Jan, I'm hoping to calculate/estimate the max-operating-time of a Power Bank driving a SilentSwitcher.
The SS delivers ±15V at 60 mA, to its load. The PowerBank is rated ten thousand milliamp-hours (= 10 A-h). So far I have:
But I don't know how to estimate SS_EFFICIENCY, the power efficiency of the SilentSwitcher (running ±15V @ 60 mA); also PBDISCHARGEFACTOR, the % of power bank rated capacity that I can extract, realistically, without damaging the batteries or drooping the "5V" excessively.
Do you have any guidance or recommendations?
The SS delivers ±15V at 60 mA, to its load. The PowerBank is rated ten thousand milliamp-hours (= 10 A-h). So far I have:
SS_Pout = (30V * 60mA) = 1.8 Watts
SS_Pin = SS_Pout / SS_EFFICIENCY
PBankCurrent = SS_Pin / 5.0V
PBankLifetime = 10 A-h * PBDISCHARGEFACTOR / PBankCurrent
SS_Pin = SS_Pout / SS_EFFICIENCY
PBankCurrent = SS_Pin / 5.0V
PBankLifetime = 10 A-h * PBDISCHARGEFACTOR / PBankCurrent
But I don't know how to estimate SS_EFFICIENCY, the power efficiency of the SilentSwitcher (running ±15V @ 60 mA); also PBDISCHARGEFACTOR, the % of power bank rated capacity that I can extract, realistically, without damaging the batteries or drooping the "5V" excessively.
Do you have any guidance or recommendations?
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The SS efficiency will be somewhere between 85-95%. Use 85% as worst case.
I have a Powerbank 10AHrs running a SS hat delivers 110mA per polarity and it runs for half a day easily. Those Powerbank ratings are only for one specific discharge rate, the capacity varies with discharge rate.
And the advertised capacity like 10AHrs is for the 3.7V internal battery. The Powerbank converts that 3.7V to 5V so there you lose both capacity and efficiency as well.
Jan
I have a Powerbank 10AHrs running a SS hat delivers 110mA per polarity and it runs for half a day easily. Those Powerbank ratings are only for one specific discharge rate, the capacity varies with discharge rate.
And the advertised capacity like 10AHrs is for the 3.7V internal battery. The Powerbank converts that 3.7V to 5V so there you lose both capacity and efficiency as well.
Jan
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Thanks, Jan!
110mA @ +12V and -12V is 2.64 watts. If SS efficiency is 90% then 2.93 watts are drawn from the power bank. Which equals 5V at 590 mA.
590 mA from a 10 Amp-hour bank is a "come on get real, it can't possibly be this high, lifetime" of 17 hours. But your real life + real world experience is that the lifetime is about 12 hours, so PBDISCHARGEFACTOR is 12/17 = 70% in your experience.
That's great to know. Thank you!!!
Mark
110mA @ +12V and -12V is 2.64 watts. If SS efficiency is 90% then 2.93 watts are drawn from the power bank. Which equals 5V at 590 mA.
590 mA from a 10 Amp-hour bank is a "come on get real, it can't possibly be this high, lifetime" of 17 hours. But your real life + real world experience is that the lifetime is about 12 hours, so PBDISCHARGEFACTOR is 12/17 = 70% in your experience.
That's great to know. Thank you!!!
Mark
Friends,
The SilentSwitchers in the diyaudio store are almost gone and I've been thinking about doing another run, or take the opportunity to update the design.
One comment I often hear is the limited output current of 150mA at +/-15V. I could update the design to provide at least double that, probably up to 400mA at +/-15V.
Also provide for a wider input voltage range than max 11V, like up to 20V so you could supply is also from a power brick.
One thing to remember is that if you want 400mA at +/-15V, that is 12W or more than 2A from a USB port or Powerbank so that may max that out. If you then also draw 1A from the +5V, you need something more powerful than a USB charger.
That bring me to the next question: is that auxiliary 6.5V/5V/3.3V supply useful? Do you normally use that too or would you just want the +/-15V?
Jan
The SilentSwitchers in the diyaudio store are almost gone and I've been thinking about doing another run, or take the opportunity to update the design.
One comment I often hear is the limited output current of 150mA at +/-15V. I could update the design to provide at least double that, probably up to 400mA at +/-15V.
Also provide for a wider input voltage range than max 11V, like up to 20V so you could supply is also from a power brick.
One thing to remember is that if you want 400mA at +/-15V, that is 12W or more than 2A from a USB port or Powerbank so that may max that out. If you then also draw 1A from the +5V, you need something more powerful than a USB charger.
That bring me to the next question: is that auxiliary 6.5V/5V/3.3V supply useful? Do you normally use that too or would you just want the +/-15V?
Jan
6 months ago I would have said being able to run of a 12v battery (so 14.4. float) would have been wonderful, but then I discovered many lithium booster packs on ebay with 9V output which removes that need.
Personally I find the aux supply ideal for driving relays. I may be an outlier in that though as I have a stash of 5V relays.
Personally I find the aux supply ideal for driving relays. I may be an outlier in that though as I have a stash of 5V relays.
Good news!
Even better news, on both counts!
Definitely, please keep it!
It would also be great if we could have the option to increase the +/- supply voltage to 17 or 18 volts. If we can have 400mA at +/-15V, what could we have at +/-18V?
Best regards.
Going on vacation in May?
Good news - the last I had just went into a project!
Am on vacation now! But the work must go on ...
Jan
Running it at 12V is tricky, you never know when the input slightly drifts above 12V, and that can be harmful.
There is a protection zener of 11V across the input for that. I don't know how adventurous you are or what you experience is. You *could* remover the zener and just do it, but don't come to me when something goes wrong ;-)
Jan
There is a protection zener of 11V across the input for that. I don't know how adventurous you are or what you experience is. You *could* remover the zener and just do it, but don't come to me when something goes wrong ;-)
Jan
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Great. BTW, like NicMac said, what happened to May?
Need one to supply a Soekris DAC board. The current 15v version SS is a little (too) hot for the DAC board. It will be perfect with 8-10v.
I am definitely NOT going on vacation; so far I am still in a single prison cell at home
The delivery is a bit wavy as the company has issues with staff staying home, sick or worried, but they said they would still deliver and of April. That's end of the week ...
Jan
