Supercap Time Fluke 289 - Page 1
Forum section: electronics / repair

author: kdl1950
author_rank: Contributor
timestamp: May 18, 2023, 04:04:11 pm
content: Hello folks,I have a question about the Fluke 289. The supercap on mine was defect.Is a known problem.I soldered a new one. (0,22F 220mF Farad 3,6V)Now the question, how do I test the "bridging time" when replacing the battery?Or to put it another way, how long does the supercap last?Is there an approximate timeline?Greet Alex

author: bdunham7
author_rank: Super Contributor
timestamp: May 18, 2023, 04:24:22 pm
content: I asked a rep (online chat sort of rep) from Fluke this exact question and didn't get a clear answer. From what I've been able to tell, it should be days or weeks and it may vary quite a bit. After a supercap replacement (that didn't really change anything IMO) mine would last long enough to change the batteries but not long enough to take them all out and charge them--several hours since there are 6 cells and I have a 4 cell charger. I asked, the rather poorly informed rep who at first claimed this was normal, then when I persisted he referred me to someone more senior who simply told me to send it in if I thought it wasn't working correctly.I did and the tech working on it stated that there was some component (not the supercap) with excessive draw when the meter was turned off. This component apparently is no longer available so they replaced the meter with the new version that doesn't use the supercap. The new version holds the memory for at least a few days, but that doesn't say anything about what the old version does.FWIW, my original 289 was perfectly usable as it was as long as I had two sets of batteries. I didn't actually compare or measure battery life but the new one seems to require less charging, especially if sitting for a while.

author: kdl1950
author_rank: Contributor
timestamp: May 19, 2023, 07:39:58 pm
content: Thank you bdunham7 for your answer and experience.My experience agrees with yours. a few minutes are bridged. But hours or days I don't think that's possible.Since time continues to run through the supercap, i think that a processor is supplied with it.greetings

author: CapLeaker
author_rank: Regular Contributor
timestamp: May 19, 2023, 10:11:48 pm
content: Look at my thread post #32 over at badcaps.https://www.badcaps.net/forum/showthread.php?t=72162&page=2

author: mwb1100
author_rank: Frequent Contributor
timestamp: May 20, 2023, 12:42:31 am
content: What I have in my notes from a test done a while back (with an original supercap):QuoteKeep in mind that all the supercap does (AFAIK) is keep time between battery changes. So it's by no means an essential component.

author: AleXis6
author_rank: Newbie
timestamp: July 23, 2023, 09:42:52 am
content: 1 year ago I cnanged supercap to Panasonic 0,33Fand 1 week ago I did a quick testquick measurement - voltage of the supercapacitor (Panasonic) in FLUKE 289HH:MM - V00:00 - 3,22300:08 - 3,20700:22 - 3,1401:00 - 2,97301:32 - 2,83302:00 - 2,71502:31 - 2,59303:00 - 2,48403:20 - 2,406Date &time have been saved after 210 minutesafter about 360-400 minutes Date&time was lostThe minimum required voltage I think in a range 2-2.4 V