Choosing Li+ batteries
Hotshot
Joined: Oct 2015
Posts: 19,698
Likes: 12,824
From: Wyoming
If I use an Orion fed by the charge lead can I not simply jumper the charge lead + in to feed the +switch to signal the ignition is on? Seems pretty straight forward and the cost is not bad. If it is that simple I can't see any reason not to do it. However, given the limited output of the charge lead I don't see how I will get a boost unless I change the charge lead input on the truck? So splice in the DC/DC converter and change the feed source on the TV?
Senior User
Joined: Jul 2020
Posts: 449
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Wow, Steve. That is some box and secure mount for the gen. Deluxe DIY or purchased?
I think I saw someone the other day that had their small gen front mounted and had their camper AC power cord run up to it. Had it running while driving to charge the batteries. Was a bit surprised to see that.
I think I saw someone the other day that had their small gen front mounted and had their camper AC power cord run up to it. Had it running while driving to charge the batteries. Was a bit surprised to see that.
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Hotshot
Joined: Jan 2010
Posts: 10,060
Likes: 491
From: Bristol, TN.
All DIY. I worked my way through college doing HVAC work when folks still had to know how to form metal. I buy 5' x 10' sheets of aluminum from a local shop that come painted black on one side and white on the other and I have a small sheet metal brake in my garage. My welding sucks as I don't do it often enough so no "stack of quarters", but it holds well enough. It's all pretty basic. I didn't want to go with the standard front hitch and Torklift as using the front hitch low, the approach angle is terrible even for our limited off-road use. I didn't want Torklift as I think a lot of their stuff is easy to duplicate at a fraction of the price. 
Steve
Steve
Mountain Pass
Joined: May 2009
Posts: 127
Likes: 0
That's great.
I was thinking about spec'ing lith's in the new camper, but stuck w/ AGM. To start, the camper dealer seemed to be dodgy knowledge-wise about Lith's and in their supplier catalog, they only had schmeg brand, which I didn't want. Plus it's a new TC and I don't know how thoroughly optimal the stock system is should it indeed be lith compatible. Plus I figured I can see how the solar panels do at charging given we're in the PNW (cloud/big trees).
And I just plain old didn't want the extra stress of something else on my plate at this time! LOL!
How much camp time have you had with your system? Have you been out under various weather conditions?
Thanks!
I was thinking about spec'ing lith's in the new camper, but stuck w/ AGM. To start, the camper dealer seemed to be dodgy knowledge-wise about Lith's and in their supplier catalog, they only had schmeg brand, which I didn't want. Plus it's a new TC and I don't know how thoroughly optimal the stock system is should it indeed be lith compatible. Plus I figured I can see how the solar panels do at charging given we're in the PNW (cloud/big trees).
And I just plain old didn't want the extra stress of something else on my plate at this time! LOL!
How much camp time have you had with your system? Have you been out under various weather conditions?
Thanks!
I'd say if two batteries and one panel works fine now for your consumption now then 1 lithium is fine. They only bulk charge so solar recharging is a lot faster than an agm.
Senior User
Joined: Jul 2020
Posts: 449
Likes: 51
I try to use the rig monthly, either at the race track or camping. Camping is in northern AZ under the pines so I'm generally very shaded, that's why I went with as much panel in parallel as I could fit without being creative. I have a victron 12|12 9 dc-dc, I see about 7.5a at the battery with it, I usually don't use it as long as I have good sun while on the road.
I'd say if two batteries and one panel works fine now for your consumption now then 1 lithium is fine. They only bulk charge so solar recharging is a lot faster than an agm.
I'd say if two batteries and one panel works fine now for your consumption now then 1 lithium is fine. They only bulk charge so solar recharging is a lot faster than an agm.
I don't know yet how our usage will look. We haven't taken delivery of the new F350 or the NL 10'2 LE yet. The 10.2 comes with 2 x 185w panels on the roof standard, so quite a bit. I have no experience with solar, but I know that it's not as great for up here as it is for sunny places like AZ. But looking forward to seeing how our usage is. We'll be taking along our Honda EU2000 so backup is on hand. But I know Mrs. isn't a fan of listening to it, which I get. But if you want the juice, it's gotta be squeezed from somewhere.
Mountain Pass
Joined: May 2009
Posts: 127
Likes: 0
The small gen is a great idea, and once again the bulk charge is great. 1 pretty depleted lithium with a 40a charger will pull that up in less than 2hours, that'll take about 700-750W so around half the load of your honda.
Hotshot
Joined: Oct 2015
Posts: 19,698
Likes: 12,824
From: Wyoming
If the AC (not air conditioning) system can handle it, using a higher amp converter means less generator time. The OEM converter in my RV was 45 amps and I bumped that to 55 amps for the LiFePO4 system. I would have gone higher but I was a bit unsure about pushing the limits of my AC system. My battery bank can - in theory - handle as much as 250 charge amps. The solar can - in theory, on a really good day - provide 100 amps.
Tuned
Joined: Nov 2018
Posts: 398
Likes: 110
From: Southwest Montana & Idaho
Their ability to take greater charge seems to be a big plus.
I don't know yet how our usage will look. We haven't taken delivery of the new F350 or the NL 10'2 LE yet. The 10.2 comes with 2 x 185w panels on the roof standard, so quite a bit. I have no experience with solar, but I know that it's not as great for up here as it is for sunny places like AZ. But looking forward to seeing how our usage is. We'll be taking along our Honda EU2000 so backup is on hand. But I know Mrs. isn't a fan of listening to it, which I get. But if you want the juice, it's gotta be squeezed from somewhere.
I don't know yet how our usage will look. We haven't taken delivery of the new F350 or the NL 10'2 LE yet. The 10.2 comes with 2 x 185w panels on the roof standard, so quite a bit. I have no experience with solar, but I know that it's not as great for up here as it is for sunny places like AZ. But looking forward to seeing how our usage is. We'll be taking along our Honda EU2000 so backup is on hand. But I know Mrs. isn't a fan of listening to it, which I get. But if you want the juice, it's gotta be squeezed from somewhere.
Cheers!
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Tuned
Joined: Nov 2018
Posts: 398
Likes: 110
From: Southwest Montana & Idaho
Battleborn is pretty much the standard that everything else compares to. Rounding up, it's about $1000 for 100 Ah. There are sales on them that will take that price down by about $100.
However...
Many of the off-the-shelf LiFePO4 battery manufacturers/retails want these batteries to seem like they are 100% drop-in replacements. My opinion is that they aren't. A LiFePO4 battery doesn't want the same charge profile as the typical lead acid battery. That means there are two immediate changes needed to your typical RV.
1. The charge from the tow vehicle should go through a DC-DC charger with a LiFePO4 charge profile. A LiFePO4 battery can suck up a bunch of amps. The typical Superduty has a 30 amp charge circuit on the 7-pin. While I haven't heard of anyone frying this circuit, there is a theoretical potential. There is a video on YouTube showing how unrestricted charging of a LiFePO4 battery directly from the alternator fried the alternator. It's a good bit of FUD (Fear, Uncertainty, Doubt) and I question the testing method, but it does point out how a LiFePO4 battery can really suck the life out of a 12v charging system.
2. The on-board AC-DC converter likely doesn't have the right charge profile either. This is particularly important if the converter has a four stage charge profile. The Equalization stage is way more volts than a LiFePO4 battery should ever see.
The counter argument to the two points above is that the BMS in the battery should limit the over charging. However, the BMS should be the last line of defense for your battery. The upstream devices need to be smart enough to provide good charging for a LiFePO4 battery.
Then there is the temperature issue. LiFePO4 batteries should not be charged below 32° F. Discharge below that temperature is OK. Studies have shown that the closer you get to 32° F the lower the charge rate (amps) should be. If you're going to use the batteries in cold weather, they need to be out of the cold or have a warming system. Some off-shelf batteries can be ordered with an add-on warming and some of them have it internal to the battery. The internal option means that when the BMS detects that the battery is below about 35° F and a charge is detected, it will send that power to the warmers to bring the battery up to an acceptable temperature. The downside is that it could take an hour for that to come up to temperature and the battery has missed out on that entire hour of charging.
Did I lose you already? I hope not. I really, really like my LiFePO4 batteries. Lighter weight, more compact, way more power, more usable power (none of this 50% discharge limit like you have with a lead acid battery), and they're safe to keep inside the trailer with no venting.
For a little more than the full retail cost of a Battleborn battery, I build my own LiFePO4 batteries from cells I purchased from China. I have 560Ah of capacity.
However...
Many of the off-the-shelf LiFePO4 battery manufacturers/retails want these batteries to seem like they are 100% drop-in replacements. My opinion is that they aren't. A LiFePO4 battery doesn't want the same charge profile as the typical lead acid battery. That means there are two immediate changes needed to your typical RV.
1. The charge from the tow vehicle should go through a DC-DC charger with a LiFePO4 charge profile. A LiFePO4 battery can suck up a bunch of amps. The typical Superduty has a 30 amp charge circuit on the 7-pin. While I haven't heard of anyone frying this circuit, there is a theoretical potential. There is a video on YouTube showing how unrestricted charging of a LiFePO4 battery directly from the alternator fried the alternator. It's a good bit of FUD (Fear, Uncertainty, Doubt) and I question the testing method, but it does point out how a LiFePO4 battery can really suck the life out of a 12v charging system.
2. The on-board AC-DC converter likely doesn't have the right charge profile either. This is particularly important if the converter has a four stage charge profile. The Equalization stage is way more volts than a LiFePO4 battery should ever see.
The counter argument to the two points above is that the BMS in the battery should limit the over charging. However, the BMS should be the last line of defense for your battery. The upstream devices need to be smart enough to provide good charging for a LiFePO4 battery.
Then there is the temperature issue. LiFePO4 batteries should not be charged below 32° F. Discharge below that temperature is OK. Studies have shown that the closer you get to 32° F the lower the charge rate (amps) should be. If you're going to use the batteries in cold weather, they need to be out of the cold or have a warming system. Some off-shelf batteries can be ordered with an add-on warming and some of them have it internal to the battery. The internal option means that when the BMS detects that the battery is below about 35° F and a charge is detected, it will send that power to the warmers to bring the battery up to an acceptable temperature. The downside is that it could take an hour for that to come up to temperature and the battery has missed out on that entire hour of charging.
Did I lose you already? I hope not. I really, really like my LiFePO4 batteries. Lighter weight, more compact, way more power, more usable power (none of this 50% discharge limit like you have with a lead acid battery), and they're safe to keep inside the trailer with no venting.
For a little more than the full retail cost of a Battleborn battery, I build my own LiFePO4 batteries from cells I purchased from China. I have 560Ah of capacity.
Hotshot
Joined: Oct 2015
Posts: 19,698
Likes: 12,824
From: Wyoming
Finally a thread that is informative. We are looking at replacing the two lead acids in our rig soon and adding a mobile Zamp 140w panel kit that can be connected through a port on the outside of the rig in addition to the panel on the roof. Are you saying the charge controller that allows us to select the battery type will require replacing? Despite having solar on the roof of our home I'm fairly ignorant to the components and how they work. Will having a single or double LiFe battery installed while going down the road fry our alternator or connection to the truck if it is receiving current from the alternator?
Due to very low resistance, the LiFePO4 batteries will suck every possible amp out of your alternator, possibly overheating it. That's just one reason to put in a DC-DC charger. The other reason is that the charge profile for LiFePO4 is much more picky than for lead acid batteries. The 7-pin connection shouldn't get more than 30 amps to the RV battery. But I don't know of anyone testing that continuously for 4+ hours. You still have the charge profile issue..
Tuned
Joined: Nov 2018
Posts: 398
Likes: 110
From: Southwest Montana & Idaho
Jim,
Good info and much thanks. Yes our current charge controller is for solar. Our 2018 F350 has dual alternators from what I've read one is used primarily until the draw is exceeded then the other kicks in. This DC to DC converter, where would this device be installed in the scheme of the electrical system? I'm thinking maybe in the battery compartment between the charge source and batteries themselves.
Good info and much thanks. Yes our current charge controller is for solar. Our 2018 F350 has dual alternators from what I've read one is used primarily until the draw is exceeded then the other kicks in. This DC to DC converter, where would this device be installed in the scheme of the electrical system? I'm thinking maybe in the battery compartment between the charge source and batteries themselves.
Hotshot
Joined: Oct 2015
Posts: 19,698
Likes: 12,824
From: Wyoming
Jim,
Good info and much thanks. Yes our current charge controller is for solar. Our 2018 F350 has dual alternators from what I've read one is used primarily until the draw is exceeded then the other kicks in. This DC to DC converter, where would this device be installed in the scheme of the electrical system? I'm thinking maybe in the battery compartment between the charge source and batteries themselves.
Good info and much thanks. Yes our current charge controller is for solar. Our 2018 F350 has dual alternators from what I've read one is used primarily until the draw is exceeded then the other kicks in. This DC to DC converter, where would this device be installed in the scheme of the electrical system? I'm thinking maybe in the battery compartment between the charge source and batteries themselves.
The DC-DC converter would usually be installed as close to the target batteries as possible. The bigger the cable used, the lower the voltage drop.
Tuned
Joined: Nov 2018
Posts: 398
Likes: 110
From: Southwest Montana & Idaho
I think I'll add the DC to DC converter to the list when we switch to lithium before the end of the month. Plan is to run a single lithium for now and add another if needed. Now I'll have to figure out the model of converter and size. And I thought this was a simple 'plug and play' swap....ugh!
Hotshot
Joined: Oct 2015
Posts: 19,698
Likes: 12,824
From: Wyoming
I think I'll add the DC to DC converter to the list when we switch to lithium before the end of the month. Plan is to run a single lithium for now and add another if needed. Now I'll have to figure out the model of converter and size. And I thought this was a simple 'plug and play' swap....ugh!
LiFePO4 is more complicated than I expected when I started on my project. I blew right through my budget, but a good $400 of that was just tools. I learned a crapload about solar and electronics. I made plenty of mistakes too. Fortunately, the helpful folks over at DIYSolarForum.com looked over my plans and made corrections where needed. Even with the corrected plan I still bought the wrong circuit breakers. AC rated instead of DC rated.
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Hotshot
Joined: Jan 2010
Posts: 10,060
Likes: 491
From: Bristol, TN.
Can't tell when following if it is clear the built-in power converter that charges the batteries when hooked to shore power also needs to be changed unless one of the new switchable models.
Steve
Steve