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-   -   I did a search on battery power supplies, but... (http://www.diyaudio.com/forums/chip-amps/52286-i-did-search-battery-power-supplies-but.html)

Septimus 25th February 2005 02:22 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 02:28 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 02:29 AM

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

jleaman 25th February 2005 04:39 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 11:57 AM

Use one charger per battery please.

protos 25th February 2005 12:53 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 12:59 PM

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

Have fun

Thomas

Septimus 25th February 2005 04:34 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 chipamp.com kit. What exactly does the ah rating mean? again, sorry for being such a noob.

protos 25th February 2005 04:46 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 07:24 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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