Renogy batteries

Just a suggestion, I personally like to use 6 volt (or other batteries with few cells) to make into a series string, then parallel them.

Especially with AGM batteries, the only way you can monitor the health of individual batteries is to measure the voltage across each battery. Then you can tell if you have a weak/problem battery with a simple voltmeter reading across each 6 volt battery.

With 12 volt batteries in parallel, the battery bus voltage is the result of the highest voltage of one of all the parallel cells. So, you are left having to disconnect each battery and letting it rest a few hours, to read the "true" battery voltage.

For example, if you get 8x 6 volt @ 200 AH -- Put two batteries in series (makes a 12 volt @ 200 AH "string"), then parallel 4x strings, you have your 12 volt @ 800 AH battery bank.

Another question... 4x 12 volt @ 200 AH = 12 volt @ 800 AH battery bank. That is a pretty good size battery bank. You are about at the dividing point where you may want to think about a 24 volt @ 400 AH battery bank. It allows you do use smaller AWG wiring (save on copper costs, 1/2-1/4 thickness wiring also is easier to terminate and route). Although, for RV use, many choose to stay with 12 VDC to run easy to obtain 12 VDC lighting and appliances.  Although, there are a fair amount of 24 VDC devices out there too (heavy truck, marine).

Another issue is paralleling a relatively large numbers of batteries... Wiring needs to be well thought out:

http://www.smartgauge.co.uk/batt_con.html

And, ideally, each battery string should have its own fuse/circuit breaker (in case there is a short circuit/somebody drops a wrench on the battery connections, etc.).

I, personally, like to limit a design to 3 parallel strings... And I prefer 2 parallel or 1 string if possible. So, looking at larger AH batteries (or even cells) is a possibility:

Here is an example of "2 volt" single cell batteries:

https://www.solar-electric.com/residential/batteries-battery-storage/deep-cycle-batteries.html?nav_battery_type=443&nav_battery_voltage=387

https://www.solar-electric.com/concorde-sunxtender-pvx-7680t.html (2 volt, 768 AH, 75 lb, $370 each--Use 6x series for 12 volt @ 768 AH)

And back to the 800 AH battery bank... ideally, you want 5% to 13% rate of charge, with 10%+ being better for full time off grid usage (vs weekend/summer use).

10% of 800 AH is 80 Amp charging current nominal. If you are using solar panels for all of that charging:

• 800 Amp*Hour battery bank * 14.4 volts charging * 1/0.77 panel+controller derating * 0.10 rate of charge = 1,486 Watt array nominal

If you are planning on using for winter sports--Solar is generally difficult, especially the farther north you go.

Generally, for an off grid home, we suggest 2 days storage and 50% maximum discharge (for longer battery life). For RV use, 1 day storage and perhaps even deeper discharge is "better" (smaller, lighter, cheaper battery bank). Sizing your battery bank for maximum DC load:

• 160 Amps * 5 hour discharge rate = 800 AH for a Flooded Cell Lead Acid battery (max suggested for FLA)
• 160 Amps * 2 hour discharge rate = 420 AH for an AGM bank (perhaps even 1 Hour or faster discharge OK)

And use a genset during the day for normal/heavy loads. And just use a smaller battery bank at night for quiet time loads.

Use a 600 Watt microwave (~900 Watt 120 VAC load) to reduce your peak current draw is helpful too.

https://www.amazon.com/Counter-Rotary-Microwave-WCM660B-Westinghouse/dp/B00BGTO1WC

Your thoughts/questions?

-Bill