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Listening impressions of Regen battery tweak

Posted by jkeny (M) on November 27, 2015 at 06:21:15

I started a thread on this which has become polluted by know-it-alls & various numbskulls with gripes. As a result any listening impressions of this tweak are lost in the "noise" of the chattering numbskulls

So here's a thread (which will hopefully avoid the "noise" of numbskulls) in which to report on your experience with this modification.

I have repeated the modification details below from the other thread

I was asked for details of an easy & reversible modification to the Regen that greatly improves its sound quality.

This is not another PS to plug into the DC input of the Regen - it's a bypass of the 3.3V on-board regulator with a 3.3V LiFePo4 battery supply. I know the regulators are said to be state of the art but a LiFePO4 battery smashes this out of the park.

Obviously you need to open up the Regen to connect a battery to the output from the 3.3V regulator & ground, thus bypassing the regulator. There is a ceramic capacitor C3 right at the output of that regulator - the reg at the top of the pic - REG33.

There's a copper via with a 5 beside it at top of that C3 capacitor - this is the GROUND point for connection. The other side of the capacitor is the connection to 3.3V positive (the one with two vias side-by-side). You need to attach the battery + & - poles to these points - soldering to these vias is best. It's very easy to reverse this if desired.

This powers the USB hub chip & the clock which is all that's needed for audio devices that don't need USB Vbus 5V power for signalling or for powering the audio device. You can still do this tweak but you need to supply the 5V separately

BTW, I forgot to include this: this provides a far superior sound than using 2 of the same batteries to power the Regen through its DC input so it's not just the batteries that make the difference but bypassing the REG33 also. This signifies, to me, that the regulator is a limiting factor.

I don't exactly know how a better PS on the Regen's clock & USB hub chip translates into a better sound downstream at the audio device - I don't believe any measurements have yet revealed this?

Try it & post your reports

Edit: I am reminded by some of the posts on this thread to warn people that they do this at their own risk & that they should be somewhat competent in DIY to do this. These batteries can put out a lot of power - treat them with respect - as you would a car battery - they are that powerful

Edit: To find suitable batteries do a search for "26650 LiFePO4 batteries" - make sure they are 3.2V & get the ones with tabs welded to the ends (they are easier to solder a wire to). Something like this http://www.ebay.com/itm/2X-26650-3-2V-3-3AH-LiFePO4-Rechargeable-Battery-w-tabs-/320657847254?hash=item4aa8b273d6:g:puoAAOxyPH9RvsJ2

You need to trickle charge the battery with a 3.3V regulated supply. This is just an ordinary 3.3V supply, NOT a LiFePO4 battery charger (a LiFePO4 battery charger will output 3.6V which you don't want)

Finally, if you want to make this permanent, you will need to put a switch after the battery that turns the Regen on/off unless you want to leave it on permanently

Edit: I also see John Swenson has posted about this & he is correct. So let me reiterate what I originally proposed

- trickle charge the LiFePO4 battery with a regulated 3.3V PS permanently connected, NOT a LiFePO4 battery charger (thus avoiding > 3.3V)
- I didn't propose using the Regen's onboard 3.3V regulators as the trickle charger but when people asked about using it, I suggested trying it. Once this regulator is ONLY ever trickle charging, there should be no strain on that regulator chip.
- Don't allow the batteries to go low in charge. This could happen if you don't have the 3.3V trickle charger connected/powered & you are running the Regen off the battery. If you are going to store it away for a period of time then disconnect the battery from the unpowered charger.

If these recommendations are followed this should operate without a hitch, no need for battery bypass capacitors etc.

NOTE: If you allow the battery to run low (you should never let it run lower than 2.7V) you need a different approach to recharging/reconditioning back to 3.3V. As pointed out by JS these batteries will attempt to draw a significant current from any PS that is connected to charge them. Thus the 3.3V PS needs to be self-limiting & this is probably where you can usefully use a LiFePO4 battery charger while the battery is disconnected from the Regen (i.e switched off)

As I said, this shouldn't be needed if you permanently trickle charge the battery

Edits: 11/30/15 11/30/15 12/01/15 12/01/15

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