Class C motorhome install

[Mash]

Please forgive my newbie questions. I did research before posting.

I have a Class C Motorhome from 2003 with Deep Cycle LDA batteries. I am starting the process of converting to Lithium but every time I think I understand it, another issue pops up.

I modified the diagram on the Renogy page, does this look correct?

I currently have:
2 100ah 12v Amperetime (LiTime) Lithium batteries
1 Renogy DCC30S 12V 30A Dual Input DC-DC On-Board Battery Charger with MPPT
1 PowerDrive 1000W Bluetooth Pure Sine Wave Power

Stuff to add according to my diagram unless I am wrong. I realize Solar addition can happen after.

300-400 Watt solar panels
Converter/Charger replacement since the current one I assume won't work with lithium batteries.

I am assuming there is already an automatic transfer switch between the on board generator and shore power prior to the converter/charger. Is that a correct assumption?

Does the on board Onan generator use the house batteries to start? Will the Lipo batteries be able to do that? I don't use the generator much, but would like to keep it as an option.

 

[Mash]

Thinking about my diagram, I don't need a switch between shore power and generator, because those are the same. Because you plug the cord into the generator. So disregard that.

 

[Factsmanmp]

How is your project going?

 

[Mash]

How is your project going?

Not done yet, although I have a ton of stuff now ready

 

[Browneye]

Friends don't let friends buy renogy. LOL Victron gets high marks, there are others. It's all fine and good till something breaks and or you need support. My install is also a motorhome, 12V system.

I did not ground my PV array - not sure if that is proper - never heard of that. I did put mine on a 2-pole DC breaker at the controller so I can easily disconnect them without going up on the roof. Controller is on a switching breaker to the battery, same deal, plus circuit overload/short protection. A single or pair of panels don't need to be fused - more than three in series do. Be sure to size wire and fusing to suit your loads and distance.

Most converter/chargers have volts and functions incompatible, but some do work - whatcha got? I replaced my IOTA IQ4 for FLA with a Meanwell NPB lithium compatible charger - works great. I find I don't need a constant 12V supply from shore power with solar and the LFP battery. The charger is on a switched outlet so I can just turn it on if I need/want it. A victron orion charges the house while driving - it's very slick.

 

[Generis]

You can use the stock rv power panel and convertor, assuming you disconnect or disable the 'charger' portion of the convertor forever... don't use that with lithium. The 12v will come from the batteries forever.
You also have your invertor going into the 120v side of the box, but also the shore/generator. NO. you have to have ONE feed for the 120v and then 3 supply options. 1: invertor 2: shore 3: generator. You have to eliminate the slight possibility of having 2 things supplying 120v on at the same time.

 

[Mash]

Yeah, well I put the blame on myself :-( Hopefully stuff will work.

I am replacing my Magnetek 7345 converter with a Progressive Dynamics PD4645V. I talked and emailed with Progressive Dynamics techs and they walked me through the jumper setting to make it work with Litium batteries. It isn't installed yet, but it is supposed to be a direct wire replacement.

 

[Mash]

You can use the stock rv power panel and convertor, assuming you disconnect or disable the 'charger' portion of the convertor forever... don't use that with lithium. The 12v will come from the batteries forever.
You also have your invertor going into the 120v side of the box, but also the shore/generator. NO. you have to have ONE feed for the 120v and then 3 supply options. 1: invertor 2: shore 3: generator. You have to eliminate the slight possibility of having 2 things supplying 120v on at the same time.

Thanks, well, I guess I could have saved myself some money on the converter. But I have it now....

I am not sure I understand the second part. I currently have the Shore power and on board Generator that feed the converter. My assumption is that there is a switch already there that takes those two inputs and goes to the converter. The inverter is coming from the batteries 12v side and going to a dedicated outlet. Not sure if I understand where in the diagram you see the inverter going to the 1210v side of the box. I am sure that I am just not understanding it correctly.

At this point, I feel like I screwed everything up with all the wrong equipment and should just give up.

 

[dcg9381]

Thinking about my diagram, I don't need a switch between shore power and generator, because those are the same. Because you plug the cord into the generator. So disregard that.

Most RVs with a generator have a transfer switch. If you have to manually plug your RV into the generator OR shore power, but it's not possible to do both, then you likely do not have a transfer switch.

 

[Mash]

Most RVs with a generator have a transfer switch. If you have to manually plug your RV into the generator OR shore power, but it's not possible to do both, then you likely do not have a transfer switch.

I have to plug the shore line connector to the output of the generator for it to power. So it only gets the 30A input from one line coming in. I am the transfer switch for that.

 

[dcg9381]

I have to plug the shore line connector to the output of the generator for it to power. So it only gets the 30A input from one line coming in. I am the transfer switch for that.

I see a transfer switch in the diagram, so you're perhaps thinking about adding one. Just watch for N/G bond issues on the inverter. Shore power and generator power are probably already bonded.

 

[Mash]

I see a transfer switch in the diagram, so you're perhaps thinking about adding one. Just watch for N/G bond issues on the inverter. Shore power and generator power are probably already bonded.

Yeah I modified the diagram since then. Here is a link to a thread with the updated diagram. https://diysolarforum.com/threads/feedback-on-class-c-rv-diagram.60503/

 

[Browneye]

The PD converter should work - some complaints that they switch to float too soon, and 13.6V won't really charge the battery - at least it would take a very long time. On the flip side, 13.6 is also a little high to just leave plugged in long term.

The MeanWell chargers put out a full CV at your chosen setting, tapering current as the battery nears full charge, and terminates charging at 5% tail current. They do not re-boost - have to be power-cycled to start the charge cycle over.

Victron makes some nice chargers for LFP as well.

 

[Mash]

The PD converter should work - some complaints that they switch to float too soon, and 13.6V won't really charge the battery - at least it would take a very long time. On the flip side, 13.6 is also a little high to just leave plugged in long term.

The MeanWell chargers put out a full CV at your chosen setting, tapering current as the battery nears full charge, and terminates charging at 5% tail current. They do not re-boost - have to be power-cycled to start the charge cycle over.

Victron makes some nice chargers for LFP as well.

Progressive dynamics said it charges in lit mode at 14.6v https://www.progressivedyn.com/wp-content/uploads/Support/manuals/4600_test.pdf

 

[Browneye]

Which is too high, but they generally switch to float long before your battery gets charged, or never do switch to boost/bulk.

Play with it…see what you get.

Most charge leads are too light as built in RV’s, or it’s a long run, so there’s a lot of voltage drop. YMMV

 

[Factsmanmp]

Not done yet, although I have a ton of stuff now ready

I too get lost in confusion. I’m trying to figure out how to change the emergency jump start for the coach battery switch next to steering wheel to an on / off switch. I saw ”Tito” remove a solenoid that was under the hood close to the switch but mine isn’t there. He joined all the wires together on a bus bar then changed the rocker type switch to a on off switch. My switch appears to have current running through it all the time. Maybe if I go ahead and find that solenoid , remove it and connect everything together, one wire will be hot anthe other will be activated by the on / off switch.

 

[Browneye]

I eliminated the isolating solenoid and used the ignition lead for the Victron Orion dc2dc charger. Dash switch disabled.
Could join house and chassis with jumper cables for a starting battery failure. To prevent that ever happening I installed parallel starting batteries and their own 100W panel and charge controller. They live where the old lead house batteries were in the “outside” tray.

 

[Factsmanmp]

I eliminated the isolating solenoid and used the ignition lead for the Victron Orion dc2dc charger. Dash switch disabled.
Could join house and chassis with jumper cables for a starting battery failure. To prevent that ever happening I installed parallel starting batteries and their own 100W panel and charge controller. They live where the old lead house batteries were in the “outside” tray.

Thank you. Made a note on that.
Another question, can I start with replacing the lead acid with a lithium battery with no dc to dc charger? I’ve heard that my existing setup charges the house battery at such a low rate that I don’t have to worry about burning up my coach alternator. Is it true that the dc to dc charger is more to allow the alternator to charge the lithium batteries at a prescribed rate ?

 

[Browneye]

In a word, no. LFP batteries have such low internal resistance it will draw all your alternator can output. At hiway speeds this may not create an issue with cooling, but it will also do this at idle and overheat your alternator- cook it. A DC-to-DC charger pulls a set amount, you choose a charge rate compatible with your loads and alternator output, and it isolates your LFP battery from your alternator.

I chose a Victron Orion 18Ah, it's sufficient for some charging time while driving - 145A alternator and 230A LFP house battery. I have it set to max out at 13.8V, float at 13.4, as it restarts its charge cycle each time you power-cycle the charger - which is initiated by starting the engine.

LFP also is not well suited as a starting battery, so keep a lead starting battery for that, supply your house loads with LFP in a sufficient capacity to suit your usage requirements.

A 120V converter/charger, if the coach came with one, generally does not output correct charge voltage for LFP. Usually they're too high or two low, some include equalization which will over-volt LFP, and charging needs to terminate when the battery is full - not to keep charging it. You're better off with a LFP compatible 120V charger - Victron, MeanWell, etc.

 

[Factsmanmp]

In a word, no. LFP batteries have such low internal resistance it will draw all your alternator can output. At hiway speeds this may not create an issue with cooling, but it will also do this at idle and overheat your alternator- cook it. A DC-to-DC charger pulls a set amount, you choose a charge rate compatible with your loads and alternator output, and it isolates your LFP battery from your alternator.

I chose a Victron Orion 18Ah, it's sufficient for some charging time while driving - 145A alternator and 230A LFP house battery. I have it set to max out at 13.8V, float at 13.4, as it restarts its charge cycle each time you power-cycle the charger - which is initiated by starting the engine.

LFP also is not well suited as a starting battery, so keep a lead starting battery for that, supply your house loads with LFP in a sufficient capacity to suit your usage requirements.

A 120V converter/charger, if the coach came with one, generally does not output correct charge voltage for LFP. Usually they're too high or two low, some include equalization which will over-volt LFP, and charging needs to terminate when the battery is full - not to keep charging it. You're better off with a LFP compatible 120V charger - Victron, MeanWell, etc.

Thank you. That answers my concerns. So I will install the Dc to Dc charger with the LFP battery.
Yeah the coach came with a WFCO converter. I contacted them and they told me the model I had would probably charge the LFP battery up to about 85% and recommended a newer model. But as someone pointed out on this Forum, the spec’s were almost exactly the same with the one I have. So I was advised to wait and use the one I already have and see how it charges.
Yes, I will stick with the lead acid battery that starts and runs the RV.