Reddit mentions of Uni-T B4Q094 UT210E True RMS AC/DC Current Mini Clamp M W Capacitance Tester

I saw this one on Big Clive's YouTube channel and it's served me very well.

Uni-T B4Q094 UT210E True RMS AC/DC Current Mini Clamp M W Capacitance Tester https://www.amazon.com/dp/B00O1Q2HOQ/ref=cm_sw_r_cp_apap_SCHenkNd6Avzz

Here are some links for you to read and learn from people that have gone before you....

Handy Bob, kind of grumpy but knows how to make solar work, will give you the basics. It is getting dated but a good place to start.

Voltage Drop Calculator,you need to know how much loss will be in the wires and compensate for it or else watts are just heating wires and not charging batteries.

A Multimeter so that you can troubleshoot and verify that your system is working.

Ohm's law, you should at least understand the concept and relationship between voltage, amperage, and watts. Watts are universal. a 1,000 watt device be it Ac or Dc is always 1,000 watts. But 1,000 watts at 12 VDC draws 84 amps (lots of current. AT 120 VAC 1,000 watts draws 8.4 amps. See the relationship there? Volts x amps = watts.

Where are you measuring the AC voltage, at the battery? Any ripple will read as AC voltage, 40millivolt ripple isn't much.

If you have a DC clamp meter, put that on the alternator cable and you can easily read if thats the cause. If you don't own one, they're handy and this ones nice for the price: link. Another option is to measure the other circuits in your car like this with a regular meter: https://www.youtube.com/watch?v=lRcj1fQcWwU

Unfortunately the alternator is the one thing that cant be measured this way since it doesn't go through the fuse box. But you can eliminate everything else this way.

Great work! You've basically made a bombe calorimeter of sorts.

Your figures might be a little low because I don't see any mention of the mass of the light/battery. That is at least 85 grams of stuff also being heated with the 300 grams of water.

(The UT210E is a great cheap clamp meter for this.)

I have two Uni-T UT210E's and theyre great value. Pretty accurate, they can sense in the 1's of milliamps but there is a bit of noise & drift at that range. At 10 milliamp scale its pretty much golden. Good for automotive. Amazon: link. There's a bunch of reviews on youtube you can search for also.

I've had one of these for years and it works pretty well, but it is unnecessarily big and clunky. Personally, I would go with this one instead. I bought it a little over a year ago and it has been a very good meter. I would honestly take it over pretty much any of the Ames meters we sell. If you need one with a current clamp on it, this one will probably do it for you. I don't have one personally, but Big Clive on YouTube does and he seems to like it.

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If you don't already have a meter, don't even bother getting the $4 one. I have a couple that I got with a free coupon and they are all junk. The leads are downright trash. The only time I use one is if I am doing current measurement and I don't want to risk blowing a fuse in one of my good meters.

I read the same warnings and had the same concerns about the sata cables. So I bought one of these: Uni-T B4Q094 UT210E True RMS AC/DC Current Mini Clamp M W Capacitance Tester https://www.amazon.com/dp/B00O1Q2HOQ and measured the current. Each of my GPUs pulls 0.3A from the sata connector, which is well within spec for sata.

It's easy enough to check :) Have fun on your trip. RV camping without facilities is a good skill to have under your belt. A camping group I'm in took our three RVs up to Rocky Mountain National Park. It was a great time and we were all nerding out about how much battery we had, etc because you have a pretty narrow charge window there. It really became useful when a 4th showed up with no generator and we were able to help them out because we knew exactly what our status was and what we needed to get through the night.

If you are a gadget guy, this can be a handy thing to have:

https://www.amazon.com/gp/product/B00O1Q2HOQ

What makes it different from other meters is it can show you DC current as well as AC just clamping over a wire. Most cheap meters only do AC current via the clamp and measuring DC current is more involved.
That can be SUPER handy for seeing how much power your batteries are taking in during the charge cycle or putting out during the discharge part of the day. The meter does other stuff too a multimeter would which is good to have in the field.

Time for a new meter. For home use I recommend this one to people.

are you using one of these to measure?
https://www.amazon.com/Uni-T-B4Q094-UT210E-Current-Capacitance/dp/B00O1Q2HOQ/ref=sr_1_5?ie=UTF8&qid=1499406313&sr=8-5&keywords=current+clamp

Take the time to learn how to use a multi meter. It will help you for the rest of your life. Electricity and electronics should be taught in primary school and everyone should know how to use a multimeter. A multimeter is simply a combination various meters and testers into one device: a voltmeter to measure volts, ohmmeter to measure resistance in ohms, an ammeter to measure current in amps, and various other things like electrical connection continuity, temperature (with temp probes).

You can purchase a simple multimeter for less than $10, however for your specific electrical problems, I recommend one that has a DC clamp-on ammeter like this one. That lets you clamp the meter around a wire to measure how much current is flowing, like on brake light circuit to see if it's drawing the correct current needed for the light bulb, or whether there's a short circuit that's drawing a lot more current than it should be doing.

If you aren't willing to learn how to use a multimeter, then don't bother attempting to fix this problem by yourself. Find another mechanic. You need to know basic electronics to diagnose and fix most electrical problems, and it can be dangerous to you and to others for you to mess with electrical things without that knowledge.