Keeping lithium batteries warm in passthrough

[rarebear.nm]

For owners of ORV travel trailers.


I may have to place four Battleborn batteries in the forward pass through compartment of a 19MKS. I may not have enough space under the dinette seats in a 19MKS trailer to place the batteries plus other equipment. The inverter is already planned for the pass through.



We do cold weather camping, near 0F off grid and must be able to keep the batteries charged at these temperatures. We do not yet have this trailer, just doing my planning. I already have BB100AH, heated batteries I can use and do not want to buy new batteries. I do know Victron batteries will fit under the seats, but the batteries plus BMS and buss components adds lots to the price tag.


My question is for folks who have a similar setup and provide additional heat beyond what the battery heaters can provide. How have you solved this design issue?


In another RV with a under floor battery box I did it by adding 3" dense foam insulation and silicone heat pads with thermostatic control Just wonder if someone has come up a better solution.


The trailer will have 800 watts of solar as planned right now. Plus external generator.

[d23haynes57]

How are you planning to heat the trailer? Furnace? Can you duct some of the furnace heat to the battery compartment? If relying on the battery heaters you need to know how much power those heaters need and time for recovery. Since you plan on a generator have electric compartment heat to help the batteries get up to temp once cold. This may be a time where AGM is a better fit.

[rarebear.nm]

Yes the trailer will be heated with the propane furnace. I have considered porting some of that heat in to the pass through or perhaps only an insulated battery compartment in the pass through. It would be hard to really regulate how much heat got pumped through.



A couple of wisper quiet push/pull fans with a thermostat might to it as long the furnace is running. Might not work so well while driving. Could be a hybirid solution.

[d23haynes57]

Duct heat into the compartment and have a return path back to the trailer interior.
Insulate compartment, if possible, to reduce that heat loss. How are the water compartments heated? Follow that design path

[SafariBen]

I haven't done it in and RV, but helped do it in unheated installs. 2" foam is plenty if it's sealed, a 2" duct on each end with a fan would work, 3" would work better, no need for furnace heat if the inside is warm, just circulating the warm air will be enough. 40-60F is fine for Li.

[TimtheToolGy]

I have a 21RBS Anniversary and have been surprised how warm areas stay when main part of camper is heated, and even with a space heater and not running furnace. The coldest spot I could find was the inside of the outdoor shower box area, no surprise, but it was far from freezing when outdoor temperatures were in the teens. I hope I am remembering this figure correctly.

In a few weeks I'll be in cold very/cold conditions when traveling from Denver area to southern part of Texas and plan to measure temperatures in the storage area, which I never monitored before. I believe the front cap is insulated so the storage area may stay well above freezing.

Like OP, I recently built two insulated (about R10-R15) boxes (starting with boxes that batteries were shipped in) with disc temperature switches (safety shut off if Inkbird gets stuck closed, i.e. two methods to regulate), one Inkbird temperature controller (optionally could have been a second disc in each heated box) and silicone heating pads (4 25W rating each, in series to avoid excess surface temperature, w total watts 25W/4=6.25W. Two heaters were used in each box. V=I*R.This is not intuitive and will sound incorrect to most). System was tested in 5F freezer and kept batteries just above freezing. Surface temperatures between heating pads and battery was measured at about 125F while insulated battery was in freezer. Heaters are sandwiched between insulation and battery.

I plan to not heat camper while traveling so I think I may need heaters then and will be starting with warm batteries. If camper was heated when charging is needed the batteries maybe warm enough in storage area wo heaters/insulation.

It is surprisingly time consuming to plan, build and test heating and insulating system. I feel the insulation should be easily removed when battery area is quite warm in the summer (or possibly southern Texas in the winter) to avoid excess battery temperatures because batteries generate heat.

I hope this makes a little sense...

[Stormpeakco]

https://m.youtube.com/watch?v=DuwuA8xHofQ

~8min mark, 'game changers' in the pass through.



Perhaps send a message to the RV Geeks (home base MI?)

[rarebear.nm]

Originally Posted by Stormpeakco

~8min mark, 'game changers' in the pass through.



Perhaps send a message to the RV Geeks (home base MI?)

If I were starting from ground zero, I would conside the GameChanger. But since I already have a good set Battleborn 100AH batteries, I'm not interested in springing for more batteries. I have a plan for the BB100AH to mount in the passthrough, but I was hoping to keep them totally inside fully headed space. The BB heated batteries are good below freeing, but not for as cold as we'll be camping. Thus the need for supplemental heat.

[Stormpeakco]

Originally Posted by rarebear.nm

If I were starting from ground zero, I would conside the GameChanger. But since I already have a good set Battleborn 100AH batteries, I'm not interested in springing for more batteries. I have a plan for the BB100AH to mount in the passthrough, but I was hoping to keep them totally inside fully headed space. The BB heated batteries are good below freeing, but not for as cold as we'll be camping. Thus the need for supplemental heat.

Didn't mean for you to consider buying new batteries (you made that clear) suggested only to seek advice if theRVGeeks found the need to add a battery pad or something else?

[Nwtravler]

If I was starting from scratch or wanted to minimize space and cost and maximize my system I'd get the Epoch 460 with heating.

[Stormpeakco]

Originally Posted by Nwtravler

If I was starting from scratch or wanted to minimize space and cost and maximize my system I'd get the Epoch 460 with heating.

++++
agree....lot to like about their systems (reviews) and especially the reduced significant $ outlay for the more DIY leaning folks.

[4everlooking]

One thing to keep in mind with the larger batteries is their weight IF you have the need to remove them regularly (winterizing in the midwest comes to mind personally). As I age, I don't believe that an 80# =/- battery would be easy for me to remove, store in house for a few months, then replace. I'm looking at the Victron 330 AH batteries, around 60# each. Bought as much as I want to tackle. In a few years, those might require my grandson's help. Maybe I will get the biggest battery & have another reason to see the grands.

Larry

[d23haynes57]

All considerations should be made to avoid needing heated batteries. They only heat when an adequate charge source is present and once cold, heating is not immediate accomplishment. You are heating mass. How much heat and how long will it take to get 70 pounds of battery raised 10, 20, 30 degrees. Think of all the electric car stories from last winter when folks couldn't get their batteries charged. Somehow if you need to run a genny for 2 to4 hours to heat the batteries before you can charge them then AGM may be the better choice.

[inthepines]

they sell adhesive heating pads that you can stick to the battery.
That will be all you really need. Buy one test it on a battery and see if you are comfortable with that. Cheaper and easier than running new ducts. They are used on car batteries, oil pans and anything else mechanical that needs to be kept warm. I use one on the hydraulic tank of my log splitter when it gets really cold out.

You really only need them warmed up to charge, they can discharge with no issues to -4
biggest issue I see is the pads are usually 120v but I believe still workable.