to replace engine oil, spark plugs, air and fuel filters. Actually there’s no need to see a mechanic at all. This makes harder for me to see my mechanic friends. But maybe in 2 years I still get to see my friends at tyre shop at least.

I have to admit charging the car in the garage is very easy, just like I charge my phone at night, but with a much bigger plug. The wireless charging bays for mobile phones are a nice touch too. But again, feels like I lost the opportunities to go to petrol stations, where I can buy other nice stuff too.

And zero carbon emission? That’s just advertising right? Besides if the government doesn’t care about the environment, why should you do?

After all, I think this Tesla car is just a glorified tablet bundled with seats and wheels. However if you still insist to buy one here’s a referral link. How does this work? If you buy a Tesla with this link, you and I will each get 1500KM of super charge for free, a silver-lining of this disaster(but again, I have solar power, ie. free power, so this will be less incentivising).

Just kidding, I absolutely love this car 🙂

一时冲动,入手特斯拉二代电墙(PowerWall 2)

阴雨天,电墙二代艰难的在下午充电

特斯拉(Tesla)电墙二代(PowerWall2)已经上市一段时间了。我早就想装一个,因为家里太阳能发电系统已经用了很多年,省钱效果显著,但早晚高峰时段依旧要依赖电网,而家用电池系统可以弥补太阳能系统的这个缺点,用自家发的电供应早晚高峰家用。

但是获得老婆的赞同票相当不容易。

  • 首先当然是钱!在猫本电墙2 + 备电网关 + 材料 + 人工要14k,这是我比较多家供应商后找到的最好价格。这不是个小数目。
  • 虽然我用电磁炉取代了煤气炉,但是按照自家的用电规律,指望电墙在十年内把自己身价省出来是不现实的
  • 自家所处位置电网还算稳定,一年停电一次两次而已,所以应付断电这个借口也很勉强

关键时刻还得感谢土澳总理,他不停的说,只有火电(烧煤/油/天然气)才能保证家里的灯能点亮。老婆对此很是反感,投资太阳能发电后家里从电网取电量下降了60%左右,再努力一下99%能源自己并不是很遥远的。而像我们一样在屋顶安装太阳能PV板的家庭已经很普遍,只是安装家用电池的还少。况且,感谢COVID这一年没花什么钱在旅游上,于是老婆同意了这笔花销!

然而,貌似和我们有一样想法的家庭还真不少,这是2020年11月的事情。我交了定金后被告知还要等至少二个月才能轮到安装。然后,在漫长的等待中,突然我接到电话说附近有一家取消了安装,所以那个名额可以转给我,幸福来的很突然,我也懒得去想为啥有人会取消安装。

电墙二代未开箱的样子

安装日那天电工天刚亮就来了,午饭前完成安装。

防晒很重要

由于安装位置会晒到下午的太阳,我用木材和遮阳布给电墙做了个罩子,感觉土洋结合的很好。电墙是不怕淋雨的,但高温肯定会折寿的。几周以后再看看我家用电报告,轻松拿到榜首

几点心得:

  • 电墙二代充满后有13.5度电可用,一般保留10%应急后有12度电
  • 所以除了连日阴雨,一般家庭基本可以自给自足的
  • 虽然瞬间最大功率有7KW,但持续最大功率5KW,所以家里总功率避免超过5KW
  • 如果白天因为阴雨充电不足,只要“熬”过晚高峰,即使用电网的电也是相对便宜的
  • 保证电墙联网,否则特斯拉会缩短质保期

🙂

Ethereum(Crypto) Mining with Nvidia 3070(Ampere) on Ubuntu 20.04 with Renewable Energy

Snagged a pair of RTX 3070 cards. With only 2 cards this is more like an experiment than an investment.

I’ve done Crypto mining before and since the price is now almost all time high I’ll do that again, but only with my solar energy. Mining with dirty coal power isn’t ethical any more as the climate change has accelerated in the past few years.

To start ETH mining here are some prerequisites:

  • Energy efficient video cards, in this case I got RTX 3070. 3060TI is also a good choice but it was sold out already
  • A desktop computer where you can attach multiple video cards to PCI express slots. But I’m not focusing hardware installation here, ie. not showing how to install the card and connect cables, etc.
  • My OS is Ubuntu 20.04 so I choose t-rex miner which has better support for Nvidia Ampere architecture. The releases can be found here

Here are the steps with which I set up t-rex miner on my Ubuntu 20.04 desktop:

# as root user
sudo -i
# install nvidia 460 driver for Ubuntu
apt install nvidia-driver-460
# install t-rex to /opt/t-rex
mkdir /opt/t-rex
wget https://github.com/trexminer/T-Rex/releases/download/0.19.9/t-rex-0.19.9-linux-cuda11.1.tar.gz
tar -zxvf t-rex-0.19.9-linux-cuda11.1.tar.gz -C /opt/t-rex
# change ownership for security reasons
chown -R nobody:nogroup /opt/t-rex

Now in directory /opt/t-rex there are many shell script(.sh) files. I was using ethermine.org so I had a look at ETH-ethermine.sh, it has:

#!/bin/sh
./t-rex -a ethash -o stratum+tcp://eu1.ethermine.org:4444 -u <ETH wallet address> -p x -w <worker name>

Since I’m proudly an experienced Linux user, I choose to create a systemd service out of that shell script:

# cat /etc/systemd/system/ethminer.service 
[Unit]
Description=Ethereum Miner

[Service]
Type=simple
User=nobody
ExecStart=/opt/t-rex/t-rex -a ethash -o stratum+tcp://us2.ethermine.org:4444 -u <my ETH wallet address> -p "" -w <my worker name, can be hostname>

Restart=on-failure

[Install]
WantedBy=multi-user.target

I choose us2 node as it’s geologically close to me. The user is set to nobody so it won’t cause harm to my system if it wants to. Then the service can be enabled and started with systemctl command:

# reload systemd as a new service is added
# following commands run as root user
systemctl daemon-reload
# enable the service so it starts automatically
systemctl enable ethminer
# start the service
systemctl start ethminer
# check status
systemctl status -l ethminer
# watch the logs
journalctl -f |grep t-rex
Jan 24 13:55:30 hostname t-rex[6621]: 20210124 13:55:30 Mining at us2.ethermine.org:4444, diff: 4.00 G
...

According to other miners online, the TDP of 3070 is better set as 50%(130W), because it can run hotter with higher wattage but won’t make it compute faster. Here’s how I use a cronjob to set TDP to 130W except when I’m playing a game(assuming I’ll stop the miner when playing some game on it).

EDIT: 115W is good enough.

# still as root user, as only root can use nvidia-smi command
# crontab -l
*/10 * * * * /bin/ps -C t-rex && /usr/bin/nvidia-smi -i 0 -pl 115 2>&1 >>/var/log/nvidia.log

This can be verified in t-rex ‘s logs

journalctl -f |grep t-rex
Jan 24 13:55:30 hostname t-rex[6621]: 20210124 13:55:30 GPU #0: Gigabyte RTX 3070 - 52.07 MH/s, [T:53C, P:129W, F:60%, E:404kH/W], 1370/1370 R:0%
# it's running at 129W and temperature is 53 degree and fan speed cruising at 60%

Regarding mining solely with solar energy, there can be 3 approaches:

  • Switch electricity supplier to the renewable-friendly ones such as Ember, so you can use solar energy generated by community and enjoy the low wholesale price and mine crypto when the sun shines. This requires the API access supplier so you know when the energy is from renewables and cheap
  • Install and use your own solar energy to mine crypto when the sun shines. This requires API access from your inverter so know when to start mining with enough solar energy.
  • Install solar and battery so it’s guaranteed to mine with your own solar energy until the battery runs flat of course

I’m going with the last option 🙂

电磁炉

最近在家闲着没事我就把旧的天然气炉子换成了电磁炉,然后我立刻就后悔了,为啥才想起来换电磁炉呢?下面简单对比一下燃气炉灶和电磁炉灶的优缺点供朋友们参考。

燃气炉灶(天然气/煤气)
优点:
– 火力可以开到很大
– 可以使用超大尺码的锅
– 可以颠大勺,很帅很专业
– 对炊具材质没有要求,可以用钢锅也可以用砂锅
缺点:
– 使用燃气带来的危险是很多的,燃气泄漏可能会致命(一定要买有熄火保护的炉灶)
– 正常使用时的明火温度在1000到2000摄氏度,有烧伤烫伤的危险
– 抽油烟机必须给力,室内通风要好,否则有二氧化碳中毒的危险
– 热效率低,因为大量的热气并没有被锅吸收,直接跑掉了
– 火力不宜控制,高峰时段气压可能降低导致火力下降
– 脏,锅底和灶台都被炭黑覆盖了
– 而且不容易清洗
– 碳排放,加速气候变化。十年后可能什么事都没有也可能恶劣天气成为日常

电磁炉
优点:
– 干净,没有炭黑,不锈钢炊具用过之后也是崭新的样子
– 超级容易清洁,其实就是一大块钢化玻璃
– 没有尾气,除非做油烟很大的炒菜基本不需要通风
– 热效率超高(90%左右),因为热量是直接在锅底产生的,开启后瞬间锅就热了
– 没有明火,最高温度在300摄氏度以下
– 多数有空载保护,锅烧干或者被拿走以后电磁炉会自动关闭
– 除了锅和接触锅底的部分玻璃表面,其它部分都不会热
– 火力完全可控,可以多达20档,而且稳定
– 定时器,计时器都很方便
– 如果家里有太阳能发电系统,可以抵消部分烹饪消耗的电力
– 即便家里没有太阳能,随着电网内可再生能源(风/太阳能)的比例逐年增高,还是有利于环保的
缺点:
– 必须搭配铁/钢质炊具,合金平锅或者砂锅是不能在电磁炉上用的
– 一般不支持直径超过30厘米的锅
– 没法颠大勺,因为锅离开电磁炉表面后就得不到能量。电磁炉因为空载会关闭

对我来说,电磁炉对比燃气炉是个很大的进步。你觉得呢?

🙂