wendy1 avatar image
wendy1 asked

Help defining specs charger/inverter and battery protect CAMPERVAN

Hi all! :-)

I am a young an enthousiast girl buzy with a camperitzation of a van (not sure how far I will get but I'll try!) and I saw and read a lot of information, but I have some doubts about which criteria to follow when choosing Victron equipment. Hopefully someone can help me! My apologies upfront if I'm asking stupid questions :(

My system will have:

- 2x320W solar panels

- 2x170 Ah 12 V batteries (link 1 or link 2, to be decided) --> are these ok for the application?

- 1x Relay RL-180/200 12 V to connect to the alternator

- 1x SmartSolar charge controller 100/30 (because max current both panels is 21 A)

But I am not able to define what are the specs that I need for the:

- Multiplus inverter/charger from Victron:

First question is, do I want a module that does alltogether or shall I buy separate components? Second question: which is the power that I need for the charger and inverter side?

My consumers in 230 V are:

Total A/day = 23,73; Total W/day = 5458

My consumers in 12 V are:

Total A/day = 102,88; Total W/day = 1234,6

Third question is: I want to install an outer power take off to connect to the camping 230 V socket and charge/use the 230V consumers with the electricity of the camping mains. If I would connect the vehicle to the camping socket, will the multiplus inverter/charger charge the batteries and allow me to use my 230 V consumers at the same time? I want to avoid the situation of connecting to the camping grid, batteries not full and using 230 V consumers and not having enough power, since with a 10 A socket from the camping, I can only consume 2300 W (3680 W max with 16 A). Like: I plug to the camping socket and I plug my hairdryer, does the inverter charge at the same time the auxiliary batteries? If so, with a 12/1600/70 model and a 1000 W hair dryer, I could not connect many more things since the inverter can deliver max 1300 W!

Is the 12/1600/70 indicating the max charging current of the battery? What is the maximum charging current of the batteries? 170 A?

Also not able to define which:

- battery smart protect: fourth question: which of these 65A/100A/220A ? or another?

Sorry for my lengthy email, but I am new in this field. Every help is very appreaciated!

Many thanks in advance,


MultiPlus Quattro Inverter ChargerPhoenix InverterBattery Protectvictron products
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spirou avatar image spirou commented ·

100/30 is far too small for the size of panels you have. Everything else seems to be oversized to me with possible exception of diesel heater. My webasto is running at about double what you have.

The hairdryer is pretty much the only thing requiring the big inverter so consider charging everything else on 12V for a big increase in efficiency and the hairdryer only when plugged in. If you still need an inverter just get something small like 300W.

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Joshua Warren avatar image Joshua Warren spirou commented ·

Why do you say the 100/30 is undersized for this application? If those two panels are connected in series their amperage and power will both be well within the specs of that MPPT.

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Vance Mitchell avatar image Vance Mitchell Joshua Warren commented ·

at 12v the 100/30 will only be able to make use of around 440w of solar.

up to 200w of possible solar would be wasted.

Admittedly that is only if the panels reached their maximum output which doesn't tend to happen very often.

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Joshua Warren avatar image Joshua Warren Vance Mitchell commented ·

Got it -- so the 30A is the limitation on the output side, regardless of voltage?

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Vance Mitchell avatar image Vance Mitchell Joshua Warren commented ·

Thats correct.

The MPPT controllers are named by Input voltage/ output current.

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5 Answers
Alexandra avatar image
Alexandra answered ·


There is certainly a lot to process when it comes to solar! The only stupid questions are the ones that were not asked though.

On your batteries the links you provided are not working. But I would think you would need more to keep up with your consumption. 170A x 12v x 2 = 4040 Watts of storage drawing them to 100% flat.

In total according to your list you have about a 7kWh usage. so your panels would need to produce this during the solar day (solar day not the same as daylight hours - for example where we live our shortest day is about 11 hours daylight but we budget about a 5/6 hour solar day, in other words when the panels are producing enough to cover full load and charge the batteries. helps with seeing your solar yield and checking with your proposed mppt for your panels. The bottom of the page has a handy graph for projections as well. I would get a higher amp output one - the 30A is the max it will output it will chop off your production. 2x320W = 640W (max output in ideal conditions) divide that by 12v = 53A so 20 amps or so will be wasted when it could be charging or running loads.

The inverter can charge at the same time as running loads the 12/1600/70 is a 12V system 1600VA 70A transfer ability. That is for loads and charging, but you can set it lower in the settings to draw the shore/docking limit. But if your shore limit is 2300W then maybe consider a 3000va system.

The 1600VA will limit how many big draw items you do at once but it is enough for one item at a time - so that really is a personal choice. If you want to boil the kettle and dry your hair at the same time go bigger.

The maximum charging of your battery is set by the c rating of the batteries you choose. Example if it is C10 rated then it is a 17A charge.

I do suggest getting some kind of GX device for monitoring into the system as well like a venus or CCGX it brings the system together and allows for and interactive personalizing of settings.

Buying all in one or separate is usually determined by cost and if the all in one meets the needs so again a personal choice especially if you want a customized setup.

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wendy1 avatar image wendy1 commented ·

@Alexandra I do have a remark and a question from your answer;

Remark) I added the data from my solar panels in the website you mentioned and the maximum current obtainted is 45 A. So all the models end with /45. I think your calculation 640 W / 12 V should be 640 W / 16 V = 40 A since to charge the 12 V batteries you need to apply higher voltage than 12 V. These 12 V are open circuit voltage. Therefore, any model ending in /45 will be still ok. Or do you think I should increase it to 150/60 or 70 to be sure? It is more expensive though.

Question 1) When you mention 6 h solar-day for my panels, do you mean the solar panels are charging during max 6h at max power, at its maximum efficiency (20%), perpendicular radiation?

Question 2) Is my statement below correct?
'' In my solar calculation I considered best and worst case scenario, that is winter and summer to plan accordingly (more stops in the camping in winter, for example).

Winter: 1,5 h max sun --> 1,5h x 40A = 60 Ah -> solar panels only as an energy support, not self-sufficient

Summer: 6 h max sun --> 6h x 40A = 240 Ah

That means: the batteries will get charged with these Ah each winter or summer day''

Thanks again!


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Vance Mitchell avatar image
Vance Mitchell answered ·

To power the loads you mentioned would require a regular grid/shore connection or a lot larger system.

I would double check your consumption first to see if you really require that much. You mention AC outlets for your phone using 1000wh per day. If you are talking about charging your mobile, a 12v USB socket would do the same job and only require 100-200w per day. It would also allow you to turn your inverter off when it is not required saving you further power.

Be wary of cheap batteries, I purchased some 170Ah batteries that ended up being only around 100Ah. Due to your links not working I can’t tell what the batteries are. An old fashioned rule of thumb for lead acid batteries is that 100Ah @ 12v should weigh around 30 kg (60 lb). If you are using lead acid you only want to use half the capacity or you will quickly damage them.

Lithium batteries however are a completely different scenario.

A bit more information about how you plan to use the system could help as if you plan to plug in at a campsite each night, a lot of your use won’t actually be using your batteries.

I agree with most of what Alexandra posted, except that the 12/1600/70 has 70A charging capacity and 16A transfer capacity. If you are plugged in to a 15A campground you should be able to run your 1000-1500w loads and be putting up to 70A of charge into your batteries. The batteries themselves will only accept a certain maximum charge rate and for 340Ah I would consider around 35A to be better for extending the life of your batteries.

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wendy1 avatar image wendy1 commented ·

Hi! Thanks for your extended explanation. Indeed, I'll think about replacing the schuko sockets with USB inputs. I actually considered that because my phone has a fast charger of 1,2 A and when you are travelling you use a lot your telephone for navigation, searching stuff, etc so I might need to charge it couple of times a day (or battery for camera, etc). I am aware I was considering big loads, but hey! I just started with the concept of ''luxury'' or ''mini-house-on-wheels'' and now I am realizing that this is not the case! :-)

Regarding the charging current to the batteries, when I choose the 12/3000/120 Multiplus unit: are these 120/70/35 A shown in the datasheet programable values in the device? Otherwise, how does the unit decide to which current must it charge?

What is charging capacity? What means this 16 or 50 A?

I imagine that 3000/230=13 A --> protection 16 A? But what about the 50 A? What does these 50 A extra from the eg. MultiPlus 12/3000/120-50 230V model?

Thanks again for your time!


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Joshua Warren avatar image Joshua Warren wendy1 commented ·

Can you clarify on the AC input voltage you're going to connect to? You mention 230V (common in Europe) but you're talking about a Multiplus 12/3k/120 which is for 120V AC voltage (i.e. North America).

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Vance Mitchell avatar image Vance Mitchell Joshua Warren commented ·

the 12/3000/120 is 230v with 120A charging capacity. It is available in 120v as well which gets confusing with the 120A charge models.

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wendy1 avatar image wendy1 Vance Mitchell commented ·

Yes, indeed 230 V Europe. Good point

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Vance Mitchell avatar image Vance Mitchell wendy1 commented ·

The 120/70/35 is programmable charge current to your battery, either through switches inside the unit or by software.

The 16/50 is the AC current which can be transferred through the unit when connected to a grid/shore input. With a camper van this is limited by the power input as most campsite power at 230v is 16A anyway.

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wendy1 avatar image wendy1 Vance Mitchell commented ·

Clear, thx!

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michelg avatar image
michelg answered ·

Hi Wendy, my two cents : in my house, I use a Phoenix 800VA 24VDC / 230AC for light, and fridge (take a look at Waeco / Dometic, they are great and take little power). I also run my laptops and screens. There is still plenty of power available.

Using a 24VDC configuration will reduce the size of the cabling and reduce the stress induced on the batteries when using higher loads.

Consider using a solar mppt, a DC-DC Orion to reload the batteries when driving, an AC Charger when you are bondocking, a BMV-702/712 to monitor the status of the batteries, and of course, the inverter Phoenix.

It may be a little bit more expensive having specialized units for each task, but if one fails, you won't get stuck for too long.


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wendy1 avatar image wendy1 commented ·

Hi Michel, thanks for your answer. The reason why I chose 12 V is because most of the campervans use it and I wanted to connect the 12 V auxiliary battery with the main 12 V cranking battery through a relay. Then the alternator could charge both bateries

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Erik Sporns avatar image
Erik Sporns answered ·

Disclaimer: im sharing my experiences and im not claiming to be an expert!

Due to the fact that you plan on drawing a lot of power from your battery is strongly suggest using lithium batteries. Ive done a very similar setup to yours (only difference only 320w of solar) for my vw caddy camper. at one time i had 400ah of lead acids in my bay. They deplete very fast under load (see peukert factor). Basically under these loads you've listed in your sheet id expect 50% usable capacity. Conservatively speaking id be comfortable with at least 200ah of lifepo4.

There are options to build you own pack and save a lot of money, e.g. using the rec bms, which ties very good into victron setups.

Other than that is second what the other commentors said.

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kevgermany avatar image
kevgermany answered ·

Old thread, but the phone charger current is at 5V. So negligible at 240V. Better bet is to install USB sockets on the 12V system.

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