Emilius wrote:

Max,

I don't think there is such thing as a 120v AC battery. If there is, it's probably a 12 or 24 volt DC battery with an inverter (a device that lets you plug a mains socket into it). Also keep in mind that we use 220~230v AC in Europe.

Inverters are pretty inefficient. This means you will get much less out of your battery than you could otherwise.

A much better solution would be to check the battery compartment of your ghetto blaster, and try to come up with a solution where you're pretty much just plugging in a better battery. If it uses 8 D-cells, you're in luck, because at 1.5 volts each, this adds up to 12 volts, which is about what a car battery can supply.

If this is the case, all you need to do is pull a wire from the plus side of the battery, to the plus side of the battery compartment (where the last cell dimple goes) and a wire from minus to the other end. This has worked for us before, albeit with a pussy boombox and 2 liberated 6 volt roadworks batteries.

Max skrev:



Hey Emilius (or anyone with some advice)

I checked the ghetto blaster and it takes 10 x D so needs 15V to run. Is my only option to use a 24V battery or can an inverter output 230V AC from a 12V battery? Either way does anyone know a good place in CPH to pick one up at a reasonable price?

The battery compartment consists of springs on plastic so if i want to scrap using an inverter and tap straight into the battery compartment will I have to break the plastic to get the wires? (iam guessing that's so but just want to check before i damage it)

cheers

Saturnus wrote:



Try it straight on a car battery first, it'll probably work fine but have a slightly lower output, meaning the power will be 50% lower (from 30 Watts to 20 Watts as an example) that mean about 1.21 dB which is barely audible.

Remember a car battery is only nominally 12V, it will really be 13.5V fully charged and 10.5V when almost fully discharged. Likewise alkaline batteries are only nominally 1.5V, they usually measure between 1.1V and 1.3V under load (read: in use), that's why you can replace 1.5V batteries directly with 1.2V rechargable ones without any difference because it's just the open voltage that differs, the load voltage is about the same (1.2V rechargable batteries have this voltage under load during 90% of it's lifecycle, starting at 1.65V fully charged and rapidly dropping to 1.2V which it then holds).

In short, 10 1.5V standard batteries in serial does not equal having to use a 15V power source, a stable 12-13V source is more suitable, and that's just what a car battery is as long as you keep it from discharging more than 50%.

Max skrev:

Sorry mate, so are you saying if i use it straight on a car battery the power will be 50% lower therefore inaudible ruling out the option of a car battery?

If not, how much play time do you think i would get from the battery before it was 50% discharged? and is there anyway to slow the process apart from a solar panel?

Saturnus wrote:



No, it's the other way around ... I think I made that perfectly clear when I even explained how different batteries work?!

10 1.5V standard alkaline batteries _IS NOT_ 15V ... it's closer to 13V in use and therefore a car battery that is more than 50% charged will be exactly the same ... even if the car battery nears full discharged you'd hardly notice any difference in volume.

Max skrev:



Ok, got ya. How much play time do you think i would get then? and do you recommend a place in CPH for car batteries?

Saturnus wrote:



It's impossible to say without measuring the power consumption ... it could be anything from 10 to 100 hours on a car battery but going by a good guess would be 20-30 hours and not much more from fully recharged to fully discharged. Harald Nyborg is the cheapest place I know selling car batteries but Silvan and T.Hansen has them too at a reasonable price.

DarkCity wrote:

Ups Max!
Come Roskilde you better bring an apple to camp og something. You just pissed the teacher of
If Saturnus say jump, you don´t ask how high but rather how he would like the landing! Heheh

Don´t feel bad, we are all pre-padawans next to master saturnus!

The Coffin Camp skrev:

Well I'll swing by anyway
I'm the only one from Christianssand, and I'm 24. Our camp consists of people between 19 - 26. Hehe

Sune skrev:

@ThokN
No I didn't, wasn't aware he sold enclosures as well. How much did you pay for it?
I was just planning to mount the amplifier under some kind of cover, haven't thought that much about it yet. Still waiting for my speakers etc., they aren't being shipped till later today

Sune skrev:

By the way, you mentioned a potentiometer in an earlier post. Could you give a link to which one you have purchased?

ThokN skrev:

The bonus is that there are holes pre-drilled in the bottom that fits the screw-holes of the Amp6-Basic perfectly!

Sune skrev:

Thanks, I'll have a look at those and consider whether or not we should install one in our unit.

Saturnus skrev:

You don't need to but those enclosures are watertight and acidproof, so if you use it with a car battery then even if you have acid spills you won't ruin the amp.

Sune skrev:



Was primarily the potentiometer I was thinking about. If the enclosure is 100% closed, won't it then easily get very hot in there when the boomer is playing for a long time and the weather (hopefully ) is very hot?