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Discussion Starter #1
I basically copied TRHOPPE's diagram with some changes to wire size and added more fuses/CB. etc. I would really like to go with #2 where I have 2/0 as I have seem equal number of diagrams of both so please let me know if this is possible and why #2 can suffice. Also I think the 30A fuse from the PV's is not necessary based on many comments on that, Midnite does call for it though. Finally, do I need a fuse at the van battery?

Thanks for your help.

 

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2014, 138WB, High Roof, Gas, SW MT
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Hi,
Couple of thoughts on your diagram...

- The Midnight Solar Kid controller is a quality produce (I have one), but it seems like overkill for two 100 watt 12 volt panels. When I bought the Kid, it was $250, which seemed like plenty, but it looks like its now north of $400. There are lots of MPPT solar charge controllers you can get for FAR less that are good and will handle a couple 100 watt panels easily.

- The 2/0 wire from van battery to house battery seems oversize. If you run the BlueSea Circuit Wizard for 6 ft total of wire and 2% voltage drop at 150 amps, it comes up with #4 wire. So, seems like 2/0 is several sizes larger than needed?
I'd also consider lowering the 150 amp breaker to something less. If you ever actually got 150 amps of charging current, it would be be 0.75 of the C20 capacity, which would likely be way over what the battery manufacturer recommends.
I'd check with the manufacturer on what the max charge rate they recommend is, and then change the 150 amp breaker to a bit over the max charge rate -- this way if the breaker opens you will know that you are charging your battery to fast. It will also allow you to size down the 2/0 wire to something that matches the smaller breaker. The BlueSea Circuit Wizard is a good way to do the sizing http://circuitwizard.bluesea.com

- You do need a fuse or breaker at both ends of the wire going from the van battery to the house battery. One of the fuses should be as close as possible to the van battery and the other as close as possible to the house battery. The reason is that if you have a short to ground along this wire, and you don't have a fuse on each end, the end you don't have a fuse on will supply all that battery can and will melt the wire and maybe burn your van down.

- It looks like you are relying on a chassis ground for the negative side of the van battery to house battery connection. I would run a full size negative wire from van battery to your shunt (same size as your wire to the + terminal since they both carry the same current). Its hard and time consuming to make really good chassis ground connections (especially for high current connections like these), and they tend to deteriorate over time adding resistance or worse as they corrode.

- Not sure how the AC distribution works, but seems like you might want some kind of AC distribution box with circuit breakers for your AC loads? Or, maybe that's what the box inverter is?

- No shore power?

Gary
 

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2017 159, w/dual sliders. SF Bay area
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Why a 110 fridge vs a 12V model? I would expect the 12V model to operate more efficiently.
 

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2014 136” HR
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I don't understand why, but you are going to have an issue with the 200Ah battery/Xantrex Prowatt 2000/800W microwave combo. We found out the hard way this week with a 700W microwave, which drew 900W on our MSW inverter, but draws 1,000W on the pure sine.

The net result was that while the microwave ran happily, quietly, powerfully on the pure sine, it drew down the batteries under load so badly that we could not use it when the battery was less than 80% full. We did not have this problem when the microwave was loud and sluggish on modified sine. Also, with modified sine, the voltage only blipped down. With pure sine, the voltage dropped and stayed low.

Can someone explain this in language I can understand?
 

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Discussion Starter #6
Gary, thanks for the feedback and explanations.

I went with the Kid because I saw alot of them on the various forums and wanted to make sure I could add more panels in the future. I got mine for $295.

Will change battery feed to #4 , add 100A fuse at van battery, reduce CB at house battery to 100A.

Will also change 2/0 to inverter to #4 , this the smallest the owners manual allows.

Keep 2/0 to connect 12v batteries in parallel.

Finally will run shunt ground (#4 ) to van battery.

As for shore, will likely pick up a NOCO G26000 charger and do a manual hookup as necessary. Assume the ground needs to go to far side of the shunt so the BMS can keep track of the progress.

Again, thanks
 

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Discussion Starter #7
MsNomer, I guess I should run the vehicle just prior to using the microwave, assume that would help out. What size is your wiring and length from the battery to your inverter?
 

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Discussion Starter #9
ThomD, I was trying to save some money, the 12v models are pretty expensive, I think the load (.7 amps) for the small fridge is low enough to not eat into my daily allowance.

Please let me know if I am going to get in trouble with the 110 fridge.

Thanks
 

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ThomD, I was trying to save some money, the 12v models are pretty expensive, I think the load (.7 amps) for the small fridge is low enough to not eat into my daily allowance.

Please let me know if I am going to get in trouble with the 110 fridge.

Thanks
One thing that doesn't get talked about a lot with the fridge is the difference how loud a regular 110v fridge is. My fridge is my biggest consumer of AHs so I would buy a 12v again for sure.

Sent from my Pixel XL using Tapatalk
 

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The .7 amps for that 110 fridge is probably AC amps. So, more likely 7 amps DC. Factor in the inverter inefficiency and it might be more like 8 amps. Most DC fridges will draw 5 amps or less.
 

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Our NovaKool R-4500 DC fridge is rated at 36A/24hrs (average), which is only 1.5A/hr. We briefly considered a cheap 120V Walmart dorm/beer fridge, but we didn't want to be forced to run our (relatively expensive) 2000W inverter all the time. Plus, the cooling units in cheap 120V fridges were probably not designed to withstand bouncing or tipping, and they can be noisy. But some people apparently get away with it. Your call of course.
 
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