question

wlgrau avatar image
wlgrau asked

Multiplus drawing current

I have a Multiplus 12/3000/120. I hook one Battleborn lithium 100Ah battery to it, fully charged at 13.6. Immediately the voltage at the battery drops to about 5V, even when the Multiplus is switched OFF.???? Any idea what's wrong? I have 6 of these batteries. If I connect them all in parallel then the inverter comes on but depletes the batteries within 1 hour

MultiPlus Quattro Inverter Charger
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6 Answers
linqf avatar image
linqf answered ·

I can only boldly guess if the battery life is reached.

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

The inrush current of the Multiplus can be quite high and trigger BMS overcurrent protection.

That can either show as no volts or low volts.

Review how you are balancing 6 parallel 12v batteries.

Imbalanced batteries connected in parallel can also cause issues. The Victron Battery balancer exists for this reason, though is intended for some of those to be connected in series which doesn’t suit your installation.

https://www.victronenergy.com/batteries/battery-balancer

2 comments
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wcn00 avatar image wcn00 commented ·

I have built my own batteries using CALB cells and a bms system. If I don't have the viktron 3000 online everything works fine. Soon as I cable in the victron to the 12V crcuit and turn on the battery switch the bms's trip off the batteries and I have a low voltage indication.

I will experiment with the max current setting on the bms but I wasn't expecting this. Is there a "Proper" solution for this? Need I do a one time setup with a ressistor to get the viktron programmed and its capictors charged? Doesn't sound like a good long term solution.

Thnx wcn

P.S. This victron replaces a renogy 3000w inverter charger that did not have this problem. Of course the problem it did have was that it went on fire...

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schroeder avatar image schroeder commented ·

Thanks for the link, keep sharing this type of info , i will try to figure it out for more


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boekel avatar image
boekel answered ·

After reading the manual I'm afraid they might be damaged by the inrush current als Guy Stewart suggests:

https://battlebornbatteries.com/wp-content/uploads/2017/09/Battle-Born-Manual.pdf

https://battlebornbatteries.com/shop/current-surge-limiter/

use a current meter (one that can measure DC) to measure what batteries do give output and if they survived.

depleting in 1 hour: with what kind of load on it?

What can also get a bms to fault is the 120 Hz ripple (100Hz from 50Hz systems) and/or PWM frequency ripple.

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Matt Knight avatar image
Matt Knight answered ·
@wlgrau we have been running the Victron MultiPlus 12/3000/120 with 3x 100Ah Battle Born batteries for 4 months now without any issues. You should be aware that the BMS on the batteries will trip if you try and draw too much current (>100A for 30 seconds or >200A for 0.5 seconds).


How are you charging the batteries? Did you configure the MultiPlus yourself or was it configured by Battle Born for you? What load are you putting on the inverter when it appears to drain within an hour, and how are you discerning that the batteries are fully drained?

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vannie avatar image vannie commented ·

Hey @Matt Knight, so you run your 3kW inverter on 300ah batteries and no issues? I currently have the same 3kW MultiPlus but only 2x 100ah batteries and keep running into issues. Do you run anything like an induction stove or other high draw items on your system? Also, how to you recharge your batteries? I am in a van with 400W solar and the Orion which charges via alternator running. I think I either need to get another 100ah battery (so 300ah total) or switch to lower loads on my system (i.e. cut out the induction stove and go propane). Curious how your run yours! Thanks

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Matt Knight avatar image Matt Knight vannie commented ·

@vannie yes, we use the Victron 12/3000 with 300Ah of batteries. It's technically a 2,400W (3,000VA) inverter, and not 3,000W. We can run any appliance in our RV using our batteries & inverter - including our microwave, electric water heater, AC, etc. We don't have an induction stove but assuming it's ~1,800W then that wouldn't be an issue.

You don't mention which batteries you use, but assuming it's lithium batteries like our Battle Borns, you're still going to run into problems with just 200Ah of batteries. The reason being that it's not just battery capacity you need to pay attention to, but also the maximum current that each one can provide.

Assuming that each battery has a maximum continuous discharge current of 100A (which is what ours are), then with 2 batteries you have a maximum discharge current of 200A. Under heavy load your battery voltage will sag, so let's assume the voltage is 12.5V. 200A @ 12.5V DC is 2,500W. But, some of that power will be lost in the DC-AC conversion (i.e. inverter losses), so your practical maximum is probably closer to 2,200W.

As a rough rule of thumb, I always recommend a minimum of 100Ah of lithium battery capacity to 1,000W of inverter power, so in your case I'd highly recommend a 3rd batteries. Even so, there are some very rare situations in which you can trip the battery BMS because the inverter can peak for longer than the batteries - but this has only happened to us a handful of times in the last few years.

We have more about our full setup on our blog here: https://www.adventurousway.com/blog/perfect-off-grid-rv-solar-system

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vannie avatar image vannie Matt Knight commented ·

Awesome. Super helpful info @Matt Knight. Great website and build. I like the collapsible solar panels you came up with! Makes sense about the third battery for the 3k MP. Good thing I built in a spot for a third battery to be dropped in! Space is tight in the 140" wheel base sprinter. I went ahead and ordered a third battle born. For solar, I have 400W on the roof now and do get some charge through diriving via Orion so hopefully that will keep things topped up. I have a spot for another 100W panel so could get up to 500W too. I like the portable setup if docked somewhere for a while too. We don't live in ours full time and live in California so can keep an eye on the charge and adjust. Thanks for filling out that question for me. Best!

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wlgrau avatar image
wlgrau answered ·

I'm charging with a Victron SmartSolarCharger 150/100 only - no generator. Usually I'm floating around noon. I configured the Multiplus myself following the instruction guide from battleborn. When the batteries drain within an hour it has no load at all. The BMV712 shows 2.4A which is the Multiplus itself. The voltage drops from 13.55V (floating) to 13.28V within an hour with 2.4A load. The biggest load that I have ever applied to the inverter was 1700W AC = 130A DC witch is only 22A per battery

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Matt Knight avatar image
Matt Knight answered ·

@wlgrau 13.55V sounds a little on the low side for floating - mine sit around 13.7V. Also, beware that the voltage curve is non-linear for LiFePO4 batteries, so 13.28V doesn't by any stretch mean the batteries are discharged. Have you configured the BMV-712 with the right settings for your battery bank? It should use Coulomb counting to track the power usage - also check in the history settings for what the deepest discharge has been, but at 2.4A, it'd take nearly 10 days to drain those batteries.

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