Incredulocious
Member
I've written to StarkPower and SmartBattery to ask each about what sort of protection they offer for below freezing temperatures for their "drop-in replacement" lithium battery systems. I've read that some (many?) lithium batteries can be damaged if charged at below freezing temperatures. When converting to lithium-based batteries, I see that some folks move their battery bank into the heated interior or add some mechanism to warm the batteries and I see that AM Solar adds a "cold charge disconnect" to their systems. Part of my concern is that even if moved inside, an unattended, cold-soaked battery would still potentially receive a charge via the solar system. Also, it would be simpler to replace the provided house batteries in their existing battery compartment.
So I asked these two manufacturers if this was an issue with their batteries and, if so, do their battery management systems (BMS) protect against charging at temperatures that are too low?
----- SmartBattery (Operating Range: 4°F To 158°F):
So far, I've only received a brief reply from SmartBattery that didn't exactly answer my question:
------ StarkPower (Operating Range: -22˚F to 140˚F):
With StarkPower, it took several back and forth emails to get a more definitive answer:
Here's my follow-up: "That’s nice to hear. However, I’m still concerned because on your web site your specifications include specific over- and under-voltage cutoffs and limits on charge and discharge current but no mention is made of any temperature safety cut-offs. Can you reference written documentation or warranty information on this temperature protection? I would not want to have to rely on just this email if it turns out there was a misunderstanding and that installing these as house batteries for my Sprinter-based RV and allowing them to charge via the alternator or my solar charge controller (even when parked and unoccupied) might damage them when the temperature drops well below 32 F. (I see that some installers like AM Solar actually add expensive cold charge disconnect systems.)"
This was eventually forwarded to their "head engineer" and CTO, Martin Koebler:
So I asked these two manufacturers if this was an issue with their batteries and, if so, do their battery management systems (BMS) protect against charging at temperatures that are too low?
----- SmartBattery (Operating Range: 4°F To 158°F):
So far, I've only received a brief reply from SmartBattery that didn't exactly answer my question:
I've tried a couple more times to get a definite answer on charging at below freezing temperatures and I'll update this thread with any reply I receive.The main effect low temperatures will have on our batteries is reduced capacity. [chart showing usable capacity from 103% at 140˚F down to 60% at -22˚F]
------ StarkPower (Operating Range: -22˚F to 140˚F):
With StarkPower, it took several back and forth emails to get a more definitive answer:
Note that this is not strictly true – keep reading to their final answer.You are correct. You should take caution when charging below freezing temperatures. However, we do recommend operational temperatures for the unit between -22-140F. Again, you are correct that the BMS will protect the cells and battery from temperatures out of the recommended operating range. The unit will turn itself back on once in safe operating temperatures.
Here's my follow-up: "That’s nice to hear. However, I’m still concerned because on your web site your specifications include specific over- and under-voltage cutoffs and limits on charge and discharge current but no mention is made of any temperature safety cut-offs. Can you reference written documentation or warranty information on this temperature protection? I would not want to have to rely on just this email if it turns out there was a misunderstanding and that installing these as house batteries for my Sprinter-based RV and allowing them to charge via the alternator or my solar charge controller (even when parked and unoccupied) might damage them when the temperature drops well below 32 F. (I see that some installers like AM Solar actually add expensive cold charge disconnect systems.)"
I replied with: "That product description you referenced seems to only say that your BMS monitors these parameters. It’s difficult to presume from this whether it disconnects the battery at high or low temperatures. If it does disconnect, you don’t specify at what temperatures this occurs and whether these numbers are different for charging vs. discharging. May I suggest that you really need to describe these parameters as you do for the over- and under-voltage cut-offs and max currents in your specifications?"Yes. You can view specifications under the description tab at the bottom of the product page:
StarkPower Deep Cycle 12V9-EP has 12 volts and a 9Ah capacity and is perfect for powering your deep cycle systems. StarkPower Deep Cycle has an internal microprocessor controlled battery management system (BMS) that monitors the key operational parameters during charging and discharging, such as voltages, currents and internal temperatures. Easy drop-in replacement solution for antiquated lead-acid battery system with no modifications necessary.
This was eventually forwarded to their "head engineer" and CTO, Martin Koebler:
Thank you for your feedback.
You are correct we should provide more data information on our website on temperature parameters along with max peak current. Usually our peak current allows for 3x of the continuous rating for 5 seconds. For our 12V 100Ah battery rated at 100A continuous our peak max current would be able to provide 300A for 5 seconds.
The BMS does turn off when the battery temperatures reaches 60C and typically needs a 10C temperature drop to automatically turn ON again. We do not have low temperature charge control since 99% of the time the battery can take a charge even at lower temperatures. Our batteries are used outside in the field in extreme conditions such as in Alaska where customers do insulate the batteries with extra insulations.
The exact values do have some variations with other variables involved such as part tolerances along with single cell voltage measurement vs entire battery pack voltage measurement.
I hope this helps some, we will continue improve information on our website to provide accurate information.