Roast my DIY solar system on my camping truck

[mesquito_creek]

@rrrr
@Uncle Dave

1) Why do I get 3 different amp readings off of my panel? Amp Clamp on the panel (1.5a) vs Probes at the end of the panel wire (7.18a) vs Amps at the controller input connection (4.42a).
2) Does using the amp clamp at the pigtail of my 12v fridge give me a good reading on what the amp use is on the Dometic CFX 50 fridge (2.92a)?
3) Based on all the discussion in 2FF's battery isolator thread, does my Truesmart battery isolator present problems for my X2 Power house battery? Charging of the stock Chevy 6.0L gas alternator?


What am I doing wrong and what am I doing right.... Fire away, I can take it!

 

[Shlbyntro]

It looks to me like the wire coming off of the solar panel might house both the positive and negative lead within that one sheath. An amp clamp will never be able to get an accurate reading when both the positive and negative are passing through the clamp at the same time.

Isolators do tend to eat a little bit of current while performing the job of isolating which may be the cause of the different readings at you isolator and battery.

Thats my best guess without being able to trace your wires myself or seeing a drawing of how everything is wired up.

 

[evantwheeler]

That clamp appears to be for AC amps (~). Aren’t you trying to measure DC amps?

 

[evantwheeler]

McMaster Carr sells the proper clamp for DC amps. I know this because I spent 250 bucks on an AC ammeter to measure amps on a DC welder and had to go back an buy the right ammeter after my data didn’t make any sense.

 

[Shlbyntro]

That clamp appears to be for AC amps (~). Aren’t you trying to measure DC amps?

The symbol indicates that the meter does both

 

[mesquito_creek]

It does both AC and DC... DC is the solid line with a dotted line underneath like in the pic... AC is the squiggly line and would not give a reading if set that way.

 

[lbhsbz]

That’s a big clamp for low amp DC. Probably anything but accurate. Where are you located? If around Long Beach, I have a good DC low amp probe you’re welcome to borrow....although since everything is less than 10A, if your connections are easily disconnectable...run it through any volt meter with amp capability (most handle 10A) for the most accurate reading.

EDIT: Pro-tip....after running the load through your meter...pull the leads out and turn it off immediately...so you don’t forget it was on amps, then go measure volts 2 minutes later and blow the goddam fuse (I can’t tell you how many times I’ve done that)

 

[Uncle Dave]

got to noodle on 1 and 2. Run the same test looking at volts.

I would expect the output of a PWM charger to be higher - it isnt really outputting a continuous stream but a set of pulsed outputs that fool your meter into thinking its continuous, I wonder what my fluke would show at the same places.

For #3 I doubt it to no- your AGM can accept a very high charge rate for a brief time.

 

[mesquito_creek]

got to noodle on 1 and 2

I would expect the output of a PWM charger to be higher - it isnt really outputting a continuous stream but a set of pulsed outputs that fool your meter into thinking its continuous, I wonder what my fluke would show at the same places.

For #3 I doubt it to no- your AGM can accept a very high charge rate for a brief time.

On #1 all three measurements on on the input side from the solar panel to the controller. The 7.18a reading by directly probing the wires directly off of the panel confuses me since the panel says its Ipmax is 5.5. But maybe measuring voltage/amps directly off the panel isn't valid? The 4.42a where the panel connects to the controller seems more reasonable, suggesting that the panel is putting 4.4 of the 5.5 rated amps into the controller?

On #2 Its seems as if my measurements on the fridge compressor vary alot. I somewhat assumed that when the compressor is on, its on and draws a pretty consistent amount of amps. But maybe the hotter it is both externally and internally, the more amps the compressor draws? The manual says that its "rated current" is 12 Vg: 7.8 A

 

[Uncle Dave]

Not often, but occasionally panels are underrated. I just don't see it in this case though.

See what the volts are in each location - just curious.

Is that an ARB fridge? If so it has a variable speed component to it (at least mine does)

UD

 

[mesquito_creek]

Not often, but occasionally panels are underrated. I just don't see it in this case though.

See what the volts are in each location - just curious.

Is that an ARB fridge? If so it has a variable speed component to it (at least mine does)

UD

It is a Dometic Fridge, CFX 50.... My guess is that it maybe does the same thing as the ARB and requires less energy once the contents are cold and the outdoor temps are lower.

 

[Uncle Dave]

It is a Dometic Fridge, CFX 50.... My guess is that it maybe does the same thing as the ARB and requires less energy once the contents are cold and the outdoor temps are lower.

Its a variable speed unit, or at least the newer 55 version is
Considering my 2016 arb has a fast cool mode Id guess thats the difference you are seeing.

Dave

 

[racetrash]

Select switch on the meter changes it from ac to dc. Picture shows a dc reading, ac would show small sine wave.

 

[stingray11]

I think your biggest problem is the fact that you would think that solar panels are going to work to power anyting especially in the desert where you need some big time cooling and heating[emoji23][emoji23][emoji41]

Sent from my SM-G930VL using Tapatalk

 

[spectracular]

If you coil/loop the wire from the panel x times and then put the clamp around the coil/loop you will see x time higher amperage. Could be useful just to get enough amperage for the meter to register. Even still, your are only going to get 100 watts max out of the panel at around 18v. So that works out to a little offer 5 amps at 18v and a tad more at 12v. Panels are rated for perfect conditions...like in Space!!! They will always make less than rated power in earths atmosphere.

 

[mesquito_creek]

I think your biggest problem is the fact that you would think that solar panels are going to work to power anyting especially in the desert where you need some big time cooling and heating[emoji23][emoji23][emoji41]

Sent from my SM-G930VL using Tapatalk

Why would I need heating and cooling in Arizona right now? Its 74-80 degrees during the day and 65 at night? This small solar system powers an off the grid camping truck and has no problems running a fridge, inverter for coffee pot and charging miscellaneous devices like phones and Bluetooth speakers..

There is another RDP member who posted his whole journey to be completely off the grid here in Arizona, so its hardly even a question that its doable... Its completely doable...

 

[2Driver]

Post a pic of the whole set up as in the truck. Like to see it.

 

[mesquito_creek]

I am the original owner of this 2005 Chevy 2500HD 6.0L gas truck CrewCab Longbed with factory 4:10 gears and the locking rear diff. Stock drive train with 185K miles on it. This build is my "after 50 years old", a lot of bolt on stuff project, but I did have to build the carpet kit/sleeping platform. Not meant to be a real expo truck, but more of a get out of the heat in Arizona weekender. Hopefully, capable enough to get far enough away from the masses....

Suspension Front: Cognito Motorsports upper control arms, steering upgrade, green keys, and fox 2.0 shocks.
Suspension Rear: Removal of the overload spring replaced with a Deaver progressive on AirLift air bags , with fox 2.0 shocks.

 

[mesquito_creek]

I accidentally left my cheap Chinese inverter on and vampired my battery down to 10.2v. So as an experiment, I fully charged the battery back up with solar only on my morningstar controller. It took 2 days in the 115 degree heat...

The misunderstanding about Arizona is that there is lots of sun for solar, but the heat protection and bad performance of the overheated panel pretty much brings the battery charging process to a halt in the hottest part of the day. My house battery is in the engine compartment along with the solar controller, so that doesn't help. It works a lot better in the mountains and cooler temps for sure. But regardless, it eventually got the job done.