Critique my solar charger/battery monitor setup?

Buddha.

Finally in expo white.
Get a volt meter on the AC and DC side. What is the DC voltage? AC voltage? If the aren't where they need to be, something could be wrong.
The inverter in the back of the truck has a display that shows DC and AC voltages but I didn't verify with a volt meter. I also wasn't watching it when the converter started to get noisy. I'll check it.
 

luthj

Engineer In Residence
A true sine wave won't cause trouble, but if the inverter produces a significant harmonic distortion, you will have some noise at the charger.

Some noise is okay though, I would monitor the charger to make sure its not getting crazy hot, but it should still work fine even with some harmonic distortion.
 

Buddha.

Finally in expo white.
Go back through this thread and add up how much time and money has been spent on this already that now has to be thrown away...


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Are you talking about my 12v-36v converter I was going to use? That was like 35$.
 

Bayou Boy

Adventurer
Are you talking about my 12v-36v converter I was going to use? That was like 35$.

Plus that $250 inverter, $20 extension cord, and now none of it works.

There is a lot to be said for not reinventing the wheel and there are much cheaper DC-DC chargers than that Redarc. I just like that one because it is sealed and watertight.


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Alloy

Well-known member
Plus that $250 inverter, $20 extension cord, and now none of it works.

There is a lot to be said for not reinventing the wheel and there are much cheaper DC-DC chargers than that Redarc. I just like that one because it is sealed and watertight.


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Bul
Alright, I got the inverter installed. I ran 50' of 120v extension cord back to the converter.
Time for a test. I unplugged the converter and drew the batteries down to 85%(this took 3 hours with all lights on, three roof fans on and the furnace fun running continuous). I fired up the truck, turned the inverter on and plugged the converter into it. I saw a little over 30 amps for a few seconds and then it quickly dropped off to mid 20's and then low 20's in about a minute. It was at this point I heard a very high pitched buzz coming from the converter which I never heard before. I unplugged the converter and it stopped. I plugged the converter into shore power and the buzz started again. It was my intention to let the inverter charge the batteries back up but the high frequency buzz gave me a concern so I let it the converter charge off shore power, which it did just fine.

The inverter is advertised as "pure sine wave". Is this thing gonna damage my converter? Did it already damage my converter?

The converter. https://www.progressivedyn.com/rv/p...onverters/pd9260c-60-amp-rv-convertercharger/

Th inverter. https://www.amazon.com/gp/product/B07T2GNHQM/ref=ppx_yo_dt_b_asin_title_o04_s01?ie=UTF8&psc=1

Can you return the inverter and buy one that is UL or CSA listed?
 

luthj

Engineer In Residence
I have tested a few cheaper inverters in the ~500W range. IIRC, of the 3 I tested, only 2 were "pure sine" despite all three being labeled as such. The 2 were under 5% harmonic distortion, the third was roughly 20%, and wasn't too far off a square wave...
 

Rando

Explorer
I have been using a 12 - 24V DC-DC converter into a Victron 100/20 MPPT for months and it works swimmingly - I would go back to that option. If you already have the MPPT controller, for about $30 you get a fully configurable and monitorable battery-to-battery charger. It also works seamlessly with solar, as long as your boosted voltage is somewhat near the Voc of your panels you can leave both connected and when you stop the MPPT will just draw from the solar panels.

Here is a diagram of how to do this that I posted some time ago:
dc-dc-charger-1-png.540304
 
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Bayou Boy

Adventurer
Rando. What does somewhat near the voltage mean? How close is somewhat near?

19VOC isn’t remotely close to 24V in my mind but if that works...


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Rando

Explorer
If you have your panels in series to output 72V, you probably shouldn't use a 12-24v boost converter. This is more of an issue for the boost converter than for the panels, the output electronics of the converter are likely only rated for a bit over the boost voltage. I can't say specifically without seeing a spec sheet.
 

Buddha.

Finally in expo white.
Now that going to Alaska for the summer is out of the question this project was put on the back burner. I finally got around to testing my Renogy 40amp DC-DC setup. I let the batteries discharge for a while so I could test the re-charge. I meant to let the batteries go down to about 50% but I got down to 28%. Also I had set my 712 battery monitor to my total AH and not my usable AH. It was saying I had something like 70% capacity at 11.8v. So I told the monitor what my usable AH was instead.
Note: The truck was sending power back through the factory trailer wiring in addition to the 2awg I installed. Hence the more than 40amps.

I let the batteries charge soley off the truck for a while to get an idea how that would go. Note the times in the top of the images.

1704A1E1-1216-4D0C-9379-CCD6CA6B3707.png
99D6A4A5-677F-4CBE-8DBB-450DF34B0B62.png
 
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