Louwrentius

Skip to the bottom two paragraph for instructions on how to replace the battery.

I bought my Bose SoundLink on-ear Bluetooth headphones for 250 Euros around 2017 and I really like them. They are small, light, comfortable and can easily fit in a coat pocket when folded.

Up until now (about 7 years later) I have replaced the ear cushions in 2019 (€25) and 2024 (€18).

Early 2025, battery capacity had deteriorated to a point where it became noticeable. The battery was clearly dying.

Unfortunately these headphones aren't designed for easy battery replacement:

• Bose hasn't published instructions on how to replace the battery, doesn't offer a replacement battery and hasn't documented which battery type/model is used.
• The left 'head phone' has two Torx security screws and most people won't have the appropriate screwdriver for this size
• There is soldering involved

I wanted to try a battery replacement anyway as I hate to throw away a perfectly good, working product just because the battery has worn out. Maybe at some point the headband needs replacing, but with a fresh battery, these headphones can last another 7 years. Let's prevent a bit of e-waste with a little bit of cost and effort.

Most of all, the cost of this battery replacement is much lower than a new pair of headphones as the battery was €18 including taxes and shipping.

Right to repair should include easy battery replacement

Although my repair seemed to have worked out fine, it requires enough effort that most people won't even try. For this reason, I feel that it should be mandatory by law that:

1. Batteries in any product must be user-replaceable (no special equipment or soldering required)
2. Batteries must be provided by the vendor until 10 years after the last day the product was sold (unless it's a standard format like AA(A) or 18650).
3. Batteries must be provided at max 10% of the cost of the original product
4. The penalty for non-compliance should be high enough such that it won't be regarded as the cost of doing business

For that matter, all components that may wear down over time should be user-replaceable.

What you need to replace the battery

1. Buy the exact battery type: ahb571935pct-01 (350mAh) (notice the three wires!)
2. A Philips #0 screwdriver / bit
3. A Torx T6H security screwdriver / bit (iFixit kits have them)
4. A soldering iron
5. Solder
6. Heat shrink for 'very thin wire'
7. Multimeter (optional)
8. a bit of tape to 'cap off' bare battery leads

Please note that I found another battery ahb571935pct-03 with similar specifications (capacity and voltage) but I don't know if it will fit.

Putting the headphone ear cushion back on can actually be the hardest part of the process, you need to be firm and this process is documented by Bose.

Battery replacement steps I took

Make sure you don't short the wires on the old or new battery during replacement

The battery is located in the left 'head phone'.

1. Use a multimeter to check if your new battery isn't dead (should be 3+ volt)
2. Remove the ear cushion from the left 'head phone' very gently as not to tear the rim
3. Remove the two philips screws that keep the driver (speaker) in place
4. Remove the two Torx screws (you may have to press a bit harder)
5. Remove the speaker and be carefull not to snap the wire
6. Gently remove the battery from the 'head phone'
7. Cut the wires close to the old battery (one by one!) and cover the wires on the battery to prevent a short
8. Strip the three wires from the headphones a tiny bit (just a few mm)
9. Put a short piece of heat shrink on each of the three wires of the battery
10. Solder each wire to the correct wire in the ear cup
11. Adjust the location of the heat shrink over the freshly soldered joint.
12. Use the soldering iron close to the heat shrink to shrink it (don't touch anything), this can take some time, be patient
13. Check that the heat shrink is fixed in place and can't move
14. Put the battery into it's specific location in the back of the 'head phone'
15. Test the headphones briefly before reassembling the headphones
16. Reassemble the 'head phone' (consider leaving out the two Torx screws)
17. Dispose of the old battery in a responsible manner

My 4U 71 TiB ZFS NAS built with twenty-four 4 TB drives is over 10 years old and still going strong.

Although now on its second motherboard and power supply, the system has yet to experience a single drive failure (knock on wood).

Zero drive failures in ten years, how is that possible?

Let's talk about the drives first

The 4 TB HGST drives have roughly 6000 hours on them after ten years. You might think something's off and you'd be right. That's only about 250 days worth of runtime. And therein lies the secret of drive longevity (I think):

Turn the server off when you're not using it.

According to people on Hacker News I have my bearings wrong. The chance of having zero drive failures over 10 years for 24 drives is much higher than I thought it was. So this good result may not be related to turning my NAS off and keeping it off most off the time.

My NAS is turned off by default. I only turn it on (remotely) when I need to use it. I use a script to turn the IoT power bar on and once the BMC (Baseboard Management Controller) is done booting, I use IPMI to turn on the NAS itself. But I could have used Wake-on-Lan too as an alternative.

Once I'm done using the server, I run a small script that turns the server off, wait a few seconds and then turn the wall socket off.

It wasn't enough for me to just turn off the server, but leave the motherboard, and thus the BMC powered, because that's just a constant 7 watts (about two Raspberry Pis at idle) being wasted (24/7).

This process works for me because I run other services on low-power devices such as Raspberry Pi4s or servers that use much less power when idling than my 'big' NAS.

This proces reduces my energy bill considerably (primary motivation) and also seems great for hard drive longevity.

Although zero drive failures to date is awesome, N=24 is not very representative and I could just be very lucky. Yet, it was the same story with the predecessor of this NAS, a machine with 20 drives (1 TB Samsung Spinpoint F1s (remember those?)) and I also had zero drive failures during its operational lifespan (~5 years).

The motherboard (died once)

Although the drives are still ok, I had to replace the motherboard a few years ago. The failure mode of the motherboard was interesting: it was impossible to get into the BIOS and it would occasionally fail to boot. I tried the obvious like removing the CMOS battery and such but to no avail.

Fortunately, the [motherboard]¹ was still available on Ebay for a decent price so that ended up not being a big deal.

ZFS

ZFS worked fine for all these years. I've switched operating systems over the years and I never had an issue importing the pool back into the new OS install. If I would build a new storage server, I would definitely use ZFS again.

I run a zpool scrub on the drives a few times a year². The scrub has never found a single checksum error. I must have run so many scrubs, more than a petabyte of data must have been read from the drives (all drives combined) and ZFS didn't have to kick in.

I'm not surprised by this result at all. Drives tend to fail most often in two modes:

1. Total failure, drive isn't even detected
2. Bad sectors (read or write failures)

There is a third failure mode, but it's extremely rare: silent data corruption. Silent data corruption is 'silent' because a disk isn't aware it delivered corrupted data. Or the SATA connection didn't detect any checksum errors.

However, due to all the low-level checksumming, this risk is extremely small. It's a real risk, don't get me wrong, but it's a small risk. To me, it's a risk you mostly care about at scale, in datacenters⁴ but for residential usage, it's totally reasonable to accept the risk³.

But ZFS is not that difficult to learn and if you are well-versed in Linux or FreeBSD, it's absolutely worth checking out. Just remember!

Sound levels (It's Oh So Quiet)

This NAS is very quiet for a NAS (video with audio).

But to get there, I had to do some work.

The chassis contains three sturdy 12V fans that cool the 24 drive cages. These fans are extremely loud if they run at their default speed. But because they are so beefy, they are fairly quiet when they run at idle RPM⁵, yet they still provide enough airflow, most of the time. But running at idle speeds was not enough as the drives would heat up eventually, especially when they are being read from / written to.

Fortunately, the particular Supermicro motherboard I bought at the time allows all fan headers to be controlled through Linux. So I decided to create a script that sets the fan speed according to the temperature of the hottest drive in the chassis.

I actually visited a math-related subreddit and asked for an algorithm that would best fit my need to create a silent setup and also keep the drives cool. Somebody recommended to use a "PID controller", which I knew nothing about. So I wrote some Python, stole some example Python PID controller code, and tweaked the parameters to find a balance between sound and cooling performance.

The script has worked very well over the years and kept the drives at 40C or below. PID controllers are awesome and I feel it should be used in much more equipment that controls fans, temperature, and so on, instead of 'dumb' on/of behaviour or less 'dumb' lookup tables.

Networking

I started out with quad-port gigabit network controllers and I used network bonding to get around 450 MB/s network transfer speeds between various systems. This setup required a ton of UTP cables so eventually I got bored with that and I bought some cheap Infiniband cards and that worked fine, I could reach around 700 MB/s between systems. As I decided to move away from Ubuntu and back to Debian, I faced a problem: the Infiniband cards didn't work anymore and I could not figure out how to fix it. So I decided to buy some second-hand 10Gbit Ethernet cards and those work totally fine to this day.

The dead power supply

When you turn this system on, all drives spin up at once (no staggered spinup) and that draws around 600W for a few seconds. I remember that the power supply was rated for 750W and the 12 volt rail would have been able to deliver enough power, but it would sometimes cut out at boot nonetheless.

UPS (or lack thereof)

For many years, I used a beefy UPS with the system, to protect against power failure, just to be able to shutdown cleanly during an outage. This worked fine, but I noticed that the UPS used another 10+ watts on top of the usage of the server and I decided it had to go.

Losing the system due to power shenanigans is a risk I accept.

Backups (or a lack thereof)

My most important data is backed up trice. But a lot of data stored on this server isn't important enough for me to backup. I rely on replacement hardware and ZFS protecting against data loss due to drive failure.

And if that's not enough, I'm out of luck. I've accepted that risk for 10 years. Maybe one day my luck will run out, but until then, I enjoy what I have.

Future storage plans (or lack thereof)

To be frank, I don't have any. I built this server back in the day because I didn't want to shuffle data around due to storage space constraints and I still have ample space left.

I have a spare motherboard, CPU, Memory and a spare HBA card so I'm quite likely able to revive the system if something breaks.

As hard drive sizes have increased tremendously, I may eventually move away from the 24-drive bay chassis into a smaller form-factor. It's possible to create the same amount of redundant storage space with only 6-8 hard drives with RAIDZ2 (RAID 6) redundancy. Yet, storage is always expensive.

But another likely scenario is that in the coming years this system eventually dies and I decide not to replace it at all, and my storage hobby will come to an end.

I've always been fond of the idea of the Raspberry Pi. An energy efficient, small, cheap but capable computer. An ideal home server. Until the Pi 4, the Pi was not that capable, and only with the relatively recent Pi 5 (fall 2023) do I feel the Pi is OK performance wise, although still hampered by SD card performance¹. And the Pi isn't that cheap either.

The Pi 5 can be fitted with an NVME SSD, but for me it's too little, too late. Because I feel there is a type of computer on the market, that is much more compelling than the Pi.

I'm talking about the tinyminimicro home lab 'revolution' started by servethehome.com about four years ago (2020).

A 1L mini PC (Elitedesk 705 G4) with a Raspberry Pi 5 on top

During the pandemic, the Raspberry Pi was in short supply and people started looking for alternatives. The people at servethehome realised that these small enterprise desktop PCs could be a good option. Dell (micro), Lenovo (tiny) and HP (mini) all make these small desktop PCs, which are also known as 1L (one liter) PCs.

These Mini PC are not cheap² when bought new, but older models are sold at a very steep discount as enterprises offload old models by the thousands on the second hand market (through intermediates).

Although these computers are often several years old, they are still much faster than a Raspberry Pi (including the Pi 5) and can hold more RAM.

I decided to buy two HP Elitedesk Mini PCs to try them out, one based on AMD and the other based on Intel.

The Hardware

The AMD-based system is cheaper, but you 'pay' in higher idle power usage. In absolute terms 10 watt is still decent, but the Intel model directly competes with the Pi 5 on idle power consumption.

Elitedesk 705 left, Elitedesk 800 right (click to enlarge)

Regarding display output, these devices have two fixed displayport outputs, but there is one port that is configurable. It can be displayport, VGA or HDMI. Depending on the supplier you may be able to configure this option, or you can buy them separately for €15-€25 online.

Click on image for official specs in PDF format

Both models seem to be equipped with socketed CPUs. Although options for this formfactor are limited, it's possible to upgrade.

Comparing cost with the Pi 5

The Raspberry Pi 5 with (max) 8 GB of RAM costs ~91 Euro, almost exactly the same price as the AMD-based mini PC³ in its base configuration (8GB RAM). Yet, with the Pi, you still need:

1. power supply (€13)
2. case (€11)
3. SD card or NVME SSD (€10-€45)
4. NVME hat (€15) (optional but would be more comparable)

It's true that I'm comparing a new computer to a second hand device, and you can decide if that matters in this case. With a complete Pi 5 at around €160 including taxes and shipping, the AMD-based 1L PC is clearly the cheaper and still more capable option.

Comparing performance with the Pi 5

The first two rows in this table show the Geekbench 6 score of the Intel and AMD mini PCs I've bought for evaluation. I've added the benchmark results of some other computers I've access to, just to provide some context.

Sure, these mini PCs won't come close to modern hardware like the Apple M2 or the intel i9. But if we look at the performance of the mini PCs we can observe that:

1. The Intel i5-6500T CPU is 13% faster in single-core than the AMD Ryzen 3 PRO
2. Both the Intel and AMD processors are 42% - 62% faster than the Pi 5 regarding single-core performance.

Storage (performance)

If there's one thing that really holds the Pi back, it's the SD card storage. If you buy a decent SD card (A1/A2) that doesn't have terrible random IOPs performance, you realise that you can get a SATA or NVME SSD for almost the same price that has more capacity and much better (random) IO performance.

With the Pi 5, NVME SSD storage isn't standard and requires an extra hat. I feel that the missing integrated NVME storage option for the Pi 5 is a missed opportunity that - in my view - hurts the Pi 5.

Now in contrast, the Intel-based mini PC came with a SATA SSD in a special mounting bracket. That bracket also contained a small fan(1) to keep the underlying NVME storage (not present) cooled.

There is a fan under the SATA SSD (click to enlarge)

The AMD-based mini PC was equipped with an NVME SSD and was not equipped with the SSD mounting bracket. The low price must come from somewhere...

However, both systems have support for SATA SSD storage, an 80mm NVME SSD and a small 2230 slot for a WiFi card. There seems no room on the 705 G4 to put in a small SSD, but there are adapters available that convert the WiFi slot to a slot usable for an extra NVME SSD, which might be an option for the 800 G3.

Noice levels (subjective)

Both systems are barely audible at idle, but you will notice them (if you sensitive to that sort of thing). The AMD system seems to become quite loud under full load. The Intel system also became loud under full load, but much more like a Mac Mini: the noise is less loud and more tolerable in my view.

Idle power consumption

Elitedesk 800 (Intel)

I can get the Intel-based Elitedesk 800 G3 to 3.5 watt at idle. Let that sink in for a moment. That's about the same power draw as the Raspberry Pi 5 at idle!

Just installing Debian 12 instead of Windows 10 makes the idle power consumption drop from 10-11 watt to around 7 watt.

Then on Debian, you:

1. run apt install powertop
2. run powertop --auto-tune (saves ~2 Watt)
3. Unplug the monitor (run headless) (saves ~1 Watt)

You have to put the powertop --auto-tune command in /etc/rc.local:

#!/usr/bin/env bash
powertop --auto-tune
exit 0

Then apply chmod +x /etc/rc.local

So, for about the same idle power draw you get so much more performance, and go beyond the max 8GB RAM of the Pi 5.

Elitedesk 705 (AMD)

I managed to get this system to 10-11 watt at idle, but it was a pain to get there.

I measured around 11 Watts idle power consumption running a preinstalled Windows 11 (with monitor connected). After installing Debian 12 the system used 18 Watts at idle and so began a journey of many hours trying to solve this problem.

The culprit is the integrated Radeon Vega GPU. To solve the problem you have to:

1. Configure the 'bios' to only use UEFI
2. Reinstall Debian 12 using UEFI
3. install the appropriate firmware with apt install firmware-amd-graphics

If you boot the computer using legacy 'bios' mode, the AMD Radeon firmware won't load no matter what you try. You can see this by issuing the commands:

rmmod amdgpu
modprobe amdgpu

You may notice errors on the physical console or in the logs that the GPU driver isn't loaded because it's missing firmware (a lie).

This whole process got me to around 12 Watt at idle. To get to ~10 Watts idle you need to do also run powertop --auto-tune and disconnect the monitor, as stated in the 'Intel' section earlier.

Given the whole picture, 10-11 Watt at idle is perfectly okay for a home server, and if you just want the cheapest option possible, this is still a fine system.

KVM Virtualisation

I'm running vanilla KVM (Debian 12) on these Mini PCs and it works totally fine. I've created multiple virtual machines without issue and performance seemed perfectly adequate.

Boot performance

From the moment I pressed the power button to SSH connecting, it took 17 seconds for the Elitedesk 800.

The Elitedesk 705 took 33 seconds until I got an SSH shell.

These boot times include the 5 second boot delay within the GRUB bootloader screen that is default for Debian 12.

Remote management support

Some of you may be familiar with IPMI (ILO, DRAC, and so on) which is standard on most servers. But there is also similar technology for (enterprise) desktops.

Intel AMT/ME is a technology used for remote out-of-band management of computers. It can be an interesting feature in a homelab environment but I have no need for it. If you want to try it, you can follow this guide.

For most people, it may be best to disable the AMT/ME feature as it has a history of security vulnerabilities. This may not be a huge issue within a trusted home network, but you have been warned.

The AMD-based Elitedesk 705 didn't came with equivalent remote management capabilities as far as I can tell.

Alternatives

The models discussed here are older models that are selected for a particular price point. Newer models from Lenovo, HP and Dell, equip more modern processors which are faster and have more cores. They are often also priced significantly higher.

If you are looking for low-power small formfactor PCs with more potent or customisable hardware, you may want to look at second-hand NUC formfactor PCs.

Stacking multiple mini PCs

The AMD-based Elitedesk 705 G4 is closed at the top and it's possible to stack other mini PCs on top.

The Intel-based Elitedesk 800 G3 has a perforated top enclosure, and putting another mini pc on top might suffocate the CPU fan.

As you can see, the bottom/foot of the mini PC doubles as a VESA mount and has four screw holes. By putting some screws in those holes, you may effectively create standoffs that gives the machine below enough space to breathe (maybe you can use actual standoffs).

Evaluation and conclusion

I think these second-hand 1L tinyminimicro PCs are better suited to play the role of home (lab) server than the Raspberry Pi (5).

The increased CPU performance, the built-in SSD/NVME support, the option to go beyond 8 GB of RAM (up to 32GB) and the price point on the second-hand market really makes a difference.

I love the Raspberry Pi and I still have a ton of Pi 4s. This solar-powered blog is hosted on a Pi 4 because of the low power consumption and the availability of GPIO pins for the solar status display.

That said, unless the Raspberry Pi becomes a lot cheaper (and more potent), I'm not so sure it's such a compelling home server.

This blog post featured on the front page of Hacker News.