Collective Custom Boombox Project?

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Superduper

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Staff member
Hey Trippy, can you tig weld? For thin material and best apperance, that would be ideal. However, we aren't building a car so we don't have to weld like structural considerations are paramount. In fact, I think a few strategically placed tack welds would suffice. First,t he chassis/cage should be welded or we can just secure with fasteners. However, small C,U or L pieces should ideally be tacked along the panels to make them more rigid and minimize bowing. Securing those with fasteners might not be as good. This would only be necessary if the material is thin. Not sure how thick it needs to be... maybe Joe is the best judge of that since he has the stuff in hand and can tell better than I.

Reli, design wise, although it would be nice if this has the sexy design of say a ferrari or lambo if this were a car, keep in mind that we are only talking about a handful of boxes here, not 50,000, so that's a reality and compromise that we have to consider. But as you say, in my mind, I dismissed the option of just a square rectangular flat box. However, a few raised areas and depressions I believe is all we need to add interest, and this can be doable. Also, lets not get too carried away design wise. Again, remember that we are only talking a handful of boxes and aren't mass producing. Anyhow, I don't want to go to the other site and introduce this idea there because then I would have to monitor both sites for reaction and I'm barely here now, lol. So we are limited to easy to obtain off the shelf parts. That strobe thing you want, remember that Sony probably had those drivers custom made. The more custom made stuff we add to this, the higher the cost. In fact, I'm going to say that by far, the highest costs for this project is going to be those things we have to professionally commission and it's just not practical cost wise to do it for a run of a dozen or two. A huge center sub might seem like a good idea but we would lose a lot of real estate in the center to place all the features we want. I don't want top controls. Due to the large size, front controls only, otherwise on the table, you might need a chair or ladder just to see the top of the box. Anyhow, maybe back or side subs (ala kaboom might be an option?). In other words, the effect without the visual feature.

Any artists here that can help with rendering a photoshop visual on what this might look like? I'm going to try to fit most of the display into a top tuner sized acrylic panel display, maybe about 24" x 4" or so. If someone knows how to etch a square line around the edge around 1/2" from edge of an acrylic window, this will light up nicely with side illumination. Maybe even add some lettering (the Boomboxery project?). Inside this window will be the digital tuner LCD display, spectrum analyzer, MP3 LCD, CD control LCD, and maybe along the bottom edge, a LED VU meter. Acrylic etching can be done with a hobby CNC laser engraving. The top 1/4th of the front can be raised proud by maybe 1/4". Maybe just the acrylic panel ala M9994? Then we need to reserve enough room in the center for the front loading CD player, controls, etc. Otherwise, design wise, the lower part of the center is open to suggestions. Once complete, all of the internals will be revealed so anyone else can duplicate this into their own cabinet. Well, to a point. I think I will have to rig up a custom power supply with various rails to accommodate all these modules with differing power requirements. This might be challenging since this could lead to ground loop noise issues. Also, until all these parts are integrated, there is no telling what the final S/N ratio is going to be. Since we aren't designing this from scratch, not for such a small run,and these "modules" are all going to be made in china, it's probably going to mean that there is going to be some less than perfect S/N issues. The only question is whether it's going to be something we can live with.
 

Superduper

Moderator
Staff member
Hmm, just a thought. Any car bodywork guys out there? If so, can a simple sheetmetal cabinet be worked to make them look nice? But with the high cost of car body work, that's probably out of the question.
 

Reli

Boomus Fidelis
Are you thinking of just a flat acrylic sheet for the tuner window, with some etching on it? I was thinking about some perpendicular extensions behind that sheet, which would insert into the boombox and serve as a brace for the window as well as a possible mounting point for some lights. Because if you mount lights to the edge of a frosted acrylic sheet, the light will carry through the rest of it.

See this post to see what I mean:

https://boomboxery.com/forum/index.php/topic/20421-super-pimp-leds/

This would, of course, require some extra thought and labor, but if we got it right, it would look sweet. Perhaps an acrylic company could cut something to our specs.
 

BoomboxLover48

Boomus Fidelis
It is a great thought!

If one is looking for the automotive console area finish we need so many experts for each component.

The question is what level of aesthetics we are looking for.

I love that mahogany wood sidings idea from Ira. Those two sides alone can give lots of structural integrity if it designed well and can have so many shades based on the stain and wood coating over it. We can go from clear piano finish to dull matte.

Is it possible to have glass touch screen controls. Just a thought! It is easy for me to say that but Norm will only know the difficulty level based on technology and economics.

Now they have glass touch screens with LED that light up only when you activate an exterior door or main power switch.

Here are some nice designs.....
 

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Superduper

Moderator
Staff member
Reli said:
Are you thinking of just a flat acrylic sheet for the tuner window, with some etching on it? I was thinking about some perpendicular extensions behind that sheet, which would insert into the boombox and serve as a brace for the window as well as a possible mounting point for some lights. Because if you mount lights to the edge of a frosted acrylic sheet, the light will carry through the rest of it.
See this post to see what I mean:
https://boomboxery.com/forum/index.php/topic/20421-super-pimp-leds/
Reli, I was thinking more along the lines of something like this: [ebay]121914872109[/ebay]
Of course instead of iron man lighting up, I would have a rectangular border and some text for branding, module caption (such as tuner, mp3, cd-player, etc. This panel would be inside the cabinet face and side lit which as we know, only lights up the engraved areas. External to this would be a flat protective panel like the M9994. Those little thumbscrews are very cool too.


BoomboxLover48 said:
I love that mahogany wood sidings idea from Ira. Those two sides alone can give lots of structural integrity if it designed well and can have so many shades based on the stain and wood coating over it. We can go from clear piano finish to dull matte.
Is it possible to have glass touch screen controls. Just a thought! It is easy for me to say that but Norm will only know the difficulty level based on technology and economics.
Now they have glass touch screens with LED that light up only when you activate an exterior door or main power switch.
#1, if done, they are all going to be the same. Any customizing whether finish or what not will have to be done by the individual owner.
#2, No touch screen. We are only making a small run, not 50,000 units. And as I said, we are using off the shelf modules and integrating them.
#3, Yes, nowadays they have touch screen and all kinds of features. BUT we are only making a tiny tiny tiny run, and integrating OFF THE SHELF modules. In order to integrated a touch screen feature, that means the entire boombox will be MPU controlled, and custom programmed to handle all the controls. And since there is no way to integrate the various off the shelf modules (all built from different manufacturers) with a central processor control without extensive modification to every module, that means the only practical way to build such a thing would be to:
  1. A fresh from scratch design from CD Rom controller to Tuner to MP3 to Aux-In, to Tone Controls, etc.and then design all the solid state switching to handle all the switching and program an MPU to control all those features and end up with a boombox that costs countless hours of design time and huge $$$$$ PCB manufacture costs for a handful of boards.
  2. Buy an already made unit with all the fancy features you already want so as not to have to invest the money to engineer a new one, strip out the internals and then chuck the engineered cabinet, and stick them all into a new custom designed cabinet in which case it's exactly the same as the one you bought except that won't have the manual bass/treble and volume controls anymore, will rely on a menu system to adjust whatever you want, etc.
Not saying a touch panel is no good. Just saying highly impractical to make a few units like this. Also, I like to have a knob when I want to adjust the volume and not have to rely on a menu control for things like that. And after all, isn't that one of the greatest features about our old classics? Oh how I miss being able to reach onto the dash of my old classic car and adjust the radio by feel without looking, something that is impossible these days.
 

Lasonic TRC-920

Moderator
Yes Norm, If you're talking 10 to 20 boxes, I could handle the assembly process, just not 100 :-O

I have designed a few radio's for a possible one off customization,

I can have a look at your list of options / requirements and try to draw something up.
 

Lasonic TRC-920

Moderator
Norm, I think what you're touching on here is what I personally want out of a project like this.

Old School design, old school tactile feel, modern reliability.

Question:
Would you consider a rechargeable battery?
 

Superduper

Moderator
Staff member
Reli, check this out:
[video=youtube;I_FmlorBGqg]http://www.youtube.com/watch?v=I_FmlorBGqg[/video]


Lasonic TRC-920 said:
Norm, I think what you're touching on here is what I personally want out of a project like this.
Question:
Would you consider a rechargeable battery?
If you get D cell rechargeables, then they should work seamlessly. However, if you are talking about an internal gel cell or something, then that means instead of using something available at any home depot, walmart or target, you would have to design to accommodate the specific battery you wish to use. What about the charger, will that be internal too? Because when recharging modern cells, you really need a smart charger for life and safety reasons. However, it should be easy enough to install external binding posts so you can use any external rechargeable, even car battery size if desired. I think that would be more desirable than to build in a non-standard battery that might be problematic in terms of future when they wear out. Actually, an external battery connection might even be desirable since #1 you can use large high capacity cells since I expect this to be quite a hog and #2, I really don't see a unit this large being used much on batteries anyhow. Who runs their mega boomboxes on batteries anyway? Be honest, I bet almost everyone plugs in their large boomboxes for 95% of their listening.
 

caution

Member (SA)
The C-100F trims I made are 26 gauge (18-19 mils) brushed T304 stainless. It was the thinnest the laser cutting shop had and as far as I can tell it's the thinnest brushed stainless anyone carries. It's thin enough to use as trim but tough enough to avoid denting. It's also the thickest stainless you can use on about any bending brake, if that comes into play.

For the lettering, silkscreening would work best but dry transfer works just as well, it just takes a lot of time to apply.
 

Superduper

Moderator
Staff member
caution said:
The C-100F trims I made are 26 gauge (18-19 mils) brushed T304 stainless. It was the thinnest the laser cutting shop had and as far as I can tell it's the thinnest brushed stainless anyone carries. It's thin enough to use as trim but tough enough to avoid denting. It's also the thickest stainless you can use on about any bending brake, if that comes into play.

For the lettering, silkscreening would work best but dry transfer works just as well, it just takes a lot of time to apply.
Wasn't there a guy that did a 777 with some kind of transfer? I think he told the company what he wanted and they did the design setup. That would be great except I think he's in the UK. :-/ :sad:
 

Lasonic TRC-920

Moderator
Superduper said:
Reli, check this out:
[video=youtube;I_FmlorBGqg]http://www.youtube.com/watch?v=I_FmlorBGqg[/video]



If you get D cell rechargeables, then they should work seamlessly. However, if you are talking about an internal gel cell or something, then that means instead of using something available at any home depot, walmart or target, you would have to design to accommodate the specific battery you wish to use. What about the charger, will that be internal too? Because when recharging modern cells, you really need a smart charger for life and safety reasons. However, it should be easy enough to install external binding posts so you can use any external rechargeable, even car battery size if desired. I think that would be more desirable than to build in a non-standard battery that might be problematic in terms of future when they wear out. Actually, an external battery connection might even be desirable since #1 you can use large high capacity cells since I expect this to be quite a hog and #2, I really don't see a unit this large being used much on batteries anyhow. Who runs their mega boomboxes on batteries anyway? Be honest, I bet almost everyone plugs in their large boomboxes for 95% of their listening.
I always use my Mega Boxes on batteries (J1, Helix HX4700, Wheely) and they are PIGS regular D cells, would be nice to have a built in solution that you could just plug into the wall and charge.
 

Reli

Boomus Fidelis
The issue with D-cell NiMH rehargables like Tenergy, Energizer etc. is that they usually only start at 1.2V when new. So you don't get as much power from your boombox. The only way to get a full 1.5V is to buy special NiZn batteries (Nickel-Zinc), but they are only available in AA size, meaning you'd have to put them in a D-size adapter, which does work but wouldn't last very long because a AA doesn't have nearly as many miliwatt hours as a real D-cell does.
 

Superduper

Moderator
Staff member
Hey Chris, I hear ya. Maybe that's worth investigating further, but remember, I'm thinking to create a run that are all identical. That means that what we do for one should be done to all. And this battery option will not be cheap. Firstly, there is the option to run the system at 12, 18, 22... up to 26 volts. The higher the voltage, the greater the power to the speakers. HOWEVER, it takes a lot of current and run in series, will provide higher power but lower life. Doubling the cells (say, 24 D cells instead of 12) would mean 18v at 20kmA which should offer double the battery life. Now, if we were to make a built in rechargeable, we would be building the pack using the exact same NiMH battery cells anyhow except with solder tabs instead of button tops that are present on individual cells. The difference is that instead of using individual cells, we would solder all the cells together and shrink wrap them into a "pack". However, this means that they can't be charged individually and needs to be charged all together as 1 unit. Then the charger itself needs to be very robust. If a linear charger, then it's going to need a cinder block sized transformer to charge up a 24 cell pack of D's. Are we going to build that into the unit? Of course a switched power supply can be considered but I don't know if such a supply will introduce noise or not. It also is not nearly as easy to build as a traditional linear supply so I would prefer to just go that route.... simpler and don't want to over complicate a project that hasn't even gotten off the ground yet. Traditional supplies are more costly to build at lower volume but simpler. Switching supplies are far far cheaper when manufactured in high volumes since there is no huge transformer like the linear supplies, but is far more complex so more costly for small runs due to engineering. Switching supplies are also less reliable. However I wonder if old computer power supplies (the ones in the performated sheetmetal boxes) might be an option. I know old computers are put out on curbs all the time since they are pretty much obsolete. But they have 5v and 12v rails which might be a terrific option. Would need to test them to see if they can handle the power of the amps though. Anybody have a source for say ~20 identical ones in the 350w range?

As for charging the internal cells, plug in boombox and forget, that's not possible unless you get a smart charger. Otherwise there could be safety issues involved from overcharging which reduces battery life and fire from overheating batteries. In truth, except for lead acid batteries, NiMH and Lithium shouldn't really be placed on chargers all the time anyhow. And with the size of these packs, there is no way to charge the cells and operate the boombox at the same time since a single power supply likely can't supply enough juice to do both chores at the same time unless oversized.... again increasing costs and weight. Or you can have 1 supply for the boombox and another for the charger. But then I wonder if the charging process will introduce noise to an operating boombox when both are within the same unit. I dunno, this requires more thought.

Reli... 1.2v vs 1.5v is no problem. All that means is we use more cells if we want the same voltage. In other words, 10 cells to get 12v instead of 8 cells. The more important thing with NiMH vs Alkaline is that there is less voltage sag during use, due to lower internal cell resistance, and longer run time until they die. Alkalines turn to gradually drop in voltage whereas NiMH would exhaust almost all of their power before suddenly dropping off. With Alkalines, the voltage might drop to a point that is unusable while still having maybe 1/3 to 1/2 life left for other less demanding chores.
 

trippy1313

Member (SA)
Superduper said:
Hmm, just a thought. Any car bodywork guys out there? If so, can a simple sheetmetal cabinet be worked to make them look nice? But with the high cost of car body work, that's probably out of the question.
I'm actually a bodyman. Lol. I don't do too much fabricating, but I do a lot of metal straightening, cutting, and welding. Always trying with little to no bondo/filler.

Regarding welding, I haven't done much Tig welding, we have one but it never gets used. Although I'd love to practice with it if you think that's the way to go. I am however, without a big head, the best mig welder in our shop.
 
Superduper said:
Hey Chris, I hear ya. Maybe that's worth investigating further, but remember, I'm thinking to create a run that are all identical. That means that what we do for one should be done to all. And this battery option will not be cheap. Firstly, there is the option to run the system at 12, 18, 22... up to 26 volts. The higher the voltage, the greater the power to the speakers. HOWEVER, it takes a lot of current and run in series, will provide higher power but lower life. Doubling the cells (say, 24 D cells instead of 12) would mean 18v at 20kmA which should offer double the battery life. Now, if we were to make a built in rechargeable, we would be building the pack using the exact same NiMH battery cells anyhow except with solder tabs instead of button tops that are present on individual cells. The difference is that instead of using individual cells, we would solder all the cells together and shrink wrap them into a "pack". However, this means that they can't be charged individually and needs to be charged all together as 1 unit. Then the charger itself needs to be very robust. If a linear charger, then it's going to need a cinder block sized transformer to charge up a 24 cell pack of D's. Are we going to build that into the unit? Of course a switched power supply can be considered but I don't know if such a supply will introduce noise or not. It also is not nearly as easy to build as a traditional linear supply so I would prefer to just go that route.... simpler and don't want to over complicate a project that hasn't even gotten off the ground yet. Traditional supplies are more costly to build at lower volume but simpler. Switching supplies are far far cheaper when manufactured in high volumes since there is no huge transformer like the linear supplies, but is far more complex so more costly for small runs due to engineering. Switching supplies are also less reliable. However I wonder if old computer power supplies (the ones in the performated sheetmetal boxes) might be an option. I know old computers are put out on curbs all the time since they are pretty much obsolete. But they have 5v and 12v rails which might be a terrific option. Would need to test them to see if they can handle the power of the amps though. Anybody have a source for say ~20 identical ones in the 350w range?

As for charging the internal cells, plug in boombox and forget, that's not possible unless you get a smart charger. Otherwise there could be safety issues involved from overcharging which reduces battery life and fire from overheating batteries. In truth, except for lead acid batteries, NiMH and Lithium shouldn't really be placed on chargers all the time anyhow. And with the size of these packs, there is no way to charge the cells and operate the boombox at the same time since a single power supply likely can't supply enough juice to do both chores at the same time unless oversized.... again increasing costs and weight. Or you can have 1 supply for the boombox and another for the charger. But then I wonder if the charging process will introduce noise to an operating boombox when both are within the same unit. I dunno, this requires more thought.

Reli... 1.2v vs 1.5v is no problem. All that means is we use more cells if we want the same voltage. In other words, 10 cells to get 12v instead of 8 cells. The more important thing with NiMH vs Alkaline is that there is less voltage sag during use, due to lower internal cell resistance, and longer run time until they die. Alkalines turn to gradually drop in voltage whereas NiMH would exhaust almost all of their power before suddenly dropping off. With Alkalines, the voltage might drop to a point that is unusable while still having maybe 1/3 to 1/2 life left for other less demanding chores.
I know I'm stating the obvious here but I can personally vouch for SLA batteries. You want a simple and reliable 24v power source? - 2 X 12v SLA batteries and a 24v automatic charger - just plug in and forget. SLA batteries love continual top ups which should suit this size box that will spend most of its time indoors.

With the various D class amps I've tested, SLA batteries provide a nice,safe & clean power source. Whilst on charge, no noise is feed to the amp. SLA batteries are heavy but lighter than 20 D cells!! :-)

So no internal transformer needed, just a simple 2.5mm charge jack on the box and you're done.

James.... :-)
 

caution

Member (SA)
Superduper said:
Wasn't there a guy that did a 777 with some kind of transfer? I think he told the company what he wanted and they did the design setup. That would be great except I think he's in the UK. :-/ :sad:
Yeah, squeezebox had some dry transfers made, the ink has a pressure-sensitive adhesive that will prefer the target surface over the backing paper once pressed, although not always. You have to be careful in its application, especially when you're dealing with fine pieces of text or lines. The one I did fell just above the minimum recommended line weight of 0.5 points (1/144", about 7 mils) to ensure intact separation, and it does get challenging, but if you go very slow it works out beautifully.

As it turned out I was in Minnesota when I had mine made, so I got to visit the shop in a side building on his property, been doing it for years. He'll store your screens for 3 years. He showed me how resistant it gets by scraping some with a knife, and squeezebox confirmed that by taking a knife to one of his. It's meant to last years. He's at drytransfer.com, but his site sort of stinks now, it was better last year.

Standard silkscreen may almost work out for cost for ten, there are shops all over that do that, but there are possible drawbacks with that too if the ink isn't as robust for small elements, and if you saw an error you made in the original or the shop made a slight goof, you'd have no way of your own to (easily) fix it.
 

Reli

Boomus Fidelis
Superduper said:
Reli, check this out

That does look good.....Kind of the same effect as painted numerals on classic tuner dials, but this time it isn't paint.
 

Superduper

Moderator
Staff member
Reli said:
That does look good.....Kind of the same effect as painted numerals on classic tuner dials, but this time it isn't paint.
Laser etching is ultra cool. I purchased some custom made dog tags. You buy the tag (tiny things as it were) and insert it into this machine. You then get to watch as the machine takes this piece of coated metal as the laser "writes" the text onto the part. Ultra fine text can be done. The tags I bought had 4 lines of text of approximately 20 characters per line, all in a tag about 3/4" x 1-1/4".


jimmyjimmy19702010 said:
I know I'm stating the obvious here buy I can personally vouch for SLA batteries. You want a simple and reliable 24v power source? - 2 X 12v SLA batteries and a 24v automatic charger - just plug in and forget. SLA batteries love continual top ups which should suit this size box that will spend most of its time indoors.

With the various D class amps I've tested, SLA batteries provide a nice,safe & clean power source. Whilst on charge, no noise is feed to the amp. SLA batteries are heavy but lighter than 20 D cells!! :-)

So no internal transformer needed, just a simple 2.5mm charge jack on the box and you're done.

James.... :-)
As I said in my long post, lead acid batteries like to be constantly charged but I was thinking more NiMH instead of lead acid.

James, a couple questions:

a. how much does 2 SLA batteries weigh? About 5 or 6 pounds each? Since SLA batteries are chunky as opposed to D cells which can all be spread flat in rows, SLA option mean a beefier chassis to handle the more concentrated weight. Also, that means they are better suited for semi permanent installation and probably aren't designed for regular removal as they are probably connected with 1/4" tabs?

b. How many volts is the charger? I'm thinking that they are 12 volts? If 12 volts, then it can't be used to charge the system and run at the same time since it poses some issues. Firstly, the dual batteries would ideally be run in series (24 volts) for the amp, and center tapped for everything else. A 12v charger would need the batteries to be connected in parallel during charge. Now, if the charger is 24 volts, then that can charge the batteries in series but the circuitry probably should not be operated in this manner without further testing since I'm not sure what will happen with the circuits tapped from center of the batteries during a charge. Additionally, the amps I have in mind are close to their max rating with the batteries at 24v. To charge a 24v system, the charge voltage would have to be higher than 24v. Not knowing anything about the chargers themselves, I would not trust the electronics to be run in this configuration. When SLA batteries reach near full charge, the charging voltages goes very very high. In fact, 12v lead acid batteries I've seen can reach charging voltages of up to 18volts when fully charged. I'm sure that a 24v charger will go much higher than 24v's when the batteries start to resist the charge. That the charger is automatic also means that it pulses.

Lastly, going back to one original goal which is to be able to make all the boomboxes the same. There is good reason for this. First is practicality. If we got 5 or 10 or 15 participants wanting boxes, and each wants different things, in other words, build to suit, then we are instead of building 15 of one design, we are building 15 separate boxes, each individualized and each with a new separate set of challenges. Each will have to have unique tweaks worked out and trust me there will always be issues that need resolving. In the end, some will get finished, some will be a never ending source of issues, some owners will be unhappy, etc. etc. Like I said, I think any customization to suit should be done by the individual owner of their own example and any participants should be familiar enough with how the thing is setup to be able to modify to their hearts content. I know I would like the ability to install standard readily available batteries without having to have them permently inside the boombox for a couple reasons. #1, it would be lighter, #2, I personally would likely never use that feature, and #3, there is less risk that I forget the batteries are in there and they eventually leak. Now there's no reason why anyone who gets one of these couldn't simply rig up some SLA batteries internally and connect to an external jack for a charger. But there's no reason to make them all like that unless that's what every participant wants. Anyhow, that's my feeling.

I know SLA they are a cheaper option than getting NiMH but NiMH does have it's advantages. First lead acid batteries do not like to be deep cycled. They lose life very quickly when run like this (how much depends upon the exact battery). Also once discharged, they better be recharged like RIGHT NOW or they might go dead forever. Lead acid batteries begin sulfating the moment charge is level is low. Then there is capacity. A 7ah SLA battery is a common size but it's still fairly large. NiMH batteries with 10,000mAH is common (10AH). They have no memory effect and can be charge hundreds of times, deep cycle is no problem at all so run em until they are dead, not an issue. Then there is weight. I have 7ah batteries in all my computer UPS's. They are not light and I'm not sure at all that they are lighter than 10 D cells. While I wouldn't bet my life on it, I'm pretty sure that certainly, a 10ah-12V SLA option has got to be heavier than 10 D cells.

On a side note, has anyone actually tried out the NiMH D cells commonly available on eBay? I wonder how well they do in boomboxes. Standard power tool battery packs are constructed using only sub-C cells and they last a very long time and have tremendous power. If the D cells are proportionally higher in capacity, then they should work out very very well. But in truth, I'm only going by advertised numbers and not via any personal experience.
 
A 7.2 aH SLA battery weighs 2 kilos. An equivalent sized Lithium Ion battery weighs 1 kilo so half the weight but 10 times the price. I was thinking of going with a smaller sized 4.2 aH SLA (1.5 kilos) in a 24v setup as the runtime of the 7.2 aH deep cycle SLAs I use is really over the top.

I charge my single 12v battery with a Jaycar 12v automatic 600ma charger. With this setup, I am able to run the amp at high volumes whilst charging. According to the built in digital volt meter, the battery voltage continues to rise with the charger connected and the BT receiver and amp operating.
View attachment 25837
The charger charges the battery up to 14 volts but no higher no matter how long it's connected. The charger unit is completely cold when the battery is fully charged. The amp can cope with 14.4 volts so no issues there. I've used 4 different brands of battery with identical results.

The SLA batteries can be spread out , laid on their side etc so to offer a low centre of gravity.

I've run the amp at 3/4 volume with BT & the volt meter running + charged an IPhone over a 8 hour period with the battery voltage only dropping to 12.3 volts at the end - that's good enough for me. 12.3v is actually the lowest I've ever had a battery go before charging.

But I understand if you want to stick with the old school D cell format.

James.... :-)
 
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