Charging Sodium-ion batteries using alternating current ? - Page 1
Forum section: electronics / projects

author: eneuro
author_rank: Super Contributor
timestamp: February 04, 2024, 09:05:14 pm
content: Hello,To what extent is it possible to charge Sodium-ion (Na-ion) batteries using alternating current with current limitation instead of constant current?I would like to charge multiple Na-ion 18650 batteries with rectified low voltage custom toroidal transformer with multiple secondary windingsIn the case of Li-ion batteries, I came across the following study:Quote

author: Vovk_Z
author_rank: Super Contributor
timestamp: February 04, 2024, 09:36:02 pm
content: IDK about Natrium batteries but most actual batteries have quite a tight charging voltage margin usually and typically are not supposed to work with floating (I mean very drifting) unregulated charging voltage.

author: amyk
author_rank: Super Contributor
timestamp: February 04, 2024, 10:50:53 pm
content: AC is by definition both positive and negative.How do you expect to charge any battery from that?

author: Benta
author_rank: Super Contributor
timestamp: February 04, 2024, 11:32:03 pm
content: I think you missed the little word "superimposed."

author: Slh
author_rank: Regular Contributor
timestamp: February 05, 2024, 07:10:32 am
content: My experience from talking to Li-ion cell manufacturers is that they want as little ripple as possible and hate specifying an upper bound.The impression that I've had from them is that the don't actually know how ripple effects the lifetime and don't want to admit it.The EIS plots (impedance Vs frequency) generally show lowest impedance in the 10s to low hundreds of hertz so I' be always been annoyed with their demand for low ripple across the board.

author: eneuro
author_rank: Super Contributor
timestamp: February 05, 2024, 06:35:33 pm
content: Quote from: amyk on February 04, 2024, 10:50:53 pmWhat is the easiest way to convert AC to DC?Quote

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 05, 2024, 06:44:52 pm
content: I would imagine it comes down to heating. Shouldn't be much ionic motion due to AC of modest frequency, which is where EIS comes into play. Can't speak for any particular chemistry, or manufacturer, of course.At very high frequencies (for ions, that is; kHz+), cell capacitance dominates, even in the absence of any ionic motion; and pretty soon after, lead inductance.Tim

author: eneuro
author_rank: Super Contributor
timestamp: February 05, 2024, 07:33:20 pm
content: Quote from: T3sl4co1l on February 05, 2024, 06:44:52 pmForget about AC because it is rectified DC from AC but it is not a constant voltage/current charging however I've current limiter set to 100mA per each Na-ion 18650 cell

author: eneuro
author_rank: Super Contributor
timestamp: February 07, 2024, 05:02:22 pm
content: Quote from: Slh on February 05, 2024, 07:10:32 amAnyway, I've Na-ion 18650 battery cells so it will be interesting to see how long they will perform while charged directly rectified from mains 230VAC 50Hz with Zener diode 3.9Vz and a few resistors is series to limit current to ~2mA to power small Attiny85 MPU with BOD set to ~2.7V

author: Vovk_Z
author_rank: Super Contributor
timestamp: February 07, 2024, 08:39:35 pm
content: So that is not alternating current but (badly) regulated DC violtage.