Hi my friends,
I would like to convert a 15 watt guitar amplifier (Peavy Rage 158) to battery powered.
What are the first steps I need to do?
What things do I have to look for?
How can I build it? (just give me some tips to start)
Any opinion is more than welcome.
Thank you a lot. 🙂
I would like to convert a 15 watt guitar amplifier (Peavy Rage 158) to battery powered.
What are the first steps I need to do?
What things do I have to look for?
How can I build it? (just give me some tips to start)
Any opinion is more than welcome.
Thank you a lot. 🙂
You'd either need to take a look at the schematic to see if the amp and preamp voltages are within practical battery range, or you'll need to use an inverter supply to step up 12V to 120V for the normal mains plug.
The second one is easy, but maybe not as efficient as the first.
The second one is easy, but maybe not as efficient as the first.
I just looked at the schematic. It's all single ended supply, so that makes battery easier.
But you'd need 28V for correct operation. You should be able to use two 12V batteries in series, especially if they are closer to 13V each. Not perfect, but should be close enough.
That would be similar to running it on 110V mains, instead of 120V.
But you'd need 28V for correct operation. You should be able to use two 12V batteries in series, especially if they are closer to 13V each. Not perfect, but should be close enough.
That would be similar to running it on 110V mains, instead of 120V.
It's 28VDC, so two 12V car batteries in series would last plenty long enough.
Connect them at the output of the bridge rectifier. Do you need the battery pack to be portable?
sorry guys but I'm not from USA but from a european country. In my country the voltage is not 120 volt, but 230 volt. So, the schematic that you looked is probably a USA version? Here is the photo of the back of the amplifier:
An externally hosted image should be here but it was not working when we last tested it.
here's a schematic from Peavey of a mid-90's model. Probably the only real difference is the step-down transformer. Looking at the schematic, and the associated solid-state componentry, you could rig this amp to a single 12V car battery, and it would most likely work. It might only deliver 6 to 8 watts to the speaker, but the thing is only rated at 25 watts anyway.
If you wire the batteries to the output of the rectifier, you will need to add a series diode of proper current capacity (6A10) to prevent the bats to be charged without current limit by the PSU when used in mains.
Car batteries are typically rated over 80 Ah. Multiply by 12V, and you have nearly 1000 watt-hours of capacity. Enough to power a guitar amp drawing 10 watts for 100 hours continuously. 😱
The "two car batteries" solution is expensive, enormously heavy, and physically huge. It's also about twenty times more battery than the OP needs. I've never met a musician who wants to play for more than maybe 5-6 hours in a row.
I would suggest a seven-cell lithium iron phosphate (LiFePO4) cordless tool battery is much better suited for your purposes. Something around the 2 Ah size, which is common nowadays.
You will also need a special LiFePO4 specific charger - don't cut any corners here, using the wrong charger with lithium batteries is very dangerous.
-Gnobuddy
The "two car batteries" solution is expensive, enormously heavy, and physically huge. It's also about twenty times more battery than the OP needs. I've never met a musician who wants to play for more than maybe 5-6 hours in a row.
I would suggest a seven-cell lithium iron phosphate (LiFePO4) cordless tool battery is much better suited for your purposes. Something around the 2 Ah size, which is common nowadays.
You will also need a special LiFePO4 specific charger - don't cut any corners here, using the wrong charger with lithium batteries is very dangerous.
-Gnobuddy
There is no need for such a bulk batteries, perhaps a couple of 12V 7Ah are more manageable, and with more than a pair of hours of playing.
ok guys, so I need only battery? No modification or extra circuits? Just connect the battery and maybe use a diode?
I'm thinking of a 12 Volt - 9Ah battery for motorbikes, here in my country these batteries are common and cheap. And yes, I know that I need a charger.
I'm thinking of a 12 Volt - 9Ah battery for motorbikes, here in my country these batteries are common and cheap. And yes, I know that I need a charger.
Yep. Motorbike battery is fine. As mentioned earlier, one might work, two in series would be better
Agree. With one you play alone at home; with two in series you can become a street player.
You will have same power as when mains powered, because the mains 28V supply drops under load; the battery one does not.
You will have same power as when mains powered, because the mains 28V supply drops under load; the battery one does not.
24V (2 batteries) and a diode will work. But lead is a poison, sulphuric acid is dangerously corrosive, hydrogen gas emitted during charging is explosive. Lead-acid batteries of the type used in cars and motorcycles are really not safe to have inside your house.
Finally, lead-acid batteries are not designed to be deeply discharged; you cannot use much more than 2Ah or 3Ah of your 9Ah battery capacity without recharging, otherwise, the battery will not last long.
There is a type of lead-acid battery called a "gel cell". There is no liquid in these, and they are completely sealed so they cannot spill sulphuric acid inside your house. These could be used for your application, though they too are very heavy for their size (and suffer from the same inability to tolerate deep discharging). Lead is a very dense metal, there is no getting around the weight!
Seriously, even old-fashioned NiMH batteries are a better choice than lead-based ones. These were used in all sorts of cordless tools, radio-control toys, et cetera, until about five to ten years ago, when lithium batteries began to take over.
Modern LiFePO4 batteries are far and away the best option, if you can find some at an affordable price.
LiFePO4 chargers are made for radio-control model cars and aircraft; that may be the cheapest way to get a charger capable of charging an 8-cell LiFePO4 pack.
Those LiFePO4 cells can be soldered, but you have to know what you are doing, and the soldering has to be done very quickly to avoid heat damage.
IMO, lead-acid batteries for your guitar amp are a terrible idea. Try strapping about four or five bricks to your amp, carry it around for a few days, and see if that much weight is still acceptable to you!
-Gnobuddy
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I agree, although for the intended use, I like the nickel-based batteries better. The main difference is when they discharge, they will let you know it's time for a battery change before they quit. They tend to sag for awhile before they go completely dead, just like alkaline batteries. I'm sure everyone has had a radio or flashlight that did this.
The lithium-based batteries have battery management circuitry built into them, because if they completely discharge, they are done forever, and will never hold a charge again. The battery management circuit cuts the output abruptly when it decides the battery is low on charge. This always happens at the worst possible time: right in the middle of a solo with people watching and such.
At least with a nickel battery, you can "milk it" and have a few minutes to finish what you are doing. With the lithium batteries, that option has been removed.
If you give a proper use to the Pb batteries, they aren't dangerous in any way. I repaired thousands of UPS of different capacities (from 1KW 12V 7Ah to 20 batteries for 15KW) and all them use Pb + H2SO4 units, and they are effectively used in home, office and industrial environments without (Until this date) any inconvenience.
These use the sealed Pb+H2SO4 gel cells that I mentioned in my last post. They are not the same as the Pb+H2SO4 batteries in cars and motorcycles - in these gel cells, there is no liquid sulphuric acid to spill, and no vents in the case for acid to leak from.
-Gnobuddy
7 amp hour gel cells too heavy? Then use the 4 amp hour version. Still more than enough for a little 15 watt amp. Lead based batteries are a bit heavy, but are much more tolerant to different charge/discharge cycles than most other technologies.
Several years ago, MIT researchers created a LiFePO4 cell that they later spun off into a commercial venture, A123 Systems. This company made 18650-sized, 2300 mAh cells, surprisingly light weight for the capacity, and incredibly electrically robust.
DeWalt began using these A123 cells in their first lithium cordless power tools - massively powerful tools using a ten-cell pack (33 volts fully charged, and 36 volts hot off the charger).
At the time I built and flew electric RC model aircraft. I, and many others, used these A123 cells in larger models, largely because they are much safer than equivalent capacity LiPo cells. I myself used them for hundreds of flights in a number of different models I built. Peak currents of 30 to 40 amperes (yes, amperes!) were the norm, and these little 2.3 Ah cells handled this with aplomb.
It was found by experiment (not by me!) that a three-cell pack of these A123 LiFePO4 cells could be charged in minutes, using nothing but the minor resistance of a length of lamp cord (copper wire) to limit the current, and charging direct from a 12V car battery.
Not the recommended charging procedure by a long shot, but the cells not only survived, but thrived on this abuse. These cells were monitored for hundreds of charge/discharge cycles, and held up extremely well, far better than other cell chemistries available then (and available now, for that matter.) And no-one ever experienced a fire, something you cannot say for the other lithium-based cell chemistries out there.
In almost every way, these are virtually the perfect battery for this application. High energy density, very robust, very low fire hazard, very long lasting.
Unfortunately, the original A123 Systems failed financially; I believe the name (and rights to the technology) was then bought up by a Chinese firm. I also believe they are still making these LiFePO4 cells, though the 18650 size cells are now up to 3000 mAh as a result of improvements made to the old 2300 mAh process.
As for lead-acid, IMO, literally the only good things about them is familiarity, and wide availability. Heavy weight and high toxicity are not the only disadvantages of lead-acid batteries; they also cope very poorly with deep discharge, and you can only use a small fraction of the capacity of these batteries if you want them to survive for a reasonable number of charge-discharge cycles.
Pb batteries work well enough to start your car, where they barely get discharged at all for a few seconds before the engine starts and the alternator immediately recharges them. They are an ancient and primitive battery technology, dating back nearly a hundred years, to somewhere around 1920 or so - back then, there was no other battery technology that could do the job.
Things are very different today. It makes no sense at all to use the battery type with the worst energy density (that's stored energy per kilo) of any battery type on the market) for a portable bit of electronics kit.
Think about it, none of us has ever seen a commercially manufactured flashlight using a lead-acid battery, or a laptop computer, or a digital camera, or a Bluetooth speaker. That's because they are heavy, toxic, horrible batteries!
-Gnobuddy
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