2004 Holiday Rambler-44' Navigator, Xantrax Inverter

2004HRNavigator44

I have a 2004 Holiday Rambler, 44' Navigator with a 3000 Watt (Modified sine wave) Inverter and want to upgrade to a new 3K (or larger) Victron Inverter.  My concerns are that the new Inverter with hook-up to all the extra features that my coach has Like (AGS) Automatic Generator Start, Etc...I'm also going to upgrade my Batteries from the eight Lead-Acid to some number of Lithion type batteries.  Any thoughts?

Photowhit

Run a higher system voltage than 12 volt, go with a pure sine wave inverter/charger that will handle Lithium chemistries...

2004HRNavigator44

Don't I have to stay with the 12 volts, which is what my coach system voltage is? I'm going with a new (Pure Sine) Inverter and don't know if 3K or 4K Watts?  I'm in the process of doing these upgrades and will do the Batteries last as they are very expensive.
Thanks for the comment.

BB.

More or less, highly suggest that 12 VDC battery systems support a (useful) maximum of ~1,200 to 1,800 Watts of AC inverter. The DC input current for a 3 kWatt inverter at 12 volts would be:

• 3,000 Watts * 1/0.85 AC inverter efficiency * 1/10.5 volts battery cutoff voltage = ~336 Amps max DC input current

If you use NEC codes (recommended--Marine codes are less "conservative"), the wire size would be:

https://lugsdirect.com/WireCurrentAmpacitiesNEC-Table-301-16.htm

In the 350-500 kcmil size copper cable. Or roughly 3/4" diameter cable...

And you have to worry about voltage drop. For a 12 volt battery bus, suggest 0.5 volt maximum drop. a 350 kcmill cable, 336 amps, the maximum (one way) cable run would be ~20 feet (0.4 volt drop):
https://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=0.09722&voltage=12&phase=ac&noofconductor=1&distance=20&distanceunit=feet&amperes=336&x=0&y=0

LiFePO4 batteries have very little voltage drop (under heavy load)--But the size wiring needed is pretty difficult to work with.

If your coach is 120 VAC throughout, then 12 volts is not needed.

If you have a mix of 12 and 120 volt appliances/lighting/etc... You are left with figuring out what to do with a 24 volt conversion. There are 24 volt LED lights these days, and some marine/heavy truck appliances are available in 24 volt. Or you can convert to 120 VAC devices instead throughout.

There are also issues with large AC inverters... They can take 10-20 Watts (or more), just turned on. So--Leaving them running 24 hours per day just to run a few lights and USB chargers (for example) is not very practical either (especially for an RV with limited solar panels).

You could run a separate 12 battery bus for lighting, usb chargers, etc. Or even a 24 to 12 VDC down converter (if loads are relatively small).

I have seen that Induction (electric) cookers are becoming popular with RVs and Li Ion battery banks. So the high power AC inverters are becoming more common too (and the Li Ion battery banks to power them).

If you keep the 12 volt wiring short, and use the marine standards--Then 2/0 could support up to ~330 Amps. (2/0 is about 0.419" in diameter).

-Bill

Marc Kurth

My first question is to understand what is driving your decision to go to Lithium?

I see a lot of coaches with 24v battery banks for a single large inverter and a smaller 12v bank for the rest. It is common for large coaches to have two 12v inverters each with its own battery bank. 12 KWH to 24 KWH battery banks are common and I have been involved with several motor coaches with 50 KWH battery banks.

I am going to assume that your coach has (8) 6v GC2 size batteries so you are around 10 KWH of total storage capacity?