Supercapacitors voltage monitoring IC (6s) - Page 1
Forum section: electronics / beginners

author: Najgel254
author_rank: Newbie
timestamp: April 28, 2023, 12:41:17 pm
content: Hello,i would like to ask if anyone would recomend a monitoring IC for 6 series connected supercapacitors, (single SC maximum voltage is 2,7V). I selected a BQ76925 which was great fit for this application, but then i checked recomended operating conditions and differential voltage VCn to VCn+1 is 1,4V minimum. This is problem because a supercapacitor can have a lower voltage than 1,4V. Can someone recomend some IC with cell voltage monitoring and if this IC would have a current measurement capability that would be great. I dont want any fancy ICs with lot of options and protections, i would like to monitor a cell voltages, flowing current and be capable of cell balancing, but this is not necessary.This IC was great fit, but i dont know how voltages below 1,4V will affect this IC and his behaviour.https://www.ti.com/lit/ds/symlink/bq76925.pdf?ts=1682513004561&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ76925Thank you for your advices.

author: MrAl
author_rank: Super Contributor
timestamp: April 28, 2023, 12:57:48 pm
content: Quote from: Najgel254 on April 28, 2023, 12:41:17 pmHi,Those look like they are made for Li-ion batteries. That means they 'may' have a limit for the lower voltage where the charge current is reduced because when cells get below 2.5v some circuits will reduce the charge current to a much lower level than normal until it reaches a higher voltage like 2.5v or so. This isn't to say that they definitely will not work though.What i would do is look up a super capacitor charge protection board. They would have everything needed to regulate the charge current and protect the caps from over charging or over voltage. It's always better to get something made just for the application you are working with.

author: Najgel254
author_rank: Newbie
timestamp: May 01, 2023, 12:17:25 pm
content: Charging is handled by other circuits, but I cant find any IC which offers a monitoring for supercapacitors. Capable of measuring differential voltages from 0V

author: Infraviolet
author_rank: Super Contributor
timestamp: May 01, 2023, 11:49:59 pm
content: What about using a microcontroller (whatever type you are most familiar with) with an ADC, use resistive voltage dividers if needed if the highest peak voltages are going to get above the maximum your MCU's ADC can handle. Read the ADC to get the capacitor voltage and write software running on this MCU to perform the functions a specialised management chip typically would. Supercapacitors should be a lot simpler to manage than Li or NiMH cells are.Also, you could always consider some sort of op amp arrangement to amplfiy the voltages before supplying to a prebuilt "battery" management chip?

author: Kim Christensen
author_rank: Super Contributor
timestamp: May 02, 2023, 01:14:40 am
content: Why not just an ordinary voltage clamp circuit across each capacitor? (Basically a precision zener) You're just trying to avoid over-volting an individual capacitor right? Or are you trying to balance the charge voltage equally across all of them, at the same time, all the time, regardless of the total voltage?

author: Faranight
author_rank: Unknown
timestamp: May 02, 2023, 06:55:18 am
content: Why do some supercapacitors have a minimum recommended operating voltage while some do not?Example:A,B

author: Miha
author_rank: Contributor
timestamp: May 08, 2023, 05:22:45 am
content: Because "A" is hybrid.But "B" is usual supercup, and have no minimum working voltage.