Battery powered PSU implementation

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matejS

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Joined 2007
#1
Hi, all!

We all know that battery power is easiest way to get very clean power supply (if not the cleanest way to get it). But batteries are realy PITA to use. So... I ended this saga.
I've done a 4 SLA battery power supply, seperately charged, fully automatic (not switches at all, relays used, triggered from the client - 12V DC trigger). Charging is very advanced - UC3906 based (severale states: trickle charging, current charging, voltage charging, float mode). Connectors are RCA (standard and good contact). Everything is protected with fuses and very heavy (chassis very robust).

Here is how it looks:

An externally hosted image should be here but it was not working when we last tested it.


Anything that I've missed?

Cheers,
Matej
 
#2
The output voltage would change with state of charge, so you'll need a voltage regulator.
The voltage shouldn't drop very much with those batteries unless you're drawing lots of current from them. And they should be charged with the terminals facing up to avoid moisture loss or leakage (yes, that even applies to AGMs).
 
#3
Nice setup. I'm also using SLA batteries for an outboard DAC and also for an upcoming preamp. I also used the UC3906 for charging.
I have to disagree with the previous post. I don't think there's any need for a regulated supply with most applications (although I am using a cap multiplier filter). If your preamp or whatever has serious problems with a slowly reducing supply voltage, I'd be surprised.
Also, I don't recall ever seeing anything about having to charge sealed batteries terminals up. But I would check the actual datasheet to be sure.
 
#4
paulb said:
Nice setup. I'm also using SLA batteries for an outboard DAC and also for an upcoming preamp. I also used the UC3906 for charging.
I have to disagree with the previous post. I don't think there's any need for a regulated supply with most applications (although I am using a cap multiplier filter). If your preamp or whatever has serious problems with a slowly reducing supply voltage, I'd be surprised.
Also, I don't recall ever seeing anything about having to charge sealed batteries terminals up. But I would check the actual datasheet to be sure.
Click to expand...
For hermetically sealed batteries (generally cylinder type), it doesn't matter. But those batteries are most likely AGM, which have vents. In that case, it's best to charge with the terminals up.
I would have made the battery packs and charger separate to reduce weight. And secure them so they don't move in the case.
 
#5
star882 said:

For hermetically sealed batteries (generally cylinder type), it doesn't matter. But those batteries are most likely AGM, which have vents. In that case, it's best to charge with the terminals up.
Click to expand...

Generally, I'd agree, but you might get away with not having the batteries terminales up if you don't charge them very hard. A ball part would be around 1/20c before you'd have to have the terminales facing up.
 
#6
I do not have regulator since I say: "It's up to "user" circuit to have it, if needed.". For instance, DAC needs +/-5V and it has its own regulators. I use batteries even for heaters... sound is outstanding! Very clean and once you hear "black silence" you cann't get on without it anymore.

I also did not notice any instuctions on charging position (a searched the web). Therefore I will wait for a year or two and will see what happens.

All batteries are glued with double-sided tape that can hold up to 50kg and is very good temparature resistive (up to 100'C and more). I did carry it around without any problems.

I take care not to go below half of battery capacity. Since I sleep during the night 😉, the battery have to hold for max. 10h. Not a problem for my current setup.

It's really cool, I do not even know I have it 🙂

Matej
 
#7
matejS said:
I do not have regulator since I say: "It's up to "user" circuit to have it, if needed.". For instance, DAC needs +/-5V and it has its own regulators. I use batteries even for heaters... sound is outstanding! Very clean and once you hear "black silence" you cann't get on without it anymore.

I also did not notice any instuctions on charging position (a searched the web). Therefore I will wait for a year or two and will see what happens.

All batteries are glued with double-sided tape that can hold up to 50kg and is very good temparature resistive (up to 100'C and more). I did carry it around without any problems.

I take care not to go below half of battery capacity. Since I sleep during the night 😉, the battery have to hold for max. 10h. Not a problem for my current setup.

It's really cool, I do not even know I have it 🙂

Matej
Click to expand...
One of the AGM batteries I worked with failed almost open circuit after 3 years of operation lying on the side. Autopsy revealed some deposits in the vents and loss of electrolyte. I tried adding some water but it didn't work. Another AGM battery of about the same age and service but operated with the terminals up still works fine.
 
#11
Your battery enclosure

If your batteries have vents (look at the top of the batteries, if there is one round cut out per cell [6 cells in a 12V battery]), the enclosure that you put them in should also be properly vented incase one of your batteries cells decides to vent hydrogen gas.

--Dave from NJ.
 
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