Battery power supplies for the Regen

[sandyk]

Hi John!

I own the KingRex uPower myself and use it to power the USB Regen. There is two things that have haunted my mind lately and I cannot really find a good answers online. If you have any knowledge about this I would appreciate some advice!

 

1. Battery supplies are sensitive to ground and tend to store the current in the chassi. Would it ve a good idea to ground the chassi to an external grounding point like Entreq Minimus?

 

2. I know that batteries just store energy from chemical reaction and in my "sensible mind" the power charging the batteries will not make any difference. My "mad scientist mind" say that the mains noises should penitrate the batteries and will make a difference with a "cleaner" output battery power...so using linear power (or even battery power charging the battery) should increase battery performance to the supplied SPMS. Which part of my mind is speaking the truth?

 

/Micael

 

Cornan

You have completely lost me with point 1.

It doesn't make much sense to me.

Yes, charging a battery while in use will result in noise modulating the battery power to some extent.

Even several banks in parallel of 24 series 2.2V 2,200 AH (or higher) batteries in a Telephone Exchange can't completely silence the effects of the huge rectifier cabinets that "float" them. As usual, it depends on the quality of the charging apparatus and the filtering of it's output. I use either a low noise Linear PSU followed by a Super Regulator, or a 12V 4,000mAH Li Ion rechargeable battery regulated down to +9V followed by a "Shunt" type of Super Regulator. This slightly outperforms the Linear PSU when powering the Regen, due to the capacitive coupling between Primary and Secondary sides of the transformer back to mains earth, which results in a minor earth loop.

 

Alex

[sandyk]

Hi Cornan

 

Superdad beat me to it.

BTW, it's always best to completely remove the charger, whether SMPS, or a Linear PSU, while playing music, unless you are using a supply like the soon to be released Uptone Ultracap supply which according to it's designer John Swenson, completely isolates the supply from the mains, However, it can't stop crap getting back into the A.C. Mains sewer from an SMPS plugpack, and to a far lesser extent from a well designed Linear PSU.

 

It would'nt surprice me if the currents is mixed in the chemical reaction and affecting the DC output...even if the sensible me says no way!

That seems highly unlikely, even if you are using unfiltered rectified D.C .

A typical SMPS has a reasonably low ripple output and the high equivalent capacitance of the battery itself should take care of that very small residual, just as a large value low ESR electrolytic capacitor at it's output would.

 

 

 

Alex K.

[sandyk]

However, since this battery have a separate lead for the charger and have a charger with over-voltage protection and under-voltage protection it will be ok to charge it at the same time as powering the USB Regen.

 

No, it won't be O.K. for best results.

The USB Regen should be if possible, powered from a source that has no connection to the A.C. mains, and hence some degree of an earth loop. John has already stated that the power source should be unplugged from the battery when playing.

 

The whole purpose of a system like this is that you unplug the charger from the wall (and the REGEN) while in use.

[sandyk]

That is what I wrote in my reply as well. This part of the reply is just me explaining that it is safe to charge while the USB Regen is connected.

 

You mentioned that the output voltage is cut off when the battery voltage drops down to 5.5V, but you haven't mentioned what the over voltage limit is. Obviously the charger's output voltage will need to somewhat over 7.2V to fully charge a 7.2V battery.

Personally, I wouldn't rely on a charger's over voltage limiter to protect something like a Regen.

If you really need to use the Regen while the battery is charging, it's better to buy 2 batteries that you can use alternately.

[sandyk]

Cornan

There are just as many Li Ion batteries listed as 7.2V. If you do some research you will find that the basic voltage is stated to be 3.65V with 2 in series . 7.4V sounds more impressive than 7.2V though doesn't it, when it is actually more like 7.3V ?

This is like with a "9V" Ni MH battery where the actual voltage is more like 8.4V.

 

Lithium-ion

 

The nominal voltage of lithium-ion is 3.60V/cell. Some cell manufacturers mark their Li-ion as 3.70V/cell or higher.

This offers a marketing advantage because the higher voltage boosts the watt-hours on paper (voltage multiplied by current equals watts).

The 3.70V/cell rating also creates unfamiliar references of 11.1V and 14.8V when connecting three and four cells in series rather than the more familiar 10.80V and 14.40V respectively. Equipment manufacturers adhere to the nominal cell voltage of 3.60V for most Li-ion systems as a power source.

 

 

 

Battery Voltage Information – Battery University

[sandyk]

a USB Regen that has to provide 5V power to a DAC will fail before you can get down to 4.6V.

 

In fact, it will fail to remain in regulation after it drops below 5.3V which is well above the battery's cut off voltage.

[sandyk]

Thanks Alex. In the absence of any kind of voltage monitoring alarm, what would you expect a user to hear, while listening to music, when the USB Regen suddenly fails to get 5.3V? Would it just go immediately silent or do you think there might be a transition period, during which the sound quality starts to erode in some way?

 

I would expect the latter. Given the rating of the battery, perhaps one of the attached connected on the device side of a toggle switch etc, could be worthwhile ?

DC 0 100V 3 30V Digital LED CAR Voltmeter Gauge Voltage Panel Meter 2 3 Wire PRO | eBay

[sandyk]

As I previously shared, even allowing cells to fall all the way to the recommended 3.0V minimum can leave you having to soon replace a pack.

 

Another good reason for using the mini DVM module, and ensuring that the voltage doesn't drop below 6V.

With the Regen it will still be in regulation with a 6V input, and you won't be able to tell by a change in the Regen's performance.

[sandyk]

I love this voltage meter Mike! I have been looking for something like this ready made all over without success.

A couple of $ will get you one of the attached or similar , which are available in different LED colours ( I have a couple with White LEDS )

DC 0 100V 3 30V Digital LED CAR Voltmeter Gauge Voltage Panel Meter 2 3 Wire PRO | eBay

They are also available from quite a few other ebay suppliers such as

Bang good.com which has many other interesting gadgets too.

led volt meters - Buy Cheap led volt meters - From Banggood

They only draw about 20mA from the battery, so they won't shorten the listening time by much with a larger AH battery.

[sandyk]

IME battery power will always be more laid back and smoother than a good SMPS and LPS...but will gain in transparency and a lower noise floor.

 

That is simply not correct. A very good linear PSU can have a lower impedance that is maintained, unlike that of a battery that is discharging, lower noise, and far greater voltage stability under varying load conditions.

You also need to take into account the proximity of the battery to the device to be powered (lead length and gauge of wire) as well as the type of connection made to the battery. e.g. soldered or via a push fit holder etc.

Long leads from a battery may also pick up RF/EMI.

[sandyk]

That is why i wrote IME (in my experiance) Alex. I am not saying that batteries are overall more silent than a well made (and usually more expensive) LPS...but when batteries are used disconnected from the mains you will have a potensially lower noise floor since the noise cannot come through the "back-door" which is (so far) impossible to prevent with a LPS. Batteries do have their specific noises as well which is likely one of the reasons why I personally hear such a good improvement from externally grounding my Kingrex uPower through the USB output.

 

Hi Cornan

I agree that it is hard, but not impossible to isolate a typical LPS from all mains related effects like the new Ultracap PSU will do. I.M.O. the best way to avoid battery problems is to start with a higher battery voltage. e.g. 12V and regulate it down to 9V or whatever is needed, using a low noise voltage regulator located near the device to be powered. You will then have a constant voltage from a low impedance source that has a noise level that can rival the best of batteries, but still with the A.C. mains removed from the equation.

 

Regards

Alex

[sandyk]

I would also be very interested to know if someone have used Ultracapacitors in combination with batteries to power a USB Regen.

 

That thought has crossed my mind too, but since I use a low noise shunt regulator after the voltage regulator, I decided it probably wasn't worth the trouble.

I did check ebay for suitable Ultracaps though.

[sandyk]

I indeed read of such an odd thing using the repeated discharge of inductors to recharge a battery, the findings were very odd indeed.

 

You can get quite a high voltage from the "back EMF" of an inductor.

In the old Step by Step analogue Telephone Exchanges which typically used -52V supplies, the Signalling relays could develop a back EMF as high as 800V when the circuit was opened during 10 I.P.S dialling ! (monitoring those circuits caused my hearing damage)

The back EMF from a Motor UniSelector was very painful with it's higher current demands if you weren't careful.

Another example is the Kettering car ignition system where you may develop as high as 30KV from a 12V ignition coil.