Adding Lithium batteries and an inverter

[Ramorton]

I have a Redhawk 24b and I am adding lithium batteries with a Renogy 3000-watt inverter on sale at about the same price as a 2000-watt inverter. Due to space constraints I am considering placing the lithium batteries and the converter in the same storage area. The Convertor manual says to keep them separate in case it sparks. I am thinking this is a concern with Gel or Acid batteries but not so much with Lithium. Any suggestions? Space is fairly limited in my rig to have them separate.

[ARoamer]

Correct, no worries of explosive hydrogen gas with lithium iron phosphate batteries. Size your cables properly, a 3000 watt inverter can draw 250 amps from your 12v batteries.

[Ramorton]

Thanks, I have 1/0 cables and a 200amp circuit breaker so that the first thing to go would be the breaker. Glad to get the verification as I also hoped any heat put off by the inverter would keep the batteries warm should I need to.

[TomC_AZ]

Be careful with that 1/0 cable, for a 3000w 12v inverter you should be using the larger 4/0. That inverter can pull 300-400amps if needed and if running something higher powered for a while it could cause some big problems with heat.

I have my setup using a 2000w inverter but wired in to run the whole rig, including AC. When doing so my 2/0 (original wire used) got pretty warm, not hot but uncomfortable warm. Lesson learned and swapped to 4/0 and no more heat issue at all.

You will also need at least 2-3 100ah batteries or two larger batteries that can do 150-200amps continuously.

[ependydad]

Originally Posted by TomC_AZ

Be careful with that 1/0 cable, for a 3000w 12v inverter you should be using the larger 4/0. That inverter can pull 300-400amps if needed and if running something higher powered for a while it could cause some big problems with heat.

I have my setup using a 2000w inverter but wired in to run the whole rig, including AC. When doing so my 2/0 (original wire used) got pretty warm, not hot but uncomfortable warm. Lesson learned and swapped to 4/0 and no more heat issue at all.

You will also need at least 2-3 100ah batteries or two larger batteries that can do 150-200amps continuously.

I mostly agree but I think the 300-400 amps is high with a 3000 watt inverter:

3000 watts / 12 volts = 250 amps

Now, I guess that doesn't include for whatever surge capability the inverter is.

But, I do agree with verifying the wire-size. Size for the load (250 amps) and then fuse to protect the wires. Best is if the inverter instructions indicate recommended wire + fuse sizes. Second to that, online wiring guides will indicate the proper wire size for the application.

[TomC_AZ]

While you are correct on the simple premise of the 3000w you're forgetting the surge potential for the inverter and load. A microwave vs an AC vs a hairdryer etc... It depends on which Renogy model as to how high that surge could be and last. But both (inverter no charger and inverter with charger) will easily go up to 6000w on surge, the one with charger can do 9000w according to their spec (for 1second). Planning for the 250amps is going to be the minimum one should go for and then add buffer to be safe.

Another consideration is that it also depends on distance/length of cable needed to/from battery to the inverter. The longer there will be loss/heat that will be created from that. The shorter the better. Mine are only two feet long between the inverter and battery. With the 2/0 that I originally used it got HOT...

Either way to each their own, just know that smaller or just right is not always the correct answer. Trying to skimp on something like wire is a lesson in disaster waiting to happen. Spending the $20-30 more to get the larger wire does not hurt anything and it will help, that's all.

Also if bigger wire is used make sure to up the size of the fuse as well.

[ependydad]

Originally Posted by TomC_AZ

While you are correct on the simple premise of the 3000w you're forgetting the surge potential for the inverter and load.

Originally Posted by ependydad

Now, I guess that doesn't include for whatever surge capability the inverter is.

I mentioned it, but I do understand what you mean.

Originally Posted by TomC_AZ

Trying to skimp on something like wire is a lesson in disaster waiting to happen. Spending the $20-30 more to get the larger wire does not hurt anything and it will help, that's all.

You're putting words in my mouth here. I didn't say it to suggest anyone should skimp on wire due to trying to save money. I was just trying to help the OP with instruction on how to calculate it. As I said, the documentation for the inverter itself is going to be the best option. Second to that, math. How much over/safety net you want/need is up to each installer.

[TomC_AZ]

Didn’t mean to sound that way. Was not intended. The math is correct and sound.

The other part of this that we have not talked about is the battery side. The inverter docs state when using 100ah batteries to use a min of 3. More is better and more usable time. Each 100ah battery usually has the ability to put out 100amps or more. This means with three batteries they can easily do 300amps (or more). This is where it can be very confusing and may be somewhat frustrating.

[ependydad]

Originally Posted by TomC_AZ

Didn’t mean to sound that way. Was not intended. The math is correct and sound.

The other part of this that we have not talked about is the battery side. The inverter docs state when using 100ah batteries to use a min of 3. More is better and more usable time. Each 100ah battery usually has the ability to put out 100amps or more. This means with three batteries they can easily do 300amps (or more). This is where it can be very confusing and may be somewhat frustrating.

Yep, you’re absolutely right about the battery side and the allowed power through.

[RogerR]

Have you thought about calling/email Renogy? They would be a good source of advice on wire sizing. Make sure you know the length between battery and load. For 2 or three feet I would .Assume the $ would be insignificant.

[Fork in the road]

Originally Posted by Ramorton

I have a Redhawk 24b and I am adding lithium batteries with a Renogy 3000-watt inverter on sale at about the same price as a 2000-watt inverter. Due to space constraints I am considering placing the lithium batteries and the converter in the same storage area. The Convertor manual says to keep them separate in case it sparks. I am thinking this is a concern with Gel or Acid batteries but not so much with Lithium. Any suggestions? Space is fairly limited in my rig to have them separate.

I also have a 24B and I am considering a similar upgrade to run the entire coach with the exception of the AC, unless it was for a very short time. I was thinking of utilizing the space under the bed area. Is that where you are planning on locating your system?

[Ramorton]

I thought about that but didn't like sleeping on top of the batteries and running cables required a lot of holes. I decided to use the larger compartment behind the slide. I found I can fit 3 (200) watt-hour batteries in the bottom and still fit my griddle and other items. I can put the DC-DC w/MPPT and all the circuit breakers on a board and place it on the ledge on the left. Invertor either in the back wall or on a board above the batteries not sure yet. I can then use the same cables from the batteries under the steps and use junction blocks splice in cables to run underneath the coach to the back of the compartment and in without a lot of customization and still use the Gen switch and the cut-off by the door. Should be easy to run a cable from the inverter to the 30amp shore plug and dogbone them together to run the coach via a switch that I will mount inside the coach. BTW my coach is a 2020 and the converter that came with it will not fully charge Lithium so you would have to check to see if yours will, I had to upgrade to one with a switch for Lithium. You can send your VIN to motorizedservice@jayco.com and they will tell you. They will also send you blueprints, wiring schematics or whatever you ask them for. Another head-scratcher is that Jayco splices into one connector for the Alternator and Converter to the battery. Not sure why they do that maybe I will ask them but right now I am separating them to run separate lines so that my alternator wire goes to the DC-DC converter and the wire from the converter and fuse box goes to my Bus Bar.

[Fork in the road]

Originally Posted by Ramorton

I thought about that but didn't like sleeping on top of the batteries and running cables required a lot of holes. I decided to use the larger compartment behind the slide. I found I can fit 3 (200) watt-hour batteries in the bottom and still fit my griddle and other items. I can put the DC-DC w/MPPT and all the circuit breakers on a board and place it on the ledge on the left. Invertor either in the back wall or on a board above the batteries not sure yet. I can then use the same cables from the batteries under the steps and use junction blocks splice in cables to run underneath the coach to the back of the compartment and in without a lot of customization and still use the Gen switch and the cut-off by the door. Should be easy to run a cable from the inverter to the 30amp shore plug and dogbone them together to run the coach via a switch that I will mount inside the coach. BTW my coach is a 2020 and the converter that came with it will not fully charge Lithium so you would have to check to see if yours will, I had to upgrade to one with a switch for Lithium. You can send your VIN to motorizedservice@jayco.com and they will tell you. They will also send you blueprints, wiring schematics or whatever you ask them for. Another head-scratcher is that Jayco splices into one connector for the Alternator and Converter to the battery. Not sure why they do that maybe I will ask them but right now I am separating them to run separate lines so that my alternator wire goes to the DC-DC converter and the wire from the converter and fuse box goes to my Bus Bar.

Sounds like you have all planned out. Good luck!

[RogerR]

My Renogy Lithium battery and MPPT are both as close together as I could get, about 2 feet. And I am considering adding an inverter mounted on the same board as my MPPT. Lithium batteries don't outgas like lead batteries and keeping everything on a short wire setup is ideal.

[Seaninnj]

I did this same job myself after months of planning and reviews with a licensed electrician as well as feedback from a helpful Facebook group (DIY RV Solar).

It was challenging but worth it in the end. Be sure you get a qualified person to review your design or else you may have a serious issue.

Good luck!

[dvspl]

Originally Posted by Ramorton

BTW my coach is a 2020 and the converter that came with it will not fully charge Lithium so you would have to check to see if yours will, I had to upgrade to one with a switch for Lithium.

If you have a Progressive Dynamics converter, you may also be able to add the remote Charge Wizard pendant. This will allow you to manually switch the converter from boost (14.4V) to bulk (13.6V) or float (13.2V). It's not as convenient as the newer "lithium capable" converters that automatically do the switching, but it's a lot cheaper (<$20) than a new converter. I've been using this solution for about two years and it has worked great with my 200AH LIFEPO bank. When we boondock, I switch to boost mode when I start my generator and they get about 60 amps until fully charged. When we're on shore power, I leave the converter in float mode and the batteries stay at about ~60% SOC.

https://smile.amazon.com/gp/product/B007HS0PAI/

[Ramorton]

Thanks, I should have asked about this earlier I ended up buying a whole new panel and swapping the old converter for the new one.

[Ramorton]

Thanks for the advice I will do that

[Ramorton]

I sure hope so we shall see. You could always add 2 100AH batteries where the originals are but you will have to locate a place for the controller. The good thing is that is really close to where the solar wires are coming into the bay right after the Propane. You would need to sheet metal the area the batteries are to close it up, I will be doing that as well for storage.