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Develop ultra capacitor power supply and LiFePO4 battery power supply
Develop ultra capacitor power supply and LiFePO4 battery power supply
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Old 14th September 2018, 02:52 AM   #41
iancanada is offline iancanada  Canada
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Develop ultra capacitor power supply and LiFePO4 battery power supply
Quote:
Originally Posted by hellokitty123 View Post
Ian, why not just do Regulator -> LifePO4 -> Super capacitor?
The regulator will keep the battery and the capacitor charged 100% of the time and the battery+capacitor act as low impedance power delivery while also filtering out the remaining noise from the regulator.
The best of all worlds.
I never understood why people want to place a battery or super cap before the regulator.
1. LifePO4 and ultra capacitor are much better power supplies for DAC and I/V stage than any active regulator with feedback. You can google the principle;

2. Any regulator or LDO after LifePO4 or ultra capacitor will degrade the power supply performance;

3. Floating charging has two problems here:One is that the battery or ultra capacitor will work as decoupling capacitor in this case, they will switch between charging and dis-charging rapidly for dynamic load current demand. Switching between two states will cause ripple thus add noise to voltage rails. The other problem was mentioned above, yes, it's the isolation.

Regards,
Ian
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Old 14th September 2018, 03:02 AM   #42
iancanada is offline iancanada  Canada
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Develop ultra capacitor power supply and LiFePO4 battery power supply
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Originally Posted by wtnh View Post
Hi Ian - I am looking forward to your progress on this. Just as a reference, I built a quick and dirty LiPO supply for my Allo isolator and Boss DAC. The Raspberry Pi is powered by a 5 volt linear supply (which also powers the battery charging module). 2 relays are used to switch the LiPOs between parallel for charging and series for powering the isolator. A third relay switches the power out to the isolator between battery and unregulated power, so that the isolator and DAC are totally galvanically isolated from the Pi.

The relays are controlled by a GPIO pin which goes high when the player is active (it is running PiCorePlayer). When the player is quiescent, the batteries are switched into charge mode. This works well enough so that the batteries always have enough charge for extended listening.

This is pretty simplistic, so for my next project, I would like to implement your idea.

Pictures (one is the custom PCB I made for this) and schematic attached for anyone who wants to duplicate.

Regards

Whit
Hi Wtnh,

Your PCB looks very good. I think you are very happy with your battery power supply and the sound quality.

I did some thing similar years ago. But this time, I have to take a lot of things into design consideration.

Regards,
Ian
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File Type: jpg 19_BatteryManagement.JPG (207.5 KB, 2299 views)
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File Type: pdf BatteryManagementV2.5.pdf (163.0 KB, 244 views)
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Old 14th September 2018, 03:08 AM   #43
hellokitty123 is offline hellokitty123  United States
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Quote:
Originally Posted by iancanada View Post
1. LifePO4 and ultra capacitor are much better power supplies for DAC and I/V stage than any active regulator with feedback. You can google the principle;

2. Any regulator or LDO after LifePO4 or ultra capacitor will degrade the power supply performance;
I meant that you use a regulator before the battery/capacitor, not after.
Quote:
Originally Posted by iancanada View Post

3. Floating charging has two problems here:One is that the battery or ultra capacitor will work as decoupling capacitor in this case, they will switch between charging and dis-charging rapidly for dynamic load current demand. Switching between two states will cause ripple thus add noise to voltage rails.
Since the battery and/or super capacitor act as a decoupling capacitor with <1miliohm impedance how can they cause ripple?

That would be like saying that a bypass capacitor on the output of any regulator will cause ripple. It doesn't make sense.

Last edited by hellokitty123; 14th September 2018 at 03:20 AM.
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Old 14th September 2018, 04:36 AM   #44
iancanada is offline iancanada  Canada
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Develop ultra capacitor power supply and LiFePO4 battery power supply
@hellokitty123

In my design, no regulator is used before LifePO4 battery or ultra capacitor. The output voltage rails are pure and isolated.

Both LifePO4 and ultra capacitor are pretty different to normal capacitors.

LifePO4 has different charging and dis-charging curve. So, output voltage will drop or rise when switched in between.

Ultra capacitor also has slow issue when switches between charging and dis-charging, because of the material.

Designing this kind of power supply would be a bit crazy. A lot of issues have to be taken into consideration to avoid any degrading to the performance.

Regards,
Ian
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Old 14th September 2018, 06:12 AM   #45
ofswitched is offline ofswitched  Taiwan
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Using a 18650 battery to charge supercapacitor and then power it directly from the supercapacitor without LDOs. This is much simpler, anyone can DIY without the PCB.

According to experience, it is better to use multiple supercapacitors in parallel.

Supercapacitors have poor voltage endurance performance. If you use a general DC power supply, even if you use LDOs, there is still a risk of damage to the supercapacitor. If LDOs are not specifically protected, LDOs are easily destroyed by the discharge of supercapacitors. Therefore, using a stable output battery to charge supercapacitor is the most ideal method.

mobile01-d926d80b7877a0e7bff84de0e284dec0.jpg
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Old 14th September 2018, 06:28 AM   #46
ofswitched is offline ofswitched  Taiwan
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Quote:
Originally Posted by iancanada View Post
@sontero

The whole idea is to use LifePO4 battery directly in order to get rid of any LDO/regulator after it.

There is no problem if you DAC runs at 3.3V but with LDO which has 5V input. LDO will be bypassed automatically if the input is lower than the dropout voltage. In this case, you can still feed the 3.3V LifePO4 power into it.

However If your DAC chip runs at 5V originally, you have to use ultra capacitor power supply which will have pure 5V output.

Regards,
Ian
Can BUFFALO-IIISE PRO be used directly?

The Buffalo-IIIse Pro (Stereo Edition) 2-Channel DAC
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Old 14th September 2018, 08:28 AM   #47
hellokitty123 is offline hellokitty123  United States
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Quote:
Originally Posted by ofswitched View Post
Using a 18650 battery to charge supercapacitor and then power it directly from the supercapacitor without LDOs. This is much simpler, anyone can DIY without the PCB.

According to experience, it is better to use multiple supercapacitors in parallel.

Supercapacitors have poor voltage endurance performance. If you use a general DC power supply, even if you use LDOs, there is still a risk of damage to the supercapacitor. If LDOs are not specifically protected, LDOs are easily destroyed by the discharge of supercapacitors. Therefore, using a stable output battery to charge supercapacitor is the most ideal method.

Attachment 703421
Not bad. I like it.
I still have to wonder why batteries or super capacitors are better than a good regulator though. All 3 of them will be useless @ RF no? The output impedance @ audio frequencies is also similar between them. What makes batteries or super caps superior?

Last edited by hellokitty123; 14th September 2018 at 08:46 AM.
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Old 14th September 2018, 10:57 AM   #48
merlin el mago is offline merlin el mago  Europe
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Quote:
Originally Posted by iancanada View Post
Hi Wtnh,

Your PCB looks very good. I think you are very happy with your battery power supply and the sound quality.

I did some thing similar years ago. But this time, I have to take a lot of things into design consideration.

Regards,
Ian
Congrats Ian looks very good & promising.

Click the image to open in full size.
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Old 14th September 2018, 11:06 AM   #49
sq225917 is offline sq225917  United Kingdom
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Quote:
Originally Posted by hellokitty123 View Post
Not bad. I like it.
I still have to wonder why batteries or super capacitors are better than a good regulator though. All 3 of them will be useless @ RF no? The output impedance @ audio frequencies is also similar between them. What makes batteries or super caps superior?
There does seem to be a bit of assumption going on in this thread as regards the audible differences between these different types of PSU. Where's the measurements boys?
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Old 14th September 2018, 11:42 AM   #50
starkeyg is offline starkeyg
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"There does seem to be a bit of assumption going on in this thread as regards the audible differences between these different types of PSU. Where's the measurements boys?"

Let me be the first and say it plainly: Don't need no stink'n measurements. What do you think this is, science?
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