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stavros avatar image
stavros asked

Total Newbee - Multiplus Inverter upgrade question!

Hi there - hoping somebody can help with what I hope is a simple question...

I recently bought a camper, and am hoping to upgrade some aspects before I go away.

It has a Victron system with the exception of the battery which is another brand (100Ah Lithium).

Installed is 200 solar (I think in series - 2 100 panels), a 75 / 15 mppt controller (I think - van is at my folks & my pictures didn't save) and a multiplus 12/500/20 charger inverter..

I'd like to increase the potential output on the inverter for those 'just in case' moments rather than it being primary (will mostly be on EHU).

I plan to add some more domestic sockets in the van at the same time (only one location currently with 3 sockets)

I suspect the easiest way to do this would be to upgrade the Multiplus to at least the 1200 unit?

The real question is - will this be as simple as swapping out the units with the existing set up/wireing, or will I need to address any further parts or settings which make it more complicated?

Indeed if there is another potential solution, like adding an additional inverter I'd like to hear about it - but suspect the former to be the neatest solution... but like I say - absolute NEWBEE!

multiple inverters
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Fideri avatar image Fideri commented ·
@Stavros

You might need to think about how much your solar panels can produce. Detailed specifications of your solar panels?

Is expanding the battery bank an option? The battery discharge figure is very important.

In summary, it is more complicated than you assume and provide details of your gear.

F.

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klim8skeptic avatar image klim8skeptic ♦ commented ·
@Stavros do look at your existing battery specs.

Esp the max charge and discharge current.

The multi 1200 will charge up to 50a.

It will discharge the battery at currents over 100a, given enough load.

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kevgermany avatar image kevgermany ♦♦ klim8skeptic ♦ commented ·
@Stavros

Look at the battery to multiplus cabling, the higher current will probably mean replacing it with a heavier guage. Same goes for AC cabling, breakers etc.

Otherwise it's a straight swap, provided you have space and ventilation. Take note of ba5tery as previously mentioned.

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stavros avatar image stavros kevgermany ♦♦ commented ·
Thank you to all posts so far...

I think already 16mm cable from the battery so may be just swap out the multiplus unit..

I will get the full spec as best I can tomorrow when up at the van and then post so you all have the full details as requested.

I think it may then lead to some more questions from me as to if I did then increase the battery size - looking at a frogstar 12v 230ah, but I guess will then depend on if the rest of the chain is adequate, for which any help appreciated once I've shared all the specs I can tomorrow..

Many thanks again

Cheers

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pwfarnell avatar image pwfarnell stavros commented ·
While you could argue that 16mm² cable can be run at 100A, this is not recommended for an inverter feed where voltage drop is much more important at these higher loads. The 1200VA 12V Multiplus installation manual recommends 25mm² for a distance up to 1.5m and 50mm² above this to a distance of 5.0m. When fusing equipment, the current drawn should be less than 75-80% of the fuse to avoid overheating the fuse connections.
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stavros avatar image stavros pwfarnell commented ·
Thank you for the response - I will double check the cable width today when at the van also and post with the other details..

Cheers

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kevgermany avatar image kevgermany ♦♦ stavros commented ·
It's not width, it's cross section area, , sorry if you knew it, guess it's a language thing.
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1 Answer
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klaus78 answered ·

Assuming you have 300Wp solar panels at 12V, these will give max. 25A charger output.

The 75/15 loads with max 15A, which is suitable for 200Wp solar panels.

100Ah lithium battery is 1.2kWh, I suggest to add another 100Ah if you feel this is not enough.

Be aware that the battery also becomes charged when driving.

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stavros avatar image stavros commented ·
Hi - thanks for this...

Am I able to add another 100ah lithium battery easily?

What would I need to consider?

I would still need the bigger inverter I believe - but have not been able to check the mm2 of the cables in place as yet

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