Powering amps and pedals with a battery

[Ben79]

I'm planning on doing some busking and have already built a Ruby amp, a Tiny Giant, a 2 x 10 cab and some fuzzes to use on the street.

Now I need a battery.

I've been looking on ebay and found lots of cheap Chinese 12v li-ion battery packs that claim false mAh ratings so I started looking at batteries for Radio Control stuff thinking this would be a tougher market and better products.

I need something that can deliver 12v for my amps and 9v for my pedals and last a few hours and not cost more than about £50 including the charger.

What might the considerations be with this kind of application?

[italianguy63]

I don't know what size limit you are looking for... but, the last time I replaced my battery on my motorcycle, I got a new fangled -- I think "gel" type.  It lasted like 3 years which was quite good.  You may look at those.  MC

[antonis]

A "naughty" behavior of batteries is the raised cost per decreased Ah...
( a 15Ah Lead-Acid battery costs a lot more than half of a 30Ah one..)

You have to calculate your total current consumption x time to get a close capacity battery - bigger is better but raises chargers cost..

http://tech-tut.com/ruby-amp-lm386-3-circuit-power-consumption-test/
http://static1.squarespace.com/static/54696a3ee4b05a85cbfe56e5/t/54697502e4b0b41e0cc90a88/1416197378362/Tiny-Giant-Build-PDF-rev2.pdf
http://www.diystompboxes.com/smfforum/index.php?topic=89687.0

[amptramp]

You are asking about the considerations you would have to take into account.

1. Weight

Lithium-ion batteries will be much lighter than lead-acid (including gel cell and adsorbed glass mat).  NiCd or NiMH will be somewhere in between.

2. Charger

What amount of intelligence does the charger need?  What does it cost?  How long does it take to recharge?

3. Voltage regulation

Does the battery decline in voltage as it is discharged or does it hold its voltage then suddenly drop out?  Which do you prefer?  Is your equipment consistent with its range of voltages?  Can you run your 9-volt loads off 12 volts or a regulator or do you need two separate batteries?

4. Lifespan

Can you afford batteries that have to be replaced every year or do you want something more permanent?

5. Running time

How long does the battery have to work before recharging?  You can calculate the value you need in terms of amps and sort out what value of amp-hours suits your needs.

I will probably think of a few more things after I hit post, but these are questions you have to answer yourself.