Issue Measuring Large Capacitors with Multimeter - Page 1
Forum section: electronics / beginners

author: clansd99
author_rank: Contributor
timestamp: January 02, 2023, 08:58:33 pm
content: Hi all,I am having an issue measuring capacitors with my EEVBlog BM235 multimeter, which I've had for quite a few years. It does a bang on job measuring capacitance down around 100nF, but when attempting the same with 470uF and 2200uF electrolytics, the meter doesn't do much for a second or two and then the screen light starts flashing and the meter beeps incessently.I've tried replacing the batteries with known good ones, but no luck. I haven't used this functionality much before, so perhaps I'm just missing a way to set the range? Overall I love this meter and it has served me well. Figured I should ask on here before contacting customer support-Chris

author: Vincent
author_rank: Regular Contributor
timestamp: January 02, 2023, 11:40:35 pm
content: Larger electrolytics need a not unsignificant amount of charging for the multimeter to perform any kind of useful measurement.While I don't have this specific model, I've measured a fairly large number of capacitors over the years with this thing:The bigger the cap, the longer the meter takes to spit out a measurement. And 1 000uF seems to be the practical upper limit. I think I did manage to measure a larger capacitor at some point but it took like 30 seconds, it was ridiculous LOL.I wouldn't be surprised if other multimeters with a capacitor function have a comparable limit in the lower 3-digit uF range.

author: BeBuLamar
author_rank: Super Contributor
timestamp: January 03, 2023, 12:23:06 pm
content: May be you can try to discharge the capacitor first. That is recommended in the manual. Other than that it should measure up to 10,000 Microfarads.

author: jonpaul
author_rank: Super Contributor
timestamp: January 03, 2023, 12:30:39 pm
content: Use RLC bridge, HP, Wayne Kerr, most have models with very high C.But no need to measure the C, a bad cap will show visible leakage, sweliogn and test high for leakage at rated V.Just a DC PS and ma meter are enough.Jon

author: Kleinstein
author_rank: Super Contributor
timestamp: January 03, 2023, 12:36:04 pm
content: Discharging is needed and if used with a high voltage before it can take a longer/repeated discharge (e.g. a few minutes) because of the relatively high DA of electrolytic capacitors.The measurement just takes time - this could be some 5 seconds, how much depends on the meter.

author: EPAIII
author_rank: Super Contributor
timestamp: January 04, 2023, 09:22:48 am
content: A suggestion:https://www.amazon.com/Aideepen-Mega328-Transistor-Capacitance-Battery/dp/B01M0UXHYY/ref=sr_1_1_sspa?crid=1N2IFO0PQB356&keywords=electronic%2Bpart%2Btester&qid=1672823944&sprefix=electronic%2Bpart%2Btester%2Caps%2C4410&sr=8-1-spons&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExU0JQUklGQ1RPTVVDJmVuY3J5cHRlZElkPUEwNzE5MDEwMUg3M0JOVllLMkJFMCZlbmNyeXB0ZWRBZElkPUEwODAwODUxQ1VPNEZTWEpPMTg3JndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ&th=1They work amazingly well. Wish I had one in the 1960s.

author: MrAl
author_rank: Super Contributor
timestamp: January 04, 2023, 11:28:47 am
content: Hi,Try to measure the DC voltage across the cap with another digital meter and see what the voltage is doing.As others said, it may take longer to read the value with a larger capacitor.I would think the meter would charge the cap at least a little because it is polarized. With non polarized caps you can test with pure AC.If the cap has a high leakage then it may not test right. You might be able to test that with an Ohm Meter, or meter set to the Ohms scale.