I'm about to use 3 of these LiFePO4 batteries in a USB DAC. These are 3.3V and I will be using 3 of them - 1 to provide 3.3V directly to digital chips on a DAC board & another 2 (with a series R voltage knock-down) to provide 5V to the relevant chips.
Some issues:
- I thought of using some of the many mobile phone 3.3V chargers that have gathered in the house over the years. It is recommended to charge batteries individually even the ones in a battery bank so as to balance the charge across all the batteries evenly. I thought I would have the 3 charges inside my DAC box & just plug it into the mains when not in use. One question, these mobile chargers automatically stop charging when they have reached a threshold - is this cut-off circuitry typically in the charger or in the phone?
- I wanted to avoid a regulator to bring the 6.6V 2*battery pack down to 5V because I wanted to compare the raw battery source against various battery/regulator sources. An R will burn off some excess voltage for me, I believe. How I calculate the needed R is by knowing the current draw on the existing 5V. Is the best way to do this to put a 1R 5W R in the existing 5V PS line & measure the V drop across it? Then I can calculate the needed R for my proposed 1.6V drop.
- The final thing I hope to do is have some LEDs on the box to indicate when voltage drops below 3.3V or 5V respectively - any quick schematic for this?
Some issues:
- I thought of using some of the many mobile phone 3.3V chargers that have gathered in the house over the years. It is recommended to charge batteries individually even the ones in a battery bank so as to balance the charge across all the batteries evenly. I thought I would have the 3 charges inside my DAC box & just plug it into the mains when not in use. One question, these mobile chargers automatically stop charging when they have reached a threshold - is this cut-off circuitry typically in the charger or in the phone?
- I wanted to avoid a regulator to bring the 6.6V 2*battery pack down to 5V because I wanted to compare the raw battery source against various battery/regulator sources. An R will burn off some excess voltage for me, I believe. How I calculate the needed R is by knowing the current draw on the existing 5V. Is the best way to do this to put a 1R 5W R in the existing 5V PS line & measure the V drop across it? Then I can calculate the needed R for my proposed 1.6V drop.
- The final thing I hope to do is have some LEDs on the box to indicate when voltage drops below 3.3V or 5V respectively - any quick schematic for this?
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Hi Jkeny,
- The battery charge management for cell-phone batteries is normally inside the phone itself. It is then often software-based, or a dedicated part of the power management IC's. The adapters that come with your phone are usually very simple DC power supplies with no battery management.
- If you have a multimeter with current measurement, then this would be the simplest option. Otherwise, a 1R / 5W resistor would also do the job. I suppose you're note expecting many amps to flow right?
- Google around for "under-voltage detector" or "battery low-voltage alarm" or such... I'm sure you'll find something.
- The battery charge management for cell-phone batteries is normally inside the phone itself. It is then often software-based, or a dedicated part of the power management IC's. The adapters that come with your phone are usually very simple DC power supplies with no battery management.
- If you have a multimeter with current measurement, then this would be the simplest option. Otherwise, a 1R / 5W resistor would also do the job. I suppose you're note expecting many amps to flow right?
- Google around for "under-voltage detector" or "battery low-voltage alarm" or such... I'm sure you'll find something.
I suspected as much - that's a pity!
not many amps flowing in this DAC!
Will do, thanks
John,
theres a sch on the DDDac site for just such a LED system. He is using 12V battery and he has it set up that if V>11.5 a green LED lights and <11.5 a red one comes on. It can also be set up for 2 colour LEDs.
Might not be that big a stretch to have it hooked up to a relay to allow charging automatically?
Fran
theres a sch on the DDDac site for just such a LED system. He is using 12V battery and he has it set up that if V>11.5 a green LED lights and <11.5 a red one comes on. It can also be set up for 2 colour LEDs.
Might not be that big a stretch to have it hooked up to a relay to allow charging automatically?
Fran
You should have a lok at this before you get too far, just so you understand the charge/discharge needs of your batteries.
http://www.batteryuniversity.com/
Once you know this stuff you understand why the micro controlled charging circuits are around.
BZ
http://www.batteryuniversity.com/
Once you know this stuff you understand why the micro controlled charging circuits are around.
BZ
Easiest way I can think of is to have a diode over both the plus and the minus giving a 1.4V drop in total. But you might want to look into a real ultra low loss regulator as the voltage from the LFP cells will vary from about 3.6V fully charged to about 3.2V when almost discharged.
Thanks Saturnus, you seem to have some knowledge of these battery types - have you used them in audio?
I guess as long as the voltage stays within the PS compliance range for the chips it may be OK but I intended to keep the batteries topped up to full charge (will prolong their life, as long as they're not overcharged). My chips are the Cypress EZUSB-FX2 (3.15 to 3.45V);
Xilinx Spartan 3A VCC(3.00 to 3.6V), VCCint (1.14 to 1.26);
PCM1793 VDD (3.0 to 3.6V), VCC (4.0 to 5.5V)
I was hoping to stay away from any regulators as I believe & have seen reported, that any & all regulators imposes their signature. This might be mistaken but I wanted to evaluate it's sonic effect
Yes, I have been testing them for use in my next boominator. And they are a no brainer for that. Best battery on the market. Period.
I'd be interested in your impressions of these batteries powering the Tripath amp as this is my next step - I have a TA2020 amp that my transformer output DAC is DC connected to - sounds excellent with SMPS 12V power - will be trying a Salas shunt reg & then the batteries.
In my opinion a battery supply is superior. It's like on some live recordings the music gets more relaxed and stop being a concert but becomes an evening with guys jamming. With a SLA battery the bass may at times seem hesistant (but still better than on a grid powered power supply) but with the LFPs it has perfect timing and appears endlessly deep.
Good thread
Hi Jkenny,
I'm also searching for a simple charger for a Hyperion LiFePO4 battery powering the digital part an ESI Juli@ soundcard.
Are you using HyperionA123 batteries ?
For these, I'm afraid MCP73123 would not be adequate, as the standard charge methods are:
1100mAh: 1.5A to 3.6V CCCV, 45 min.
2300mAh: 3.0A to 3.6V CCCV, 45 min.
and MCP73123 is limited to 1100 mA.
Not 100% shure, but CCCV is CC and CV charging (CC first, and, as as charge goes on, the current charge is then voltage limited). A L200 regulator can do that, except swithing off after 45 min.
For SLAs, it's better to charge it individually; do not know for LiFePO4, but can't be wrong doing it.
Best regards,
Alain
Hi Jkenny,
I'm also searching for a simple charger for a Hyperion LiFePO4 battery powering the digital part an ESI Juli@ soundcard.
Are you using HyperionA123 batteries ?
For these, I'm afraid MCP73123 would not be adequate, as the standard charge methods are:
1100mAh: 1.5A to 3.6V CCCV, 45 min.
2300mAh: 3.0A to 3.6V CCCV, 45 min.
and MCP73123 is limited to 1100 mA.
Not 100% shure, but CCCV is CC and CV charging (CC first, and, as as charge goes on, the current charge is then voltage limited). A L200 regulator can do that, except swithing off after 45 min.
For SLAs, it's better to charge it individually; do not know for LiFePO4, but can't be wrong doing it.
Best regards,
Alain
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Alain,
You seem to be correct, I overlooked the specs on these but should have noted that they are meant for mobile devices so probably limited current.
Here's a cheap single charger for $13.75 which seems to suit - only problem is shipping is US only http://www.all-battery.com/tenergylifepo4batterycharger01300.aspx I've too many things to DIY & an off-the-shelf solution appeals to me now.
Yes, I have the Hyperion A123 2.3Ah batteries (good prices). Individual charging is recommended - all the muti-cell chargers have balancing circuits to protect individual cells from overcharge (>3.7V) damage, so my simple approach would be to charge individually but in parallel.
Where are you using your batteries & with what result? I'm only starting to use mine so too early to give any feedback but I intend to power a ESS Sabre32 DAC with some of these. First, I'm experimenting with them on powering a Musiland USB DAC pcb & ESS 2 channel Vout DAC as well as a Tripath (TA2020) amp.
You seem to be correct, I overlooked the specs on these but should have noted that they are meant for mobile devices so probably limited current.
Here's a cheap single charger for $13.75 which seems to suit - only problem is shipping is US only http://www.all-battery.com/tenergylifepo4batterycharger01300.aspx I've too many things to DIY & an off-the-shelf solution appeals to me now.
Yes, I have the Hyperion A123 2.3Ah batteries (good prices). Individual charging is recommended - all the muti-cell chargers have balancing circuits to protect individual cells from overcharge (>3.7V) damage, so my simple approach would be to charge individually but in parallel.
Where are you using your batteries & with what result? I'm only starting to use mine so too early to give any feedback but I intend to power a ESS Sabre32 DAC with some of these. First, I'm experimenting with them on powering a Musiland USB DAC pcb & ESS 2 channel Vout DAC as well as a Tripath (TA2020) amp.
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Jkenny,
My little experience with batteries are with tube heaters, Fertin's driver field coil and for cathode bias. Except for the last on, I liked the result more than the on I had before. Just subjectively cleaner, looking deeper in music; not tested anything.
Now, I have not yet powered the Juli@ soundcard, so I can't tell anything about it. I'm using it with cMP PC audio setup, with I2S to Sabre DAC.
On my to do list about batteries: power my Sabre DAC and the computer.
For monitoring discharge, I found a little voltage comparator, which seems simple to implement (see: "simple comparator" in application notes) : LM139.
Best regards,
Alain
My little experience with batteries are with tube heaters, Fertin's driver field coil and for cathode bias. Except for the last on, I liked the result more than the on I had before. Just subjectively cleaner, looking deeper in music; not tested anything.
Now, I have not yet powered the Juli@ soundcard, so I can't tell anything about it. I'm using it with cMP PC audio setup, with I2S to Sabre DAC.
On my to do list about batteries: power my Sabre DAC and the computer.
For monitoring discharge, I found a little voltage comparator, which seems simple to implement (see: "simple comparator" in application notes) : LM139.
Best regards,
Alain
we all need the poor man solution! is there someone who arranged to feed a ta2020 with a li-ion notebook battery?
do you think it may be possible to use a 60W step up converter boosting a 7.2v to 14.4v with a ta2020 amp?
they're rated from 5000 to 10000 mah... and the only expense would be the converter and a low battery alarm.
do you think it may be possible to use a 60W step up converter boosting a 7.2v to 14.4v with a ta2020 amp?
they're rated from 5000 to 10000 mah... and the only expense would be the converter and a low battery alarm.
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