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Russell Brown avatar image
Russell Brown asked

Battery size for MultiPlus II 12/3000/120-32

I would like to confirm my thoughts on battery size for the MultiPlus II 12/3000/120-32

I am new to Victron and the Victron community. I will be doing a full Victron GX setup for a Van with Lynx Smart BMS 500, Cerbo GX, Lynx Distributor, DC to DC Orion-Tr Smart 12/12-30A and SmartSolar MPPT 100/20. With 460 Watts solar on the roof. DC to DC as the main re charge source, solar as the top up, and shore power only as a backup if needed.

I chose to go Victron and the eye watering price of Victron batteries and eco system as I wanted an off grid van system that would "look after itself". Be able to hook up Victron batteries in parallel knowing zero issues with the whole multiple batteries and BMS shutdowns etc. Finally a 3Kva rather than 2Kva so was not running the inverter to its capacity every time a large draw was used, toaster, induction and the ability when needed to run 2 large loads, like short use of roof air con (inverter air con) while being able to cook etc.

My question: I would love be able to grab a couple of 200Ah Victron Smart batteries for a 400Ah system, a 3rd battery later for 600Ah.

But looking at the max current draw on the 200Ah Victron smart battery, MAX does say 400Ah BUT recommended max says < 200ah. ( 200Ah x 12V = 2,400 Watts)

This means with the 3,000 watt Multiplus II max performance of 3,000watts, the recommended max battery draw is a good 600 Watts below inverter capacity. If we were using the system to its full capacity of 3,000 watts thats a 250 Amp draw on the batteries. Within max battery draw but above the recommended 200Ah draw.

If we were running the roof air con Dometic IBIS 4 ( for short periods on low) by itself its a max draw of 1,600 watts, 600-900 watts on low, and why I was looking at a 3Kva inverter rather than the 2Kva. Didn't want to be in the scenario where your limited to one big draw appliance and no capacity left.

Therefore I though that to allow full use of the MultiPlus II, I have no choice but to use the Victron 300Ah or 300Ah - leaning to the 330Ah as its 20kg lighter and smaller in size.

Am I being too OCD going with the 330Ah battery ? or would 2 or 3 200Ah be fine with the view that up to 2,400 Watts inverter power would be within the 80% normal usage and 2,400 - 3,000 watts (250 Amp draw which is 50 amps above battery recommenced but within the max 400Ah ) would be a 20% use case for a few hours at a time occasionally.



Multiplus-IILithium Batterysmart lithium
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2 Answers
klim8skeptic avatar image
klim8skeptic answered ·

If you are going to parallel 2 x 200Ah batteries, they will share the load.

Or to put it another way you end up with a 400Ah battery, capable of a "recommended continuous discharge limit" of 400a. (And a "maximum continuous discharge limit" of 800a.)

I would not expect to be able to run an AC at the same time as using an induction hot plate with that setup.

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Russell Brown avatar image Russell Brown commented ·
My understanding is the max current draw of a battery bank is limited by the max spec of a single battery. So max recommended discharge of a single battery is 200Ah, despite 2 x 200Ah in parallel you don't double the discharge, its still limited to 200Ah.
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simeyfour avatar image
simeyfour answered ·

you will be fine with that set up. I run the same with two x 320 ah lithium's with a Truma Aventa roof mounted air conditioner. looking at the VRM portal most i pulled was 63 amps.


I think the max it could do is between 80 and 90 amps.

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Russell Brown avatar image Russell Brown commented ·
Can I ask what batteries you are using. If not Victron then are the 2 non Victron batteries in parallel without an external BMS reliable ? no issues with multiple internal battery BMS playing up, charging properly ?
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