This customer’s existing set up included a single 200 watt solar panel with a single 12 volt AGM battery to run an entire 36 foot fifth wheel trailer. There was a cheap solar charge controller that came with the trailer that was non-programmable. They did have an on-board generator, but didn’t want to run it just to make coffee or watch television.
The Problem With Their Old Setup
For a 36 foot fifth wheel trailer, a single 12 volt AGM battery was highly insufficient. The customer wanted enough battery power to watch TV, run cooking appliances, run fans, lights, water pump, to last throughout a weekend of camping. The single 200 watt solar panel is only enough to keep the battery charged while in storage.
I had the customer purchase two 100 amp hour lithium batteries direct from BattleBorn. I installed two 350 watt, residential grade, solar panels, and wired them into a Victron MPPT 100/50 solar charge controller. I left the existing 200 watt solar panel, upgraded the charge controller to a Victron 75/15 MPPT. I then programmed the two controllers to work together to give the customer a total of 900 watts of solar, all going into their new BattleBorn lithium batteries.
I left their existing AGM battery in place and wired it up as a start battery for their on-board generator. I added a Cyrix battery combiner to it so that it could get charged by solar.
In addition, I added a manual main-disconnect that allowed the customer to disconnect the battery system, mostly when the trailer is in storage.
I installed a Victron Mutiplus 3,000 watt hybrid-inverter to run one-leg of the trailer. This allows use of microwave, AC and wall outlets for both TVs, bathroom, kitchen and exterior from battery power. This set up has the capacity to run their air conditioning off of battery for up 90 minutes.This system as programmed will just work.
There is redundancy for temp and voltage for the Lithium battery. If the battery is ever depleted, the inverter disconnects @ 11v, the 12v side of coach disconnects at 10.5v, BattleBorn BMS disconnects at 10v. The dedicated start battery disconnects at 12.6v leaving it fully charged to start the generator. The Converter can put 40A into battery and is retired but operational. The charger section of the inverter can put 120A into the battery from generator/shore power.
When plugged into shore power both legs of the trailer get 50A each. When the generator runs each leg still gets ~23A and the inverter can use solar and battery to add 25A to its leg in the RV. When the trailer is without power, the inverter can supply surges up to 50A to the one leg of the trailer.
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