> Pb batteries ...ancient and primitive battery technology, dating back nearly a hundred years, to somewhere around 1920 or so
They were quite old 100 years ago. On the market 130+ years.
Observed in 1801, demonstrated in 1859, improved (paste) 1881, commercialized 1886, by Henri Tudor, who died in 1928 of lead poisoning.
> back then, there was no other battery technology that could do the job.
No; Edison had a competing chemistry {link} which fared very well for a long while, good for electric cars, and produced until 1975, though not favored for engine starting.
> ...none of us has ever seen a commercially manufactured flashlight using a lead-acid battery, or a laptop computer....
I had a 80186 laptop with a sealed Lead battery.
For many years, the best piano tuning-reference box used Lead (in part because the discharge curve is VERY predictable so a low-batt monitor was easy).
Last I looked (yes, a long time back) most alarm systems used a Lead battery, readily available in Home Depot. Also the batt of choice for PC UPS boxes? Apparently still is....
For most of the century, the Telephone Company ran on a giant Lead battery, floating on a charger. The downtown switch exchanges are gone, but what is in the pole-top boxes that replaced them? I'd bet a Lead Nickel that all but the newest have an "alarm battery" (Lead) in the bottom.
They were quite old 100 years ago. On the market 130+ years.
Observed in 1801, demonstrated in 1859, improved (paste) 1881, commercialized 1886, by Henri Tudor, who died in 1928 of lead poisoning.
> back then, there was no other battery technology that could do the job.
No; Edison had a competing chemistry {link} which fared very well for a long while, good for electric cars, and produced until 1975, though not favored for engine starting.
> ...none of us has ever seen a commercially manufactured flashlight using a lead-acid battery, or a laptop computer....
I had a 80186 laptop with a sealed Lead battery.
For many years, the best piano tuning-reference box used Lead (in part because the discharge curve is VERY predictable so a low-batt monitor was easy).
Last I looked (yes, a long time back) most alarm systems used a Lead battery, readily available in Home Depot. Also the batt of choice for PC UPS boxes? Apparently still is....
For most of the century, the Telephone Company ran on a giant Lead battery, floating on a charger. The downtown switch exchanges are gone, but what is in the pole-top boxes that replaced them? I'd bet a Lead Nickel that all but the newest have an "alarm battery" (Lead) in the bottom.
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I would go with sealed lead acid batteries due to simplicity. If you plan to run the amp off both a DC wall adapter and a battery bay, the simplest solution is a toggle switch for DC adapter and battery modes. You will need a battery charger rated for Lead based 12 or 24V packs. The charger will need to be connected directly to the battery via a separate input from the DC supply. Your DC adapter will not and should not be used to attempt to charge the battery as they may provide too much charging or standby current, and overcharging the battery with more than a small trickle current is bad for it.
If you run two 12V battery packs in series, make sure they are identical in fabrication and capacity and are both fully charged prior to series wiring. It is better if you just buy a 24V battery. 6, 12, 18, and 24v are common. Be wary of deep discharging the battery. You should stop using equipment immediately if the supply voltage starts to dip.
A simple indicator light could be fabricated from an LED in series with some Zener diodes such that the total Vdrop sums to 10-11V or so (20-22V if using a 24V cell). A current limiting series resistor is connected in line with the LED to limit current to safe levels, and if at any time during operation, the LED ceases to glow completely, it is wise to shut off the equipment or switch to mains power in order to protect the battery.
I do not recommend Lithium Ion battery packs for homemade projects as overcharging them can cause the battery to explode or catch fire, causing property damage or in some cases total loss to the building. If the charging circuit is not designed properly or have a proper shut off when the battery reaches full charge, you have a ticking time bomb on your hands. Even manufacturers are often plagued with faulty charge circuits smoldering or catching fire, as reported by numerous recalls of laptop and cell phones. My advice is not to use Li-Ion cells in homemade projects.
Lead Acid batteries are incredibly nasty if bursted open, but the likelihood of this happening with a sealed battery is incredibly low, and unlike vented car batteries, sealed lead can be stored in any orientation. You should avoid deep discharge, as the charger will refuse to charge them if the voltage goes too low. I have had medium success in the past revitalizing sealed lead acid batteries that have experienced a deep discharge by trickle charging them with a small standby current from another 12V source, but useful life will suffer if it gets too low.
If you run two 12V battery packs in series, make sure they are identical in fabrication and capacity and are both fully charged prior to series wiring. It is better if you just buy a 24V battery. 6, 12, 18, and 24v are common. Be wary of deep discharging the battery. You should stop using equipment immediately if the supply voltage starts to dip.
A simple indicator light could be fabricated from an LED in series with some Zener diodes such that the total Vdrop sums to 10-11V or so (20-22V if using a 24V cell). A current limiting series resistor is connected in line with the LED to limit current to safe levels, and if at any time during operation, the LED ceases to glow completely, it is wise to shut off the equipment or switch to mains power in order to protect the battery.
I do not recommend Lithium Ion battery packs for homemade projects as overcharging them can cause the battery to explode or catch fire, causing property damage or in some cases total loss to the building. If the charging circuit is not designed properly or have a proper shut off when the battery reaches full charge, you have a ticking time bomb on your hands. Even manufacturers are often plagued with faulty charge circuits smoldering or catching fire, as reported by numerous recalls of laptop and cell phones. My advice is not to use Li-Ion cells in homemade projects.
Lead Acid batteries are incredibly nasty if bursted open, but the likelihood of this happening with a sealed battery is incredibly low, and unlike vented car batteries, sealed lead can be stored in any orientation. You should avoid deep discharge, as the charger will refuse to charge them if the voltage goes too low. I have had medium success in the past revitalizing sealed lead acid batteries that have experienced a deep discharge by trickle charging them with a small standby current from another 12V source, but useful life will suffer if it gets too low.
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Well, there's a ringing endorsement! 😀
I have two UPS at home. Both are heavy as #$@*! Yes, sealed lead acid batteries, but UPS are not intended to be portable. You pick up one, stagger to its final destination, put it down with a sigh of relief, and hope never to have to pick it up again (until the crappy Pb battery wears out after a couple of years and has to be replaced).
Ditto for alarm systems...not intended to be portable, or to ever be deeply discharged.
I know nothing about pole-top boxes, but I do know that telephone poles aren't intended to be portable, either. 🙂
-Gnobuddy
Yes, I specifically mentioned the need for a dedicated charger designed for the specific cell chemistry.
While Lipo packs have a scary history of fires, LiFePO4 ones do not. That's why DeWalt chose them for their first lithium-powered cordless tool designs. And this is the cell chemistry I'm recommending.
We can argue about the simplicity of use and ready availability of Pb batteries all day. But there's no avoiding the fact that these things are insanely heavy. Most electric guitar players are already fed up of having to haul around too many unpleasantly heavy things. The last thing we want is another ten lbs of lead boat-anchor added to our guitar amps!
It kinda looks as if the thread starter has left the building, so it may well be that we are all talking into thin air now.
-Gnobuddy
I put a Sealed Lead Acid in my Briefcase Boombox. 2.3Ah
But the briefcase was 95% air save for the drivers, still a lightweight system IMO.
Maybe you're a lot stronger than I am. 🙂
JM Fahey has an old 2013 post on this forum about using SLA (sealed lead acid) batteries for portable guitar amps he made and sold in Argentina, too. Evidently some Argentinean guitarists are also willing to haul around a lot more weight than I am. 😀
When I go out to play, I'm usually hauling a small P.A. system, an acoustic guitar in a hard-shell case, a rather heavy five-string electric bass in its hard-shell case, a small suitcase full of cables and microphones, a small Mackie mixer in a hard-shell case, two guitar stands and a (classical guitar) footrest, a briefcase full of guitar FX pedals, a couple of binders full of song lyrics, a music-stand, and a box filled with stuff like guitar tuners, spare picks and strings, capos, spare batteries, egg-shakers, and so on. All this in addition to whatever guitar amp I'm using that day.
Which is why, if I also had to haul around two sealed lead acid batteries on top of everything else, I would just give up music and take up solving crossword puzzles or something instead. 😀
-Gnobuddy
The briefcase system weighs 12.0 pounds according to my bathroom scale. My cat weighs as much for comparison.
Granted, I bought a rather lean sealed 2.3Ah battery for the briefcase because IMO it's a briefcase boombox, not a PA system. The Speakers are rated 15W each, so running at a full 30W (2.4A) the system would last an hour. However that 30W is probably top end peak power. Musical content will vary a lot and the thing gets plenty loud with the volume knob just at half-way. Assuming it uses a non-linear taper, RMS current is probably under one amp, with peak current exceeding that that. So my smallish sealed battery that doesn't weigh much would probably get minimum 4 hours playing at reasonable levels that won't destroy the speakers, and that's a very conservative estimate. It would probably run longer than that, with lower volume equals extended play time, so I'm not going to test it as I don't want to deep discharge the battery. I soldered the tabs and secured it to a wood plank with Zip ties so it's immobile. Replacing it would be a PITA. At least I won't be buying D-cells, LOL, and the SLA have extremely low impedance so peak output won't be "muddy" like they would with D-cells.
You are running an actual PA system so it's kind of apples to oranges comparison. Even a huge car battery would likely exhaust itself before long on that system. You budget is also likely higher than mine so maybe a commercial Li-Ion bank or even a massive UPS may work for you. Also you claim the equipment is heavy, so I assume you have stage help for setup and run the stuff on a dolly and aren't just carrying it. Anyway good luck for your gig.
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An 12V/1.4Ah SLA weights about 1 lb. Powering a full-bridge Class-D-amp (TPA3116..) this yields 5..10W into 8 Ohms.
With some high efficient 12 inch guitar speaker this is loud enough on stage and lasts at least one hole gig without re-charge.
just my 2c
With some high efficient 12 inch guitar speaker this is loud enough on stage and lasts at least one hole gig without re-charge.
just my 2c
Stardust4ever - don't want to give you the wrong impression, my P.A. is a little Acoustic AG30. It's a 30-watt wedge-shaped powered speaker /acoustic guitar amp / vocal amp: Acoustic AG30 30W 1x8 Acoustic Guitar Combo Amp | Musician's Friend
However this 30-watt, 8" speaker, amp weighs a full 45 lbs, thanks to the use of vast quantities of MDF in the enclosure. 😀
Include all the other stuff I have to haul, and it probably totals over 100 lbs without a guitar amp. I would not want another 12 lbs added to that.
I agree with you about power estimates. It's certainly true that bass-heavy dance music at club levels can eat up hundreds of watts, but for saner use, the 30 watts my AG30 can deliver has been more than adequate. We've used it for vocals for audiences up to 75 people a couple of times. Usually it just gets used with the jam group I go to regularly. It has never been turned up to full volume (i.e. audible clipping).
-Gnobuddy
However this 30-watt, 8" speaker, amp weighs a full 45 lbs, thanks to the use of vast quantities of MDF in the enclosure. 😀
Include all the other stuff I have to haul, and it probably totals over 100 lbs without a guitar amp. I would not want another 12 lbs added to that.
I agree with you about power estimates. It's certainly true that bass-heavy dance music at club levels can eat up hundreds of watts, but for saner use, the 30 watts my AG30 can deliver has been more than adequate. We've used it for vocals for audiences up to 75 people a couple of times. Usually it just gets used with the jam group I go to regularly. It has never been turned up to full volume (i.e. audible clipping).
-Gnobuddy
Well, we have moved the goal posts quite a bit during this thread! In post #4 of this thread, it was suggested that two lead-acid car batteries would be a good way to go. A typical car battery weighs around 40 lbs (plus or minus about 10 lbs), so that recommendation amounted to somewhere between 60 lbs and 100 lbs of battery. 😱
After that, in subsequent posts, we've discussed the possible use of two 12V 7 Ah batteries, then two 12V 4 Ah batteries, then one 12V, 4 Ah battery, and now we're talking about one single 12V, 1.4 Ah battery.
Of course, if we consider smaller and smaller lead acid batteries, there comes a point where the weight becomes manageable. Certainly 1 lb (for one 12V 1.4Ah SLA battery) is an easily managed weight.
However, it's worth pointing out that today's AA-sized alkaline cells often have over 2600 mAh capacity - nearly double the capacity of that 1.4 Ah lead-acid SLA battery. Eight AA cells (adding up to 12 V) would therefore hold nearly twice as much stored energy as that 1.4 Ah SLA. Same voltage, twice the Ah.
Put another way, half as many AA cells - just four teeny little AA cells - would equal the energy stored in that 12V, 1.4 Ah lead-acid battery. Those four AA cells would weigh about 3 ounces; less than one-fifth of the 1-lb weight of the SLA battery!
In fact we could go even smaller than AA. Eight even more tiny little alkaline AAA cells would weigh about 100 grams (a bit over 3 oz, so still about a fifth of an lb), and Wikipedia thinks they would have a capacity up to 1.2 Ah - nearly matching the capacity of that 1.4 Ah sealed lead acid battery!
Now I understand that there are good reasons for not using single-use AAA alkaline cells in a project like this one. Still, the fact that a handful of AA cells matches the stored energy of a full pound of toxic lead-acid battery make it hard to justify the latter choice; even more so, when you consider that the lead-acid battery is far more toxic to the environment than modern alkaline AAA cells are.
Of course, it isn't necessary to use single-use AAA cells. If lithium is not an acceptable option, one could always use an 8-cell pack of rechargeable AA NiMH cells. It would weigh around half a pound (half as much as the SLA), and capacities of 3500 mAh are available today - two and a half times as much stored energy as the 1.4 Ah SLA battery.
The numbers speak for themselves. Lead-acid batteries are awful. They are heavy, bulky, weak, and toxic.
Of course one could always choose to use awful batteries, as long as they are legally available on the market. But it would be really hard to find a rational justification for making that choice. Maybe if money is really tight, and one has a fairy godmother providing free SLA batteries. 😀
-Gnobuddy
Nickle Metal Hydride batteries produce a lot more current than Alkaline for the same size. D-cell alkaline may not provide enough peak current and would be more waste to the environment in the long run if you had to keep replacing them, so a rechargeable solution is best. However you would need 10 cells to amount to 12V. When 100% topped off, they would put out about 14.5V, then drop to around 12V and stay there for a while.
I still think you would find a 7Ah SLA battery more than adequate for your needs without being massive. If not, consider 10 D-cell Nickle Metal Hydride. They won't have the memory effect of older toxic Nickle Cadmium, and can be trickle charged. A 10-cell charger is a kind of odd size though so you may consider using a pair of 18V power tool batteries connected in parallel, since your amp accepts between 12-24V, 18V should be fine. You could wire in a standard power tool charger (it would take longer to charge the cells if they are parallel connected but you'd get higher peak current and longer operating times on your gear) and use those. They are fairly lightweight too.
I am happy with my SLA solution in my briefcase. I should probably add a 10A auto fuse to the (+) voltage terminal for protection as those packs can rupture or start a fire if shorted. Take care...
I still think you would find a 7Ah SLA battery more than adequate for your needs without being massive. If not, consider 10 D-cell Nickle Metal Hydride. They won't have the memory effect of older toxic Nickle Cadmium, and can be trickle charged. A 10-cell charger is a kind of odd size though so you may consider using a pair of 18V power tool batteries connected in parallel, since your amp accepts between 12-24V, 18V should be fine. You could wire in a standard power tool charger (it would take longer to charge the cells if they are parallel connected but you'd get higher peak current and longer operating times on your gear) and use those. They are fairly lightweight too.
I am happy with my SLA solution in my briefcase. I should probably add a 10A auto fuse to the (+) voltage terminal for protection as those packs can rupture or start a fire if shorted. Take care...
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Thanks for the catch! I momentarily forgot about the lower terminal voltage of NiMH (compared to alkaline) cells.
I am not the person who started this thread - that was "mplaksant".
-Gnobuddy
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