Is there a DC clamp meter with amp-hour counting? - Page 1
Forum section: electronics / testgear

author: isso
author_rank: Contributor
timestamp: December 23, 2023, 05:58:15 am
content: Hi, I often need to check a capacity of a battery during charge or discharge. It's very convenient to use a clamp meter to measure the DC current, because there's no need to break the existing wiring. But to measure the amount of energy I need to multiply the DC current by the time passed, and if the DC current changes over time, this becomes a hard task. Is there a clamp meter model that can do the calculation of amp-hours automatically?

author: Someone
author_rank: Super Contributor
timestamp: December 23, 2023, 06:09:52 am
content: "coulomb counter"But if it's attached to monitor continuously what's the value in a clamp? All the normal coulomb counters I'm familiar with use a current shunt resistor.

author: isso
author_rank: Contributor
timestamp: December 23, 2023, 06:51:12 am
content: Yes it's "coulomb counter", thank you for suggesting the correct term. Sorry I didn't get your question, I basically need to count the amount of energy flowing through a wire in some period of time without modifying the circuit (i.e. shunts don't work for me). So I thought a clamp meter with a counter (integration option) would work the best for me.

author: ledtester
author_rank: Super Contributor
timestamp: December 23, 2023, 07:36:31 am
content: This product is described as a:"Charge-Discharge Monitor, DROK 0-90V 100A DC Ammeter Voltmeter, Battery Capacity Amp-Hour Watt-Hour Power Time Multimeter, LCD Display Digital Voltage Current AH WH Watt Meter Tester with Hall Sensor"https://www.amazon.com/Charge-Discharge-DROK-Voltmeter-Watt-Hour-Multimeter/dp/B07YWVCBRN/On Aliexpress the search terms "DC power meter hall" seem to come up with what you're looking for:https://www.aliexpress.us/w/wholesale-dc-power-meter-hall.html?spm=a2g0o.detail.search.0also "DC coulomb meter hall":https://www.aliexpress.us/w/wholesale-dc-coulomb-meter-hall.html?spm=a2g0o.productlist.search.0

author: isso
author_rank: Contributor
timestamp: December 23, 2023, 11:38:13 am
content: Thank you very much for the links, I have a couple of those devices, there are a few problems with them - they aren't technically clamps (I need to clamp to the existing wiring), their accuracy is quite bad, and they aren't really hand tools, i.e. they need housing, power supply etc.

author: modoran
author_rank: Regular Contributor
timestamp: December 23, 2023, 11:40:09 am
content: There are real clamp meters that output a voltage instead of direct reading, maybe you can use one of those.

author: Pfriemler
author_rank: Regular Contributor
timestamp: December 23, 2023, 11:48:43 am
content: Quote from: isso on December 23, 2023, 11:38:13 amIsn't that the case with any (dc) clamp meters? I only use them to get an idea of flowing current instead of measuring them. One of my two is a cheap Voltcraft with useless readings if the current exceeds the measuring range only for a second.And in some cases you do not need to insert a shunt, if you can get a voltage along an existing cable.

author: isso
author_rank: Contributor
timestamp: December 23, 2023, 01:08:55 pm
content: Quote from: modoran on December 23, 2023, 11:40:09 amYes I'm leaning to that option, although I was hoping there would be an off-the-shelf device I could buy...

author: isso
author_rank: Contributor
timestamp: December 23, 2023, 01:13:31 pm
content: Quote from: Pfriemler on December 23, 2023, 11:48:43 amYes the clamp meters are much more accurate, I have an inexpensive UNI-T UT210E device that is way more accurate than those battery capacity meters. I guess more expensive clamp meters will have even better accuracy.

author: Pfriemler
author_rank: Regular Contributor
timestamp: December 23, 2023, 01:17:10 pm
content: Quote from: modoran on December 23, 2023, 11:40:09 amFor DC? The TO wants to monitor a battery discharge. I wouldn't consider DC clamps at all for that purpose.For AC, it's easy to get any kind of transformer around a wire, see the Shelly clamps of the three phase power meter.With DC, it's a lot more complicated to get offset-free readings for a long time.In other words, it's easy to zero a reading after clamping a wire with no current, and then switch the current on and get an more or less accurate reading. But do not expect an accurate longtime reading (for hours).