Our Lithium Battery and Cold Weather

[TimtheToolMan]

It was surprising to me how much time and effort it took to build heating/insulating system for two batteries. I did a solid job in some areas and cut corners in others because they will not be used much.

Some solar controllers (Zamp for one) will not wake up with battery built in heaters because batteries go in a low voltage mode that is too low for controller to recognize. For this reason, I did not buy built in heaters because I would have to then change solar controller. If I had to do again, I would consider buying batteries with heaters and upgrading solar controller. With the battery brand that I purchased I could either get BT or heaters, so that complicated things.

I camp and travel in the winter so it would have been messy to try to do without heaters. I do not heat camper when pulling it, including when pulling in single digits. Most people can do fine without them.

 

[Steven@147]

Maybe wire the heating pads to the pos and ground on the trailer plug junction box that way if the batteries every get really cold and turn off you can plug into the truck to use the heaters. You could also put in a inline switch

@ TimtheToolMan Yeah, I don't think we will use a battery warmer much that is why I wanted to keep my solution simple / cheap. But we could get caught in a big cold snow event ! Case in point a few years ago on the gulf coast - caught during the winter storm in the great Texas freeze out ! Oh boy we hope never to get caught towing in single temps !

OEM Lithium battery external warmers from the OEMs (ie battleborn) are really expensive up way over $150.
Yeah I've got maybe $50 in it so far but I'm adding a few things for future expansion/options. Maybe add a second Lithium battery !

@robmcqueen
There is a 12VDC power and ground circuit from the truck to the RV through pin 1 and pin 4 of the seven way plug, also ground is supplied by the 5th wheel hitch pin. When we are towing the battery is being charged by the truck through the OEM buss bar in the front storage compartment. So when I install my new buss bar and connect it to the OEM buss bar at the "OEM Batt Feed", the battery warmer I'm devising should work if we are towing in cold weather to keep the battery warm.

Thanks for reminding me about that. We hope not to be towing in 20 * weather !

Yeah one reason I hadn't included a switch for the battery warmer is because I didn't really like the switches I was seeing. but I found one I really like, yup its more expensive at $10 and an overkill for this simple and low power circuit, than say a $2 simple toggle switch but I really like it.
It's a DPST and if I add a second Lithium battery I can connect another battery warmer to the same switch,

 

[TimtheToolMan]

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@Steven@147 I was driving and dry camping in Big Bend for two weeks during that long single digit big freeze in Texas, that you mentioned. Now with LFP, I need and have heaters, even if they are only used a small percentage of time. I do not use a generator (not allowed where we camp) so being able to solar charge while driving and camping is a must.

 

[Steven@147]

Got my battery rewiring partially done and I changed my plan substantially. Added a second battery, same type, a few months apart on manufacturer. Prices going up in 2025?
Added main disconnect switches, better/bigger bus bars, heaverier wire etc. Added heating pads to the battery boxes for each battery and ran them through a switch. Each pull 0.5 amp.

The buss bars are rated for up to 250 amp, and have main cable connections as well as smaller secondary connections. The disconnect switches are rated up to 300 amp and I added 125 amp MRBFuses to the positive post of each battery. Some overkill on the rating of the individual components but I won't have to worry about overloading anything. I haven't got it all done to my satisfaction yet. Since a winter storm is coming Monday I just wanted to get things connected, still have a couple things I have to connect yet.

I am racing a strong winter storm coming to the gulf coast monday, snow 1-3, wind, ice forecasted for Galveston, temps down in the 20s. Got to get to the grocery yet and stock up and get the laundry done. Hope it's not a repeat of the great Texas freeze out of a few years ago ! South Texas Gulf Coast can not handle snow, ice and really cold temps ! Get ready----- here it comes!

Got to get the genny out of the truck and test run it and stage it for quick connection. I think adding the second LifePo4 will come in handy! I have no confidence in Texas keeping their electric grid up through this storm ! Got to check propane stock as well.

 

[ajg617]

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@Steven@147 I was driving and dry camping in Big Bend for two weeks during that long single digit big freeze in Texas, that you mentioned. Now with LFP, I need and have heaters, even if they are only used a small percentage of time. I do not use a generator (not allowed where we camp) so being able to solar charge while driving and camping is a must.

I think heaters are a must for cold weather but they have a down-side - they consume battery capacity. I just got my 310 back from Elkhart today and it's been in the teens there and heading down to 0 or below Tuesday here. Prior two winters, worked flawlessly as long as there was sufficient battery capacity left to keep the heaters going. However, as a caution to anyone who drops their rig off for repair in cold weather, my rig sat outside at Elkhart where the batteries were drained to 0% (not good) and left for six days (really bad) while waiting for parts from Dexter and Lippert. My solar couldn't keep up - given the orientation of their parking lot, not much sun. Trying to get the batteries charged back up to see if they were internally compromised and I'm now trying to figure out if the heating pads/sensors have a minimum voltage at which the sensor will no longer turn the pad on. Good luck in TX!!!!

 

[Steven@147]

I think heaters are a must for cold weather but they have a down-side - they consume battery capacity. I just got my 310 back from Elkhart today and it's been in the teens there and heading down to 0 or below Tuesday here. Prior two winters, worked flawlessly as long as there was sufficient battery capacity left to keep the heaters going. However, as a caution to anyone who drops their rig off for repair in cold weather, my rig sat outside at Elkhart where the batteries were drained to 0% (not good) and left for six days (really bad) while waiting for parts from Dexter and Lippert. My solar couldn't keep up - given the orientation of their parking lot, not much sun. Trying to get the batteries charged back up to see if they were internally compromised and I'm now trying to figure out if the heating pads/sensors have a minimum voltage at which the sensor will no longer turn the pad on. Good luck in TX!!!!

John, if you can get your rig hooked up to grid power wouldn't the battery heating pads run off the 12V the converter is putting out?
That's the way I got mine connected.

Our heating pads take 0.5 amps each and they will keep the batteries warm while we are towing in really cold weather. At 1 amp total a slight draw on the batteries. Then soon as we stop overnight they can get charged back up.

 

[Steven@147]

We're ready for the Gulf Coast storm on Monday, ready as can be. Finished the wiring on the batteries. Tanks dumped, fresh water full, laundry done, groceries bought, genny tested and staged with a full tank, propane full two 30s and a 20, heated water hose connected, sewer hose drained. All hatches battened down for whatever comes our way !

 

[ajg617]

John, if you can get your rig hooked up to grid power wouldn't the battery heating pads run off the 12V the converter is putting out?
That's the way I got mine connected.

Our heating pads take 0.5 amps each and they will keep the batteries warm while we are towing in really cold weather. At 1 amp total a slight draw on the batteries. Then soon as we stop overnight they can get charged back up.

Steven, I don't quite know what happened but I am plugged into my 120V garage outlet - first thing I did once Andy disconnected. Solar was putting out 10Amps and charge controller 35, but the battery voltage was not going up. I know the batteries were below 32 but the heat pads should have been warm and they weren't even though everything is connected to bussbars. Temps got up to 35 in the afternoon and batteries are now at 14.4V so I think we're ok but I'll check the pads tomorrow. One pad was noticeably warm, the other not. Our pads draw 2.5Amps each when heating.

The only thing I can think of is that the batteries were just so cold that it took the pads a long time to warm up but what concerned me initially was that there was 6 days of BMV history that showed the batteries drop to 0 Volts and stay there until the rig was picked up. Andy found the circuit breakers I installed for the pads and the solar panel shut off when he picked it up and not enough power to move the landing legs.

 

[Butcher]

I would agree about heaters sucking juice, but since the heaters are mostly needed for charging, then you would only use the heaters when......charging. If you are charging, I can only assume you are too concerned about that small current that the heaters would use. Yes, it could be the straw that ruins everything.

LifePo4 batteries can discharge at a much colder temperature [-20C] and if you want to camp at that temperature, have at it.

 

[ajg617]

I would agree about heaters sucking juice, but since the heaters are mostly needed for charging, then you would only use the heaters when......charging. If you are charging, I can only assume you are too concerned about that small current that the heaters would use. Yes, it could be the straw that ruins everything.

LifePo4 batteries can discharge at a much colder temperature [-20C] and if you want to camp at that temperature, have at it.

Not full-timer here. The danger is if you have no other means of keeping the batteries charged, taking LFPs down to 0% is not a good thing - which is what happened to mine while rig was parked outside at factory for repairs. Even with solar, they still dropped to 0% SOC combined with parasitic draw - cold enough to discharge but too cold to accept a charge once batteries were depleted. I purchased heaters in order to keep my batteries in during the winter but extended repair time took its toll with not enough sun for solar to keep them from completely discharging over time.

 

[Steven@147]

Man am I glad I got my 2nd battery installed, wiring done and battery warmers installed ! Right now in Galveston temp 30* real feel 5*, wind gusts 50mph. RV rocking pretty good!
2 inches of snow so far and still blowing snow on top of 1/4 ice. Nose and partial sides of the RV covered in ice. Outside door latch ice covered and frozen. Temp going down more snow coming!

Power grid going on and off, intermittent. Progressive Indust HW Power Monitor shutting off grid power, line voltage too low 104 VAC. Gotta say our old Solitude is withstanding it real well.

A Real nasty day ahead! Pretty much has shut down Houston and Galveston.

 

[Steven@147]

Those RV tank heating pads I used on our Lithium batteries are sure working out well. Only $34 for two of them non thermostat controlled. The size they fit nicely right down the long length side of the battery without having to wrap it around the battery end. Also the blanket material I used to wrap the batteries with, $27.

Amazon.com

https://www.amazon.com/dp/B0DNYVF84W?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

Ambient temp 34* - Batt 1 - 39* Batt 2 - 41* Warmers turned on
Ambient temp 34* - Batt 1 - 45* Batt 2 - 44* After 15 minutes
Ambient temp 35* - Batt 1 - 48* Batt 2 - 45* After 30 minutes

Like I posted they only pull 0.5 amp each. Sometimes the battery BMS shows the 1 amp total draw and sometimes it doesn't/

 

[ajg617]

@Steven@147 Don't know what brand lithium batteries you have. I'm beginning to think it is difficult to get an accurate external temperature reading on Battleborns due maybe to their cylindrical cells. For example, we were 3F last night So today I went out and measured temps. First I ran the batteries down to 12.99V and unplugged the AC. Here's what I found:

Ambient air temp 13.5°F. Ambient temp of filon external 14.8°. Ambient temp of floor inside front compartment was 15.7°.

With AC Disconnected,
Battery 1 - 23.6° on top of battery and -0.54Amps to the heat pad from my CB
Battery 1 Pad ranged from 42°-52° depending on whether gun was pointed directly at a heat wire
Battery 2 - 20.3° on top of the battery and -0.63Amps to the heat pad from my CB
Battery 2 Pad ranged from 40°-48° depending on whether gun was pointed directly at a heat wire

Total pull from the CB to the bussbar -1.63Amps (.54+.63≠1.63)

With AC re-connected, BMV immediately showed +24Amps and single battery cable from positive buss bar to Battery 1 showed +5.87Amps

Battery 1 from CB to heat pad -0.36Amps
Battery 2 from CB to heat pad - 0.23Amps

Wonder where the other DC Amps are going if Batteries are only taking 5.87?

Either way, the batteries are accepting a charge at temps in the low teens.

 

[ajg617]

@Steven@147 Hope you folks are OK - just saw some pictures. Some stats are amazing. Let us know how your new setup fared.

For January snowfall so far, Lafayette, Pensacola, New Orleans & Mobile are beating Salt Lake City, New York City, Sioux Falls, Des Moines, Boise, Flagstaff, Albuquerque, and Reno, as well as Anchorage, Fairbanks, Colorado Springs, Chicago, and Fargo.

 

[Steven@147]

@ajg617
Good morning John, We did pretty well with the cold, sleet, ice and snow. The Old Girl Solitude did great! "Affectionately called Old Girl Solitude"
Had to use a hammer to break the ice off the steps. Ice scraper was in the truck and the doors were froze and iced shut.
Yesterday was sunny and the temp got up to @40 so it's melting off pretty quick.

The power grid did the yo-yo thing for awhile and our progressive industries HW power system kept kicking the RV power off, line voltage too low at 104VAC. Thats hard on the PI power box kicking on and off like that, and the refrigerator, microwave and such kicking on and off with the grid power. Unplugged AC appliances for awhile until the power stabilized. But for the most part the Texas power grid stayed up, at least in Galveston. About the lowest the temp got down to was 28 but with 50 mph winds in the single digits, the cold would cut right through you.

Our lithium batteries are Mehrpow brand, they worked great. Not the best, but not the worst.
The controller in them is a bluetooth JBD Smart BMS. Tami and I both downloaded the XIAOXIANGE battery app on our Iphones. We can both monitor the batteries but it gets a little quirky if we try to use the app and access the batteries at the same time. The warmers worked great, I just turned on the control switch and left them on, they kept the battery temps in the mid 40 to upper 40s.

One thing I noticed, when I disconnect the batteries from the RV converter and distribution panel by using the factory Red Key battery disconnect switch, - battery warmers on - the BMS does show a 1 amp total draw - 0.5 amp for each battery warmer pad. When batteries connected back up to the converter/distribution panel, the 1 amp draw disappears and the BMS shows 0.00 amps in or out of the batteries. I know the 1 amp total draw is still there but I can't see it.

I assigned names to the batteries in the app, ASCBATT 1 and ASCBATT 2 to keep the sorted out.