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Old 9th April 2013, 11:29 AM   #3671
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Quote:
Originally Posted by stevodude View Post
Ooooo

$107.89 free shipping to australia too!

yes it's 3.2v 15ah, but it's 4 pieces per lot ie $26.97 each piece

wonder how much they weigh compared to 2 x 12v 7ah sla's?

I really want to make my boominator a tad lighter.

S.
Each cell is ~480g.

Besides this you probably also will want a battery management system and an expensive charger.
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Old 9th April 2013, 11:32 AM   #3672
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Quote:
Originally Posted by PressureFM View Post
Each cell is ~480g.

Besides this you probably also will want a battery management system and an expensive charger.

I think that an old laptop charger would do the job, we have boxes full of them at work........

BJ
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Old 9th April 2013, 12:11 PM   #3673
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LiFePO4 weigh 40% of SLAs for the same nominal capacity.

Nominal capacity in LiFePO4s is actual capacity. You do not need to retain 10-15% capacity in the cells to avoid battery death as in SLAs. Usually capacity LiFePO4 are also rated at a much higher discharge rate than SLAs. Typically for our use LiFePO4s will have 110% of nominal capacity.

In total a LiFePO4 will have an actual capacity for our use that is 30% more than an SLA if both have the same nominal capacity.

LiFePO4 cells needs battery management or specialized charger.

With battery management (as for example the LiFePO4s in SLA standard sized I posted previously have battery management built in, as do all other finished packs) you don't need a special charger. You can use an SLA charger but capacity will drop to about 85% of nominal (which will still be equal to an SLA since LiFePO4s don't not need to retain 10-15% capacity in the cells).

You can get dirt cheap LiFePO4 specific chargers that work with any pack which includes battery management. Without battery management as in clamped cells, you need an expensive specialized charger for that exact purpose.

Please note that you cannot under circumstances use a li-ion battery charger!

Last edited by Saturnus; 9th April 2013 at 12:18 PM.
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Old 9th April 2013, 12:20 PM   #3674
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Ah OK

My ingnorance has been exposed, better than setting fire to my boominator tho.....

BJ
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Old 10th April 2013, 09:20 PM   #3675
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Default gluing drivers to baffles

I've had a productive evening, drivers and grills are now glued to the baffles...
It went more smoothly than I thought.......

Here are a few photos of the prep.... baffles primed with boat primer.... started work on the control panel, inputs and throughput.....

prepping the baffle ready for gluing and they type of sealant I have used.... (The small screw to the right of the sealant is what I have used to secure the driver whilst the sealant sets.......
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Old 10th April 2013, 09:44 PM   #3676
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Default more photos of tonights build

OK

  • apply sealant around the edge of hole in baffle
  • place grill so that sealant squishes through the holes
  • apply sealant around the driver seal
  • carefully position driver over the grill
  • screw the driver to the baffle through holes, working diagonally and screwing down a little at a time (the screws do not have to go in straight so it is easy to find a suitable hole in the grill to screw through)
  • you can see the sealant squish out at the sides
  • apply more sealant to increase the surface area so that the sealant glues the driver to the baffle better


JOB DONE

(tweeters next and finish off switches, controls and the voltmeter)


BJ

ps ..... How can I upload the photos in better quality?
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Old 11th April 2013, 07:19 PM   #3677
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Default dry build

Damn

The woodyard cut my panels slightly inaccurately, the internal baffles are slightly too long and it makes my electronics compartment only 60mm wide instead of 67mm. The batteries won't fit if I don't fix it. I think I'm going to route an 12mm wide by 3.5mm deep slot in the electronics compartments walls to slot the baffle in, it'll be a stronger joint for it anyway.

Also, my magnets are about 2mm short of the center baffle, I think that I tightened the woofers down too much last night when gluing and compressed the front gasket too much, I just wanted to be sure that the woofer was holding the grill tightly enough..... I don't think that chemical metal will successfully bridge such a large gap....... any suggestions for shim material would be most welcome......

BJ
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Old 11th April 2013, 08:00 PM   #3678
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You could just use more although that'd be a fairly expensive solution. And you'd have to do it in 2 runs, letting one thick layer harden up first.

You can host pictures on another site and link them here.

And yeah, the screws are only really guides while the sealant sets.

Last edited by Saturnus; 11th April 2013 at 08:04 PM.
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Old 11th April 2013, 09:13 PM   #3679
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Quote:
Originally Posted by Saturnus View Post
You could just use more although that'd be a fairly expensive solution. And you'd have to do it in 2 runs, letting one thick layer harden up first.

You can host pictures on another site and link them here.

And yeah, the screws are only really guides while the sealant sets.
Thanks, I've just been trawling through the forum, I'm not the first person to screw the drivers in too tight, I'm going to try to loosen the screws but I am a bit concerned that to do that now may put the silicone sealer under tension and reduce its strength.. Still, once it is all glued up together some of that tension should be releived anyway........

Its a bit of a drag having to get the router out again, still, gotta get the middle compartment right, otherwise I'm screwed and will have no choice but to go down the LiFePo4 route which I have already decided not to.......

On that note, something has been playing on my mind. I want to be able to charge the SLA batteries by solar or 12v outboard charger, if I just wire in a charger socket in parallel with the solar panels, will the shottky diode stop the current from the charger damaging the solar panels or do I need to put in something more fancy to do that?

Anyhow

I'm really enjoying this build and can't wait to hear it, I'm going completely on trust here because everything has been so well thought out and there wouldn't be so many boominators built if they weren't really that good.......


BJ
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Old 12th April 2013, 02:15 PM   #3680
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Wouldn't worry about it guys. You can always get a piece of wood that fits exactly between them, and glue it/epoxy in place.
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