Discussion of LiFePO4 battery mods of REGEN and other out-of-warranty adventures

[zilch0md]

Since it looks like there are several people here that really want to try this, here are some warnings and theory behind battery charging etc.

 

[snip]

 

 

Thank you, John!

[zilch0md]

Hi tims,

 

From post 28

"Yes, that's a great idea as long as the USB Regen can perform well at voltages between mmerrill99's stated 3.0V and 3.65V (having bypassed its 3.3V regulator), and you somehow ensure that the battery pack never falls below mmerrill99's stated 3.0V minimum between charge cycles"

 

What happens if the battery's voltage drops below 3V - will it damage the Regen in some way or will the Regen simply stop working?

Also, will the LiFePO4 battery's life be compromised (reduced?) or damaged in some way If the voltage drops below 3V?

Thanks

 

Keep in mind that John Swenson has told us the USB Regen should be OK with 3.2 V (even though it expects to see 3.3V). I am not willing to assume the USB Regen would be OK with anything less than 3.2V.

 

 

Mike

[mmerrill99]

Hi tims,

 

Keep in mind that John Swenson has told us the USB Regen should be OK with 3.2 V (even though it expects to see 3.3V). I am not willing to assume the USB Regen would be OK with anything less than 3.2V.

 

 

Mike

 

"Yes, that's a great idea as long as the USB Regen can perform well at voltages between mmerrill99's stated 3.0V and 3.65V "

Mike, it's not me stating that the USB2412 USB hub chip can happily perform between 3V & 3.6V (not 3.65V) - it's directly from the USB2412 chip's datasheet where it specifies the min & max operating voltages.

 

Indeed, it's generally accepted that the battery should not be allowed to discharge below 3V & there seems to be no need for this condition to arise if the suggested trickle charging configuration is used?

[zilch0md]

^ I agree. :-)

[fmak]

Using a Super Regulator, which gives a further improvement in noise levels over a cheap LM317T I.C. based power supply, as well as a lower output impedance, would also appear to help to negate the problems noted by John Kenny re the deficiencies of the already better than average installed 3.3V regulator.

Uptone's new "Mystery" PSU seems likely to confer similar benefits for many Regen users, with possibly a further small improvement over even a JS2 supply which is shared with other areas. The better the power going into the Regen's internal 3.3V regulator, the less work it has to do, other than provide a very stable output voltage.

 

As I see it, the issue is this:

 

There is a 3.3V regulator in parallel with a battery at 3.3v or thereabouts. When powering a Regen

or anything else, which PS at a given time provides current and regulates power input into the

chip? Presumably when the voltages are equal, both provide certain percentages of power.

 

It is difficult to see, in a transparent way, how the quality of the regulator does not impact on the

quality of power into the chip.

 

There is a lot of loose 'theoretical' talk in AA about the thing is supposed to work.

 

As a manufacturer who insists that this is the way to get the best quality out of the dac, it

seems to me that he has the responsibility to measure power supply quality and show the results

before promoting it as an ultimate tweak.

 

In time to come, I shall try various powering schemes but LiFePOs are taking a hell of a lead time to arrive.

 

In the meantime, 5200 mAh LIPOs charged by a smart charger work for longer than a week and provide

very good results sonically. The downside, however, is the need to limit discharge to 6V for a 2 cell unit. I am

having to order an alarm but in the meantime, I am monitoring voltage daily. Experience has been that, if it drops

significantly, then stop.

[mmerrill99]

As I see it, the issue is this:

 

There is a 3.3V regulator in parallel with a battery at 3.3v or thereabouts. When powering a Regen

or anything else, which PS at a given time provides current and regulates power input into the

chip? Presumably when the voltages are equal, both provide certain percentages of power.

 

It is difficult to see, in a transparent way, how the quality of the regulator does not impact on the

quality of power into the chip.

Have you ever tried to charge your batteries while also playing from them to check your concerns?

 

There is a lot of loose 'theoretical' talk in AA about the thing is supposed to work.

 

As a manufacturer who insists that this is the way to get the best quality out of the dac, it

seems to me that he has the responsibility to measure power supply quality and show the results

before promoting it as an ultimate tweak.

I presume you apply the same to Alex & John - the manufacturers of the Regen - they have a responsibility to show results of their measurements? Presumably, even more responsibility as they are selling a product & this battery tweak is not!

 

Of course many people listen to the Regen & don't need measurements - they decide for themselves on it's value! Should this not apply to this tweak also?

 

In time to come, I shall try various powering schemes but LiFePOs are taking a hell of a lead time to arrive.

 

In the meantime, 5200 mAh LIPOs charged by a smart charger work for longer than a week and provide

very good results sonically. The downside, however, is the need to limit discharge to 6V for a 2 cell unit. I am

having to order an alarm but in the meantime, I am monitoring voltage daily. Experience has been that, if it drops

significantly, then stop.

Look forward to your results

[fmak]

How does this address the issues I raised?

 

It would be stupid to try charging a 5200 mAh LiPO whilst playing into an expensive dac.

[fmak]

John

A simpler way is to have 2 batteries , with the original being recharged while the other is swapped in.

I use a 12V 4,000mAh Li Ion battery regulated down to +9V for the Regen supply.

The total cost including the plugpacks is only around $30 for 2 of those.

You could similar to what you are suggesting using a 7.2V Li Ion battery into a LM317T set for +3.3V, (or a LM3940T-3.3) with a suitably sized heatsink inside a small box with a 3.9 ohm PW5 series resistor to float the LiFe P04 battery ?

The additional battery would ensure no down time between listening sessions, and there would be no mains earth loop issues.

Regards

Alex

 

I am quite happy using a 5200mAh LiPO and will buy a second, for about £30 total. However, a smart

charger is another £15 and a low voltage alarm £5.

 

This compares to a Twisted Pair 3.3V Shunt at $30 plus $10 postage!

 

I know what I'd prefer ie 3.3 and 5 V superegulators with preregulation from my array of 5V units

[mmerrill99]

How does this address the issues I raised?

 

It would be stupid to try charging a 5200 mAh LiPO whilst playing into an expensive dac.

I was simply suggesting that you seemed to have all the necessary equipment to test your issues & rather than obsessively posting about this on any forum you haven't been banned from, you could instead use this energy to answer your own questions.

 

But then maybe this isn't your objective?

[sandyk]

It is difficult to see, in a transparent way, how the quality of the regulator does not impact on the

quality of power into the chip.

 

fmak

To quote John Swenson

 

As to why having the battery across the charging supply makes the characteristics of the charging supply not matter, it is a simple voltage divider. The battery has less than 10 milli-ohm impedance across a wide frequency range, you are feeding it with a 4 ohm resistor, that is 4/.01 which is a reduction of 400 times, that is a 52db reduction in noise from the charging supply.

 

My preference (at present) is to use a 12V Li Ion battery in order to get away from mains related issues, regulate it down to +9V followed by a modified John Linsley Hood designed PSU add-on ,which is a form of low noise shunt regulator, has around 4uV noise (original design, and is very low impedance. It also has no voltage drop through it, other than via it's copper tracks.

[JohnSwenson]

I want to make this clear, I am NOT officially recommending this mod. If you do it wrong you destroy the REGEN. I have not tried it, I have no idea if it improves things or not. I refuse to produce a specific recipe.

 

There is a theoretical method by which it can produce lower noise in some frequency ranges than the built in regulator. Getting that is not trivial. Whether it actually improves SQ is probably system dependent.

 

The recent post of mine was not intended as an endorsement of this process. It seems that several people are going to try this anyway and I wanted to make sure they understand the pitfalls of different approaches and what may offer an approach that may actually work without destroying the REGEN.

 

John S.

[sandyk]

Discussion of LiFePO4 battery mods of REGEN and other out-of-warranty adventures

 

 

Hi John

I was the first to raise concerns about the use of the internal 3.3V regulator to charge a 3.3V battery.

Although I have suggested methods for others to more safely power a battery used to power the 3.3V area of the Regen, I have also counselled against doing so due to the risk of damage to the Regen. I would suggest that those who wish to further improve the PSU to the Regen either wait until the reports start to come in about the Regen being partnered with your soon to be released "Mystery" PSU, or explore other areas such as the use of a highly stable Super Reg to power the whole of the Regen .

 

Regards

Alex

[tims]

I'd prefer to run it without the trickle charging. In order to avoid draining the battery below 3v, I would like to run it through a relay together with a cct that can sense when the voltage drops to 3v and then opens the relay.

Anyone know if its possible to buy something like this or know of a cct design thay I can DIY?

 

Thanks

[sandyk]

I'd prefer to run it without the trickle charging. In order to avoid draining the battery below 3v, I would like to run it through a relay together with a cct that can sense when the voltage drops to 3v and then opens the relay.

Anyone know if its possible to buy something like this or know of a cct design thay I can DIY?

 

Thanks

 

I am not volunteering, but wouldn't a bright and efficient red LED coming on when the battery dropped to 3V be adequate warning? A 3V relay would cause the time between charges to be reduced due to operating coil requirements, as low voltage relays usually have much lower resistance coils.

[fmak]

Re: the above quote from JS's Post

 

If you examine the products Jkeny has applied his power supply to in his own product range, you will see that these are low to mid-price modules based on M2Tech modules and other dac chips like the PCM 5102.

 

His insistence that battery+3.3V supply gives the 'best' sound quality is his own opinion, supported

by a handful of others and seems to me largely untested and confirmed by a significant number if

users.

 

Sure, it will change SQ, but lots of other things do so to a significant degree as well.

 

I was trying out spdif with a Wave IO fed by the Regen and powered by an iFi usb power last night.

I first connected the Wave IO to the W4SDSDSe with a Wireworld Gold BNC cable, observing the

directional marking. This produced a focussed but edged SQ which was good for vocals but which

lacked the special qualities I heard from the usb connection. Reversing the cable direction brought

this back and the sound was a lot closer to that from the usb connection.

 

Go figure!!!!!!

[sandyk]

I was trying out spdif with a Wave IO fed by the Regen and powered by an iFi usb power last night.

I first connected the Wave IO to the W4SDSDSe with a Wireworld Gold BNC cable, observing the

directional marking. This produced a focussed but edged SQ which was good for vocals but which

lacked the special qualities I heard from the usb connection. Reversing the cable direction brought

this back and the sound was a lot closer to that from the usb connection.

 

Go figure!!!!!!

 

Let's hope that George or sal1950 don't see this post! (grin)

[ElviaCaprice]

Re: the above quote from JS's Post

 

If you examine the products Jkeny has applied his power supply to in his own product range, you will see that these are low to mid-price modules based on M2Tech modules and other dac chips like the PCM 5102.

 

His insistence that battery+3.3V supply gives the 'best' sound quality is his own opinion, supported

by a handful of others and seems to me largely untested and confirmed by a significant number if

users.

 

Sure, it will change SQ, but lots of other things do so to a significant degree as well.

 

I was trying out spdif with a Wave IO fed by the Regen and powered by an iFi usb power last night.

I first connected the Wave IO to the W4SDSDSe with a Wireworld Gold BNC cable, observing the

directional marking. This produced a focussed but edged SQ which was good for vocals but which

lacked the special qualities I heard from the usb connection. Reversing the cable direction brought

this back and the sound was a lot closer to that from the usb connection.

 

Go figure!!!!!!

 

Have you tried it out???

[tims]

I am not volunteering, but wouldn't a bright and efficient red LED coming on when the battery dropped to 3V be adequate warning? A 3V relay would cause the time between charges to be reduced due to operating coil requirements, as low voltage relays usually have much lower resistance coils.

 

I thought this was a good idea so asked Silicon Chip magazine whether they had previously published a cct for a low voltage warning LED for a Lifepo4 battery. They hadn't but John Clark (of Silicon Chip) sent me the following cct to use (Silicon Chip also gave me permission to post it here - great mag by the way!):

 

 

"It uses a 2.5V reference (REF1) and a micro power comparator (IC1).

 

The reference is supplied current via a 3.9k ohm resistor to provide an accurate 2.5V reference. The 3.9k ohm resistor provides a nominal 128uA of current.

 

A 1M ohm trimpot VR1 connects across this reference and the wiper can set the voltage for the required threshold.

 

IC1 is connected as an inverting Schmitt trigger that compares the reference voltage from VR1 with the cell voltage. The cell voltage is divided by two using two series connected 1M ohm resistors across the cell supply. The 10M ohm resistor provides for a small amount of hysteresis of around 150mV. This hysteresis prevents the LED flickering on and off at the threshold.

 

VR1 is adjusted to provide the required threshold voltage for when the low cell voltage is indicated with LED1. A high brightness red or green LED should be used as the current is only 2mA and the voltage available to drive the LED is lower that that required for a white or blue LED.

 

Note that parts can be obtained from these suppliers.

 

LM285-2.5Z is available from Jaycar Cat ZV-1626 (www.jaycar.com.au)"

 

The cct also made it into Feb 2016 the SC magazine

[sandyk]

Tims

 

Yes, Silicon Chip is a great Aussie Electronics magazine, with many of it's published projects also appearing in the U.K. magazine Everyday Practical Electronics. I have constructed many of Silicon Chip's published projects over the years, including Preamps, PowerAmps, DACs ,Dual Adjustable Bench Power Supplies etc.

 

Regards

Alex

 

P.S.

You could also fit one of the RED (NOT Blue or White) DVM modules at the attached link and check it at the start and end of each listening session. Wire it through a toggle switch though so it won't add to the current drain.

 

http://www.ebay.com.au/itm/0-28-Inch-2-5V-30V-Mini-Digital-Voltmeter-Voltage-Tester-Meter-/131735712546?hash=item1eac0f7322:g:Rw4AAOSwUuFWzeRe