Community Forums

mhbell · 09-08-2022, 08:59 AM

I am debating on getting Lifepo4 12V batteries or AGM 12V. Here is my problem I live in Utah 4 seasons and cold in the fall and winter. During the cold months I leave my 5th wheel plugged in to shore power 24/7. I don't want to have to remove the batteries when it gets cold. There would be no problem or maintenance with AGM's I would really like to go with the lifepo4's but am worried about ruining them during cold weather when they try to charge. I can unhook the solar with a circuit breaker which is installed. but not the converter as I need the lights and heater. What is the solution.
TIA
Mel

Do26 · 09-08-2022, 09:30 AM

If not in a heated space, consider tank warmer mats.

PJStough · 09-08-2022, 10:27 AM

Simply shut off the charger when it gets cold if you are concerned about battery damage from charging them when they are too cold.

LiFePO4 batteries can be discharged without damage when they get cold, damage only can occur if they are charged at temps below freezing.

mhbell · 09-08-2022, 10:49 AM

Quote:

Originally Posted by PJStough

Simply shut off the charger when it gets cold if you are concerned about battery damage from charging them when they are too cold.

LiFePO4 batteries can be discharged without damage when they get cold, damage only can occur if they are charged at temps below freezing.

Thats not a option because the slide needs the batteries to operate properly. The slide can't operate with the converter alone because of the amp draw. same with the furnace blower. I don't want to ruin the converter.

Marine359 · 09-08-2022, 10:50 AM

Disconnect the LiFePo4 completely from any potential charging source. I’ve got a built-in battery I/O switch, but a disconnect placed between positive terminal and a bus bar will work too. Discharge to 60% SOC, and the batteries will be happy to just sit there in your rv in ambients down to -5F. If it gets colder than that, they’re lightweight enough to simply remove them and store indoors/basement. When you’re ready to fire them up again, but it’s still cold, just turn on your furnace to heat up the place where your battery is mounted. Don’t use shore power until the battery is heated, as shore power will run a charge amperage to the battery from the charger, or inverter/charger. The battery can safely discharge as low as -30F to provide power to furnace. If furnace not possible, use a 12v blanket. I leave my LiFePo4 in my rv all thru the winter. We make a few trips during freezing temps, and we just turn on battery, warm up with furnace, pack up, charge up on SP, and leave. Besides, if you forget something, you’ll always be saved if your battery bms has a low temp charging shut off.

mhbell · 09-08-2022, 10:54 AM

Does the Lifepo4 have built in BMS low temp protection that will cut off the battery from being charged when temp get below a certain point even with the converter running.
Mel

Marine359 · 09-08-2022, 10:58 AM

Many do, but some don’t. Choose wisely. Read the specs before buying. I believe all American assembled brands do have low temp charging cutoff. Many of the cheap (straight from China) brands do not. This feature is definitely worth paying for.

JHinman · 09-08-2022, 12:58 PM

I put my lithium batteries under the bed. It does not get that cold there when I am camping. Coldest weather I have been camping in was 11F, and I had no issues with the batteries getting cold.

If they were on the tongue that would have been a different story. I could have used them, but not recharged them.

If it gets below 27 F inside my rig (that is the charge limit on my Battleborn batteries) I am just headed home.

wolfgolden · 09-08-2022, 01:12 PM

Get batteries with low temperature cutoff and you will be fine since you are always plugged in.
The cutoff will prevent the batteries from trying to charge when too cold.

You can also optionally get batteries with built in warmers.

Persistent · 09-08-2022, 02:09 PM

I am debating on getting Lifepo4 12V batteries or AGM 12V. Here is my problem I live in Utah 4 seasons and cold in the fall and winter. During the cold months I leave my 5th wheel plugged in to shore power 24/7. I don't want to have to remove the batteries when it gets cold. There would be no problem or maintenance with AGM's I would really like to go with the lifepo4's but am worried about ruining them during cold weather when they try to charge. I can unhook the solar with a circuit breaker which is installed. but not the converter as I need the lights and heater. What is the solution.
TIA
Mel

Thats not a option because the slide needs the batteries to operate properly. The slide can't operate with the converter alone because of the amp draw. same with the furnace blower. I don't want to ruin the converter.

Does the Lifepo4 have built in BMS low temp protection that will cut off the battery from being charged when temp get below a certain point even with the converter running.
Mel
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Mel you are correct. The batteries must be above freezing possibly above 40 degrees F to safely charge. As posted above some Li drop-in batteries are protected from charging below their cutoff temperature. Check specifications for individual battery designs. If no information, then move on to a different brand.

Li batteries have a low temperature cut off for discharge as well. The best drop in batteries have protection for that as well.

A good solution is to install the Li batteries inside a heated cabin space, say, under a bed. They work best in temperatures that people like as well.

Another solution is to install in a space previously used for lead acid batteries. The space must be kept warm in northern winter and cool in desert summer. The space must be closed to rain, snow, road spray, dust, dirt, mud, etc. If necessary include a battery disconnect switch and thermometer.

The batteries may be stored at low or high temperatures. They must be warmed or cooled before they are charged or discharged. In some cases they will not work due to internal safeties. High current slides will not work until the batteries are warm enough to power them.

There are many 120 volt devices that are designed to keep things above freezing. Many owners choose one of these devices for cold climates.

LiPO4 batteries require a BMS to charge and discharge them. The best BMS have lots of protections built into them. "Drop-in" Li batteries have a built in BMS

Cells in the batteries and in the case of multiple batteries they must all be at the same state of charge and have the same capacity. Building better batteries is more expensive than slapping things together in mother’s garage.

The best battery manufacturers have a free review service to review your entire proposed system. Use that service if you install more than 200 amp hours of battery bank. It is complicated.

xc-mark · 09-08-2022, 02:45 PM

you could keep a battery inside with a longer cable and use lithium assuming you keep it above freezing to charge it. Option 2 is put a cheapo lead battery in the cold area for the winter . lithium can be discharge and stored in a cold area with out any problems but NEVER charged below freezing. Option 3 build a insulated battery box and put a very small heater in the box. Plug in heat trace inside the insulated box should do the trick unless your in a area that is below zero for days. Raychem XL heat trace is a self regulating heat trace that only gets to about 70*F and backs off on heating typical 8 watts per foot around your batterys then in a insulated box would solve the problem.

Check with the battery manufacture, charging or dischargeing above 135*F+ would be a problem . I dont think you would be able to cool your camper above 110* so that is a NON issue in my mind. Charging or discharging makes very little increase of battery temperature assuming you under 50 amps per battery for any extended period time. I may see 2~5*f increase when I am charging my 5 battery's at 200 amps.