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Septimus 25th February 2005 03:22 AM

I did a search on battery power supplies, but...
I poked around for awhile with the search about battery supplies, but I didn't get exactly what i was looking for.

What are the pros/cons?

Also, what kind of specs do I need for a sealed lead acid batt.

48V (or 2 24v, 4 12v)?
what about Ah ratings? does that mean how many amps the thing can put out in one hour? What do I need for like, 3 hours listen time without the charger on? (not that i have that much time, but I'd rather have too much than not enough)

Sorry that I'm a complete noob at this stuff.

jleaman 25th February 2005 03:28 AM

How are you going to charge them ? Id buy 4 12v one with the higest Ah rating : O )then yo have to worry about charging them Properly : O)

DonoMan 25th February 2005 03:29 AM

Buy a UPS and modify the back to include a plug for the battery voltage.

jleaman 25th February 2005 05:39 AM

You cant buy a single ups to charge all 4 12V batterys. wont work properly one will get over voltaged : O )

Ropie 25th February 2005 12:57 PM

Use one charger per battery please.

protos 25th February 2005 01:53 PM

7ah slas are the best and cheapest to find and 4 of those should provide many hours of power.I have 8 of those for dual mono PS and do not need to recharge for days(for a gainclone).Thoroughly recommended - huge difference in sound quality.Some just buy off the shelf chargers and switch them around or make 4 separate regulators per LM317/137 schematics.Ideally you need current and voltage regulation (two regs each batt)but you could manage with just low current regulation.

tlmadsen 25th February 2005 01:59 PM

I ditto what "protos" is saying, but even 4aH are fien for most amps.

Have fun


Septimus 25th February 2005 05:34 PM

Ok, so 4 12v's with seperate chargers for each, I'd be looking at about 5ah batteries. I'll be running the lm3875 kit. What exactly does the ah rating mean? again, sorry for being such a noob.

protos 25th February 2005 05:46 PM

Amperes/hour so theoretically it can supply 5 A for one hour until recharge.But in practice you should not use a battery to provide more than 1/5 its Ah rating at max.

Septimus 25th February 2005 08:24 PM

Thanks for all your quick replies guys...

So for a few hours of listen time, 4 12v 5ah batteries would be 20ah.

Looking over the data sheets at nat. semi. it looks like 48v is a little much? or am i just not knowing how to interpret the graphs. Also, does anyone know the typical current draw these chips produce? (lm3875 in particular)

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