Solar Top Off Estimates

[tony.latham]

Everyone should get au fait with a DMM and ammeter...

John:

What do you use? Got a photo of your setup?

T

[bdosborn]

Stumbled across this connector this morning, looks pretty good. I have the Perko connector that Tony linked to and its well made but the plug isn't indexed so you can touch positive to ground if you try and insert it upside down. I've never done it but it makes me nervous.

Solar Conector to SAE Adapter

Bruce

[bdosborn]

Just got back from three days at the Great Sand Dunes. While we were camping at an RV park I left the battery charger unplugged so I could check solar usage. Looks like I was way off on my usage, we used 68 amp-hrs one night. I was running both the interior refrigerator and the Waeco CF30 off the trailer battery. The good news is the battery was completely charged by 1pm or so each day. I have a LiFePO4 battery, which makes a big difference when it comes to recharging rate. Here's battery usage versus solar collected:


The lowest blue line is battery SOC.

I'm guessing that at least 2/3 of my energy use is from the two fridges. I was having trouble with the Waeco power plug, it wouldn't stay connected and the Waeco would get warm during the day (48F). Then it would run during the night off the trailer battery and cool the beer back down to 33F. I would have set it to 40F instead of leaving it at 33F if I was worried about energy use. I think 45 amp-hrs or so is probably more typical of our usage when running both fridges.

Bruce

[John61CT]

That's not bad!

Huge variation from different ambient conditions.

And yes always more efficient to maintain a steady state compared to only running for parts of the day.

[DoctahDeane]

Stumbled across this connector this morning, looks pretty good. I have the Perko connector that Tony linked to and its well made but the plug isn't indexed so you can touch positive to ground if you try and insert it upside down. I've never done it but it makes me nervous.

Solar Conector to SAE Adapter

Bruce

This is great, I need one of these! Thank you.

[DoctahDeane]

Also, maybe most people are continually topping off from tow vehicle while driving, or solar while stationary?

That's certainly the way I did it with Flash, our old teardrop that still has it's original FLA battery from 2013.

But things changed with this new build. In fact, I hesitated during a sip of coffee to sharing.

I installed a VMAX Group 24. And as we both know, VMAX batts aren't cheap. AGMs are supposed to be charged at something around 14.5V or so and automobile charging systems don't quite put that out. (And I have no idea how "smart" they are. After all, they don't even know they are dealing with two batteries at two different states of charge. And in this case two different types of batteries.)

Now, if you Google around this forum, you'll find plenty of folks that have had good success with charging AGMs off their tow vehicle. For this new build, I chose to wire the battery to the tow vehicle but included a cutoff switch so that normally the charge would only be from the solar panels ––with the controller set for AGM.

Plan A was to turn that switch on for a travel day while we were changing camps and the battery was low because of clouds, shade, or a combination.



The disconnect switch is that big red thing. (And yes, the wires are hidden these days.)

From what I have seen so far, I doubt I'll ever have to turn it on.

Did I overthink this? Ask me in eight years how that old VMAX is doing.



Tony

Tony - I just got my Renogy Adventurer and reading through the instructions. I'm assuming I ought to put an inline fuse (30A?) on the new + battery cable, close to the battery. this cable will then run up to the controller. True? Also, I *think* 10GA wire is correct. Do you agree? Thanks a lot.

[bdosborn]

I use one of these on the battery terminal for my solar charge controller wire to the battery:

Battery Fuse


#10 AWG = 30A.
Bruce

[Tom&Shelly]

I use one of these on the battery terminal for my solar charge controller wire to the battery:

Battery Fuse


#10 AWG = 30A.
Bruce

The fuses for those look a bit pricey. Of course, you don't want to be blowing them very often...

Tom

[DoctahDeane]

OK, thanks!

[bdosborn]

The fuses for those look a bit pricey. Of course, you don't want to be blowing them very often...

Tom

Boy you ain't kidding. I blew two or three of them when I converted over to the LiFePo4 battery. The good news is that they work very quickly, so fast there's no flash or sparks during a short.

Bruce

[DoctahDeane]

Stumbled across this connector this morning, looks pretty good. I have the Perko connector that Tony linked to and its well made but the plug isn't indexed so you can touch positive to ground if you try and insert it upside down. I've never done it but it makes me nervous.

Solar Conector to SAE Adapter

Bruce

Bruce - hi, this just arrived today and it looks good. Thanks a lot for the pointer. If you look at the photo breakouts, it's easy to see that that cable connectors are there to go from the panel to the port that would sit on the side of the trailer. There's a fused cable too and I'm confused because the cable that is connected to the rubberized port that with sit on the side of the trailer just ends with no connectors so I'm assuming they should go directly to the battery posts with crimped connectors (which I have). But what about the additional fused cable? The panels I got are one of the suitcase jobs that sit outside the trailer and the controller is included and attached to them in the "suitcase" so it should be a quick connect to this cable you pointed me to and then THAT cable to the side port that I'll drill a hole for. But the open question (in my mind :-) ) is about the additional fused cable. Not sure where that sits??

[tony.latham]

There's a fused cable too ...

I'm not seeing that in the photos, but fuses on wires are a good thing.

I'm glad you've got Bruce's attention on this thing. He's the guy that got me hooked up to the sun "back-when."

Tony

[DoctahDeane]

There's a fused cable too ...

I'm not seeing that in the photos, but fuses on wires are a good thing.

I'm glad you've got Bruce's attention on this thing. He's the guy that got me hooked up to the sun "back-when."

Tony

Thanks, I'll take a photo and add so it'll be less confusing

[bdosborn]

Post a picture of the cable end on the solar panel that you'd connect to the battery and then we can figure it out...

[DoctahDeane]

Post a picture of the cable end on the solar panel that you'd connect to the battery and then we can figure it out...

I will thanks a lot. Panel due there in a few days