This little guy is awesome. I have the river pro and I use it daily.
I'd suggest using it to compliment the leisure batteries rather than to top them up. You can use it to top up the leisure batteries but not natively. Instead, by a 12v DC-DC charger plugged into its 12v socket then plug that into one of the Van's rear 12v sockets.
It can get very warm at the connector ends as this could get to around 10A or more.
This will work but I would suggest instead purchasing to compliment the leisure batteries rather than to charge them.
I researched a lot this year and finally settled on the Ecoflow River Pro as an additional power source as my leisure were draining rapidly always, because of my use.
My personal set up comprises of 3 x 100W solar panels from solarcampersolutions.co.uk which come as a very quick install kit along with a Victron MPPT controller.
This took me only an hour to fit - I'm a confident person but not in any way an expert - his supplied instructions were excellent.
These plumb into the two standard AGM leisure batteries and keep them topped up all year round as I do full time van living.
This likely wont apply to you so I would advise the single 100W panel which is sufficient for most people.
The Ecoflow happens to be the EXACT width for behind the passenger seat gap. And I mean exact. Its low enough not to prevent the passenger seat from rotating, its handle allows it to be so very versatile and when driving, it charges from a dashboard 12v socket with one of its many supplied cables at a steady 100W.
Also, it sits just below the Electric hookup socket which I leave permanently plugged into the unit for the odd occasion I connect (I'm set up for 100% offgrid).
I have a permanent 4G router velcro'd to the side of the kitchen which the Ecoflow, and the van in general, uses for wifi and this allows me to remind myself of the charge status.
This helps because I can pop it out of the van with its built in carry handle (very light compared to an AGM) and plug it in under the table of a Costa and it charges to 100% in just over an hour, from zero (which it rarely gets to, only when I've not driven for a while).
I have it because it supports most household appliances but for me it's for my toaster (700W), my milk frother (400W) for my lattes which also doubles as hot water maker, and because of its glittered array of USB support, also acts as a backup for my laptop, projector, headphones, VR headset, drone and phone charger if I'm low on solar top-up during winter months.
Foldable solar arrays arent very good, in my experience, in the UK - especially outside of summer months. I used some at very high altitude in Nepal and they were amazing but I've not ever been able to replicate that elsewhere for perhaps obvious reasons.
Peak summer the foldable array will charge your ecoflow in about 8-10 hours of direct sunlight (keep moving the panels to face the sun) which is excellent, but only in July/August. Either side of this it will struggle but that's where its ability to charge from the Van's dashboard 12v socket when driving or plugging into mains at cafes (or at home for most people!) for an hour really makes this unit amazing and practical.
Biggest advantage is the utterly amazing fit behind the passenger seat! Never gets old as it never, ever moves when driving, nor rattles. No scratches or marks, just weirdly sits perfectly.
It has a drip tray on its head already so any rogue drops from the sink above doesnt bother it at all.
It allows remote operation too - if I'm out on my electric scooter seeing friends or shopping, I can switch on the different output sockets and use it to power on my raspberry pi which I have programmed to attach automatically to wifi in the van on boot up and check various devices status and report back, as well as van location etc.
Mine has 780 watt hours which roughly means I can make 30 lattes before it's near zero. My HP spectre 360 15" 2019 laptop can run for about 7 hours with heavy gaming, I can charge my VR about 25 times, my e-scooter twice, phone about 60 times and my 3 drone batteries about 10 times.
Very very versatile and a very very small footprint. A complete no brainer for a very very quick change of power use for very little/no effort as well as an emergency for topping up leisure batteries with an additional DC-DC charger if absolutely needed.
Hope the babble helps
eu.ecoflow.com
