Caravaning

Plucka · February 2019

My van gets too hot parked in the sun to keep the solar panels charging.I would like to start again setting up.I have a Ford Transit cab chassis vehicle which I'm thinking of putting an enclosed box on the back of if for all the the stuff to good to throw away plus solar panels on it's roof and lithium batteries inside. STEP 2 buy a caravan that I can unhitch and park in the shade and connect to an 12 volt [or 240 volt ] outlet from the Transit van to run the 240 volt appliances in the van.The problem is when I use the Transit van to go shopping I have no power to the caravan This means I need enough batteries in the caravan to last till I can reconnect .I already have 12 volt 360 amp hour lithium batteries , 800 watts of solar power ,a charge on the run charger putting out 15 amps while I'm driving and this meets my needs.If I put lithium batteries in the caravan what would I need amp/hr and anything I should know reconnecting to the other set of batteries such as surging,sparking ,etc

mcgivor · February 2019

Managing two separate battery banks with a single charging source can be challenging, especially if the transfer between them is DC related. Connecting two batteries at different states of charge can result in high current transfer between a low and high bank being connected together, especially with lithium, which can cause damage to the battery itself. Have to think long and hard on how to tackle this dilemma, there is always a solution, but it alludes me at this point in time.

Plucka · February 2019

Thanks -I thought there might be a problem.Just a thought --if the outlet from the Transit van was 240 volts [inverter ] could I just then use a 240 volt to 12 volt charger to charge the caravan batteries---a bit worried about what the losses would be.

BB. · February 2019

Yes, you can use an AC to DC battery charger--And in some ways, that is probably the better solution.

Connecting 12 VDC to 12 VDC (tow to trailer) is difficult to get much current flow (usually something like 10-12 amps or so, unless you use heavy gauge welding cable). Also, generally the two vehicle's Alternator is set for something like 13.8 to 14.4 volts, and flooded cell deep cycle batteries need something on the order of ~14.75 volts to charge quickly and fully (and upwards of 2-6 hours at 14.75 volts, depending on how deeply discharged the battery bank was to start with).

-Bill

mcgivor · February 2019

There will be losses whichever way it's done, either conductor loss with 12V, or conversation DC-AC-DC with 240V . Moving energy over distance is much more efficient at higher voltage requiring smaller conductors, so the 240V AC would probably be the best solution the voltage drop could be calculated using a calculator lie this https://www.calculator.net/voltage-drop-calculator.html If using a LFP battery a charger like this https://m.aliexpress.com/item/32827172063.html?pid=808_0000_0101&spm=a2g0n.search-amp.list.32827172063&aff_trace_key=c040d35998c343fb843e8804859ca01d-1550129608931-02405-rJYNbUv&aff_platform=msite&m_page_id=7220amp-ZXkLFFJjLTwwvWd9Q8WQJQ1550887904973 for example could be used.

Wheelman55 · February 2019

Plucka. Consider a folding solar panel kit with built in charger for your caravan

I’m in TX and using a ZAMP 180 watt 10 amp kit with a 15’ extension cord. I’m running two ARB fridges off one Battle Born 100ah lithium battery.

This winter I’m fully charged by 10 am, during full sun days. Longer when it’s cloudy.

The kit also charges my T105-RE 220ah bank from 70-80% to full in approximately 4-5 hours of full sun. This bank gets charged once or twice a week.

Have fun!

Plucka · February 2019

Thank you -that is a good suggestion .

Caravaning

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