Making a rechargeable battery pack for a guitar amp.

[TVR]

Really wanted to get the AER Compact Mobile, but it is just too expensive, so figured I'd research how to make a compact 12V rechargeable battery pack for multiple uses and just get the Compact 60.

What I need to know is how many volts a 60 watt guitar amp actually uses to do the math for how long of battery amp hours (AH) I need - thinking 3-4 hours if I'm playing in the subway.

This link shows you how to do the basic math to figure it out (they use a TV as example):
http://www.satcure-focus.com/icetech/page11.htm

So far these links below are what you need, just not sure what size battery to get in relation to how much power a 60 watt amp will actually use. So far I'm thinking the 12 amp hour one:

http://store.batteriesamerica.com/universalbatteryub12120.aspx

http://www.donrowe.com/inverters/voltec_400.html

[E]

Would a lithium ion battery from a laptop work?

[tonyharker]

Well the AER Compact 60 runs from the AC mains either 110v or 220/240v. The official consumption is about 70VA.
To run that from a 12v battery you are going to need an inverter.
I don't know where you live but something like this < http://cgi.ebay.co.uk/Top-150W-Car-Charger-Power-Adapter-Inverter-12V-TO-220V_W0QQitemZ280456875174QQcmdZViewItemQQptZUK_Home_Garden_PowerTools_SM?hash=item414c884ca6 > with a car battery and a battery charger.  The battery will have to supply the 70VA - probably more like 100VA because of all the losses in the inverter say some 8 - 9 amps.
A 40AH car battery should last you approx 4 -5 hours before needing a recharge.

You should be able to build a cabinet for the battery, inverter and charger to match the amplifier but it will be mighty heavy.

Alternatively you could drive the amplifier directly from internal batteries but you will need a schematic to find out the internal supply rails. These will probably total about 65 - 70volts.

regards  Tony.   

[J M Fahey]

Hi TVR.
I've built a ton of battery powered amps, which are used, among other places, in subway stations.
60 W is too much and will force you to use a very heavy car battery which will need its own cart, besides what's used with the rest of the equipment.
I have found very cost and weight effective 20W RMS amps (with efficient speakers) powered by relatively lightweight 12V7A gel batteries, which so far have never left anybody without power in 6 to 8 hour shows.
Of course they are not playing non-stop, they usually play around 15 to 20 minutes straight, talk a little about the band, maybe say some jokes, offer CDs, talk about future shows, pass the hat around to collect, wait some minutes to allow for public change, start again.
Maybe they play 50% of the time.
Unfortunately power, which is taken for granted on regular amps, here is at a premium: twice the power means exactly half the time ... or twice the weight.
Playing more than 8 hours or playing them non stop is not my idea of fun.