Electronics > Beginners
The correspondence of capacity between accumulators and capacitors
digsys:
What you're describing is a common DC UPS, I've designed dozens of them over the years, mostly 24VDC. Yes, they will do the job you ask BUT you need to consider a couple things. Depending on the chemistry, they do NOT filter out HF ripple very well, it'll just pass straight through, so you'll still need the usual HF / MF decoupling caps at the battery, and ideally a common mode choke / filter after the battery and before the regulator / load. IF you are drawing high surge currents, then a large low ESR cap is STILL recommended. Different regulator types also vary on how well they attenuate HF noise etc, and if you need more filtering after the regulator.
What is you load / current profile ? and what are you trying to filter out ?
Kirill V.:
--- Quote ---What you're describing is a common DC UPS
--- End quote ---
You're almost right but not quite. General purpose it is reducing of ripples with frequences is multiple to power grid absolutely
Load will be low current only, such as op-amps or similar. This is laboratory power supply
I understood general thing: I should add quality charger with caps as filter for long battery life. For excellent performance this part should be turned-off.
Regulator after battery it is precision op-amp with power amplifier. Not LMxxx or similar ICs.
edavid:
It's been tried many times, and it's a bad idea. Batteries are expensive, they wear out, and they leak and damage the equipment. There's no filtering you can do with them that you can't do better and cheaper with normal methods.
digsys:
--- Quote from: Kirill V --- You're almost right but not quite ....
--- End quote ---
If it has any sort of direct connected battery ie not a RTC type, then it must have battery charging / monitoring of some sort, or as others say, you can get in trouble.
IF it continues to supply load when the Input has drop-outs / or fails, even for a short time, then it is technically a DC-UPS. Irrespective of what your main aim is after that. Just clarifying nomenclature :-)
Now, given the conditions you supplied, a series of caps - LF, low ESR, HF, bulk energy etc is FAR more practical. Batteries are really not good filters as such.
Kirill V.:
Ok, If I will make this device now, I will use battery as source only, with charge-discharge cycle.
I lean toward capacitors or supercapacitors now.
My second idea:
I can use one cap with large capacity or many caps in parallel. What can you say about this?
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