paulajayne
Active member
I am looking to log my house bank amps draw .
Suggestions of best way or tool to gather data over a long period please.
Suggestions of best way or tool to gather data over a long period please.
Logging amps draw
- Thread starter paulajayne
- Start date
Graham376
Well-known member
Would one of these do the job? Digital Monitor LCD Watt Meter Ammeter RC Battery Power Amp Analyzer DC 60V/100A | eBay
Mistroma
Well-known member
I was going to suggest something similar. I bought a slightly more expensive one years ago and it is still going strong. I just slipped the current sensor over the wire and connected 12V to get it going and it had a Bluetooth app as well as a LCD. Unfortunately, I've never seen that model again. Ones on eBay will probably not have Bluetooth and use a shunt or be wired in-line but seem good value for under £10. I imagine they will meet OP's requirements if manual readings are collected at intervals.
Not very granular data but OP could get that from an ESP32 if he wanted a winter project to collect current data over time.
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stephen_h
Active member
This sounds very useful. Do you have the name/model etc - might be able to find something similar
Mistroma
Well-known member
This sounds very useful. Do you have the name/model etc - might be able to find something similar
I've looked for it several times and nothing comes close.
This one is similar but twice the price, only 50A and fewer features: Bluetooth 50A STN LCD Hall Coulomb Meter Voltage Current Meter Power Tester | eBay
It is on my boat in Greece but I'll see if I can find any notes at home. The software is ChonFeng VIC v1.3 but I think that's just a generic package. A bit clunky but gives lots of readings (V, A, W, Ah, Wh, kWh, (Ah In & Out), times, graph of V and A vs. time
UPDATE:
I managed to find the order from March 2018 but it doesn't give any details, just "100A wireless Bluetooth DC ammeter voltmeter power Timer battery Monitor tester". The seller was "kissbuyer" and item ID: 152473084160, both deleted from eBay a few years ago.
I was actually looking for the current sensor to build my own from Arduino or ESP32. However, this unit was cheaper than the sensors available. I should have bought a couple as they were only £20 and worth it for the sensor alone. I'll probably build a replacement if this one dies but the sensor is still working.
There are a few non-Bluetooth Hall effect ones still around (e.g. VAC9010H Hall Coulombmeter DC90V Voltmeter Ammeter LCD Two-Way Current Voltage | eBay). They all lack the ability to log data over time as that came from Bluetooth. Simple to install as no shunt needed, just slip the sensor over the battery wire and connect to + & - to get Voltage (& power the device).
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paulajayne
Active member
I have a Nasa BM2 fitted at present which displays amp draw and voltage as well at percentage battery state.
What I would like to do it poll the amp data at say 10 minute intervals for several weeks to do a trend analysis and then plan for solar upgrade.
Currently have victron quatro 12/5000/120 on my 960 amp/h house bank with two 320 solar panels running into victron 75/10 solar units.
What I would like to do it poll the amp data at say 10 minute intervals for several weeks to do a trend analysis and then plan for solar upgrade.
Currently have victron quatro 12/5000/120 on my 960 amp/h house bank with two 320 solar panels running into victron 75/10 solar units.
apogee
Member
I see there are a couple of bluetooth models curently being advertised. How accurate are they likely to be?
Does the bluetooth operate between the sensor and the fixed display, or between sensor and phone/pc?
Does the bluetooth operate between the sensor and the fixed display, or between sensor and phone/pc?
Mistroma
Well-known member
It is feasible that the Bluetooth link would be between the sensor and the display but not the most likely option. Bluetooth is usually used to provide a remote display rather than a data link from a sensor. It could be used to remove wiring between sensor and a display box but is more likely to be another type of wireless link in that case. Could be Bluetooth of course and the sensor would provide data to a phone and a dedicated display, just a less common option.
All the systems I've seen have a box with or without built-in display and a phone app to provide a remote display. I simply fixed mine to the inside of a locker beside other electrical systems with very short wires to the battery and cable I wanted to monitor for current. I only look at the display when working in that locker and normally refer to my phone for the data.
Use of Bluetooth won't affect accuracy as it is just a conduit to relay the data. You would need to look at the claimed accuracy for each unit and decide whether or not to believe the claims. It is often quoted as =/- % and usually better not to buy something with a huge range.
e.g. Something claiming 1% might be OK for 0.2A if max. range 20A but 5A if 500A range.
I think my model was 100A and accuracy claimed was 0.1% and I'm happy if readings are +/- 0.1A
Sandy
Well-known member
Do the instruments listed above log* or just display the current amps being used?
log = record the date, time, amps drawn and perhaps the voltage; in a format that can be used at a later date, e.g. a CSV file?
log = record the date, time, amps drawn and perhaps the voltage; in a format that can be used at a later date, e.g. a CSV file?
Mistroma
Well-known member
I think the instruments the OP already has on his boat will simply display a single reading with no logging feature. The super-cheap Chinese Bluetooth box I have can be used to collect data because it is a Bluetooth device and uses a known standard for data transmission. I can't remember what it is called off-hand. The app. supplied does produce a graph but has no means of saving the data. However, I did once connect to a Bluetooth terminal type app. on my phone and it spooled out lines of data in an easily read format. I was able to copy and paste the output but a bit clunky. I think I'd need to find an app designed to collect the data and tweak frequency etc. Probably not very difficult to write as the functionality isn't very complex.
Not very relevant to others as the device vanished from eBay a few years ago. It would be a lot simpler for me o to write code for an ESP32 and log directly to SD card or send over Bluetooth or Wifi.
paulajayne
Active member
Yes just display data with no logging ability.
I have ordered this:-
https://www.amazon.co.uk/gp/product/B07Q6HJRYR/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
Spec seems to indicate it will do what I require.
@Mistroma I will Update here if the above works.
Paula
Mistroma
Well-known member
Very useful to have anyway. I remember when I bought one years ago that it was tricky to get one to handle DC current with the clamp. I had to read the small print carefully as many only worked with AC or required direct wired connection for AC current. The adverts were often vague and led you to believe the clamp could measure AC and DC current. I did eventually find one with AC/DC current at a reasonable price.
Things have moved on and I imagine most will now measure AC or DC current with the clamp. Bluetooth is a useful addition as it gives remote display and logging ability. I wonder what battery life is like when logging data?
paulajayne
Active member
It has arrived and app downloaded to my glass bridge - Set it to 200 amp DC and logging at once per minute (the longest it will do).
Seems to read approx 0.6 amps under but I can adjust the data in excel.
Data spec is +/- 3% with a 4000 count, so 2.7 days of logging at it's longest rate.
Not exactally what I was aiming for but I can save data on a 2 day cycle and patch it into excel to acheive what is required.
As data is being recorded the app averages reading as well as displaying Max and Min readings.
Paula
Seems to read approx 0.6 amps under but I can adjust the data in excel.
Data spec is +/- 3% with a 4000 count, so 2.7 days of logging at it's longest rate.
Not exactally what I was aiming for but I can save data on a 2 day cycle and patch it into excel to acheive what is required.
As data is being recorded the app averages reading as well as displaying Max and Min readings.
Paula
Caladh
Well-known member
Good grief with all that power why do you need to monitor current draw ? !!!!!! ?
paulajayne
Active member
Atlantic crossing and trying to go off grid, apart from diesel.
Need to ensure that solar and wind will keep up with our normal usage.
Caladh
Well-known member
You’ll just have to temper the use of the washing machine!
paulajayne
Active member
Washing machine is wired to shore power only so cannot run at sea.
We are livaboard so home comforts are geared for.
paulajayne
Active member
So far 4000 readings at 1 min intervals have produced (readings in amps) this:-
CLICK ON IMAGE TO ENLARGE
Positive reading show battery charger off and negative on.
Peak is boiling a kettle via invertor with shore power off.
Trend line is black line below zero and is showing circa 12 amps.
Calcs on this data so far indicate that I will require circa 170 watts solar 24 hours /day.
As the sun does not grace us with viable solar 24 hours / day - lets plan 6 hrs/day which gives 680 watts input during that period.
Solar cell are not very efficient - lets say 20%, then looking at the data I have collected so far I will need at least 3400 watts of solar.
This is of course early stages of planning and more data to be collected.
CLICK ON IMAGE TO ENLARGE
Positive reading show battery charger off and negative on.
Peak is boiling a kettle via invertor with shore power off.
Trend line is black line below zero and is showing circa 12 amps.
Calcs on this data so far indicate that I will require circa 170 watts solar 24 hours /day.
As the sun does not grace us with viable solar 24 hours / day - lets plan 6 hrs/day which gives 680 watts input during that period.
Solar cell are not very efficient - lets say 20%, then looking at the data I have collected so far I will need at least 3400 watts of solar.
This is of course early stages of planning and more data to be collected.
Mistroma
Well-known member
Might be worth looking at Photovoltaic Geographical Information System (PVGIS) - EU Science Hub - European Commission to get estimates of solar output. I've used it for years to forecast daily Ah from solar in a variety of locations. It works quite well but I found their old system easier to extract and convert to daily Ah. I use that as my starting point for est. daily Ah in each month.
It does become complicated as you can subtract usage during daylight hours and that leaves estd. battery drain overnight. Usage during the day reduces battery charging but is efficient. Re-charging to recover overnight battery use is very inefficient and you need to allow for Ah in and Ah out being far from equal. Much easier to plan with modern batteries having extremely high charge efficiencies vs. lead acid batteries.
It does become complicated as you can subtract usage during daylight hours and that leaves estd. battery drain overnight. Usage during the day reduces battery charging but is efficient. Re-charging to recover overnight battery use is very inefficient and you need to allow for Ah in and Ah out being far from equal. Much easier to plan with modern batteries having extremely high charge efficiencies vs. lead acid batteries.
paulajayne
Active member
PVGIS
Having a play with it now. looks useful. Thanks
Having a play with it now. looks useful. Thanks
