External battery extension for Boom

[philippe_44]

Hi - I've started a small project to add a 3x18650 Li-ion battery + charger + casing, properly attached to my Booms (I have 3). This will provide 2.5Ax11.5V = 28W, good enough for me. I've printed a box to attach the pack and the PCB properly (see picture - this is the 1st version - the casing is made of 2 pieces, one is a plaque screwed using the existing holes of the Boom and it locks the battery compartiment + charger that is inserted as tray - I've replicated the headset and power supply jacks at the back of my casing). I now need to decide on the electronic. I'm used to build Li-ion chargers, so this is fine, but I'm hesitating to add a step-up after the li-ion pack to stabilize @ 12V. Usually, I don't do that for my other 12V replacement by 3 Li-ion cells. You get 11.1v most of the time with 3 cells, very stable, with reasonnable load and this is fine with all my current design. But Boom beeing audio & power, I'm wondering ... Problem with that it is extra work, tighther design (already need a steup for charging) for me and loss of battery efficiency & heat. Anybody having an experience with the min voltage accepted by the boom and the power supply "logic" inside it (I've not opened mine - yet) ? I can do my own test, but if anybody has already a hint, that would be welcome.

Thanks

Philippe

[philippe_44]

1st version up and running - I've extended a bit the enclosure so I can fit 6800 mAh @ 11.1V (three flat pack), that should give me a good 5 hours of listening. I've design a linear charger and set the charge to be 500mA so moderate heat generation on discharged batteries. I'll test it a bit and report here. Not so many Boom users these days, but if somebody wants, I'll upload all the design files

[pippin]

A word of warning. Caleb, who designed the Boom, warned strongly against using it with LiIon batteries.
The reason is that the Boom can draw a very high current when being turned on (or when it turns on the amp) which can potentially short the battery and LiIon have the bd habit of starting to burn or even explode under such conditions.
So you might want to include a way to limit the power draw from your battery pack.

I should mention that I've used my Boom with a Laptop battery for quite a while but that was quite a high-power battery pack.

[philippe_44]

That's good to know, thanks ! The battery cells themselves have a protection at 8.5A and I have put a switch (BTS4142) to commute between the external power and the battery that has a 4.5A short load protection. I'm always very carefull with these batteries

A word of warning. Caleb, who designed the Boom, warned strongly against using it with LiIon batteries.
The reason is that the Boom can draw a very high current when being turned on (or when it turns on the amp) which can potentially short the battery and LiIon have the bd habit of starting to burn or even explode under such conditions.
So you might want to include a way to limit the power draw from your battery pack.

I should mention that I've used my Boom with a Laptop battery for quite a while but that was quite a high-power battery pack.

[philippe_44]

I'be finished my small project of adding a rechargeable option to the Boom. This was my only real complain about the Boom, no battery ==> not transportable. With 3D printers, I've now been able to get what I wanted.

This option I've made consist of a sort of "tray" that slides in the cavity behind. A holder piece is bolt on the boom using the 4 screws for the wall mount, then the box containing the battery and charger slides on the holder piece an connects to the power jack and the audio line-in (see picture)

Battery is a pack of 3 LiIon 18650 cylinders giving 2500-3000mA @ 11.1V (can be find in many places, http://www.all-battery.com for example) . The boom seems to consume ~300mA in idle and ~6-800mA in active mode, medium volume. So you should have 6-8 hours standby and 2-3 hours play. Charger is of linear type, using TI BQ2057. It handles charge, end of-charge and maintenance, hence it can stay plugged 24/7 as you expect the Boom to be normally by default. When AC power adapter is plugged, the Boom is fed by the AC adapter and the battery is charged (or maintained) - battery is _not_ feeding the Boom. When disconnecting the AC, the power automatically switch to battery, as expected. Switch itself contains a 4.5A current limitor, so nothing harmful can happen, even if the Boom tries to drain a lot of current (I've been told that).

Battery pack itself contains a current limiter and over/under voltage limitation (please do not use non-protected cells). I've added circuitry to disconnect the battery around 9V, to avoid using the internal under-voltage protection. There is an hysterisis about 1V so the battery will not feed the Boom unless it reaches again 10V. Charge is pretty slow, on purpose (250 mA) - I do _not_ recommend going above that because of heat dissipation (this is a linear charger and I needed to add a font DC-DC step-up, so it is not the most power efficient in term of heat generation). Personally, I don't mind the slow charge as, one the battery is fully drained, whether it takes 5 or 10 hours to recharge does not matter a lot to me. Doing a 1 hour charger is also beyond the ability of the default Boom AC adapter.

I'v included the schematics, the PCB layout (both using Diptrace), the 2 pieces of the "tray" in STL and source format (using 123Designer). All components can be found, for example, at Digikey. I'v also added a zip file that contains a set of gerber that can be sent directly to a PCB company like http://imall.iteadstudio.com/open-pc...ototyping.html (I have a few PCB left that I can send - for free - if somebody is interested)

If you are interested in doing this, please make sure that you are confortable with electronic design, soldering and battery handling - this is LiIon and you have to be careful with that. I'm giving this "as is" and this is not "consumer-grade" / foolproof design.

https://dl.dropboxusercontent.com/u/26754471/Boom%20Charger.zip

[johnas]

Really nice job and thanks for sharing with the community!

Sent from my XT1032 using Tapatalk

[chill]

Hi Philippe

I've only just discovered this thread. That looks like a very useful addition to the Boom. I'd like to have a go at building one myself - any chance you've got any of the PCBs left?

Has it worked the way you wanted it to? Would you change anything for a second version? I can't really tell from the photos - is the clip in part easy to remove regularly, and could it be charged while disconnected from the Boom?

[philippe_44]

Hi Philippe

I've only just discovered this thread. That looks like a very useful addition to the Boom. I'd like to have a go at building one myself - any chance you've got any of the PCBs left?

Has it worked the way you wanted it to? Would you change anything for a second version? I can't really tell from the photos - is the clip in part easy to remove regularly, and could it be charged while disconnected from the Boom?

I have a few PCB left. It can be charged connected or disconnected from the Boom, either way. I've been using it 24/7 on 2 Booms for a year now and did not experience any problem. It is a linear charger and I hesitated a bit at the beginning because it does produce more heat than the other DC/DC-based charger that I designed, but it has the benefit of simplicity and has a very good control chip on it for battery maintenance. I've limited the charge to limit the heat dissipation, so it is not super fast, but that works for my use case. Once the battery is discharged, whether it takes 1 or 3 hours to recharge is a bit irrelvant as you have to stopt listening for an extended amount of time anyway

[chill]

Thanks Philippe - I'll send you a PM about a PCB.

[gorman]

A work of beauty. Too bad I'm electronically impaired... and I would just mess this up. But great idea and execution.

Also, haven't you thought about using high discharge batteries to avoid problems? Stuff like Sony's VTC 4/5 or LG HE4. They are rated for 20+A.

[philippe_44]

A work of beauty. Too bad I'm electronically impaired... and I would just mess this up. But great idea and execution.

Also, haven't you thought about using high discharge batteries to avoid problems? Stuff like Sony's VTC 4/5 or LG HE4. They are rated for 20+A.

Thanks The Boom power supply is rated 12V/2.5A (from memory) and the battery pack I'm using is classical LiIon 3x18650 cells that has a limiter circuit of 8.5A (they can go higher of course as these cells have extremely low impedance, but you *want* the limiter) and I also have a switch on my design to select either battery or external power supply that as a limiter at 4.5A. This is plenty of current to feed the Boom, the internal power supply has a bank of large capacitors to absorb short peaks

[chill]

Philippe started this thread several years ago, and I discovered it a couple of years after that. Philippe sent me a bare PCB, but sourcing and soldering the surface-mount components was just too much of a task for me. So then he had some fully populated PCBs made and he sent me one to test. Yet again I let him down - he provided a 3D-printable box, but my printer was (still is) in need of fettling and I could never get a good print, so the PCB lay unused for a year or two.

Fast forward a couple of years and I know a bit more about how to get better prints from my 3D printer. I've also had a lot more practice with AutoCAD, which has allowed me to tweak Philippe's original box to make it print better on my printer (rounded corners!), and to incorporate a couple of specific features that suit my own purposes.

So now, finally, I'm up and running with this little marvel. It works beautifully. It sits in the recess at the back of the Boom, and provides a pass-through for the DC supply, which also keeps a 3x18650 cell pack charged, so that when the DC supply is removed the battery pack takes over.

I have a couple of Booms that will benefit from this: The first one lives in the kitchen where I use wired ethernet (the reason for one of the tweaks to Philippe's box design), which I can now take out into the back garden. The second is one that I use in my camper van, where the 12V DC requirement is perfect. I used to use a 12V extension cable, but now I can use it completely without wires.

[ALW]

I was going to build a battery pack, then...

...I remembered I had one of these (https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1).

Sadly no longer available, but essentially a 12Ah battery pack, with built-in 19 / 16 / 12V outputs. I don't use it for it's original purpose anymore, so made a lead to connect it to the Boom. It works superbly, giving pretty much all day use in the garden, even at high volumes. I started playing at around 10am this morning and the battery died just after 5pm.

It's really amazing how fantastic this thing sounds and how loud it can go, with apparent ease, I just need to fix the display, there's not a hope of reading it outside currently!

Andy.

[Man in a van]

all day use in the garden, even at high volumes. I started playing at around 10am this morning and the battery died just after 5pm.

Other ways to annoy your neighbours during lockdown are available.......

ronnie

[philippe_44]

I've given a full upgrade to another one of my Boom (Display, Speakers, Wifi, Coating) so I decided to add my battery extension. I've used the modified casing made by @chill and I have to say that it's a much better fit than mine, it looks much more "integrated" with the rest of the Boom

It's unfortunate that the Boom does not have a "low power" or "off" mode as the battery can only last for a limited amount of time even with dark display, but still, that makes it the best portable audio device IMHO, even after all these years (just after SqueezeAMP-based devices of course )