which kind of rechargeable battery / power supply for a phono preamp?

vince666

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#1
Hi my friends,

in the next future, i will finally get a new phono preamp and, while going to get it, I am trying to figure out how to properly supply it to get the best out of it.

The two main options are some kind of high quality / low noise power supply adapter or some kind of rechargeable battery, with the latter as the preferred method.

The phono preamp has a power consumption of 50mA , then quite low, and it needs 24V DC supply.

I am googleing around a bit in order to find the most obvious/suitable ideas to feed it with some rechargeable battery (and suitable charger), while possibly getting ease/convenience of use, being able to use the preamp for a good number of hours in a row or to leave it unused for some time, possibly keeping the battery charged so that I won't need to wait/recharge it just when i need to use the turntable, getting stable voltage while i am using it, the possibility to replace the batteries in a few years without needing to restart from scratch with a new device and, also, not breaking the bank... I understand these are quite a few constraints, though.

I see there are more options around, like Ni-MH battery cells, Li-ion cells, Lead batteries... many of which are quite high capacity (and, of course, more expensive) options suitable for devices which need a lot more power than such phono preamp.

So, which would be your best choice both in regards of a suitable low noise power supply and rechargeable batteries (together with a suitable charger)?

I'd be also ready to DIY a good solution, of course.


Thanks in advance,

Vince.
 

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#2
I would look into batteries for exit sign backup. Charger I don’t know.

Inhad a similar idea where it would charge when in “off” position and when turned on, would disconnect from the line and run off the battery.
 

vince666

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#3
I would look into batteries for exit sign backup. Charger I don’t know.

Inhad a similar idea where it would charge when in “off” position and when turned on, would disconnect from the line and run off the battery.
yes, i also was thinking about something like that... which would rule out Ni-MH batteries which would suffer of being charged when not totally discharged... maybe lead batteries, like the ones into computer UPS, would work fine in such situation? Two of such 12V batteries to put in series would maybe be the ones with the lowest price of all the available options.
And, maybe, modifying a computer UPS by keeping only the recharger part and removing the AC inverter output part might work?
Like keeping it always on so that the batteries are always kept in full charge, save while they're disconnected while being used to supply the preamp.
Just, most computer UPS (at least the consumer affordable ones) do use only one 12V battery.
 
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vince666

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#5
Screw that, go SOLAR!!!! :)

Then you only need to worry about distortion from solar flares :)
HUH? didn't even consider thinking about this! :D

anyways, i would still need some batteries to store energy to be able to play vinyl at night, don't I?:cool:

a windmill blade might also be a "green" solution, though.
 
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vince666

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#6
and, about those 12V lead batteries usually found into computer UPS (which do cost here like 7 eur each)...

I wonder about any possible drawbacks related to such kind of batteries, which are like about 7 Ah ones, by making them powering a device which needs only 50mA.
 

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HUH? didn't even consider thinking about this! :D

anyways, i would still need some batteries to store energy to be able to play vinyl at night, don't I?:cool:

a windmill blade might also be a "green" solution, though.

You just need to do what they did in the "Olden Days" (when Lee was a youngster) and work during the daylight.
 

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#9
and, about those 12V lead batteries usually found into computer UPS (which do cost here like 7 eur each)...

I wonder about any possible drawbacks related to such kind of batteries, which are like about 7 Ah ones, by making them powering a device which needs only 50mA.
That would not be a problem. You would get 140 hours of operation between recharges
 

vince666

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#10
Those exit sign batteries are sealed 12V I believe.

Motircycke battery might be an option too. Well, two of them.
i believe we are both talking about something like these, which i have into my computer UPS and use to replace each few years, only that the price they ask there at the link is quite a bit higher than how I usually pay them here:

https://www.amazon.it/Batteria-piombo-capacità-FIAMM-FG20721/dp/B00L0GG7A0/ref=asc_df_B00L0GG7A0/?tag=googshopit-21&linkCode=df0&hvadid=194982122770&hvpos=&hvnetw=g&hvrand=15379052296377671634&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9050631&hvtargid=pla-467018634365&psc=1

of course, two of them would be needed to get 24V


That would not be a problem. You would get 140 hours of operation between recharges
Sure, even if such kind of batteries don't usually love to be totally discharged, then i won't use them 140 hours before recharging them.
But, if i am correct, they still will not suffer by being recharged while they are still almost at full charge or also in always being under charge (like what happens on my computer UPS which i always leave on, even while the computer is off) which is a good thing.

So, if they will keep very stable voltage while i feed/use the phono preamp (which should easily happen since it sucks only 50mA) , it seems there are only pros and no apparent cons in choosing just these... also, they would satisfy all the "constraints" i mentioned at the opening post, included the fact that they cost less than putting together 24V with Ni-MH or Li-ion cells.

Of course, i must still refine the project a bit, regarding how to exactly recharge and manage them... but choosing the actual kind of batteries is just the needed starting point.
 
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vince666

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#11
Of course, i must still refine the project a bit, regarding how to exactly recharge and manage them...
thinking out loud about this point....
I might simply rely on some computer UPS, since it just works which such kind of batteries and it's quite cheap to get, by keeping only the recharger circuit and removing the AC inverter part... then, since the UPS works with only one battery at a time, it will recharge only one 12V battery... unless there are models which work with two batteries like put in parallel to get more power...
So, I will recharge them like two individual 12V batteries (or together put in parallel but still at 12V) and, while using them for the phono amp, I will simply put them in series to get the needed 24V.
Then, to also avoid any dangerous mistakes while switching from "recharge mode" to "use mode" and back, more than using any switches, I might simply arrange some suitable plugs to connect them in parallel to be recharged or in series while using the preamp.
With a suitable plug system, it would be impossible to mistakenly connect the batteries to the charger (parallel) and to the preamp (series) at the same moment.

sounds as a good starting point for now, i guess.
 

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#13
i believe we are both talking about something like these, which i have into my computer UPS and use to replace each few years, only that the price they ask there at the link is quite a bit higher than how I usually pay them here:

https://www.amazon.it/Batteria-piombo-capacità-FIAMM-FG20721/dp/B00L0GG7A0/ref=asc_df_B00L0GG7A0/?tag=googshopit-21&linkCode=df0&hvadid=194982122770&hvpos=&hvnetw=g&hvrand=15379052296377671634&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9050631&hvtargid=pla-467018634365&psc=1

of course, two of them would be needed to get 24V




Sure, even if such kind of batteries don't usually love to be totally discharged, then i won't use them 140 hours before recharging them.
But, if i am correct, they still will not suffer by being recharged while they are still almost at full charge or also in always being under charge (like what happens on my computer UPS which i always leave on, even while the computer is off) which is a good thing.

So, if they will keep very stable voltage while i feed/use the phono preamp (which should easily happen since it sucks only 50mA) , it seems there are only pros and no apparent cons in choosing just these... also, they would satisfy all the "constraints" i mentioned at the opening post, included the fact that they cost less than putting together 24V with Ni-MH or Li-ion cells.

Of course, i must still refine the project a bit, regarding how to exactly recharge and manage them... but choosing the actual kind of batteries is just the needed starting point.
Li-Ion batteries are a PIA to charge and need careful charge management. Lead Acid batteries just need a constant voltage source (usually 13.8V for a 12V Lead Acid cell). Much easier to charge.
 

vince666

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#15
i do really appreciate any kind of inputs/ideas from you all, as it's all food for thought, thank you all. :)

anyways, at now, as suggested by Gepetto, the lead acid battery solution seems to be the easiest to arrange and manage and also easy to get parts as they are all commonly and easily available here.
Actually, just my brother at his own computer shop/repair-shop here below has the 12V lead acid batteries in stock then it would just be the most obvious choice... in fact, when i need to replace them into my computer UPS i simply go down, grab the battery and don't even pay it... then, indeed, it's the cheapest option of them all. LOL :p
He also sells power banks, btw, then i will ask him how they do work, if anything, just out of curiosity.
 
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vince666

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#17
well, after googleing/thinking a bit more, i guess i have the right solution...

getting a common home computer UPS, since the way it handles the battery is just OK and it can be left always on so that it will keep the battery in full charge without worrying, because it's designed to work on its own.

connecting two batteries in parallel to the UPS, which will only take some more time to charge but it's not a problem since it will be always left on and connected to the batteries when i am not using the phono preamp.

while using the phono preamp, i disconnect the batteries from the UPS and connect them in series to the preamp.
the very low power required by the preamp won't discharge the batteries that much.

organizing the battery switching between preamp/UPS (series/parallel) with a few suitable plugs and routing the wires accordingly.

the advantages are that by using a computer UPS (and by removing the unneeded AC inverter output) i just have all i need ready and also quite cheap, or also for free is, somehow, my brother happens to have in his laboratory storage area a semi-broken UPS with the charger part which still works, otherwise i will simply need to buy a home computer UPS which isn't a too expensive item.
 
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