Battery Power Supply

[nige2000]

edit my error
because i was using light cable for charging which was limiting the current

just ran a test and they suck all that they can get my supply tops out at 5.3 amps

so dont let them run down
and if they do monitor the heat of the teradak regs

*****I Dont think I've ever seen a discharged cell say of 2.5v draw any more than 0.5 amps at 3.3v
My variable linear lab supply has both current and voltage displayed
The current been taken from the cell by any device will be an additional load on the float charger supply which for these type applications is negligible

Long story short
Don't worry bout it ;)***********

[jkeny]

Sorry Nige but these batteries will draw as much current as the PS will supply - as the internal charge reduces they appear as a short circuit to the supply - I've a bench supply & I've often seen 2-3 Amps current draw from low batteries.

Battery chargers have 2 stages - first stage is constant current & then constant voltage stage. The constant current stage is used to limit the current into the battery as it can be damaged from over-current - same as it can be damaged from over-voltage.
http://www.powerstream.com/LLLF.htm

We are using constant voltage charging so we have to be careful of over-current charging - which can only happen when the battery is low in charge - as it approaches fully charged the battery appears more & more like infinite high resistance & this limits the current being drawn.
http://www.powerstream.com/lithium-phos ... oltage.htm

So, after all of this - it isn't a problem as long as the battery is constantly trickle charged & not allowed to go low in charge.

[nige2000]

my bad :)

[randytsuch]

I've added a very small value resistor, like 1.5 ohm 2 watt, to limit the battery charging current in some of my projects.

I had a variety pack of resistors, so I found a value that worked.

This is in my dac, and if I used a larger resistor, the battery would slowly discharge if the dac was on.

[sima66]

My Teradak output is set at 3.3v and charge the batteries.
Is it normal that battery voltage to raise above 3.3v?
At the moment is almost 3.5V and still probably raising! Should I start to evacuate my wife and kids?!

[jkeny]

My Teradak output is set at 3.3v and charge the batteries.
Is it normal that battery voltage to raise above 3.3v?
At the moment is almost 3.5V and still probably raising! Should I start to evacuate my wife and kids?!

The battery can't go above the voltage setting of the regulated PS - are you sure your Teradak output is 3.3V - have you measured it?
There's no risk of fire or explosion - LiFePo4 batteries are one of the safest battery chemistries - as safe as a lead acid car battery!!

[sima66]

My Teradak output is set at 3.3v and charge the batteries.
Is it normal that battery voltage to raise above 3.3v?
At the moment is almost 3.5V and still probably raising! Should I start to evacuate my wife and kids?!

The battery can't go above the voltage setting of the regulated PS - are you sure your Teradak output is 3.3V - have you measured it?
There's no risk of fire or explosion - LiFePo4 batteries are one of the safest battery chemistries - as safe as a lead acid car battery!!

I just measured now, on the reg inside the Teradak is 3.465v (if my voltmeter is 100% acurate).
The batteries are at 3.455V.
Should I lower down the reg in Teradak?

[jkeny]

I just measured now, on the reg inside the Teradak is 3.465v (if my voltmeter is 100% acurate).
The batteries are at 3.455V.
Should I lower down the reg in Teradak?

Right, so it won't rise above this fixed voltage & the batteries are very happy at 3.455V
I haven't seen a 3.3V chip that doesn't run happily on 3.45V but if you want to reduced to 3.3V, it's not a problem, either.

[sima66]

I just measured now, on the reg inside the Teradak is 3.465v (if my voltmeter is 100% acurate).
The batteries are at 3.455V.
Should I lower down the reg in Teradak?

Right, so it won't rise above this fixed voltage & the batteries are very happy at 3.455V
I haven't seen a 3.3V chip that doesn't run happily on 3.45V but if you want to reduced to 3.3V, it's not a problem, either.

Thanks John, I might lower a bit.......latter! :)
I'm happy that I was finally able to play some music! ;-)

EDIT:
I lowered to 3.33v and its' perfectly stable. :)

Sent from my SM-N910W8 using Tapatalk

[jkeny]

I just measured now, on the reg inside the Teradak is 3.465v (if my voltmeter is 100% acurate).
The batteries are at 3.455V.
Should I lower down the reg in Teradak?

Right, so it won't rise above this fixed voltage & the batteries are very happy at 3.455V
I haven't seen a 3.3V chip that doesn't run happily on 3.45V but if you want to reduced to 3.3V, it's not a problem, either.

Thanks John, I might lower a bit.......latter! :)
I'm happy that I was finally able to play some music! ;-)

EDIT:
I lowered to 3.33v and its' perfectly stable. :)

Sent from my SM-N910W8 using Tapatalk

Cool!