Heating the LFP compartment

[PbdBlue]

I saw this post over in the Shading thread and thought I'd start a new discussion rather than take that one off track.

Originally Posted by Reed Cundiff

We use the 70% Aluminet. We bought a 30’ x 12’ section which covers one side of fifth wheel. We place a 12’ section of PVC Pipe between the two slides on left side of fifth wheel to support Aluminet. Cut the 12’ section in half so it would fit in main bay (section of wood rod fis used to join them). The Aluminet comes with grommets every two feet so it is connected to roof with bungie cords to solar panel brackets. The bottom is connected with bungies to ground stakes.

A simple comparison of shaded siding and unshaded shows quite a few degrees difference. I am 78 so I prefer using the 12’ telescoping ladder to get tonroof than the ladder up the back side.

The question now is insulating bottom of fifth wheel and pumping cabin area into LFP battery compartment. Am purchasing a small blower that uses 3 W and moves 6 cfm. We are at 8000’ in northern NM above Las Vegas, NM

Hi Reed -

I assume your trying to raise the temperature of the LFP compartment? I recently installed LFP's (Battleborns) in the battery compartment under the stairs of the coach and I insulated the outside of the battery compartment with 1" construction foam to minimize the effect of road heat but thinking also about cold weather camping. The compartment next to the batteries houses the water tank\pump and is heated by the coach heater so my thought is to connect to it with a small fan and some kind of duct hose. What kind of fan are you planning on using?

[Itinerant1]

Here is an idea for folks that might have there heat duct ending in the front compartment. I'm sure if a person wanted they could tap into the heat run and add a small run towards the batteries. Eventually I'll add some sort of louvered vent that can be opened or closed when needed.

Also, Inside the front compartment I added 2" foam insulation on all exposed walls to help hold the heat which there is some from the inverter seen in pics. There is roughly 14"×20" piece of foam that snugly fits into a section near the propane compartment that can be removed during warmer periods of temps to allow some air circulation.
So far it has helped retaining the compartment at a warmer temp than the outside air temp, which was 25f and the compartment was 40+f and individual lfp cell temps of 43-45f.

[Reed Cundiff]

PbDBlue - I am purchasing a Zephyr 12 V blower. This is designed to blow 6 cfpm at 3W. Will work out plumbing which will be 2” PVC. The Zephyr is usually used to evacuate gases from lead acid battery arrays.
I did somewhat hijack that thread.

I have been using a 60 W safety lamp which has kept front bay above 40 F at 9 F outside. This is fine if we have sunny days to recharge batteries. Since we are at older son’s, he asked us to plug in. He is totally off grid with 10 or 15 kW of solar and about 50 kW-hrs of lead acid in basement. His home is 18” rammed earth with 2” of hard foam. The temperature inside is ideal at -20 F to 90 F.

Itinerant1 - will be utilizing thin aluminized foam sheeting to line forward bay where we have the 9.5 kW-he’s if Manzanita Micro LFP batteries. Will Velcro tape some 2” foam on outside under the batteries since there is no room to do such inside.

Glad you have started this new thread.

Reed and Elaone

[PbdBlue]

Originally Posted by Reed Cundiff

PbDBlue - I am purchasing a Zephyr 12 V blower. This is designed to blow 6 cfpm at 3W. Will work out plumbing which will be 2” PVC. The Zephyr is usually used to evacuate gases from lead acid battery arrays.
I did somewhat hijack that thread.

Reed and Elaone

Wow they are pretty proud of that fan. I was thinking a 3" bilge blower (Amazon ~$20) but they do tend to move a lot more air than probably needed and draw much more current. I suppose I could add a PWM motor controller to reduce the airflow and current. Maybe something like this:

https://www.amazon.com/Amarine-made-...s=bilge+blower

https://www.amazon.com/RioRand-Contr...+speed+control

[Reed Cundiff]

Originally Posted by PbdBlue

Wow they are pretty proud of that fan. I was thinking a 3" bilge blower (Amazon ~$20) but they do tend to move a lot more air than probably needed and draw much more current. I suppose I could add a PWM motor controller to reduce the airflow and current. Maybe something like this:

https://www.amazon.com/Amarine-made-...s=bilge+blower

https://www.amazon.com/RioRand-Contr...+speed+control

130 cfpm is a bit much for a 40 cubic foot compartment, which I plan to further compartmentalize to about 16 cubic feet. 30 W compared to 3 W can add up if not tied in and it is snowing. 12 V means the inverter is not on for another 30 W or more drain.

Son did the same for our Roadtrek. He ran an exhaust from the battery compartment (4.5 kW-hrs LFP) that turned on when battery compartment dropped below 40 F.. that really startled us when it turned on at 2 am at Balmorrhea State Park on our way to Yucatan.

Alas, Elaine requires shoulder surgery so we are not headed to Latin America for first time in 9 years.

[Itinerant1]

PbDBlue if you're going to run some sort of hose duct isn't there a place that you can tap into and just let the furnace fan push the heat while it cycles. As Reed said as small as the battery compartment is it won't need a lot. Insulating the compartment is key. Plus if using the batteries they will generate their own heat some which they can be used below freezing just not charged. Just a thought.

[PbdBlue]

Originally Posted by Itinerant1

PbDBlue if you're going to run some sort of hose duct isn't there a place that you can tap into and just let the furnace fan push the heat while it cycles. As Reed said as small as the battery compartment is it won't need a lot. Insulating the compartment is key. Plus if using the batteries they will generate their own heat some which they can be used below freezing just not charged. Just a thought.

Maybe. Not sure where the duct goes into the water tank area or how accessible that is. I realize that the air flow is much higher than needed but PWM controllers are pretty efficient so I figured I could lower the air flow and power requirement way down. I glued 1" foam around the outside of the battery compartment with Gorilla construction adhesive and sealed all the seams with silver tape. I haven't \been in any real cold weather yet but just thinking ahead. Only had the batteries for about a month but I'm sold already

[hclarkx]

I'm assuming that the "front compartment" or battery compartment that is being discussed here is like mine, with vents for lead acid batteries so that the warm air being pumped into that compartment to keep an LFP warm will flow out through that vent. If I'm wrong, read no further.



Just thinking out loud here ... pumping air from the coach forced-air heating system into a battery bay (and from there to the outdoors?) would seem to require outside air flowing into the coach somewhere. I'm wondering 1) where that would be, 2) would it create any nuisance drafts, 3) how much propane would be used to heat that outdoor air just to blow it out a vent in the battery compartment? The only leakage in my 5er that I know of is little drains under each window that feed condensate running down the window to the outside.


It just seems like there should be a better way. Insulation is a no-brainer but I have to wonder if a waste tank heater pad with a thermostat wouldn't be a better idea. Electric heat is not efficient, but I think beats pulling cool air in somewhere and heating it and blowing it out vents in the battery compartment. Being 12V the pad wouldn't run the inverter but that's fine because the pad is equally efficient at generating heat and would put the heat closer to where it's needed. A thermostat nearby in contact with the LFP case would control the pad.


Do be sure your LFP does not already have it's own internal heater ... I think some do.



My inclination is to put that pad under the LFP (on top of 2" of foam). My concern would be excessive localized heat on the lower end of the battery. I'd guess the 80# LFP (in my case) would conduct heat well enough that the area just above the pad would not get all that warm. I believe I've seen this done with lead acid but I'd think about this a bit or do an experiment (pad on the side of the LFP) before going forward.


I'm thinking this would be the most efficient approach and likely the most economical and easiest to install.



PS: We never camp where it gets below about 30F so our LFP has never seen 40F. I open the compartment door if the LFP gets over about 75F in warmer months (due mostly to heat from the inverter). My solar controllers are also in that compartment but generate very little waste heat.

[PbdBlue]

Originally Posted by hclarkx

I'm assuming that the "front compartment" or battery compartment that is being discussed here is like mine, with vents for lead acid batteries so that the warm air being pumped into that compartment to keep an LFP warm will flow out through that vent. If I'm wrong, read no further.



Just thinking out loud here ... pumping air from the coach forced-air heating system into a battery bay (and from there to the outdoors?) would seem to require outside air flowing into the coach somewhere. I'm wondering 1) where that would be, 2) would it create any nuisance drafts, 3) how much propane would be used to heat that outdoor air just to blow it out a vent in the battery compartment? The only leakage in my 5er that I know of is little drains under each window that feed condensate running down the window to the outside.


It just seems like there should be a better way. Insulation is a no-brainer but I have to wonder if a waste tank heater pad with a thermostat wouldn't be a better idea. Electric heat is not efficient, but I think beats pulling cool air in somewhere and heating it and blowing it out vents in the battery compartment. Being 12V the pad wouldn't run the inverter but that's fine because the pad is equally efficient at generating heat and would put the heat closer to where it's needed. A thermostat nearby in contact with the LFP case would control the pad.


Do be sure your LFP does not already have it's own internal heater ... I think some do.



My inclination is to put that pad under the LFP (on top of 2" of foam). My concern would be excessive localized heat on the lower end of the battery. I'd guess the 80# LFP (in my case) would conduct heat well enough that the area just above the pad would not get all that warm. I believe I've seen this done with lead acid but I'd think about this a bit or do an experiment (pad on the side of the LFP) before going forward.


I'm thinking this would be the most efficient approach and likely the most economical and easiest to install.



PS: We never camp where it gets below about 30F so our LFP has never seen 40F. I open the compartment door if the LFP gets over about 75F in warmer months (due mostly to heat from the inverter). My solar controllers are also in that compartment but generate very little waste heat.

Actually on the Fleetwoods the battery box is a pretty much a sealed sheet metal assembly. It does have about six 2" holes in it about half of which are occupied by cables. When I insulated the box I covered over all the empty holes and intend to foam the holes with cables. My main concern was insulating the road heat since the bottom of the box is exposed. So far that seems to be working. Of course with the Battleborns I have no way to read the actual battery temp however I have a wireless thermometer probe mounted in the box next to the batteries. There's already heat from the LP heater being ducted into the holding tank area by the factory tank heater setup so my thought was just pump a little of that warm air into the battery compartment. I wouldn't think it would need much. My other thought was to use a blanket heater. Something like a Kats battery wrap. They are 120 volt so I would need to run a generator for a bit but then if it's that cold I'm probably going to be charging with shore power\genset anyway? Again like you I don't routinely camp where it's really cold but here in the desert southwest it can happen during the winter time. I may be overthinking this ???

https://www.etrailer.com/Vehicle-Hea...s/KH22200.html

[Itinerant1]

As boondockers or folks that just want to get away from the crowds nothing wrong preparing for a "what if" it's easier to do near civilization than out and away when mother nature decides to give a wakeup call.

I'll admit there was once I did cover the batteries with my Carhartt jacket before insulating the compartment when a cold front blew in before we wanted to leave and head for warmer weather.

[PbdBlue]

Originally Posted by hclarkx

My inclination is to put that pad under the LFP (on top of 2" of foam). My concern would be excessive localized heat on the lower end of the battery. I'd guess the 80# LFP (in my case) would conduct heat well enough that the area just above the pad would not get all that warm. I believe I've seen this done with lead acid but I'd think about this a bit or do an experiment (pad on the side of the LFP) before going forward.

I had a thought of doing something similar but maybe glue the heat pad to the bottom of a thin sheet of aluminum (.060"?) and then setting the batteries on top of that. Still might go that route.

[Reed Cundiff]

Thread is providing further ideas which need to finalize

There is no room in battery compartment for heating pads. The LFP batteries have about.1/4” between them and propane tank assemblies. So heating pads would be placed outside and insulated.

There is some 2” hard foam lying about and need 2 pieces of 2’ x 2’.

These pads apparently draw 80 W each. This is fine for line power such as we have now and where a 60 W incandescent lamp has kept compartment in mid 40s when outside is 9F. We are insulating as others in thread have suggested. Such power loads are not viable when boondocking with overcast or snowy days.

Either blowing in cabin air (which we keep above 50 F) or furnace are viable. Choose to run at 12 V (battery suite is 48 V nominal with a 500 W Meanwell 48 to 12 V converter and avoid major parasitic draw of inverter.

[hclarkx]

Originally Posted by PbdBlue

Actually on the Fleetwoods the battery box is a pretty much a sealed sheet metal assembly. It does have about six 2" holes in it about half of which are occupied by cables. When I insulated the box I covered over all the empty holes and intend to foam the holes with cables. My main concern was insulating the road heat since the bottom of the box is exposed. So far that seems to be working. Of course with the Battleborns I have no way to read the actual battery temp however I have a wireless thermometer probe mounted in the box next to the batteries. There's already heat from the LP heater being ducted into the holding tank area by the factory tank heater setup so my thought was just pump a little of that warm air into the battery compartment. I wouldn't think it would need much. My other thought was to use a blanket heater. Something like a Kats battery wrap. They are 120 volt so I would need to run a generator for a bit but then if it's that cold I'm probably going to be charging with shore power\genset anyway? Again like you I don't routinely camp where it's really cold but here in the desert southwest it can happen during the winter time. I may be overthinking this ???

https://www.etrailer.com/Vehicle-Hea...s/KH22200.html

Yes, that does sound like a plan and hard to beat. Where does the air pumped into the waste tank area go? Outdoors or back into the living area? If you put air into the battery compartment, where will it go? Outdoors or back into the living area? There has to be an air outlet or the box will pressurize and no warm air will flow.

[PbdBlue]

Originally Posted by hclarkx

Yes, that does sound like a plan and hard to beat. Where does the air pumped into the waste tank area go? Outdoors or back into the living area? If you put air into the battery compartment, where will it go? Outdoors or back into the living area? There has to be an air outlet or the box will pressurize and no warm air will flow.

I think there’s enough leakage in the tank bay that return is not an issue there. The battery box is pretty much sealed up now but I suppose I could open one of the holes in the box and duct it back into the tank bay.