reflectix insulation

[dewdev]

Where to buy a small quantity of reflectix insulation?

What type of adhesive should I use to keep it in place on the battery door and the cellar door? 

Edited March 25 by dewdev

[Snackchaser]

7 minutes ago, dewdev said:

Where to buy a small quantity of reflectix insulation?

Amazon carries it, but theirs is sometimes low quality and thin.  I got some from an HVAC contractor/supplier for free. It is used for duct insulation and was much better quality. 

[jd1923]

32 minutes ago, dewdev said:

What type of adhesive should I use...?

I used carpet tape and just some honeycomb insulation that came as packing in something we purchased.

Edited March 25 by jd1923

[topgun2]

Both Home Depot and Lowes carry Reflextic in fairly small rolls.

For the battery door - I used foam board that I had laying around the shop.

p.s.  Foil tape can be used to secure the Reflextic  to the door and/or to virtually anywhere inside between the hulls if you want to put your excess in there.

 

Edited March 25 by topgun2
added detail

[DanielBoondock]

Checking the BMS temps the problem with my Lithionics was more of too much heat, easily getting up to the high 90’s in early March. The batteries produce heat too from the BMS board and just from charge/discharge. The battery has a built in heater so if it gets cold no problem, that’ll take care of that. On my list is to add a automated fan to a top vent, I won’t otherwise insulate it. When we got to camp I’d open up the door to get it to cool down faster as the sun went down. 

[theOrca]

I chose the "peel and stick "Reflextic."  There is as much as six layers of it under the driver side bunk and under the bathroom sink. If there was room for a 4" x 4" piece, a chunk went there. 

[FloraFauna]

For those of you that have the upper refrigerator vent to the left of the door but a refrigerator that doesn't require it, you have a big thermal hole there even with the Oliver supplied insert.  The Oliver-supplied insert is simply a thin piece of plastic with no significant thermal barrier.  I plugged mine with a piece of foam caulked in, then put the Oliver insert over it and the Oliver vent cover over that.  Otherwise, cold air pours in between the hulls. I can try to find my pictures if anyone is interested but it is a simple fix to an easily overlooked thermal opening between the hulls.

[Hokieman]

11 hours ago, DanielBoondock said:

Checking the BMS temps the problem with my Lithionics was more of too much heat, easily getting up to the high 90’s in early March. The batteries produce heat too from the BMS board and just from charge/discharge. The battery has a built in heater so if it gets cold no problem, that’ll take care of that. On my list is to add an automated fan to a top vent, I won’t otherwise insulate it. When we got to camp I’d open up the door to get it to cool down faster as the sun went down. 

 I cut two 2” holes in the battery box for venting, no fan.   I also plugged the vents in the door and insulated with two layers of Reflectix.   Used 3M heavy duty spray adhesive, it’s been holding well for 5 years.   I did the same on the Basement door.   I measure battery compartment temps with my Victron BMV712 monitor, and also a remote temp sensor that I move around in the basement depending on ambient temps.   I have not needed to open the battery door,  the small vents keep the battery box relatively cool in Summer, warm in Winter.  I have camped in 100+ temps and below 10F for several consecutive nights with no problem.   

[jd1923]

18 hours ago, DanielBoondock said:

Checking the BMS temps the problem with my Lithionics was more of too much heat, easily getting up to the high 90’s in early March. The batteries produce heat too from the BMS board and just from charge/discharge. The battery has a built in heater so if it gets cold no problem, that’ll take care of that. On my list is to add an automated fan to a top vent, I won’t otherwise insulate it. When we got to camp I’d open up the door to get it to cool down faster as the sun went down. 

Not good! We camped Monday and ran the fridge and hot water heater together (-120A) for 30 min, until the water was hot. Then turned on the A/C on all afternoon, not plugged in, all on inverter.

Temp on the Victron inverter rose to 90F, in its closed space, well within the 104F warning . I installed a basement exhaust fan, yet rarely use it.

The Epoch app had been acting up, so I manually tested voltage with a multimeter. It read 12.9V, certainly a very good number considering the -120A load of the HWH.

Battery tops and 4/0 wiring were all cold to the touch. I sealed the vents in our battery bay to keep dirt out.

IMHO, call Lithionics, fix the issue vs. venting heat away that should not accumulating!

 

Edited Wednesday at 09:42 PM by jd1923

[DanielBoondock]

On 4/29/2026 at 10:43 AM, jd1923 said:

Not good! We camped Monday and ran the fridge and hot water heater together (-120A) for 30 min, until the water was hot. Then turned on the A/C on all afternoon, not plugged in, all on inverter.

Temp on the Victron inverter rose to 90F, in its closed space, well within the 104F warning . I installed a basement exhaust fan, yet rarely use it. ..

IMHO, call Lithionics, fix the issue vs. venting heat away that should not accumulating!

 

The battery is rated to 131 which is pretty usual for lithium so that’s ok, I just don’t like it. It was a warm March with a heat wave (another 100 year event) and the battery was getting plenty of solar charging so I think it was just conditions. Back coastal it’s normal temps again. Anyhow I’ll try the temp activated fan and do a write up 

[jd1923]

1 hour ago, DanielBoondock said:

Anyhow I’ll try the temp activated fan and do a write up 

You’d be a first! I’ve have added 2 temp-activated exhaust fans, behind our absorption fridge and in the basement cavity for the inverter.

But for the battery bay, I closed up the vent holes that were designed for lead acid venting and added insulation to the door, to close the air, minimize collection of road dust. Many of us have done this (two examples shown in pictures above).

Uncertain the specs of other brands, but the Epoch Essentials batteries many of us have installed, will supply 200A continuous, in or out as designed, without overheating and 400A Max Amps capacity.

Most we used camping this week was -120A with the fridge, the Chill Cube A/C and electric HWH all running on battery/inverter.

We’re camping again this Sun-Mon again, so besides these 120V appliances, I’ll boil water in our electric kettle. Power them all on at once should hit or exceed the 200A Continuous Rating. The Victron MP2 can also exceed its 3KVA rating, found it up at 4.5K for a spell when once I turned on the power-hungry Dometic P2 A/C (thank Goodness that’s gone) not realizing the electric HWH was heating!

Good thing I have a back-up 400A ANL fuse for the Victron! I’ll test and post the app screen prints that lists 3 internal temps per our 3x 300 Ah batteries! I expect to feel a cool cabin, hot water at the tap, a pot of boiled water for coffee and battery and inverter temps within spec! We’ll see… 😎

Edited 8 hours ago by jd1923

[jd1923]

On 4/28/2026 at 7:58 PM, DanielBoondock said:

The batteries produce heat too from the BMS board and just from charge/discharge.

Hopefully only the latter. The BMS should be efficient, but movement of high amperage causes heat within its design.

On 4/28/2026 at 7:58 PM, DanielBoondock said:

When we got to camp I’d open up the door to get it to cool down

When I removed our battery tray, it gave our batteries a lot more headroom. How much clearance do you have above your batteries?

Don't leave that door open too long, or those expensive items may walk! I have ours locked down double and only open the door to remove ground when doing an electrical mod.