Boombox Battery

Hi,

I'm currently using a 12v 8ah motorbike battery in my boombox but i think the batterys on it's last legs and I'm not getting the same performance out of it these days. Does anyone have any recommendations for a new battery. I'm using the AM6-Basic amp which can take up to 15volts i think so if anyone has tried higher voltage batteries please let me know with your recommendations.

Also want to try and stay clear of bike/ car batteries as they are designed to be constantly charge etc.

Cheers,

Jayson UK :)
 

wakibaki

Banned
2008-01-08 11:51 pm
It really depends what your budget is and what's readily available.

Lead-acid batteries like the one you have already got are fine for portable amps, but have the disadvantage that they can spill acid. You can get them in 'leisure' (jelly) types such as the Yuasa brand, but they are expensive. Both tend to be heavy.

NiCd (nicad) batteries are 1.2V each and come in standard battery sizes, they have better shelf-life than NiMh (nickel-metal-hydride) which also come as standard cells with a bigger capacity/size than NiCds but they self-discharge pretty quick, so you need to use them frequently or top them off a lot. You could run 10~12 NiCds or NiMh.

Then there are a variety of lithium cells, they run 3~3.6V, so depending on flavour you could run 4 in series, they have the best weight/charge but are the fussiest to maintain, some older flavours spontaneously caught fire when charging but this is less common now, they tend to be expensive but are popular for electric flight.

All types require care when charging, you can destroy them by overcharging at high rates, but most will tolerate continuous trickle charging.

NiCds are being phased out (I was told) but still seem to be readily available, the 'D' cell types intended for emergency lighting are probably an economic way to buy them or NiMh would get my recommendation for convenience versus utility versus cost if you can tolerate the comparatively high self-discharge.

You need a charger of some kind, the ones designed for modelling use are probably the cheapest way to go with a fast charge option and auto shut-off, although many of these are designed to run off a car battery so you need an additional 14.4V supply (CB mains adapter).

w
 

lost eden

Member
2009-09-02 10:47 am
As far as leas acid goes, Yuasa NP7-12 can be had for £15 or less, they are unspillable & can even be used in any orientation except upside down - I've been using one on its side for years.

You might also consider 12v li-ion battery packs from China like this one (no affiliation)

12V/9800mAH Portable Li-ion Rechargeable Battery Pack ! | eBay UK

More expensive, I'm dubious of whether they really hold 9800mAH, but much lighter. Can't draw as much current from them as a SLA though, so for a powerful boombox it may not be enough.
 

fraction

Member
2011-04-04 4:07 pm
I don't recommend those blue plastic wrapped li-ions, the connections are flimsy and break easily. Also the 4.8ah one I had was nowhere near the stated capacity.

I've just ordered a 6.8ah li-ion 12v cctv in a black plastic case for £15 sterling. I'll report back on how it performs.

Right now I'm using Yuasa NP7-12 like lost-eden or 10xAA batteries.
 

carlsbad64

Member
2009-10-08 9:39 pm
I don't recommend those blue plastic wrapped li-ions, the connections are flimsy and break easily. Also the 4.8ah one I had was nowhere near the stated capacity.

I've just ordered a 6.8ah li-ion 12v cctv in a black plastic case for £15 sterling. I'll report back on how it performs.

Right now I'm using Yuasa NP7-12 like lost-eden or 10xAA batteries.

which ones are you referring to? I have a bunch of cheap blue Li-ion and the majority are working fine. cobaltox and ironphos' 14500's, 18650's, and 38120S's

Your ideal solution would be 4S LifePO4. get a good cheap charger like a Turnigy Accucel 6 and wire in a balance plug (JST-XH) and a voltage monitor.

3S Li-ion is 11.1V nominal. 4S LiFe is 12.8V nominal with a much longer operational lifespan, decades.

something like these... http://www.ebike-bmsbattery.com/index.php?url=products.php?did=1&did=1
 
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Motsey

Member
2011-09-11 7:46 pm
I don't recommend those blue plastic wrapped li-ions, the connections are flimsy and break easily. Also the 4.8ah one I had was nowhere near the stated capacity.

I've just ordered a 6.8ah li-ion 12v cctv in a black plastic case for £15 sterling. I'll report back on how it performs.

Right now I'm using Yuasa NP7-12 like lost-eden or 10xAA batteries.

Hi im deciding on what battery to use on my project, I want something light so was wondering if you had any more info on the "6.8ah li-ion 12v cctv in a black plastic case"

I am going to use a lepai LP-2020A+ amp and would like to get over 10 overs of use - maybe i'll go for a 9800mah version // the battery packs are soo light compared to a SLA battery

whats your opinions on a solar power charger?
 

Motsey

Member
2011-09-11 7:46 pm
The ebay cctv battery packs are li-po batteries, not li-ion, even though they state that.

Capacity is roughly 2/3rds of the stated, and voltage is 11.1V average, not 12V.

so i guess you wouldnt recommend them then?

Whats your opinion on a battery - I would like something to run the lepai LP-2020A+ for like over 10 hours - Am I expecting too much from a cheap solution?
 

Motsey

Member
2011-09-11 7:46 pm
I know someone with Ion IPA06 Block Rocker Portable ipod PA Speaker White
The description states it can run for 12hrs on a single charge!
From my working out (rough googled formula) I can run my amp on a 12V 7am sla for only aprox 3.5hrs - thats a huge difference!
Any idea how they last so long, do they use a special battery or do they have special low power commponents?
 
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I'm not saying I wouldn't recommend them. You should just know they aren't what the claim to be, so if you're looking for 6Ah, you must buy the "9.8Ah" battery pack (it's actually 6.2Ah).

I know the Ion Block Rocker well, and let's just say that 12 hours of battery time is very much best case. 6 hours at full volume is more realistic (and full volume isn't very loud).

Your TA2020 amp will run 20 or 36 hours at maximum volume on a single 7.2Ah battery, depending on it being with 4 or 8 ohms speakers. This is the tested and measured battery lifetime from the hundreds of people that have built a clone of my Boominator, not a manufacturer claim.
 
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Motsey

Member
2011-09-11 7:46 pm
I'm not saying I wouldn't recommend them. You should just know they aren't what the claim to be, so if you're looking for 6Ah, you must buy the "9.8Ah" battery pack (it's actually 6.2Ah).

I know the Ion Block Rocker well, and let's just say that 12 hours of battery time is very much best case. 6 hours at full volume is more realistic (and full volume isn't very loud).

Your TA2020 amp will run 20 or 36 hours at maximum volume on a single 7.2Ah battery, depending on it being with 4 or 8 ohms speakers. This is the tested and measured battery lifetime from the hundreds of people that have built a clone of my Boominator, not a manufacturer claim.


wow thank you that has made my day

I googled a formula which was obviously wrong =
w / v = ahu (amp hour usage) - ah / ahu = hrs it will last

20 / 12 = 1.6 - 7 / 1.7 = 4.1hrs

I am going to definately go for a 7ah sla battery now
 
I like sealed lead-acid batteries. While they're not exactly light weight, charging is more straightforward than the Ni and Li types. Limit the charging current to about C/5 or less, and voltage to around 14 volts (see the manufacturer's data sheet for specifics). The main weakness is that they will not survive over-discharging, so an idiot-proof system should include something that will disable the power amp or otherwise remove the load once the voltage hits the danger zone (11V?). And users must be educated to treat charging like watering a house plant or feeding a pet; dead is dead.

Unless you habitually listen to music with no dynamic range (pure sine waves, Merzbow), average power consumption will be some fraction of the peak power. For a stereo 10 watt amp, I'd guess less than 1 watt. So that's roughly 100 mA, which a 7AH battery should supply for a long time (3 days?).

Some users of the Ion IPA06 at Amazon.com report over 48 hours of use on a charge. So 12 hours sounds like a conservative rating, based on playing at "full volume" (however that is defined). According to the specs at Ion, it is a sealed-lead-acid battery, the very common 12V 7AH size. Like the one that's sitting on my kitchen counter that came out of a 250VA APC UPS.
 
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Motsey

Member
2011-09-11 7:46 pm
Limit the charging current to about C/5 or less, and voltage to around 14 volts (see the manufacturer's data sheet for specifics). The main weakness is that they will not survive over-discharging, so an idiot-proof system should include something that will disable the power amp or otherwise remove the load once the voltage hits the danger zone (11V?). And users must be educated to treat charging like watering a house plant or feeding a pet; dead is dead.

I am thinking of getting this charger for this battery - will that set up be ok?

Also can I buy premade devices or circuits that will disable the power amp when it goes below voltage?

-Thanks
 
I prefer a smart-ish charger with V and I limiting. That can be done with a couple of 3-terminal regulators, like LM317. (You'd need to allow several volts drop across each, so the raw supply might have to be around 24V; an HP DeskJet transformer might work.) I don't know anything about that trickle charger. I've come across smart chargers for Power Wheels toy cars, but I think they are sized for bigger batteries (I measured several amps in the initial Quick Charge mode, followed by 1A to top it off, then a pulsed trickle charger.) If you can scrounge a UPS in the 250 VA range, those usually have a 7AH 12V battery, and should make an OK charger, though not suitable for building into a boombox.
This looks like a decent charger.

As for the overdischarging protection... here's a suitable circuit at Maxim.com. Unlike a relay or bipolar transistor, that MOSFET should need essentially no current. On-resistance can be extremely low (I once made a MOSFET speed controller that had lower voltage drop at 100% than the relay it replaced.)

It would be good to include a way to measure battery voltage. That could be a dot mode bar graph display configured as an expanded-scale voltmeter, so all 10 LEDs cover 11V to 13V. But an eBay digital panel meter would be less work, and much more precise. Wire it with a momentary switch to check battery voltage directly, but have it normally powered from the switched 12V, unless current drain really is negligible.
 
There's no need for undervoltage protection when you use a TA2020 amp with an SLA battery. Minimum voltage for an SLA is 10.5V but the amp will start to lack bass performance at about 11-11.5V battery voltage, cut out completely when you try to play loud at voltages of around 10.5V.

Practically any 2-3A SLA charger will work fine with a single 12V 7.2Ah SLA but keep in mind this is primarily for festival use and select one that have no venting holes so that you don't risk any fluids, beer most likely, water less likely, coming into the charger.
 

fraction

Member
2011-04-04 4:07 pm
There's no need for undervoltage protection when you use a TA2020 amp with an SLA battery. Minimum voltage for an SLA is 10.5V but the amp will start to lack bass performance at about 11-11.5V battery voltage, cut out completely when you try to play loud at voltages of around 10.5V.

Practically any 2-3A SLA charger will work fine with a single 12V 7.2Ah SLA but keep in mind this is primarily for festival use and select one that have no venting holes so that you don't risk any fluids, beer most likely, water less likely, coming into the charger.

does that mean a 11.1v li-po cctv battery is going to produce quieter bass when compared with a 12v SLA?