New Inverter/Charger

[JHinman]

I just installed a Victron Multiplus 3000 in my ORV trailer. I just turned it on, and it is pumping 75 amps into my two lithium batteries. It will do that from my little Honda generator, too.

I am really excited about this, partly because it charges three times faster than the stock converter did, and partly because now I can make toast for breakfast 😁 when I am camping.

My battery monitor says I am charging at approx 76 amps, while the Smart Dongle on the batteries says 83 amps. Any thoughts about why these devices report different values?

Also, the Multiplus is supposed to charge at 120 amps, so I am getting much lower current than that. The leads from the Multiplus to the batteries are 1/0 welding cable, just under 5 feet in length.

I am not terribly worried about these differences. I ask the question mostly out of curiosity.

Thanks!

[astrocamper]

Which device is the battery monitor? What device is the smart dongle? Which pair of LiFePO4 batteries.

If the 83 amps is the output at the time of the Multiplus and the batteries are seeing 76 amps, the rest can be going to other loads.

The battery state of charge will affect how much current the batteries will accept.

The VE Multiplus is configurable on the charge current and the charge voltage.

I used 4/0 cables with my Multiplus 3000VA inverter/charger. I have seven 100 amp-hour BattleBorn batteries with 2/0 cables to 650 amp bus bars and 4/0 cables to the rest of the circuit involving the disconnect, fuse, shunt and inverter/charger.

[twinboat]

1/0 cable sounds light gauge for a 3000 watt inverter.

[JHinman]

I appreciate the responses.

The battery monitor is Victron BMV-712. The dongle is Victron’s VE.bus Smart Dongle. The batteries are Battleborne 100 amp-hour batteries.

Battleborne configured the Multiplus before they shipped it to me. I don’t know the settings, but will ask just to put the info in my files.

I had planned on 4/0 cable. Battleborne recommended cabling no larger that 1/0, because I have only two batteries. The explanation is that the inverter can gave a very large but very brief current draw on startup, which can cause the BMS to shut the batteries down. Limiting the cable size is supposed to limit this inrush. If I had three batteries there would not have been an issue.

I have never had an inverter before, so it will be interesting to see the difference this makes in our camping. In 25+ years of camping we have gotten by with a couple of Group 27 lead-acid batteries, and very rarely had hookups.

[757driver]

I myself would be listening to the inverter manufacturers recommendations on battery cable size NOT a battery manufacturer. Battery cable size should not be used as a resistor to limit inrush current.

[twinboat]

If that's the case, your inverter is to large for the battery bank.

[astrocamper]

I considered three BattleBorn 100 amp hour batteries the minimum I considered when I installing the 3000VA inverter charger. Three can sustain 300 amps until the battery charge is depleted.

I originally installed 4 originally to give me some decent run time and the ability to store a few days of solar energy. I added 3 more when I started running my air conditioning a lot in the late part of the day. I wanted enough battery to allow me to run the air conditioner 2-3 hours past sunset and still have plenty overnight. 7 is the most I can fit in the space behind my sit and sleep sofa base and the pass through storage wall. This space was unused before I installed the batteries.

I have 1440 watts of solar on the roof and carry 640 watts of portable solar during the hottest months when I need the extra for the air conditioning. 2080 watts gives me a lot of charging capability before the afternoon heat requires air conditioning. This works well in the very dry Great Basin when staying above 5000 feet. Evenings cool off and it stays cool enough until the afternoon.

I no longer bring the Honda EU2200 unless I plan to travel to hotter, lower altitude places like Arizona.

[JHinman]

Fortunately, where I camp I do not need air conditioning.

I could add another battery. I don’t think I will need to do so in order to run a microwave and toaster occasionally. Fitting two batteries was pretty easy, but adding a third would be a challenge. I would probably add one anyway, except that it would probably cost me a bit of storage room.

The whole system is overkill, since the drivers were to be able to make toast for breakfast and get a better battery charger. It will be very expensive toast 😏.

A 2000 watt Victron is lighter, but geometrically would not fit well in the available space. Cost difference was inconsequential, so I went with the 3000 watt device.

It all worked in my driveway. Soon I will find out how well it works in the field.

To the original point, though, perhaps it is the lighter cable that restricts the charging rate.

[KenZ71]

How much effort & complexity is involved with swapping out lead acid batteries & old inverter for new Lithium with a newer inverter? Would it be same scale as say a car battery?

I am looking to add Auto Gen Start which means I need a new inverter so I am thinking if I start down that rabbit hole mind as well get the batteries too. So I'll go with one of the battle born bundles since they will program everything together and presumably reduce the chance of stuff not working - unless install errors of course.

[JHinman]

It is not terribly difficult, once you decide which components to use and where to put them. Most people do not put their new lithium batteries in the trailer tongue.

You might think about where the batteries will go before you get them. The size and shape vary. My old Arctic Fox setup lent itself really well to a couple of Battleborn batteries, but when I moved them to my new ORV they do not use the available space very well.

I suspect that if you get an inverter from Battleborn they will set up the inverter to work with whichever lithium ion batteries you happen to get.