Switching to Lithium ...

[Blaise]

Looking to upgrade the single 60 AH AGM battery in our 2023 GD Reflection 311 BHS to 2 Lithium 100 AH batteries.

The trailer has 370 watts worth of solar panels and an MPPT solar converter that has a "Lithium" setting. The trailer converter is a PD-9260, which I believe is only for lead-acid batteries. Progressive says that their converter for Lithium batteries that replaces the PD9260 is the PD-9160ALV. But I have ONLY found them "used" on Amazon for $240, and on eBay where they claim to be "new" units for $200-$275, but I'm not sure I believe they're new, and I'm reluctant to buy a converter from an "unofficial" distributor - is the warranty intact? etc.

The RV control panel has a shunted Furrion battery monitor.

The existing AGM battery is in a sealed battery box that is sunk into the floor of the forward compartment under the nose. The box has a hose connected running to a vent on the wall.

Lithium batteries are sealed, so they shouldn't off-gas, right? I mean, do they require this sealed box and vent hose setup? Hoping not! If not, I'm thinking I can get rid of the existing battery box, patch the hole in the floor with sheet metal, and get a double battery box to house the 2 lithium batteries. If such a setup is appropriate, I would sit the battery box on a bit of foam padding on the floor against the back wall of the compartment, and screw the box to the floor and the wall.

Does all that - or any of it - seem reasonable and correct? Am I missing anything? I'm a little bit out of my element.

Thanks for any guidance you can offer.

 

[John From Detroit]

You want Li batteries in a flameproof box if you can do it (those are not that hard to find) The odds of them catching fire are low but not zero.... And that's one Major upgrade power wise like 20 times the usable amp hours... Good job.

 

[tlmgcamp]

I am putting my Li conversion together myself. In addition to your list, I am putting a switch between the panels and the controller. I understand that LI like to be stored at 50% charge so I want to be able to keep the panels from topping off the battery while it sits between trips

 

[xrated]

You want Li batteries in a flameproof box if you can do it (those are not that hard to find) The odds of them catching fire are low but not zero.... And that's one Major upgrade power wise like 20 times the usable amp hours... Good job.

The OP did say "Lithium", but I'm guessing that he is talking about LiFePO or LFP batteries and they are no more "at risk" for fire than a normal FLA battery. I don't know of anyone that puts a LFP battery in a flameproof box. There's a huge difference in the chemistry between a Lithium-Ion and a Lithium Iron Phosphate battery. In fact, there are many articles out there that suggest that LFP batteries are even safer than the traditional FLA batteries....and we don't normally enclose them in a fireproof box, just a box to be able for them to off gas/vent out of the RV compartment where they are stored if needed.

 

[Blaise]

You want Li batteries in a flameproof box if you can do it (those are not that hard to find) The odds of them catching fire are low but not zero.... And that's one Major upgrade power wise like 20 times the usable amp hours... Good job.

Thanks for the feedback. I should have been more specific, sorry. I'll be getting LiFePO4 batteries. As I understand it, these are as safe as FLA, unlike Lithium ion batteries, which are the ones that are notorious for catching fire and/or exploding!

 

[Blaise]

I am putting my Li conversion together myself. In addition to your list, I am putting a switch between the panels and the controller. I understand that LI like to be stored at 50% charge so I want to be able to keep the panels from topping off the battery while it sits between trips

Thanks for your comment. I'll read up on the 50% storage level you mentioned. I wasn't aware of that. As it happens, I already installed a switch like you describe, but for a different reason ...

My truck ('24 Silverado 3500) had a problem with the brake controller. If the trailer battery was at a higher voltage than the truck, current would feedback into the truck and this played hell with the trailer brake controller - it would just disconnect! Yeah, I was towing down the highway at 65 mph and the truck gave messages like "check trailer wiring", "trailer brake disconnected", and "Service brake controller"!

This happened because the solar panels charged the trailer battery to a higher voltage than the truck. So I installed a 50 amp switch between the solar charger controller and the battery. I later learned that it would be better to have the switch as you describe, between the panels and the solar charger controller (switch on the controllers input instead of its output), so I'll be changing that soon.

Thanks!

Chevy issued a TSB (#23-NA-149) and produced an updated trailer brake controller board, which I had installed last week, and it now works properly. They probably just stuck a diode on the power line from the truck to the trailer to prevent current back flow.

 

[Blaise]

The OP did say "Lithium", but I'm guessing that he is talking about LiFePO or LFP batteries and they are no more "at risk" for fire than a normal FLA battery ...... and we don't normally enclose them in a fireproof box, just a box to be able for them to off gas/vent out of the RV compartment where they are stored if needed.

Do LiFePO batteries need the box to be "sealed" and have an off-gassing hose vented to the outside? I was hoping to not have to install that on the double battery box I have an eye on.

 

[Isaac-1]

I switched to LiFePo4 batteries in 2022, and have been using a standard PD9260 converter with no problems, its voltage profile is nearly perfect for charging and maintaining LiFePo4, with the understanding that it will only output 60 amps at 14.4VDC for the first 4 hours of a charge cycle, before dropping into 13.8VDC float mode for the next 48 hours, then dropping to 13.2VDC storage mode. 60 amps for 4 hours is 240AH worth of full rate charging before dropping to the 13.8VDC slower charging float mode. This means that so long that you have less than about 240AH worth of batteries even if they are nearly fully depleted, it will stay in 14.4VDC charging mode long enough to fully charge them.

I also have the optional Charge Wizard pendant ($15) that allows me to manually change charging modes if I need to bump it back into 14.4VDC mode after it has been sitting in storage for some time, this lets me have the best of both worlds, it lets me extend the life of my LiFePo4 by floating them at partial charge while in storage, and it lets me manually bump them back up to full charge a couple of days before leaving on a trip.

p.s. 13.8VDC float mode will eventually get an LiFePo4 battery to over 99% SOC, and if you have solar they can provide that final 1%

 

[Tom_M]

I upgraded to LiFePO4 5 years ago. I upgraded my solar charge controller to one with a LiFePO4 profile. I did not upgrade my converter. It will not fully charge my batteries which is not a problem for LiFePO4. I am seldom plugged into shore power or run my generator relying mainly on solar. LiFePO4 does not need venting or a sealed container.

 

[Gary RV_Wizard]

First of all, your PD 9260 is safe to use with LiFePO4 batteries. It simply won't bring them to 100% charge (see Tom_M reply).
Second, LiFePO4 batteries only emit harmful gases if they fail catastrophically, in which case you have to worry about heat more than gases. [For what it's worth, AGM lead-acid batteries are pretty much the same in that regard. Your present battery box is apparently designed to handle flooded cells as well as AGM and thus includes a vent.]
Third, the recommendation for storing LiFePO4 is a state of charge of 50% or higher. This article should be helpful on storage.

So the bottom line is your new batteries don't require any kind of box (flameproof or vented) and your charger choice is a matter of charge optimization rather than safe usage.

 

[Lou Schneider]

Thanks for your comment. I'll read up on the 50% storage level you mentioned. I wasn't aware of that. As it happens, I already installed a switch like you describe, but for a different reason ...

My truck ('24 Silverado 3500) had a problem with the brake controller. If the trailer battery was at a higher voltage than the truck, current would feedback into the truck and this played hell with the trailer brake controller - it would just disconnect! Yeah, I was towing down the highway at 65 mph and the truck gave messages like "check trailer wiring", "trailer brake disconnected", and "Service brake controller"!

This happened because the solar panels charged the trailer battery to a higher voltage than the truck. So I installed a 50 amp switch between the solar charger controller and the battery. I later learned that it would be better to have the switch as you describe, between the panels and the solar charger controller (switch on the controllers input instead of its output), so I'll be changing that soon.

Thanks!

Chevy issued a TSB (#23-NA-149) and produced an updated trailer brake controller board, which I had installed last week, and it now works properly. They probably just stuck a diode on the power line from the truck to the trailer to prevent current back flow.

The trailer brakes and vehicle lights should be completely independent of the rest of the trailer's 12 volt circuits, including the trailer's batteries. The only thing the trailer battery used for is to supply voltage via the breakaway switch to apply the brakes if the trailer separates from the tow vehicle and the switch is open circuit when it's not activated.

The only thing I can think of is both circuits (trailer brake and trailer battery) use a common ground return. Perhaps the old Chevy control board used a GFI-like circuit to keep track of the brake's hot and return circuits and got confused and gave the error message when current returning via the neutral wasn't what they expected, battery charging current + trailer brake current, not brake current alone. This would be a problem no matter if you had conventional lead acid or LiFePo4 batteries in the trailer.

 

[xrated]

Do LiFePO batteries need the box to be "sealed" and have an off-gassing hose vented to the outside? I was hoping to not have to install that on the double battery box I have an eye on.

No, sealing and off gassing hose/vent NOT required. In fact, many folks relocate them to inside the trailer in a cubby hole or under a cabinet if there is space available. That helps keep them in a temperature controlled environment while using them. LFP batteries should not, as a general rule, be charging when the temperature gets down to 32°F or below. Most, but not all of them will have a temperature cutoff built into the BMS system to prevent that from happening, but remember, not every LFP battery has that. When I built my 302AH battery from scratch, I also build a heated/insulated box to put it in because I had no room inside to put them, and they are stored in the front compartment by the hydraulic system and and the onboard generator.....which is NOT temperature controlled.

 

[Blaise]

The trailer brakes and vehicle lights should be completely independent of the rest of the trailer's 12 volt circuits, including the trailer's batteries. The only thing the trailer battery used for is to supply voltage via the breakaway switch to apply the brakes if the trailer separates from the tow vehicle and the switch is open circuit when it's not activated.

The only thing I can think of is both circuits (trailer brake and trailer battery) use a common ground return. Perhaps the old Chevy control board used a GFI-like circuit to keep track of the brake's hot and return circuits and got confused and gave the error message when current returning via the neutral wasn't what they expected, battery charging current + trailer brake current, not brake current alone. This would be a problem no matter if you had conventional lead acid or LiFePo4 batteries in the trailer.

@Lou Schneider Hi Lou, Thanks for your post. Isn't the 12v from the truck also used to charge the trailer battery? If so, doesn't that make a direct connection between them? The problem only occurs when the trailer battery is charged to a higher voltage than the truck. I've seen where after I disconnected the solar panels, the problem still occurred - until the voltage level of the trailer battery dropped below the truck voltage, then the trailer brake worked fine.

Anyway, you are right that the problem occurs with any type of trailer battery - I saw the issue with an AGM.

 

[Blaise]

No, sealing and off gassing hose/vent NOT required. In fact, many folks relocate them to inside the trailer in a cubby hole or under a cabinet if there is space available. That helps keep them in a temperature controlled environment while using them. LFP batteries should not, as a general rule, be charging when the temperature gets down to 32°F or below. Most, but not all of them will have a temperature cutoff built into the BMS system to prevent that from happening, but remember, not every LFP battery has that. When I built my 302AH battery from scratch, I also build a heated/insulated box to put it in because I had no room inside to put them, and they are stored in the front compartment by the hydraulic system and and the onboard generator.....which is NOT temperature controlled.

@xrated Thanks! So glad I don't have to deal with the vent hose! I thought that was the deal ... in fact, I probably could have done without that setup because my battery was an AGM!

 

[Blaise]

I switched to LiFePo4 batteries in 2022, and have been using a standard PD9260 converter with no problems, its voltage profile is nearly perfect for charging and maintaining LiFePo4, with the understanding that it will only output 60 amps at 14.4VDC for the first 4 hours of a charge cycle, before dropping into 13.8VDC float mode for the next 48 hours, then dropping to 13.2VDC storage mode. 60 amps for 4 hours is 240AH worth of full rate charging before dropping to the 13.8VDC slower charging float mode. This means that so long that you have less than about 240AH worth of batteries even if they are nearly fully depleted, it will stay in 14.4VDC charging mode long enough to fully charge them.

I also have the optional Charge Wizard pendant ($15) that allows me to manually change charging modes if I need to bump it back into 14.4VDC mode after it has been sitting in storage for some time, this lets me have the best of both worlds, it lets me extend the life of my LiFePo4 by floating them at partial charge while in storage, and it lets me manually bump them back up to full charge a couple of days before leaving on a trip.

p.s. 13.8VDC float mode will eventually get an LiFePo4 battery to over 99% SOC, and if you have solar they can provide that final 1%

@Isaac-1 Thanks for the details - I didn't really know how the battery charger worked. I appreciate the info. I feel much more comfortable keeping my PD9210 and saving a couple hundred dollars!

 

[Blaise]

First of all, your PD 9260 is safe to use with LiFePO4 batteries. It simply won't bring them to 100% charge (see Tom_M reply).
Second, LiFePO4 batteries only emit harmful gases if they fail catastrophically, in which case you have to worry about heat more than gases. [For what it's worth, AGM lead-acid batteries are pretty much the same in that regard. Your present battery box is apparently designed to handle flooded cells as well as AGM and thus includes a vent.]
Third, the recommendation for storing LiFePO4 is a state of charge of 50% or higher. This article should be helpful on storage.

So the bottom line is your new batteries don't require any kind of box (flameproof or vented) and your charger choice is a matter of charge optimization rather than safe usage.

Thanks Gary, I really appreciate your feedback. In fact, I'd like to make a special shout-out to you because I think you have responded to every question I've ever asked on this forum! And you always provide useful info and or links.

Thank you!

 

[Blaise]

I upgraded to LiFePO4 5 years ago. I upgraded my solar charge controller to one with a LiFePO4 profile. I did not upgrade my converter. It will not fully charge my batteries which is not a problem for LiFePO4. I am seldom plugged into shore power or run my generator relying mainly on solar. LiFePO4 does not need venting or a sealed container.

@Tom_M Thanks for your post. You've increased my confidence in my decision to keep my PD9260 converter and not spring for a new one! Thanks!

 

[Lou Schneider]

@Lou Schneider Hi Lou, Thanks for your post. Isn't the 12v from the truck also used to charge the trailer battery? If so, doesn't that make a direct connection between them? The problem only occurs when the trailer battery is charged to a higher voltage than the truck. I've seen where after I disconnected the solar panels, the problem still occurred - until the voltage level of the trailer battery dropped below the truck voltage, then the trailer brake worked fine.

Anyway, you are right that the problem occurs with any type of trailer battery - I saw the issue with an AGM.

Yes, but like I said there shouldn't be any connection between the trailer brake line and the trailer battery - all the power to operate the brakes comes from the truck except when the breakaway switch is activated. The only thing in common is the return (negative) line which must be what is confusing the controller.