First Solar Setup. Need help.

[Loganxw]

Hey all, this is my first and I am a bit overwhelmed. I have studied through hours and I have pretty much everything that I need and want but I need advice.

I have a 2014 Travato. It currently has two AMG batteries under the middle of the camper in a holding case. They feed to a 30amp charge controller. The 120 volt only works with shore power.

I just bought the renorgy 12v 2000w inverter. I also bought heated li time 2x 12v 100h lipo4 batteries to replace the amg batteries. I also bought 4 x 12v li time batteries that go under the bed in the chassis. I got the Renorgy 50 amp dc to dc mppt controller. I have 300watts of solar going into that. I have a 40amp mppt renorgy controller with 400 watts going into that.

So I have basically one bank of 2x 100ah batteries in one section and another bank of 4 x 100ah in another. They are very close two each other, only about a foot or so away. But separated by being inside and outside because of space. What is the best way to connect these to the inverter? The inverter will be near where the 4x battery bank will be. Once again thank you for any advice.

 

[JBertok]

Hello,
I don't work here I just lurk and cause problems, but with that out of the way - welcome!

Okay, so the 2 AGM batteries and their 30amp charger are outgoing. Good - you cannot mix AGM and LiPO4 on the same DC system.

Since you're new, I need to ask, are you aware of the low temperature limitations all LiPO4 batteries have? I see you're in Colorado, so this is a relevant consideration. You got 2 heated batteries which is good, hopefully all 6 are, but heating is costly from an energy perspective and should be minimized.

Next, all of your LiPO4 batteries are 100Ah. I am going to guess that despite their relative difference in position on the vehicle, you'd like to have them all working together. This is easy. To keep them all in balance, use a pair of copper Bus Bars and connect each of your batteries to them with identical lengths of identical heavy-gauge cables. Even if there are some that are way too long it is necessary to keep them all identical for the batteries to stay as equal as possible to each other because LiPO4 is sensitive to millivolt differences. It would also be beneficial to try to give each of them matching environmental conditions - you don't want two colder than the others, for example. You make mention of them being separated by interior and exterior space. I would make the argument they all need to be inside due to the temperature requirements.

Connecting the bus bars to the inverter is straightforward. Keep the positive and negatives parallel to each other whenever possible to minimize impedance, which is a consideration with high current low voltage scenarios like this.
600Ah is a hell of a lot of power to have riding around with you, so you need to have current limiting devices inline with every source of power in case of a short. I don't know what kind of batteries you have but am aware most of the stuff marketed to RVers does not have circuit breakers built in.

Next, the chargers. You have two of them, a 40A with 400 Watts of PV attached, and a 50A with 300W of PV. That seems fine. You've got more PV than just the 50A unit can handle on its own, so this 2 is good. They need to be configurable for Lithium Iron Phosphate chemistry. Don't forget the overcurrent protection with these also.

Do you have means to monitor all this stuff - especially the batteries? All LiPO4 batteries have a BMS inside them between cells and the terminals - this is because every cell will have small variations in capacity and response. The BMS is there to balance the cells and ensure no individual cells exceed voltage or temperature range limits or else the BMS will disconnect the terminals and fully shut down the battery. The best case would be that your batteries have Bluetooth app monitoring built in. The batteries probably have some kind of on/off switch, and those need to be accessible. The charge controllers can help you determine your energy input, and the inverter determine output. The most useful metrics will be battery bank state of charge and inverter load. The upside to piecing together individual components together is convenience and choice in selection, but that comes with a downside of fragmented management and monitoring challenges with different apps, etc.

 

[Loganxw]

All batteries all Li Time. Due to space i have a compartment underneath that can hold 2 batteries and a compartment under the bed inside that can hold four. For the four batteries inside I was going to use low temp but not heated. Since they will be insulated and not outdoors. Vs the two heated that are in the compartment outside under neath. For the bus bar connection. I was going to use 1/0. Get a 8 post bus bar. Connect all 6 batteries with same size 1/0 to the bus bar. Positive and the bus bar negative. Then run a short distance from the bus bars with the 1/0 to the inverter with a 300amp fuse in between. Thoughts?

 

[Loganxw]

Or could I run the two bank under have those in parallel and then attached to the bus bar. Then have the four battery bank in parallel and also run to the same bus bar. All same lengths, just two banks connected to the bus bar separately?