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amartins avatar image

Complete system architecture for campervan (640W solar + 320Ah battery)

Hi,

I am currently converting a van to a campervan and I am currently designing the electrical system. My estimation for a full day consumption is around 250Ah @12V. I was considering installing 640W of solar panels with 320Ah of battery. But to ease the initial investment I want to be able to initially install only 320W of solar panel and a 160Ah battery.

My requirements are in line with the general requirements for this kind of application, batteries to be charger by solar power, shore power and alternator.

After some research on Victron website I got this list of critical items:

Initial setup:

  • 2x 160W-12V Mono 1480x673×35mm series 3a
  • 1x LiFePO4 battery 12,8V/160Ah - Smart
  • 1x SmartSolar MPPT 150/45
  • 1x MultiPlus 12/3000/120-16
  • 1x VE.Bus BMS
  • 1x Smart BatteryProtect 12/24V 65A
  • 1x Cyrix-Li-ct 12/24V-120A combiner
  • 1x BMV-712 Smart

Upgrade:

  • 2x 160W-12V Mono 1480x673×35mm series 3a
  • 1x LiFePO4 battery 12,8V/160Ah – Smart (in parallel with the first one)

Any advice regarding my setup?

  1. I considered the use of a Multiplus instead of a charger + inverter, is it the recommended approach for this kind of builds?
  2. Are the monocrystalline solar panels recomended for this kind of application instead of the polycrystalline?
  3. Is there any component on this list that is optional for this kind of setup? Or any critical component that I missed out?
  4. Can I mount to lithium batteries in parallel, considering that they will have different characteristics? The second one could be bought years after the first one.
  5. Is this setup valid if I use AGM batteries instead of lithium batteries?
  6. The use of only one smart battery defeats the purpose of a BMV-712 Smart? Is the same information available is a connect to the Bluetooth of the battery?
  7. How can I extract the raw information of all these devices to a server running in the van?

Thank you.

Lithium Batterysystem designcampervansystem integration
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4 Answers
wkirby avatar image
wkirby answered ·

1. Yes, this is better than a separate charger and inverter. It can "Pass-through" shore power rather than double-converting it.
2. Moncrystalline are said to perform better in low light, but I think it's marginal. Allow your budget to dictate this one.
3. In a Lithium system, it's a good list. A CCGX or Venus device might be worth considering - see answer 7.
4. You can connect them in parallel as long as the next one is also compatible with the current BMS and original battery. You may allow an amount of time before upgrading, but I wouldn't want to let the first one get too old. An upgrade within a couple of years is probably OK.
5. If you use AGM batteries then of course you can omit the BMS and perhaps the Battery Protect.
6. I'd always recommend a BMV in situations where there will be DC loads, which seems very likely in your application.
7. A van server? That sounds intriguing! A CCGX or Venus-GX is the answer if you want a central point of access to system information. Your server may access the Venus device over MQTT or Modbus-TCP. Tip: Venus also runs on a Raspberry Pi. ;)

2 comments
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Thank you for the comments. Yes, I want that in the long run that all information of the van to be gathered and acessable using a tablet. Also I want that all the van controls (lights, solar, power outlets, etc) to be controllable through the same interface. I will check how can I interface with Venus device without requiring it to be connected to Victron Remote Management Portal.

No need for VRM if you don't want it. You can run a Venus Device without registering it to VRM.

markus avatar image
markus answered ·

Hi,

I am not a professional system designer yet, but a few thoughts to this, from me:

1.) A Multiplus gives you the awesome Power Assist Feature. This is a big advantage to a separate charger/inverter solution.

2.) I use Victron Mono and Polycristalline modules in my setups. The harvest is not much of a difference in such a small setup. To me, the poly modules look better...

3.) I would suggest to use a CCGX or Venus GX device for monitoring

4.) It is never advisable to connect batteries of different characteristics and age in parallel.

5.) AGM would be a cheaper alternative, but you will have to add more Ah to have the same useful capacity. And the battery characteristics is off course worse than lithium. The advantage would be that AGM are better in cold winter situations.

6.) No, the BMV gives you much more useful information like SOC, DC consumption, temperature, Starter Battery Voltage...

7.) See 3.) Those devices give you awesome possibility of monitoring and remote control.


I hope this is somehow helpful. Feel free to ask if you have further questions.


Best Regards,

Markus


4 comments
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Warwick was faster as usual ;o)

Maybe I was faster, but your answers have still provided additional value. :)

Thank you for your comments. Regarding point 4, the batteries will be of the same type and size (LiFePO4 battery 12,8V/160Ah), just bought one or two years later. Even so do you advise to not connect the batteries in parallel? What other option do I have for this kind of situation?

The main problem is, that the new battery would be impaired by the old one. But Lithium is by its characteristics the best type of battery to mix different aged batteries in my opinion, but it's not optimal tough. It depends on how you treated the older battery and how much charge/discharge cycles the old one had to suffer.

I could think of selling the old one as used and buy 2 new ones, when the day comes...

wkirby avatar image
wkirby answered ·

Oh, the MPPT you have selected (45A) is on the limit for 640W of solar on a 12V system. It's fine if there is more solar than it can cope with, it will just be limited to 45A charge current which will only occur in full sunshine.
If you ever plan to expand with even more PV in the future (it can be addictive), then you'll be glad that you bought a bigger controller in the first place, but of course it's your budget.

1 comment
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I did plug my parameters on the MPPT excel at it only gave me warning for current limiting at cold temperature, but in fact even at high temperature it does have much margin. I am from Portugal and here the sun is almost a guarantee. :) I will consider using a 150/60 MPPT. Thank you.

Dave van Dongen avatar image
Dave van Dongen answered ·

Of you have room, I would just buy 1 or 2 big 300 Watt solar panel, the kind that is used on houses. They come much cheaper (from below 100 euros for 300Wp!) than the 12 volt solar panels. They are around 35 volt, but because we use MPPT controllers, it doesn't matter. I always recommend big panels for campervans (space allowing) and I use one myself, to my satisfaction, for years already. If you want them to last a long time, you could consider glass-glass panels.

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