question

Hi Johnny,

Your schematic is quit good.

Take care to choose the right devices for 12V battery system.

Without information of your solar panel power and your location, it's hard to know your solar energy potential. You can use https://re.jrc.ec.europa.eu/pvg_tools/en/#HR to simulate your system.

Located in center of france (Bourges), a 300 Wp horizontal panel without mask with 900 Wh daily consumption will give you 9 to 24 % days with battery empty between may to august

About the leisure battery, 150 Ah will give you about 900Wh usable energy.

I suppose your leisure battery is VRLA type, to preserve it, DO NOT discharge it below 50% SOC !

Most important things about batteries are : never discharge it more than 50%, charge it asap when discharged, Never overcharge it. Check if your battery handles equalization charge (VRLA batteries do not handle it) keep it in a dry and 20°C place as long as possible.

To know more about batteries have a look to https://www.victronenergy.com/upload/documents/Book-Energy-Unlimited-EN.pdf

As you don't have power gen or mains available any time, my advice is: add a smart switch related to BMV to disconnect your leisure battery when 50% SOC is reached.

Take care, some device like battery protect are electronic one and current flow direction is important (not just an electromachanical relay). They do not support DC current flow to inverter. Carfully read Victron battery protect user manual.

As battery capacity is temperature sensitive, use temperature sensor with your BMV and share the information to charger.

And most important : enjoy camping while respecting Nature.

Best regards.

Bruno.

Hi Bruno,

Thanks for your reply

The battery when I purchase will be a Lithium type which I understand you can discharge close to 100%. Several brands on the market have built in BMS which protect against overcharging, over discharging, short circuit, temperature and over current. My travels will be in Australia mainly during the spring, summer and autumn months of the year which if I can get 4-5 days of battery power a week to run devices I will be happy.

This website below I found useful in getting an idea of what size solar panel to go for depending on what size battery I choose. The calculator allows you to nominate the no of peak sun hours against a % discharge of battery and then you can quickly read what size panel would suit.

https://footprinthero.com/solar-panel-size-calculator

Regards JN

Hi Johnny,

OK. li-ion batteries are more efficient than lead acid one. it's the right choice.

Choose one with active BMS and don't forget to setup your MPPT and charger according to battery specs (Imax during bulk and charged voltage).

a battery protect relay controled by BMS remains useful with Li-ion batteries vhen you are off-grid into the wild with no alternative supply (may be this disconnection fonction is included in the battery.)

Regards.

Bruno.

Hi @Johnny Nova your design looks like you have most of the basics covered and the solar panel is probably the cheapest component in the system. Measure up the largest panel that you can put on the roof - if you can exceed 300 watts you should be pretty good given your battery, type, size and load. If possible keeping a common manufacturer across all products can be beneficial.

Hi Sarah

Thanks for your reply.

Yes I hope to use the Victron brand for things like the shunt, solar charge controller, DCDC charger (later if required) and Lynx distributor.

For the solar panels I have been checking out the Trina brand that sell a 425W panel.

Cheers JN

Is there a reason why you see multiple small powered panels (wired in series or parallel) on RVs or camper vans versus just one larger powered panel?

Your diagram is pretty good - one thing i would note is your running everything off that blade fuse block. Thats okay, but you might want to look at a breaker panel instead of the fuse block and size your breakers accordingly.

This would give you a way to individually turn on/off circuits - for example power is low, you might want to shut down the fridge and reduce its run time.

What sort of loads does your camper have on a daily basis, where are you located? Not sure what type of fridge you have. I have a small chest freezer thats about 30L, it burns about 35-40ah per 24/hours. My ice box is probably 100 or so L, it burns around 40-45ah per 24hours. Winter time the freezer is off, summer time it is on.

I live full time off grid on a sailboat - 2 x 350w panels - 440AH firefly batteries that i discharge down to about 30% remaining capacity(try to stay at 50% but sometimes go lower). Having breakers is very useful considering i do like to be able to keep things off(parasitic loads) unless I'm using them.

Just food for thought

You can also add a link from starter battery to smart shunt to monitor its voltage.

Also consider a reverse flow trickle charger from leisure to starter if the van will stand for long periods.