Electronics > Beginners
How to build a simple volatge buffer
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Adhith:

--- Quote from: Kleinstein on June 06, 2018, 06:51:58 pm ---It depends on the LED strip and the driver. The usual LED drivers give out an defined current (e.g. 350 mA). So the voltage over the LED strip will be whatever it takes to get that current, but not more than available.

For the LED strips, there are 2 types: some with a series resistor that can be operated at constant voltage and those made for constant current drive. If there is a series resistor in the LED chain, it will get hot if the LEDs are lit.

So you have to get and understand the manuals / data-sheets  for both the driver and the LED strip, or at least have a look at the circuit / description. Depending on the LED chain the best way is either a constant voltage regulator or a constant current regulator (e.g. the LED driver), but not both.

--- End quote ---
Ok understood Sir. I'll check the specifications and figure out the things
Adhith:

--- Quote from: capt bullshot on June 07, 2018, 09:21:23 am ---I've mentioned to put two capacitors on each side of the inductor, four in total. Each one ceramic and one electrolytic in parallel.

--- End quote ---
OK now I get it. thank you very much Sir.


--- Quote from: capt bullshot on June 07, 2018, 09:21:23 am ---This is because you shouldn't discharge your cells below 3.3V in normal (low current) use, this leaves 13.2V at the battery when it is assumed empty.

--- End quote ---
I though 2.5V was the terminal voltage of a battery up to which safe discharge is possible. or I'm wrong about it and its actually 3.3V??
capt bullshot:
Yes, these cells can be discharged down to 2.5V, if the cells rest for longer periods at this voltage, you'll damage them. Discharging to 2.5V may happen if you have large discharge currents (> 1C ... 2C), but the cells recover pretty fast to voltages abobe 3V when discharging stops.

For normal use, the cells shouldn't be discharged that deep at lower (< 1C)  currents. Most of the batteries capacitance gets discharged at voltages above 3.0 ... 3.3V, so if you go lower, there will be very little additional capacity. A Li-Ion cell at 3.3V and no discharge current, after some resting time, is considered empty, though you'll see lower voltage while discharging the cell, depending on the current.

You may want to look up some datasheets of these cells to get an idea of the discharge voltage over discharged capacity. At the end of discharging, the voltage falls quite rapidly. From my experience, when discharging these cells at rather low currents (less than 0.5C ... 1C), 3.3V is a good point to stop discharging.

Adhith:
Thank you very much for your detailed explanation. Didn't know about these facts and I'll make a habit that not to discharge lower than 3V from now onwards. I'll let you know about the progress about the filter when the new BMS arrives. Like you said I'll fully charge the pack first and connecte the BMS alone to see whether the capacity of the battery was the problem.
capt bullshot:
You're welcome!
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