Are you trying to build a battery bank to fit your needs? Do you still find it confusing when thinking about what your RV power system needs may be? I am going to give a detailed walkthrough of our system showing what we have in use for our system. I will also point out what works well for us. The material works best by breaking it into subgroups. This allows me to better explain how they work in relation to all the other equipment to build the system starting with the battery bank.
The most important part of the system really comes down to the battery bank. It is a big reason why you should build it specifically to fit your needs. It provides energy storage for the entire system. When calculating your battery bank sizing, you should evaluate several factors. Some factors being expected size of loads, duration of loads, and what available inputs.
How did we choose to build our battery bank so that it would fit our needs?
When designing our system, I wanted to make sure to build it to fit our needs. I knew that I would be powering my rig with split-phase service from two inverters. It is designed to be used in off-grid mainly boondocking situations. My loads were not going to be large for the two inverters at the same time. Most of my continuous loads were on DC circuits. Such as the Norcold propane absorption refrigerator, led lighting, and propane water heater. My AC current loads expected to be two Apple Laptops, occasional microwave or Instant Pot use for cooking, hairdryers and curling irons, and emergency use of the bedroom air conditioner for my senior dog for high temperatures.
Assessing the largest loads helps guide you to a minimum size battery bank to fit your needs.
Each of the Victron inverters recommended a battery bank capable of outputting 300 amps to supply its energy. I do not expect both of my inverters to draw heavily on the battery bank at the same time. My minimum battery bank calls for 300 amps output by following the recommendation for the minimum for a single inverter to fit my needs.
Calculating your daily battery bank needs is important.
If you do not know your individual usage yet, there are tools available to help you learn. You can check out my post on calculating your needs here. I recommend that you consider installing a BMV-712 Battery Monitor or a Smart Shunt. Also, consider purchasing a Kill-o-watt energy meter. Both will allow you to learn what your usage currently is. I knew from my first system that my average continuous usage was going to be 9-16 amps or 100-200 watts. So when looking at my bank size I wanted to be able to maintain my loads 24 hours a day. When I was not bringing in solar I would expect to see a usage of 1200-2400 watts of power overnight. Each of the Battle Born GC2 batteries has a rating of 1200 watts. This would mean I would discharge up to two batteries worth of stored energy overnight.
Knowing how long you want to go without running a generator or plugging in will allow you build a battery bank multiplier to find a good fit.
I also knew that I wanted to build my battery bank to last for at least three days before I needed to find a charging source if my solar panel array was not sufficient due to inclement weather or shading. So after two or three nights with inclement weather during the day with solar harvests sustaining daily usage, I would then have to consider using an alternative source of power. For those times I carry two 2000 watt Champion inverter generators that fill my off-grid AC power requirements in inclement weather. Individually I am not able to get full use out of the charger in the Victron inverter/charger due to current limitations. I am able to get higher charging rates when the generators are in their parallel configuration.
How did we wire everything together?
Additional components shown include 400amp BlueSea t-fuses. They are a good choice for inverter loads that have continuous high currents as well as the high surges. A common mistake that I see DIY installers make is that they try to save a few dollars on the small required components that turn out to be large weaknesses in the system. Fuses are some of those components. Most gold plated ANL audio fuses will cause trouble in a system due to their high resistance that they cause.
The inverter battery disconnect switches are after the fuses. They will disconnect the battery power in case there is a reason to isolate the inverter. Such as to change the fuse or perform maintenance to the system. For long service life, do not switch under load. Ensure the inverters are off at their power switches prior to switching the battery disconnect switches to on or off.
The last two components shown are a 120 amp circuit breaker and a pair of busbars. These components often have cheap products in their place that can cause problems in the system. The circuit breaker can be a source of high resistance and erratic tripping issues. I recommend BlueSea or Bussmann circuit breakers for reliable service. Do not utilize circuit breakers in place of catastrophic fusses for inverters. The busbars are used to make better connections. For the busbars, I recommend either the BlueSea or BEP Marine busbars. Pay careful attention to current limits and try to make connections that will aid in the least amount of resistance.
Still looking for some assistance?
If you would like a consultation to discuss your specific needs, send me a message at Justin@OptingOutofNormal.com. We can get a meeting scheduled. I do have a list of recommended vendors that do pay an affiliate fee. I could get credit based on people following links in my blogs or working with those vendors to quote packages for consultation projects. If you would like to source your own parts and equipment, consulting fees may apply depending on complexity and involvement.
A complete list of parts and equipment that we utilize in our system can be seen at Kit.co/optingoutofnormal.
Check out our blog “How to size an inverter to fit your needs“. We show how we get the most benefit out of our Victron Inverter setup. If you are boondocking in the National Forest or plugged into an outlet, you can harness the great features of the inverters. This allows you to safely manage incoming loads while still living normally in an RV.
Check out some of our other blogs to see how we use our system. Boondocking ~ How We Spent $48 in Camping Fees For The Whole Year of 2018
Free Camping in Idaho ~ 5 Epic Boondocking Areas!
Finding Resources While Boondocking
Are you in search of a like-minded group of solar enthusiasts? Maybe you are looking to find the latest tips and tricks for your install? Come check out my group on Facebook.