Yet Another Lithium Conversion and Solar Addition

[dkoldman]

Originally Posted by Fred 2106DS

Yes, You will need to run separate wiring to install a DC/DC charger.

I mainly installed a DC/DC charger to run our 2-way fridge on AC while traveling. To do this I need to run the inverter while traveling and use the DC/DC charger and solar to keep the LFP batteries charged so when we arrive at our destination our LFP batteries are not depleted.

To control the DC/DC charger I tied its trigger wire to the clearance light circuit on the trailer which allows me to turn it on/off with the light switch in the truck.

As far as the DC/DC charger putting undue strain on the trucks alternator, I haven't seen any issues.

Here's a link to my DC/DC install.
https://www.winnieowners.com/forums/...ml#post3882902

You have stated exactly why I must have a DC 2 DC charger. Our DC 2 DC is on order (Victron Orion XS 50amp), When I do go to Lithium, I will no longer be able to safely use the alternator as charging source for House Lithium batteries. We ALWAYS run our RV with Inverter ON. The fridge is set for Electric & Propane. Since the Inverter is ON, it always uses AC, but if we stop it switches to Propane.

The 2nd point is that I am just accustomed to always be fully charged after any drive without any thought.

The resultant consequence is that we never have needed Solar or wished that we had. I cannot ever think of circumstance where we boondocked and did not need the genny for something at least 2 hours per day.

I think our AH capacity position will improve because the Lithium battery we may buy may be 280 - 300ahs capacity. That will almost triple what we have to day.

[creativepart]

Originally Posted by dkoldman

The fridge is set for Electric & Propane. Since the Inverter is ON, it always uses AC, but if we stop it switches to Propane.

All those running their AC/LP fridges on 12v battery inverted AC need to realize that this is pretty inefficient. It takes a lot of AC wattage to operate the resistance heating element in a gas absorption fridge.

The basic intention with the dual fuel RV Fridge is that you run on Propane any time you are not connected to shore power. The assumption is shore power is abundant. Unlike 12v battery power into an inverter.

In fact, until recently it was never even possible to operate a RV Fridge this way. I'm a bit surprised that the fridge has a receptacle that is connected to the inverter sub-panel.

[dkoldman]

Originally Posted by creativepart

All those running their AC/LP fridges on 12v battery inverted AC need to realize that this is pretty inefficient. It takes a lot of AC wattage to operate the resistance heating element in a gas absorption fridge.

The basic intention with the dual fuel RV Fridge is that you run on Propane any time you are not connected to shore power. The assumption is shore power is abundant. Unlike 12v battery power into an inverter.

In fact, until recently it was never even possible to operate a RV Fridge this way. I'm a bit surprised that the fridge has a receptacle that is connected to the inverter sub-panel.

All true. My setup starts with what you have just outlined.

I then questioned why run the propane for fridge while driving when there is a full charge from Alternator? I made a Mod about 4 years back where I created an additional receptacle behind the fridge. At the time I thought I may need to switch it back and forth for load balance, but it has never been an issue. I think that fridge may run 500 - 600watts?

FWIW, I connected to the same circuit as used by bedroom TV which is rarely used, certainly not when driving.

Also, we NEVER run that fridge off inverter if engine is not running. When driving and the genny comes on to start up the Air Conditioners we still have electricity running the fridge. But if we stop and cut off the Inverter, it will convert to Propane.

Now my hope is that when I get the new Lithium setup, it will still work as smoothly? My house batteries will be supplied with 50amps charging; so I hope that is enough to keep everything working like we are use to if not better?

[Marine359]

Consider installing a hybrid inverter/charger. Stick with either Victron or Xantrex. Renogy doesn’t have full pass through. Installation is simplified. No separate transfer switch needed. And one of the big benefits is the charge amperage they can provide. Wiring is simpler too. Just match the cable size to the size of the inverter/charger. Most people don’t need more than a 2,000w unit which can be cabled with 2/0 cable. It will put out up to 80 amps charge current. Pretty fast charging for your dual 230ah lithiums. Big IF. If you have sufficient incoming ac power. You’ll need 15 amps for that. 30 amps incoming allows you to do other stuff while charging. It really doesn’t matter how many solar. charge controllers you have. If they are all connected to a common dc bus, their charge amperage will all dump into the battery bank. With correct cabling and fusing, it’s not an issue. A 100/30 controller should have an 40 amp fuse between controller and battery. And of course, there should be a breaker between pv array and controllers. If using multiple controllers, easiest to use a fuse block with whatever size fuses you need and a connector cable to the bus sized for the total of all possible incoming amps.