Increasing the available AH’s in RV with no solar

[quadna71]

I’m planning to increase the available 12v power to my RV but am not dabbing in solar yet. We only need the ability to get a couple days off-grid as we spend one or two nights in the camper while traveling longer distances from origination to destination and then are plugged back into shore power and can charge back up. So maybe solar down the road but not for now. The largest draw on our system is a 12v residential fridge (11 amp peak use) and after that the occasional cycle of the water pump to use the toilet/sink while at a rest stop. I’ve ordered the parts and am ready to start the install….and then of course I came across this forum. So in hindsight, I’d like to list my parts of the project and hopefully some more experienced folks can chime in and let me know if I’m on the right track.

Current setup:
70ah (group 37) 12v FLA battery on the tongue of the travel trailer - it has reached end of life and helped time the start of this project.
WFCO 55 amp charger/converter in the power panel with 3-stage charging for FLA batteries only.
Battery shut off in the front pass-thru storage compartment.

Planned upgrade setup:
Two 206ah SOK batteries in parallel secured inside under the bed.
WFCO 50 amp charger/converter in the power panel with 2-stage charging for LiFePO4 batteries only.
Battery shut off in the front pass-thru storage compartment.
Second battery shut off under the bed right after the positive cable leaves the batteries.
60 amp fuse located on the positive just after the battery shut off.
Victron Smartshunt on the negative cable right after the negative cable leaves the batteries.
The cabling is 2awg Windy Nation with 100% copper lugs. I have a good crimper, heat shrink, a heat gun and have been practicing a couple times.

So I think that is all I need to very simply increase my battery size. The OEM battery cable is 8awg, so while the 2awg I’m using isn’t as big as some folks use, it is still a good upgrade from what is already in place. I’m putting the battery shut off in place near the batteries because it is highly recommended, but I’m also leaving the battery shut off in the front pass-thru storage compartment. This is because when the slide is fully retracted the bedroom is inaccessible (where the batteries will live) and I still want the ability to kill the system easily without having to resort to using shore power to close the slide back up after killing the batteries from under the bed. While I know there are better charger options out there, using the WFCO replacement seems to be a simple swap and involves the least changes to the RV. I chose the Smartshunt so that I can monitor the batteries from my phone as a wired monitor would be less convenient to check by lifting the bed up all the time.

Okay. Thoughts? Screwed up? The right direction? Changes?

As an aside, I do have a small Renogy 100w suitcase solar kit with controller that can be placed outside and plugged in. But since we will likely be traveling during the day it won’t really be an impactful solution in this case. Solar could be an option next year (2023-24) but for now I’m only interested in the batteries. Lastly, I thought I should mention that we do not have an inverter nor do we plan to install one. So no 120v appliances to draw on the system at all. Just the fridge, an occasional cycle of the water pump, and maybe an LED light or two in the evening while parked at a Harvest Host location or someplace like that.

Thank you.

 

[rmaddy]

The battery fuse needs to be first, then the battery shutoff switch. The fuse is there to protect the wiring and everything connected to it.

What type of fuse were you planning on? For LiFePO₄ batteries the best choice is a Class-T fuse but the smallest you'll find is 100A. An ANL fuse may be OK for a 12V system.

Why did you choose 2AWG wire and a 60A fuse? 2AWG is meant to handle up to about 120A. What are all of the loads your battery will power? Since you are not using the battery for an inverter, your loads sound relatively small (which is fine). The charger at 50A may be the largest current you have to deal with based on what you've posted so far. 6AWG wire would be big enough for that. Though using larger wire is fine and does give you room to grow.

 

[John Frum]

You don't mention an inverter or transfer switch.
Do you have one or both of these units?
If you are interested in an inverter I suggest you get an inverter/charger and just disable your legacy ac2dc converter.

 

[quadna71]

Thanks @rmaddy for the questions and input.

First, I’ll definitely flip the orientation of the fuse and shut off switch like you said.

Second, it is an ANL 60 amp fuse. It was recommended by a few folks on an RV forum I frequent based upon my appliances and 12v demand. The fridge draws a max of 11 amps and is by far the largest draw we would experience on the RV. The water pump specs say it will draw 7 amps continuous but I’m sure it might have a surge when it kicks on. There is a very outside chance that the propane hot water heater might get fired up long enough to heat up the tank and then be killed in order to take a quick shower, but even then the water pump is never run for longer than 30 seconds at a time as we use water sparingly. And then the occasional light on over the couch or over the bed at night but those are all LED lights so I don’t think will be very impactful. Like mentioned before, we do not have an inverter in the RV so high demands just wouldn’t happen. No coffee maker, no microwave, no television, etc. Even running the 12v fan for the propane furnace isn’t being put into the equation as we tend to only camp in temperate seasons and bundle up with blankets in the evening.

Third, my main goal with the 2awg wire was just to improve what was there. The OEM battery wire is 8awg but horrible - it will literally stand out straight in front of you for about 2 feet without bending down even with the battery terminals pulling downward. Just not a very good multistrand copper wire. So anything would be an improvement. I landed on either 4awg or 2awg because the size of the lugs seems better suited to the bolts on the shunt, battery, fuses, and shut offs better than the lugs that were used on 6awg or 8awg. And the price difference wasn’t much between 4awg and 2awg so I just landed on 2awg.

 

[quadna71]

You don't mention an inverter or transfer switch.
Do you have one or both of these units?
If you are interested in an inverter I suggest you get an inverter/charger and just disable your legacy ac2dc converter.

We currently don’t have an inverter nor transfer switch. Our trailer doesn’t come with one from the factory and we don’t have plans to add one at any point. For the size of our camper we tend to not spend much time inside enjoying the creature comforts inverters typically provide. A majority of cooking happens on the grill and not using the microwave, coffee is water on the grill with a french press, and television rarely happens. Now our next rig, which will happen some day, will likely be larger and have more items used regularly that would involve an inverter. We even picked out our TV with the capability to pull a much larger camper down the road (no pun intended).

 

[John Frum]

If you post the exact model number for your legacy wfco converter I will look it up and see if its charge profile is suitable for lfp batteries.
I'm guessing the new one won't be much better than the old.

 

[jberger]

You might want to think about how you can insulate and keep the batteries warm. Most of the Travel trailers, especially the light weights, don't have much insulation, especially in the floor. If the batteries get too cold when traveling, you won't be able to charge or use them when you get to your destination.
A couple of inches of pink board would give you a nice R factor, and maybe a heating pad or two for those times when you know it's going to be cold heading to your destination.

Going from 80ah to 400ah is going to be great, you will love the run time!

Is your trailer connection wired so you can charge the batteries while you are towing?
if not, add that connection while you re-wire, and you might be able to recharge the pack a decent amount while you tow. If you already have a wired breakaway kit, then you just need to tap it to use it.

 

[quadna71]

@smoothJoey it’s a WFCO lithium charger. 14.6v in bulk and 13.6v in absorption. It will run for a max of 4 hours in bulk which is likely not long enough to charge my 412ah bank back from a low SOC back to full, but I am installing a switch next to the panel which will reset the 4 hour timer and put it back into bulk mode if my Victron app tells me I’m not yet full.

Here’s a link to the charger. For more of the charging profile details, click on the downloads tab, select manual, and the charging section starts on page 5. I called WFCO directly as I was interested in making the upgrade as simple as possible. Retaining the OEM style charger kept me from having to worry about a new location for a charger or maybe even having to install an actual AC outlet back in the compartment where the charger is mounted below the circuit breaker panel. Their tech department recommended either this charger or one that has switch to easily flip between FLA or LiFePO4 batteries. Since I’m relocating batteries to under the bed, I don’t see me ever going back to FLA and opted for the cheaper version that doesn’t have a switch.

WFCO Technologies - Innovating the Future of RV Power

WFCO Technologies is committed to simplifying, enhancing, and optimizing every RV owner’s experience through advanced power technology and proven support.

wfcoelectronics.com

 

[John Frum]

@smoothJoey it’s a WFCO lithium charger.

I meant the old charger.
I was trying save you the purchase price of a new charger.
I'll stop now.

 

[quadna71]

You might want to think about how you can insulate and keep the batteries warm. Most of the Travel trailers, especially the light weights, don't have much insulation, especially in the floor. If the batteries get too cold when traveling, you won't be able to charge or use them when you get to your destination.
A couple of inches of pink board would give you a nice R factor, and maybe a heating pad or two for those times when you know it's going to be cold heading to your destination.

Going from 80ah to 400ah is going to be great, you will love the run time!

Is your trailer connection wired so you can charge the batteries while you are towing?
if not, add that connection while you re-wire, and you might be able to recharge the pack a decent amount while you tow. If you already have a wired breakaway kit, then you just need to tap it to use it.

Thanks @jberger. I’ve thought about that and came to the conclusion (after speaking with my wife LOL) that we will not be in those colder environments with our camper. I think the coldest we have ever experienced while camping was a dip to 49 degrees this past fall while in Gettysburg one evening. But you are very correct about the lack of insulation. Ours is categorized as a “hyperlyte” so I think their idea of insulation is an extra coat of paint! I am in the habit of pulling the battery in the camper when I winterize it and will continue this habit with the new lithium batteries too. I think the manufacturer says to pull them down to around 70% SOC and then disconnect and/or remove. My garage is heated and that is where they will live throughout the winter.

Our truck does have a charging circuit, but after reading some anecdotal comments on a Ford truck forum I’ve concluded it won’t do much other than a trickle charge. I’d have to install a DC/DC charger if I wanted to take advantage of the driving time. And that could be a possibility at some point - but I want to wait and see how we fare with these upgrades first before taking that step.

 

[quadna71]

I meant the old charger.
I was trying save you the purchase price of a new charger.
I'll stop now.

Ah, I understand. It was also WFCO’s charger - a 55 amp 3-stage charger. But the profile wouldn’t have me in the correct higher range of voltage to suit the new lithium batteries so I purchased the new one. I am keeping the old one so it is possible to return things to how they were in case our next camper has similar power systems…but in all likelihood even the simplest of charger will have also improved over the next year or two. Seems like significant gains are happening in leaps and bounds in the world of battery tech!

 

[John Frum]

Ah, I understand. It was also WFCO’s charger - a 55 amp 3-stage charger. But the profile wouldn’t have me in the correct higher range of voltage to suit the new lithium batteries so I purchased the new one. I am keeping the old one so it is possible to return things to how they were in case our next camper has similar power systems…but in all likelihood even the simplest of charger will have also improved over the next year or two. Seems like significant gains are happening in leaps and bounds in the world of battery tech!

Actually I don't expect the ac2dc converters to improve much.
The are a sunset product and I suspect they will get just about 0 RnD going forward.

 

[quadna71]

That might be true, but it seems once you pass a certain level of power load in a larger RV they are then fitted with larger chargers and less of the simple WFCO systems. Power Dynamics seem to be more common. So chances are that I wouldn’t pull the new lithium out and instead would just leave with the RV. Batteries are staying with me though!

 

[John Frum]

Power Dynamics seem to be more common.

Its Progressive Dynamics and they are better quality but not much more sophisticated that the wfco options.
As far as increasing the power I suspect it will be quite rare for an ac2dc converter to exceed 1920 watts ac input.
There will be some but they will probably not be UL listed.

 

[quadna71]

Whoops, yep…I was close!

 

[RVLiFe]

I have that same WFCO lithium charger. It works just fine! Like you said, it charges at 14.6 for up to 4 hours and then drops to 13.6. Many times I just charge to about 13.8-14V and then just flip my breaker switch to reset it. It then just goes straight into a 13.6V float which is just perfect for those SOK’s. So I commend you on your choice of converter. Good Job! For what you are doing, I think you are on the right track. My advice to you would be to make sure that whatever size wiring you decide to add, you do it with the intention of upgrading to an inverter some day. That way, you won’t have to spend the time or money in rewiring everything a second time.
Your shunt is perfect, your controller is perfect and your batteries and wiring are all perfect for what you are doing.
You WILL want to play around with solar at some point and once you do, you WILL want to go bigger than what you currently have. Eventually, you will even want to throw in an inverter into the mix as well but you could get by with a simple 400W one that would probably suit your minimal needs but I can also assure you that you will eventually want to go bigger as well. So the moral of the story is to plan for a bigger system to future proof your yourself. For what your current needs are, one 206Ah SOK would have been more than enough. I have only one in my system as well as a 1500 Watt inverter and 600 Watts of solar and it’s enough for my power needs. I seldom ever need to run my generator to charge the batteries. But I do wish at times I had a second battery (100 Amp limit) so I could run an air fryer but that’s about it. But I also ran 1/0 AWG wire to future proof my system and dropping in a second battery wouldn’t take any additional effort or cause any more work to accomplish.

 

[quadna71]

I have that same WFCO lithium charger. It works just fine! Like you said, it charges at 14.6 for up to 4 hours and then drops to 13.6. Many times I just charge to about 13.8-14V and then just flip my breaker switch to reset it. It then just goes straight into a 13.6V float which is just perfect for those SOK’s. So I commend you on your choice of converter. Good Job! For what you are doing, I think you are on the right track. My advice to you would be to make sure that whatever size wiring you decide to add, you do it with the intention of upgrading to an inverter some day. That way, you won’t have to spend the time or money in rewiring everything a second time.
Your shunt is perfect, your controller is perfect and your batteries and wiring are all perfect for what you are doing.
You WILL want to play around with solar at some point and once you do, you WILL want to go bigger than what you currently have. Eventually, you will even want to throw in an inverter into the mix as well but you could get by with a simple 400W one that would probably suit your minimal needs but I can also assure you that you will eventually want to go bigger as well. So the moral of the story is to plan for a bigger system to future proof your yourself. For what your current needs are, one 206Ah SOK would have been more than enough. I have only one in my system as well as a 1500 Watt inverter and 600 Watts of solar and it’s enough for my power needs. I seldom ever need to run my generator to charge the batteries. But I do wish at times I had a second battery (100 Amp limit) so I could run an air fryer but that’s about it. But I also ran 1/0 AWG wire to future proof my system and dropping in a second battery wouldn’t take any additional effort or cause any more work to accomplish.

Does your camper have a 12v residential fridge? Ours does and it is a real power hog - hence going with the second battery. If it were propane we would have likely stuck to one. Since we don’t have panels up top and many of the Harvest Host locations don’t allow generators, we wanted to have that buffer of the second battery to give us better peace of mind. We fully understand that the upgrades will not be the end all solution, but at least we are sort of preparing ourselves for solar at some point down the road. Thanks for your response.

 

[RVLiFe]

Does your camper have a 12v residential fridge? Ours does and it is a real power hog - hence going with the second battery. If it were propane we would have likely stuck to one. Since we don’t have panels up top and many of the Harvest Host locations don’t allow generators, we wanted to have that buffer of the second battery to give us better peace of mind. We fully understand that the upgrades will not be the end all solution, but at least we are sort of preparing ourselves for solar at some point down the road. Thanks for your response.

My fridge is either A/C or propane in a Grand Design Reflection 337RLS fifth wheel.
I totally see your point with the second battery and a 12V fridge. You’re doing the right thing. We stay at harvest host as well but my panels are not mounted to the RV. We are parked in the shade a lot so I have the flexibility to move my panels when I need to. It’s been working out great for us. I’m envious of your two batteries actually! Solar has made a huge difference in our ability to go off grid.
My only recommendation again would just be to use wire that will support a bigger system in the future if you can. But it looks like you are well aware of that and I wish you many amazing sunsets in your future endeavors my friend!

 

[quadna71]

Thanks. We do have a little 100w suitcase panel from Renogy that can be used like you mentioned, but it’s not a game changer by any means.

 

[RVLiFe]

Thanks. We do have a little 100w suitcase panel from Renogy that can be used like you mentioned, but it’s not a game changer by any means.

I’d be surprised if you get more than about 5-6 Amps out of it honestly and that doesn’t even cover the draw from your fridge. You’d be surprised with what a difference a good MPPT controller and one or two good quality panels can make. That would be my next step and then eventually a small inverter.
This is my setup. I only had two panels deployed and the solar was powering my lights, TV, fridge and I was putting Amps into the battery.
Yes, I was at an RV park and had a pedestal next to me but I was testing the system out and wasn’t plugged in.