There is a 400Ah stated battery bank requirement for 12V Multiplus II inverters. There are often cases where someone might wish to run a smaller battery bank. I see anecdotally that the Multiplus can be configured to limit battery charge and discharge current. Given that assumption, is it possible to run a Multiplus II with a smaller battery bank provided the inverter is configured not to exceed battery bank charge and discharge current limits? What is the relationship between battery bank BMS and Victron charging and discharging characteristics?
Just buy the multiplus fitting to your battery bank.
Is so easy…
Charge current can be limited in the inverter configuration settings, but not discharge current, (at least that I’m aware of.) The practical way to limit discharge from a battery is to limit loads on the inverter.
The 400Ah @ 12V guidance is to provide enough capacity (at minimum) to meet instantaneous power demands, and to provide reasonable run time.
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Could you be a little bit more specific on the exact model of Multiplus II inverter you are researching into? afaik, minimum recommended battery capacity mainly has to do with current draw, since capacity and current draw is usually interconnected. That said, if your AC power demand is low, you can definitely use a smaller / less powerful battery. However, if the inverter is working hard and the battery cannot support the DC bus properly, you may have high DC ripple and potentially under/over voltage on you AC side. Which is not good.
I’m thinking of a 12V 1x120V Multiplus II. I work for a small company. We often have clients coming in with something like a Sprinter with limited room for a large battery bank. In some cases, they already have a Multiplus II and we are correcting DIY or third party installation problems. In the case of a sprinter van, the biggest load would be a microwave. Customers are always advised that running AC off grid is usually not a good option. It looks like the Inverter can only put out about 200-250 amps constant. Two Battleborn batteries can discharge at 100amps constant each. I’m thinking that someone with a sprinter van with 2x100 ah Battleborn batteries would have a workable solution without posing an equipment or personal safety risk.
It’s a recommendation.
A 3000VA MultiPlus can deliver 2400W that’s 200A at 12V.
Your battery can be smaller if it can deliver 200A.
A good 200Ah lithium battery can do that.
With lead it should be the recommended 400Ah.
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My 3000w multiplus regularly pulls 280A @12v for a 2500w water kettle.
You’ll have to get a very small microwave.
Many RVs here in the US have smaller microwaves rated at 1500 watts. And microwaves normally run for short periods of time.
Best regards,
Tom
I’d try ro get batteries with a better bms for a higher discharge rating.
Thank you Matthias,
Yes. Battery chemistry is important. So the Victron recommendation doesn’t seem to specify that.
Thanks again.
Constant loads is not a problem, even with small / weak batteries. High instantaneous power demands is what stresses a battery and can induce unbalancing on the AC power side. Motors starting and stuff, usually induce high currents on the DC side. That said, I believe you will be more than able to run a soft-start 1800w power tool, but probably not a 1000W water pump with no VFD circuitry. A 1500W microwave would most probably be fine with 200A of LFP battery.
Ps. I have run onto a forum issue that will not allow me to delete this post I did on another thread by mistake and repost it here. Strange.
@thanar which one would that be?
Normally when you click the three dots you get more options.
Otherwise flag it and give the reason why then mods will know you need help there.