Extreme Cold Weather Towing - Lithium

[AlexPeterson]

Problem: how to tow a lithium battery equipped trailer in extreme cold weather.

I did a number of electrical system upgrades on our new trailer this past spring, which are documented here.

This winter, we will be leaving just after Christmas for AZ for a couple months' escape from winter. As we live in west central Minnesota, this means it is possible the temperatures could be -20 or -30F when we leave. As these sorts of temperatures are below the recommended storage temperatures for the lithium batteries we have (Renogy), let alone the low temperature discharge cut-off point, I needed a solution of some sort to get around this possibility.

Since I had a small 18 amp-hr AGM battery that was new (leftover from a different project), I decided to rig up a harness to utilize this battery until we get far enough south to swap the lithium batteries back in. We will keep the lithium batteries in the house until we leave, and then put them in the cab of the truck, if the temperatures are indeed low.

I chose to only connect the break-away, tongue jack and tire pressure monitor circuits to this small AGM battery, as well as the 7 pin charge circuit. All other circuits are not powered as they are not needed until we reach civilized temperatures and can re-install the lithium batteries.

I built a small harness which plugs into the load side of the fuse panel for those three circuits. The wires which plug in to the fuse panel are simply the male side of what are commonly called fast-on connectors. Since the normal fuses are removed, there are in-line fuses in each of the three lines.



I will put the trailer in storage in the next week or so with this battery, leaving it charged but disconnected so that there is no drain on it. When it is time to leave, I'll re-connect it, hook up and go.

[Scott'n'Wendy]

Nice. I was thinking about installing lithium this November and was wondering about towing in the cold. But I also read the lithium batteries can't be charged in the freezing cold but they can discharge down to the -30* area. Thoughts?

[acoleman43]

Nice. I was thinking about installing lithium this November and was wondering about towing in the cold. But I also read the lithium batteries can't be charged in the freezing cold but they can discharge down to the -30* area. Thoughts?

Here are some temp specs from popular LifePO4 batteries:

Battle Born




SOK


Lion

[howson]

Scott'n'Wendy -- for those in the cold climates, BB makes a version with a built-in heater. See https://battlebornbatteries.com/heat...now-available/

There's a bunch of YouTube videos on it, too. Go to Battle Born's YouTube page and do a search for "heated"--there's a bunch of videos.

[Dave27]

I left a lead-acid battery in place when I installed new lithium batteries for the same reason you did. We travel from Michigan to AZ after Christmas. I use a Blue Sea dual circuit battery switch with the lithiums on 1 and the lead-acid on 2. I will use the lead-acid for all electrical needs until we get to warmer weather,

I wasn't aware of the "storage temperature". What happens to the lithium batteries if the temperatures go lower than the minimum? If I leave them in the camper until Christmas, I can guarantee they will go below that temperature. I was planning to leave them in the camper all the time.

Dave

[Guest]

The storage and discharge temperatures listed of each battery model dictates that the batteries cannot be exposed to temperature extremes of -30 to -20F that the OP is listing. So a heater would be needed to be operated during this exposure. The issue with a heater is that it draws from the battery but with a DCDC converter, this could power the battery heater while traveling. Is there a spec on the draw from the integrated battery heater?

Jim

[Guest]

I left a lead-acid battery in place when I installed new lithium batteries for the same reason you did. We travel from Michigan to AZ after Christmas. I use a Blue Sea dual circuit battery switch with the lithiums on 1 and the lead-acid on 2. I will use the lead-acid for all electrical needs until we get to warmer weather,

I wasn't aware of the "storage temperature". What happens to the lithium batteries if the temperatures go lower than the minimum? If I leave them in the camper until Christmas, I can guarantee they will go below that temperature. I was planning to leave them in the camper all the time.

Dave

Dave,

Extreme cold can have adverse effects on the electrolyte (lithium salt) and separator within each individual cell. Store lithium batteries at 50% SOC and indoors if extreme temperatures will be encountered and the battery will have a long life.

Jim

[AlexPeterson]

I contemplated the heated batteries, but, unless I leave the heaters on all the time when in storage, they do no good. To add to the specs, here are the Renogy specs. Note that they build a hysteresis into the various alarms/shutdowns (i.e., they recover from an alarm condition some number of degrees above where they trigger). This makes sense since there might be locations/cells within the battery that are colder than indicated by the temperature sensor(s).

[Dave27]

I find it confusing that you can discharge the lithium batteries down to -4 F but can only store down to +23 F (looking at the SOK batteries). Does anyone understand why the difference?
thanks, Dave

[Guest]

I find it confusing that you can discharge the lithium batteries down to -4 F but can only store down to +23 F. Does anyone understand why the difference?
thanks, Dave

Discharging creates heat as well as charging.

Jim

[Dave27]

I checked with SOK about the storage temperature. On their facebook site, they say the range in the spec sheet (quoted above) is wrong. It should be -22 F to 140 F. I found a more recent spec sheet and it shows -4 F to 140 F. This seems more consistent with the others. Either way, I'm not going worry about bringing them inside unless we have some arctic weather. 23 F was problematic because it is very common where we live from November through March.

Dave

[Scott'n'Wendy]

. Note that they build a hysteresis into the various alarms/shutdowns (i.e., they recover from an alarm condition some number of degrees above where they trigger). This makes sense since there might be locations/cells within the battery that are colder than indicated by the temperature sensor(s).

Also, deadband is needed for the heater/alarm to function. Without deadband it would be going on and off every minute or two.

Could you explain your reasoning about heaters doing no good? Or are you saying if you left them on in storage you would have a dead battery?

Alex, I see you have a Hughes EMS...what is your opinion on it?

[Country Campers]

We are currently camping and the outside temp is 23.2F, checked the battery temp in the front storage with the inferred thermometer and they are at 32F. No heat in the front storage of a fifth wheel, might have to add some.

Brian

[AlexPeterson]

Also, deadband is needed for the heater/alarm to function. Without deadband it would be going on and off every minute or two.

Could you explain your reasoning about heaters doing no good? Or are you saying if you left them on in storage you would have a dead battery?

Alex, I see you have a Hughes EMS...what is your opinion on it?

Scott - if I had the heated batteries, I would need to leave the rig plugged in the entire time during storage, which isn't a big deal, since I have power in the storage shed. But, I'd have to worry about them... I would expect if the temperatures dropped into the sub-zero range, the battery would not not last long if it was heating itself but not plugged in.

I don't have a lot of experience yet with the Watchdog - the camping we've done so far has been dry. But, it did alarm and shut down when I first hooked up the generator without bonding the neutral to the ground, so it caught that. Physically, it is a solid unit and seems well built. The app for monitoring it on the phone has been solid the few times I've used it.

[T Alan B]

Does anyone use a 12 volt Battery heating pad to keep the battery warm?