Hi, hope someone can help, I'm over my head on this one.
I'm wanting to build a battery powered system where 99% the time the battery will be hooked up to a trickle charger at home, but for the other 1% of the time I'll want to be having modest outdoor parties playing as long and loud as I can off a battery (or two?)
Speakers and tapped horns are about 100db, and amp/dsp/dac is a single one box class-D job from Mosconi with total output of about 450W/40amp.
My first question is to do with batteries...I'm pretty clueless, should I be looking at SLA or lithium iron? What would give me longest play time, do I just by as big an Ah rating as I can afford, or would it make sense to buy more than one battery?
Thanks for the help,
B
I'm wanting to build a battery powered system where 99% the time the battery will be hooked up to a trickle charger at home, but for the other 1% of the time I'll want to be having modest outdoor parties playing as long and loud as I can off a battery (or two?)
Speakers and tapped horns are about 100db, and amp/dsp/dac is a single one box class-D job from Mosconi with total output of about 450W/40amp.
My first question is to do with batteries...I'm pretty clueless, should I be looking at SLA or lithium iron? What would give me longest play time, do I just by as big an Ah rating as I can afford, or would it make sense to buy more than one battery?
Thanks for the help,
B
You will get the longest play time with the largest Ah rating be it Lead Acid or Lithium Ion.
Matt Lead Acid motorcycle batteries are compact and useful.
Matt Lead Acid motorcycle batteries are compact and useful.
It depends somewhat on the voltage requirements. Lead-acid comes in convenient 2 volt increments; lithium chemistry around 3.6 volts per cell, nickel is about 1.2V. Lead-acid works well for 12V applications; lithium not so much, since 3 cells will float at about 12V, but rapidly drop to around 11V. 4 cells will float at over 16V, which is outside the specs of some things, though I suspect most will survive. There's a case to be made for going to higher battery voltages, and using a switching regulator to provide the nominal 12V. 18V cordless tool battery packs, for example. Or a battery scrounged from a scrapped Prius or other hybrid.
But, anyway, deep-cycle sealed-lead-acid has an awful lot going for it. 12V batteries are commonly used for computer UPS, backup power for emergency lighting and alarms, ride-on toys, boats, RVs and electric vehicles. You can probably count on 3 to 5 years use if you don't run it flat too often. When deciding on capacity, remember that musical content has an average power that's a fraction of the peak power; a 100 watt amp that's on the verge of clipping may only be drawing an average power of 10 watts. It's better to err on the large side with battery capacity, though. An undersized battery will be less efficient, and wear out much faster.
As to where to buy such batteries... local general electronic parts dealers (the sort that sell a bit of everthing but cater more to business customers than consumers) usually have a selection at fair prices (and you don't pay shipping). Or, Amazon or Digikey and the like, if shipping rates are reasonable.
But, anyway, deep-cycle sealed-lead-acid has an awful lot going for it. 12V batteries are commonly used for computer UPS, backup power for emergency lighting and alarms, ride-on toys, boats, RVs and electric vehicles. You can probably count on 3 to 5 years use if you don't run it flat too often. When deciding on capacity, remember that musical content has an average power that's a fraction of the peak power; a 100 watt amp that's on the verge of clipping may only be drawing an average power of 10 watts. It's better to err on the large side with battery capacity, though. An undersized battery will be less efficient, and wear out much faster.
As to where to buy such batteries... local general electronic parts dealers (the sort that sell a bit of everthing but cater more to business customers than consumers) usually have a selection at fair prices (and you don't pay shipping). Or, Amazon or Digikey and the like, if shipping rates are reasonable.
Whatever you buy, make sure its a deep-cycle one.
I use 6v 10Ah batteries in series - a pair were cheaper than a single 12v @10Ah.
If you intend to use a number of batteries in parallel, you'll need some diodes to stop them trying to charge each other.
I'd also recommend permanently wiring a voltmeter on there, so you've got an estimate of how your batteries are doing - 14v is fine, 13v is on its way out, 11v is time to recharge.
I'd recommend against car/motorbike batteries. They're not designed for deep-cycle duties, more like occasional high-current bursts.
Chris
I use 6v 10Ah batteries in series - a pair were cheaper than a single 12v @10Ah.
If you intend to use a number of batteries in parallel, you'll need some diodes to stop them trying to charge each other.
I'd also recommend permanently wiring a voltmeter on there, so you've got an estimate of how your batteries are doing - 14v is fine, 13v is on its way out, 11v is time to recharge.
I'd recommend against car/motorbike batteries. They're not designed for deep-cycle duties, more like occasional high-current bursts.
Chris
So you're using automotive amplifiers. So...no inverter questions.
You'll go broke attempting this with lithium-ion. And the mfgr specs tend to be in "equivalent amp-hour" ratings which are simply NOT real amp-hours. They are, however, very very light! I use one on my motorcycle. It's no good in the extreme cold.
I'd go with Optima deep-cycle batteries. They're around 50 amp-hours. So one will get you less than an hour if you're lucky. Figure on a 4-hour party, and get 5 or 6. With battery cases you're talking about $1000 if you shop really well. The exact details depend on how low a voltage your amp will tolerate. You can also look at larger Odyssey batteries. Both use an acid-paste in gauze, rolled or folded between foil plates like a capacitor. And they also filter the power nicely, like a capacitor.
Have you checked out the new generation of inverter-generators? The motor speed doesn't attempt to sync to the voltage compensating for current drawn, the electronics handle the regulation and the engine speed and engine power tracks wattage demand instead. Could be nice within a fan-cooled enclosure with an absorptive inlet labyrinth and an outlet labyrinth, and several good mufflers in series. You could "hybrid" and consider a no-noise battery show, but take a half-hour break every 2 hours to charge. That way you get away with half the batteries or twice the audio power. But most such chargers I've seen have their main output at 120v, not 12, so you're back to inverters.
Personally I wish I lived in the country. I'd get a military surplus diesel generator and build a truly soundproof trailer.
You'll go broke attempting this with lithium-ion. And the mfgr specs tend to be in "equivalent amp-hour" ratings which are simply NOT real amp-hours. They are, however, very very light! I use one on my motorcycle. It's no good in the extreme cold.
I'd go with Optima deep-cycle batteries. They're around 50 amp-hours. So one will get you less than an hour if you're lucky. Figure on a 4-hour party, and get 5 or 6. With battery cases you're talking about $1000 if you shop really well. The exact details depend on how low a voltage your amp will tolerate. You can also look at larger Odyssey batteries. Both use an acid-paste in gauze, rolled or folded between foil plates like a capacitor. And they also filter the power nicely, like a capacitor.
Have you checked out the new generation of inverter-generators? The motor speed doesn't attempt to sync to the voltage compensating for current drawn, the electronics handle the regulation and the engine speed and engine power tracks wattage demand instead. Could be nice within a fan-cooled enclosure with an absorptive inlet labyrinth and an outlet labyrinth, and several good mufflers in series. You could "hybrid" and consider a no-noise battery show, but take a half-hour break every 2 hours to charge. That way you get away with half the batteries or twice the audio power. But most such chargers I've seen have their main output at 120v, not 12, so you're back to inverters.
Personally I wish I lived in the country. I'd get a military surplus diesel generator and build a truly soundproof trailer.
Last edited:
Thanks guys, that given me plenty to go on.
I hadn't considered a generator but looking into it now they seem to cost no more than a large battery. Perhaps ideally I'd have two batteries and a generator that could be placed well away from the music, to charge one battery while the other was being used...
I think I'll start with one battery and a test with the speakers when to see just how long that gets me, then I can decide on more batteries to parallel, and perhaps a generator too.
Many thanks
B
I hadn't considered a generator but looking into it now they seem to cost no more than a large battery. Perhaps ideally I'd have two batteries and a generator that could be placed well away from the music, to charge one battery while the other was being used...
I think I'll start with one battery and a test with the speakers when to see just how long that gets me, then I can decide on more batteries to parallel, and perhaps a generator too.
Many thanks
B
- Status
- Not open for further replies.