Victron Energy Temperature Sensor & Cold Weather Charging of Battleborn Battery

[Ruck_and_Roll]

Has anyone kept a battle born in through winter? And how did it perform? I'm not convinced the cell temperature inside a battery (inside a battery box inside the camper) will drop below 24 F (but I've never done extensive temperature measures inside the camper). I'm guessing some of you winter campers have had experience with this.... I expect to be using the camper this hunting and ski season in outside temps that reach single digits.

I already have the BMV-712 so my plan is to install the add-on temperature sensor to get more battery temperature data and do some actual testing.



This is per BB website:
Battle Born Batteries protect themselves from charging in cold temperatures and won’t accept a charge once the internal cell temperature drops to 24°F. At this point they will continue to discharge even down to -4°F. At this temperature we recommend no longer pulling power to avoid damaging the batteries.

Insulated battery boxes, heating blankets, and placing your battery bank inside your RV will help keep the temperature stable. On the high end of temperature range, the batteries will shut down once 135°F is reached.

 

[Vic Harder]

there was a thread not too long ago discussing battery heaters and diverting energy to the heaters until the BMV measures that the batteries are warm enough. I just bought some gear to implement something like that. I'll be using the BMV's relay function.

 

[Edgewood]

Is it possible to drop the battery into a insulated bag and add a chemical hand warmer when it gets really cold?

I'm planning to add a BattleBorn battery soon. Battery will be in camper. Sometimes the temp drops into the teens at night when I don't run the heater.

 

[Ruck_and_Roll]

@Vic...interesting, you will have to let us know how that works out....

@edgwood...I may do some testing with some insulation

I put in the battery temperature sensor and the battery is about ~5 degrees warmer than the truck temperatures, which is about 5 degrees warmer than the outside temperature.

 

[buckland]

Decided to add a second BB battery ... Has anyone installed and used the new heated 12V 100AH battery? It is $150 more and trying to decide if it is worth it. My intended travel time starting 2021 will include bugging out of New England headed south and southwest in winter. Getting there and when in high terrain it will be cold.

I will have the two batteries in parallel and only use the heated one at the end of a cold day until the camper is warm. I do have a DC DC charger (Victron) and not sure how that will play into traveling when real cold.... don't want to charge the battery that is not heated if temps are real low....
Thoughts appreciated
Rob

 

[PaulT]

If the temperature is lower than the charging cutoff, the BMS will not allow charging the battery with the cold cells. The heated cell battery should be able to take a charge. It seems like the heated battery will also be discharged further before charging due to energy it uses to heat itself. That implies that the two batteries will usually have different SOC’s so that one battery monitor won’t give a complete picture of the system.

Now, it may be that the heated battery keeps the unheated battery warm enough to take a charge for longer if the batteries are co-located within some insulation but the main drawback is that your battery monitor will give misleading information.

Perhaps, someone else will see where I am over or under thinking the implications of the situation. Heck, just turn the temperature up & avoid most of the problems, especially canned goods bursting due to being frozen. Or just get an unheated battery for the second one.


Paul

 

[Vic Harder]

If the temperature is lower than the charging cutoff, the BMS will not allow charging the battery with the cold cells. The heated cell battery should be able to take a charge. It seems like the heated battery will also be discharged further before charging due to energy it uses to heat itself. That implies that the two batteries will usually have different SOC’s so that one battery monitor won’t give a complete picture of the system.

Now, it may be that the heated battery keeps the unheated battery warm enough to take a charge for longer if the batteries are co-located within some insulation but the main drawback is that your battery monitor will give misleading information.

Perhaps, someone else will see where I am over or under thinking the implications of the situation. Heck, just turn the temperature up & avoid most of the problems, especially canned goods bursting due to being frozen. Or just get an unheated battery for the second one.

Paul

Thanks Paul... I had NOT thought of how the battery warmers would impact the BMV SOC calculations.

 

[rando]

I use my lithium batteries through the winter. Last trip out (last week) we saw outside temperatures down to about -12c (~12F), the batteries were fine, never got below about 5C, and started charging as soon as the sun came up.

Unfortunately the lithium low temperature charging 'issue' has become way overblown, and manufacturers have started offering these self heated batteries, which as Paul points out, are not a good solution. I am increasingly less impressed with battleborn. Had they thought this through and put the 'heater jumper' on the negative lead of the heater, then you could still measure the battery SOC. As they put it on the positive lead, you will no longer be able to measure the battery SOC using a coulomb counter (eg the BMV-712) when using the battery heater, regardless of batteries being in parallel with others.

My suggestion would be to skip the heated battery, and see how things go. I am assuming you will be storing water in your camper, therefore you will need to keep the average temperature above freezing anyway, so your batteries will be fine.

There appears to be little actual research quantifying the impact of cold temperature charging, but what there is suggests that it is only a very minor issue at low charge rates. One of the few quantitative studies would indicate that even charging at 0.5C at -30 is not a deathknell for a LiFePO4 battery, even though you will get very little capacity out of it at these temperatures.

 

[buckland]

I use my lithium batteries through the winter. Last trip out (last week) we saw outside temperatures down to about -12c (~12F), the batteries were fine, never got below about 5C, and started charging as soon as the sun came up.

Unfortunately the lithium low temperature charging 'issue' has become way overblown, and manufacturers have started offering these self heated batteries, which as Paul points out, are not a good solution. I am increasingly less impressed with battleborn. Had they thought this through and put the 'heater jumper' on the negative lead of the heater, then you could still measure the battery SOC. As they put it on the positive lead, you will no longer be able to measure the battery SOC using a coulomb counter (eg the BMV-712) when using the battery heater, regardless of batteries being in parallel with others.

My suggestion would be to skip the heated battery, and see how things go. I am assuming you will be storing water in your camper, therefore you will need to keep the average temperature above freezing anyway, so your batteries will be fine.

There appears to be little actual research quantifying the impact of cold temperature charging, but what there is suggests that it is only a very minor issue at low charge rates. One of the few quantitative studies would indicate that even charging at 0.5C at -30 is not a deathknell for a LiFePO4 battery, even though you will get very little capacity out of it at these temperatures.

Thanks again Lars for your explanation. Appreciate your much deeper knowledge on the subject. I will skip the heated option. Now I have to just wait for the next sale to come around.

 

[Vic Harder]

There appears to be little actual research quantifying the impact of cold temperature charging, but what there is suggests that it is only a very minor issue at low charge rates. One of the few quantitative studies would indicate that even charging at 0.5C at -30 is not a deathknell for a LiFePO4 battery, even though you will get very little capacity out of it at these temperatures.

0.5C? Wow. If so, I wonder why almost all BMS's do a low temp cutoff at or just just below freezing? It would be perfect if there was no negative side effect to charging at 0.1C (10A for the typical BattleBorn) because that is about all I see on a cool, low angle winter's day.

 

[rando]

The issue here is that there is not great data to support just how much damage you do by charging the batteries cold. The paper linked above suggests that at room temperature (15oC) the LiFePO4 batteries they were testing would provide ~9000 cycles at 20% DOD with a charge/discharge rate of 0.5C. For the same experiment at -30oC it was around 3-5000 cycles. Even at a charge of 1C and discharge of 6C(!) to 50% DOD they still saw ~1000 cycles at -30oC. Yes, the performance is degraded by operating at very low temperatures and relatively high charge/discharge rates.

However, for the use that most of us have, a few tens of low temperature charge cycles per year won't make much difference. If you are a telco running batteries at a repeater site in Tuk, then it would be an issue.

The bigger issue for heavy duty use (eg electric vehicles) is the decrease in capacity - the batteries were really unable to even provide even 50% capacity at -30C.

 

[Vic Harder]

Good info. Thanks rando!