Hello
im researching some power supply options the last couple of days and came across that in the old days pro audio pedals and stuff like the DIY studio headphone amplifier HC1 were or still are run on 9V block batteries and were playing with the idea of building some kind of constant powered 9V block battery replacement with 2s lipo cells at first... my research made me curious about "lithium ion capacitors", i heared now a few times they are not worth it but if you look at the specs they really combine lithium ion and supercap technology
since im really trying to integrate both, battery and supercaps, this might be a costeffective solution for getting the best out of both worlds
so far i plan to:
2x 3.7V = 7.4V ( to 6.6V ) as 7V supply
2x 4.2V = 8.4V ( to 7.6V ) as 9V block battery replacement / 8V supply
5/3.3V via regulator
- 2x 1000F banks should be enough for low power applications, i rather use one more supply and we are already in the 50 mOhm ESR region (so basicly like an (good) relay contact)
around 2Ah for 8.4V / 1000F
did anyone experiment with lithium caps here or compared them? and ideas/suggestions?
im researching some power supply options the last couple of days and came across that in the old days pro audio pedals and stuff like the DIY studio headphone amplifier HC1 were or still are run on 9V block batteries and were playing with the idea of building some kind of constant powered 9V block battery replacement with 2s lipo cells at first... my research made me curious about "lithium ion capacitors", i heared now a few times they are not worth it but if you look at the specs they really combine lithium ion and supercap technology
- fairly low ESR, high current capability
- can be quite often recharged in comparison to batteries (2000 vs 100k)
- more safe than lithium ion batterys
- supercaps in 500F size are alot bigger than 500F lithium caps
- 500F lithium cap costs about 5 euro, i think high quality 500F supercaps are more like 25-40euro
since im really trying to integrate both, battery and supercaps, this might be a costeffective solution for getting the best out of both worlds
so far i plan to:
- 9V unregulated pure battery isolated power supply with only the lithium caps (and maybe some protection circuitry) connected to the load
- 2 banks of lithium caps, one can be charged or be on hold and the other is in use
- lithium caps have a range of around 3V to 4.2V, with nominal 3.8V, you can extend life with not going much above 3.8V
2x 3.7V = 7.4V ( to 6.6V ) as 7V supply
2x 4.2V = 8.4V ( to 7.6V ) as 9V block battery replacement / 8V supply
5/3.3V via regulator
- 2x 1000F banks should be enough for low power applications, i rather use one more supply and we are already in the 50 mOhm ESR region (so basicly like an (good) relay contact)
around 2Ah for 8.4V / 1000F
- i still havent found the perfect charging/balancing chip combo here, one solution is switching the caps from serial to parellel for charging, no balancing needed i think...
- power monitoring and a mcu is somewhat i still question (because of "minimal design") but it would be cool to have
did anyone experiment with lithium caps here or compared them? and ideas/suggestions?
Abracon make the Lithium Hybrid cells. Not sure how many joules of energy (in Amps) one can get out of them before they destroy themselves.
Only 4volts (fully charged) but fairly innexpensive.
They don't need a balancing chip, they behave like capacitors, not batteries.
(Plenty of old Tesla battery packs available to strip down, those that havem't caught fire).
Only 4volts (fully charged) but fairly innexpensive.
They don't need a balancing chip, they behave like capacitors, not batteries.
(Plenty of old Tesla battery packs available to strip down, those that havem't caught fire).
Attachments
i think balancing is needed, even for supercaps and mentioned in this paper: https://en.cda-cap.com/wp-content/uploads/2023/08/CDA_LIC_USER-MANUAL2303171.pdf
looking at these discharge graphs there isnt much capacitance left if you limit the possible voltage range, so it might be a good idea to use a regulator and some more cells if i really wanna use lithium caps (possibly 4 cells for 10V minimum, which can be regulated to 9V)
i was looking at these: https://www.lcsc.com/datasheet/lcsc_datasheet_2212271830_CDA-LIC1840Q3R8507_C2826903.pdf 500F since these are available at lcsc.com
another idea i got was using this in parallel with lipo cells (3V - 4V), tho its usually not recommend to mix up different capacitys, is this maybe different with this lithium caps + lipo batteries?