Current draw meter and logging history of current usage

[Judo]

I've just purchased a 65L no-name 12v fridge from ebay. As much as I think my battery and solar setup will be able to handle it at least for a few days, whether it's 1-2 days, or 4-5 days, is largely unknown unless I can record some power usage stats on the fridge in different operating conditions.

I love nothing more than a good set of statistic to graph and analyse! So what device can I use (I assume it would go in-line in the fridge circuit) to record a history of current draw from the fridge over time? Something i can connect to a laptop on the road to save the data would be ideal.

Any suggestions on devices that can do this?

[Graeme]

I have a multi-meter with data logging capabilities to an RS232 i/f to connect to a laptop. IIRC it records at 1 second intervals. However max time for greater than 400mA is only 15 seconds so of no use in this application.

[scarry]

There is a company here called tech rentals that would more than likely have something that you could hire,probably not cheap though.

Dunno if they are in your area as well.

I would borrow,purchase,whatever a clamp meter that will check DC amperage and that should give you some figures to start with.I have one of these clamp meters but am a bit far away or i could check it for you.

[Judo]

Although not the out of the box solution I was hoping for, this is very temping.... I already own an Arduino that could read the sensor. Just need to think about how to store the data historically.

$2 Carabiner AC amp sensor (aka current transducer, CT sensor, amp meter, split core clamp-on ammeter)

[scarry]

would it work for DC?

Maybe not

[Judo]

I have had limited experience with these sensors before, but yes I believe that style of sensor works for both AC and DC, however the calibration would be different. It's just a coil around the power feed. I can't see how it wouldn't work.

[clubagreenie]

In relation to the indestructable. I understand the concept of creating the ring to sense, but, he's got it plugged into a multieter that has a clamp. It's not clear if that's just for demo purposes or it works on something that the clamp wont (DC or AC).

[Judo]

I think he was just using the multimeter clamp to calibrate the homemade one. Then he connected the homemade ring to the multimeter in mV mode. I.E. Something else could read the mV reading.

[bee utey]

You can't use an inductive coil to measure DC current. You have to use one with a Hall Effect sensor that creates an output voltage proportional to the magnetic field. And the ones I've seen are difficult to use on low currents as the field strength varies within the sensor. I would use a current shunt myself or a multimeter suitable for the job.

Suitable meter?

UNI-T UT71B Intelligent Digital Multimeter 2 PC USB Data Logging | eBay

[mark_coffey]

check out plasmatronics line of solar charge regulators, they will give charge current, load current, saturation of charge, and cumulative charging and loads for 24hr periods. they will also give 30days of data. Have been using these units on industrial applications and have one on my camper, very good for all of the data. www.plasmatronics.com.au/

I have used the PL20 and the Dingo, I installed a PL20 in a mates camper, we found the solar charge capacity of the panel didnt match up with his daily load, installed a bigger panel, he has never flattened the batteries.