Tír Na HiFi

Where float charging of say LiFe batteries is required (most applications), instead of polluting the batteries with a mains PSU, has anyone tried float charging them with a 12V car battery?

Cheap(ish) solution and easy to charge the car battery offline and with say a standard 40-50AH capacity battery, good for a long listening session. The load on the car battery would be low and therefore hopefully its own internally generated chemical 'noise'.

So instead of mains 'noise', substitute lead acid or other car battery technology 'noise' - my guess being that would be much lower than mains 'noise' and avoids any ground loop issue, being off grid.

Just a thought.

Jonathan

But if there's no difference in sound when the charger is disconnected during listening then it's a non-issue - it's very dependent on the rest of the audio chain & whether there are ground loops in this

BTW, it's not "mains noise"as such. The ground reference of all devices in an audio chain should be at the same voltage - anytime there is a resistance in ground connection between devices, this will lead to a voltage difference between the two grounds & can lead to noise if it gets into the signal ground

Yes I think there's noise on signal wires too
Bet you could short the gnds across the isolater without much harm
Meaning the majority of the ISO benefit is on signal wires

nige2000 wrote: ↑Fri Apr 14, 2017 12:41 pm Yes I think there's noise on signal wires too
Bet you could short the gnds across the isolater without much harm
Meaning the majority of the ISO benefit is on signal wires

Yep - in my experiments there was no difference when the same ground was used across the isolator -all the audible benefit came from isolating the signal wires although I'm sure that in some installations there is noise on the ground wire that is worth blocking

jkeny wrote: ↑Fri Apr 14, 2017 12:46 pm

nige2000 wrote: ↑Fri Apr 14, 2017 12:41 pm Yes I think there's noise on signal wires too
Bet you could short the gnds across the isolater without much harm
Meaning the majority of the ISO benefit is on signal wires

Yep - in my experiments there was no difference when the same ground was used across the isolator -all the audible benefit came from isolating the signal wires although I'm sure that in some installations there is noise on the ground wire that is worth blocking

Definitely no reason not to prevent a possible had loop

jkeny wrote: ↑Fri Apr 14, 2017 12:29 pm But if there's no difference in sound when the charger is disconnected during listening then it's a non-issue - it's very dependent on the rest of the audio chain & whether there are ground loops in this

BTW, it's not "mains noise"as such. The ground reference of all devices in an audio chain should be at the same voltage - anytime there is a resistance in ground connection between devices, this will lead to a voltage difference between the two grounds & can lead to noise if it gets into the signal ground

I was trying to think creatively in answering your good point -

One aspect that is a possible factor when connecting a charger to batteries is leakage current & the ground noise that can result from this in interconnected audio devices, especially where PCs are in the chain (SMPSes create more leakage currents than linear PSes). All AC mains PSes have leakage current but no off-grid supplies do - read batteries. Whether leakage currents generate ground noise & affect sonics is down to a lot of factors - so connecting a mains connected charger circuit may create aground loop through which leakage currents flow.

The fact that I can't detect any difference when turning the charger off only applies to my set-up and my ears! Others mileage will no doubt vary.

If I have a spare car battery to hand one day, I might try it. Annoyingly, I have just put a new one in my car!

jrling wrote: ↑Fri Apr 14, 2017 1:33 pm I was trying to think creatively in answering your good point

I know & I was just laying out both sides of the argument

The fact that I can't detect any difference when turning the charger off only applies to my set-up and my ears! Others mileage will no doubt vary.

Sure & my experience is the same - there have only been one or two who have bad enough ground loops that having the charger connected to the battery made an audible difference but the more 'correct' answer is to find & solve the ground loop issue. Once you have ground loops, it depends on what is connected in the chain as to what audible effect it may have - if it's 50/60Hz noise above a certain amplitude, you will probably hear a hum in the speakers; if it's >20KHz frequencies, how it affects sonics depends on how this folds down into the audio band or on how it affects integrated circuits/clocks which can ultimately add distortion in the audio band - a lot of this audibly effects the dynamics of the music, flattening them.

If I have a spare car battery to hand one day, I might try it. Annoyingly, I have just put a new one in my car!

Isn't that always the way :)

I believe that my best option will be this one:
"Talentcell Rechargeable 6000mAh Li-Ion Battery Pack For LED Strip And CCTV Camera,12V DC Portable Lithium Ion Battery Bank With Charger,Black"

P.S.
Why I can't post the original link from Amazon?!

Hi sima66

That pack would do the job and is very convenient. But it certainly isn't going to give you the best SQ.

I have been there too! These packs and also the ones sold as mobile phone chargers, usually contain less than optimum batteries inside, may be LiPo and not LiFePO4 and certainly not up to the quality of A123 26650 which you have. Worse they also have to contain some form of DC-DC convertor to get the voltage down to 12V (if that is what they actually put out which you cannot tell without trying and you cannot adjust). They will also have some form of cell balance management chip inside too. All that circuitry produces undesirable 'noise'.

It seems a shame to have the A123 cells and not use them, as that will definitely give you the best result. However, if it is just for your magic smoke device - then everything I have said doesn't matter!!

Jonathan

Thanks Jonathan and you have a good point!
Believe it, or not that little "magic smoke device" actually works and it's very much affected by the clean power and vibrations! At list like any other main component!
I don't like to debate about things that I didn't try, but this one I have for over 3 years and can't imagine without it! Actually I got my second one and ordered the third one!

Back to power supply! :)
For my main system I have 4 separate power lines, plus conditioner, good power cords.....
Would using the cheap switching PS to power the A123 cells make a difference, compare to linear one, even if it''s connected on the "rest of the house" power?