Power your entire pedalboard from one rechargeable battery for about $22! The only caveat is that it will be a 12V supply, not 9V. So, make sure your pedals can handle 12V before you try this (most should be able to).
Disclaimer: while I believe this is safe and often use this myself, I do not endorse any of these products or guarantee their performance. I cannot be held liable if you damage your pedals, get a faulty battery, or you have any problems whatsoever. Try this at your own risk.
While Li-ion/Li-polymer battery packs contain protection circuitry, it is generally a good idea to observe the following precautions:
- do not short-circuit the battery or pull more current than it is rated for
- use only the charger supplied with the battery
- do not try to fully discharge the battery
What you need:
You'll want a battery pack with enough current capacity to power all your pedals. Just add up the mA ratings of all your pedals and multiply that number by how many hours of run time you need. Then pick a battery pack that has at least that many mAh of capacity. For example, say you have 5 pedals with mA ratings of 5mA, 10mA, 30mA, 55mA, and 65mA; and you want at least 8 hours of run time:
( 5mA + 10mA + 30mA + 55mA + 65mA ) * 8h = 1320mAh
So, if you choose a battery pack with 1800mAh, you'll have room to spare. Higher capacities are available at a little higher cost. Pick a battery pack with a switch on it, so you can turn off power when you are not using it. Make sure the charger is included.
One more thing to look out for on eBay: many mAh ratings are highly exaggerated. I have two battery packs rated 6800 mAh and 6500 mAh, but they more like 1800 mAh ($18) and 2600 mAh ($33) according to my tests. The latter battery has multiple outputs, which is why it cost more. I believe a more accurate estimator of battery capacity is cost: expect to get around 100 mAh/$; so an $18 battery should have about 1800 mAh, given that it has no other cost-adding features.
Update: I have recently found a genuine 6800 mAh battery for about $40 shipped; look for the word "genuine" before the mAh rating.
The battery pack will have a center-positive plug, and most pedals are center-negative. This is why you need the reverse-polarity adapter. Plug this into the output of the battery pack to make the plug center-negative. If you have some pedals that are center-positive, you can still use one battery; but you will need separate power chains for center-positive and center-negative.
Here is a photo showing a battery pack with the reverse-polarity adapter attached:
Another photo showing the where the charger attaches:
Some tips about charging:
- The charger will have one or two LEDs to indicate when the battery is charging and when it is done charging. This will depend on the charger.
- Depending on your battery, you may or may not need the power switch turned on to charge the battery.
- The charger that comes with the battery will have its own mA rating, which determines how quickly it can recharge the battery. For example, the charger shown in the photo is 350 mA. To recharge a fully discharged 1800 mAh battery will take somewhat longer than 5.14 hours (1800 mAh / 350 mA). If the battery is not fully discharged, the charging time will be shorter.
- Immediately disconnect the battery if it ever gets hot to the touch or visibly bulges. This means that it has an internal short and explosion may be imminent!
- Li-ion and Li-Polymer batteries are considered hazardous waste and must be discarded at an appropriate recycling facility.