Battery-powered supplies

[Nuuk]

OK, in theory you can supply it with 31.5 volts of battery power except that you will either have to use 30 or 36!

But wiithout knowing what circuit you are powering, it is not possible to say if 30 will do or 36 will be too much.

[carlos671]

well its a graham slee phono stage. If i used 30v would i be write in assuming that the nominal voltage when charged would be higher? I can always up the voltage by swapping batts?

[Nuuk]

well its a graham slee phono stage

May be but I have never heard of it and have no idea of what the circuit is. I suspect neither has anybody else here or they would have answered your question by now. If you want help, you have to provide some detials or it is like asking "how long is a piece of string?"

And relying on the state of charge of batteries to get the 'correct' voltage is not the answer to put it politely!

[BabaRoga]

about charging batteries
could be computer power supply good for charging 12v car battery?

it can handle 10A at 12 V output, and is very stable power source

[billabong]

Hi,
I'm making a dual mono +/-24V battery power supply for a DACT CT100 Phono preamp. I'm using 8X 12V 2.2Ah Panasonic SLA batteries and 4400uF,35v Elna low ESR caps (paralled 2200uF).

I wanted the charging circuit to be as simple as possible, although it would not be as convenient as the automatic ones (might be a future project).

I've accached a rough schematic of one channel's supply.

The DACT only draws 22mA per channel, so I would need to recharge no more than once every two weeks.
The setup means only one of the four batteries per channel can be charged at a time, thoiugh each battery would recharge within 1/2 hour with a 1A SLA charger.
To shorten the charging time I would use a second charger simultaneously on the other channel.

Can you see any problems with this arrangement, other than a little inconvenience.

Audie.

[billabong]

I should mention that I would recharge the batteries at around 80% capacity or less, but no less than every two weeks, which would allow about 1 1/2 hours play per day.

I'll probably get two fully automatic 1A SLA charges, although I could just use the Arlec 6A Automatic 12V charger I use for my car battery. I have also used this charger to charge the same 1.3Ah Panasonic SLA battery for over seven years, and I used it again tonight for lighting, when we had a power failure.

Audie.

[sotoole]

When using +/- 24v batteries what is the power output of a bipolar amp in watts into 6~8 ohms?
Yes i know ohms law but theres more to it.

[sotoole]

Could you not use a 48v charger on a switch with a floating ground?
ie. the amp is grounded in the center of the pack +/- 24v then you throw the double pole switch and the charger sees 48v and charges the batteries?

maybe you could use a ti microprocessor to PWM each battery regardless of the input charger voltage and each battery would be optimally charged.

PS: I have done a lot of testing and and batteries seem to beat AC power even with all the caps,snubbers,balanced power etc... However
the sound goes through the power supply I would be interested in impedance of the sealed batteries in the audio range.

[mikelm]

about 33 watts

[mikelm]

if you float the charger cct you do not need a switch - you can just connect across the + & -

The batteries need to be of same age & condition for this arrangement