Battery Power Supply

[tony]

My Teradak turn ON automatically when I turn my PC ON.

After I turn my PC OFF, I can hear that the little hum from Teradak stops, but the light from the 3.3v reg, what's charging my batteries, remains ON.
Is is possible that Teradak is still working "slowly", or is completely OFF and actually DRAIN my batteries?!

Any thoughts??

I would think you are draining the batteries/ Something is keeping the light on!!

[sima66]

I just realized yesterday that I forgot to turn off the battery switches (10 days ago) and they are drained to 0.6v!!!

I connected them to one small 3.3V PS to slowly charge and in less than a day I got 1.2v.......yeiiii
I hope that I didn't permanently damage them! :(

[tony]

Hope they are charged up now Adam. Damn bad luck for me today the switches for my pc arrived today. Got the soldering iron nearly two months ago but now I have no excuse not to start attacking the PC build. I expect to be posting similar issues to your recent travails.

[sima66]

I need a good 12v battery what does not need to be charged simultaneously, since the unit takes very low power.
Does anyone knows a good one, or I also have 4 A123 bateries and I could make 12v with them if someone advice how to connect and how to charge them when needed.

[jrling]

Hi Sima

I am powering my audio PC, which has a low power J1900 CPU, with 4 A123 26650 batteries in series to give 12V. Power draw from the PC is about 12 watts so only 1A.

I used sleds like these - https://www.amazon.co.uk/sourcingmap-Co ... ery+holder to connect them and they are nice quality. Should be available to USA/Canada probably cheaper.

I float charge them with a Maplin XM21 mains powered linear PSU all the time. This keeps the batteries in excellent condition and theoretically could last for ever as they are not being discharged and charged, but kept at optimum voltage continually. I have also not found them getting out of balance, which is a possible downside of multiple battery PSU.

Initially, I worried about the mains PSU 'polluting' the batteries clean output, but I have tested turning off the PSU whilst playing music and cannot detect any difference. Others on this forum report the same findings.

Lastly, the 26650 battery supply is significantly better than the Maplin XM21 linear on its own and I highly recommend you give them a go.

Jonathan

[sima66]

Thanks Jonathan, that will probably work.
Just in my case, I will not float charge them. I need to be able to move them around and then recharge them when needed.
I will have to test them often to avoid depletion.

Can any 12v switching PS be used for charging?
Or maybe separately charge them at 3v each?

Also, I'm looking for one more good 12v battery.

[jkeny]

Yes, Jonathan, the only downside, as you say is the possible imbalance in the batteries when charging them in series.
I have tested this battery configuration (batteries in series, charging in series) with higher current draws than your 1A & they did imbalance - the negative polarity of the chain became imbalanced most.
It may be that with low current draws this is not an issue - I must go back & retest this when I have time. How long have you been running this config?

Yes, agree again - in my tests, these batteries sound the same driving low current circuits, when on charge or not.

My theory is that most people have the wrong handle on power supplies - it's not so much about low noise levels, it's about noise stability when delivering variable currents. In other words, a variable PS noise level is much more sonically damaging than a fixed noise level & most PSes don't get this right. Digital circuits probably represent the most difficult strain on PSes, in this regard as they have high intermittent current draws (when digital gates are firing in unison, for instance) happening across a broad frequency range.

@sima66, I see you have posted while I was writing the above.
Trickle or float charging is certainly the most convenient, lowest maintenance battery configuration
I believe you might find that without float charging, the batteries in series will likely go out of imbalance

[sima66]

I believe you might find that without float charging, the batteries in series will likely go out of imbalance

John, is it better to float charge or not to prevent the imbalance.
The unit I need to run is the RR-777 (Schumann resonator) and up till now, my small-medium lithium battery lasted for 2-3 months before recharge.

[jkeny]

I believe you might find that without float charging, the batteries in series will likely go out of imbalance

John, is it better to float charge or not to prevent the imbalance.
The unit I need to run is the RR-777 (Schumann resonator) and up till now, my small-medium lithium battery lasted for 2-3 months before recharge.

The problem with needing a 12V supply is that you have to keep these batteries at 3V each. the nominal voltage of these batteries is 3.3V @ they hold this voltage fairly steady while they are discharging. The voltage drops rapidly when their capacity is near to empty i.e they quickly drop down from 3.3V. When at 3V they are fairly/very low in capacity so you are likely to experience some dropping below 2.6V before others. A battery can be damaged depending on how much current is drawn from a battery below 2.6V & over what time period of time.

Why not try your scheme of running the 4 batteries in series @12V without float charging & carefully monitor them initially to see if what I saw holds up - it's not an expensive experiment?

Edit: Just to add to the above - keeping the batteries at 3.3V each for a total of 13.2V & using a voltage regulator to bring the voltage down to 12V is a possible approach. I have found in my testing, that direct battery powering sounds better in the circuits I have tested - don't know if this will hold for your device?

[nige2000]

My theory is that most people have the wrong handle on power supplies - it's not so much about low noise levels, it's about noise stability when delivering variable currents. In other words, a variable PS noise level is much more sonically damaging than a fixed noise level & most PSes don't get this right. Digital circuits probably represent the most difficult strain on PSes, in this regard as they have high intermittent current draws (when digital gates are firing in unison, for instance) happening across a broad frequency range.

probably esr too, having the power on demand to keep the v+ rail and the gnd rail stable with huge amounts of capacitance
built a class a amp few weeks ago its very apparent that the noise floor raises with the current demand then put on the float charging psu which in turn dumps noise on to the rails, well that at higher current rates.......
lower currents arent an issue for most part

cells charged voltage is between 3.3v - 3.6v
at 3v is a discharged state and really anything under 3.2v will need to be float charged because cell voltage will be on the steep rate of decline without been float charged

using an in series 12v pack thats not float charged will be risky as the cells will have a variance in internal impedance, i think this is what causes the imbalance and drift, the cell with the lowest impedance for the most part will be doing all the work and be the first one to die
that said ive had no issues with float charging cells in series
ive cells in such packs for 3 years and there is an imbalance but still works ok

over discharging cells will kill them any cell 1v or under is on borrowed time