Hypothetical Winter Camping Electrical Limits
Hi, I used to have a very old tow-behind trailer that I used during the winter in Colorado; 2 batteries, 2 propane tanks. Since the furnace had no fan it was easy to be out a week, dry. Now I did...
Forum Discussion
bka0721 noted that we have a fairly extensive LFP battery bank. This is 8.6 kW-hr (48 V nominal) and perhaps 9.7 kW-hr at 54 volt float. This equates to between 7 and 8 kW-hr of usable energy at 20% SOC.
There are a lot of advantages to LFP and three primary disadvantages: cost, high temperature degradation and low temperature degradation. You also have to monitor the voltage of the individual cells to keep them below 3.4 W. A Battery Management System is expensive but works superbly.
The Technomadia folks have discussed their problems with high temperature degradation. Their battery bank was installed in a small compartment with the inverter which had no air circulation with the outside. The inverter would release a lot of heat when they were running the a/c and they were parked in Phoenix with extreme insolation of the vehicle sides. Temperatures probably were well above 140 in that compartment.
Our battery suite is in forward baggage compartment under the overhanging kingpin and would not expect that the temperature would get above ambient when the front panel and side doors are open. There could be a problem of heating when the inverter is running the a/c from solar/battery suite. We have emplaced an inexpensive (cheap) remote thermometer in this compartment to monitor tEmperature and will install two 12 V receptacles so that we can operate 12 V fans (12 W) for air circulation.
LFP operates well down to -20 C; however, there are problems in charging at moderate C rates below 0 C (32 F). We have found that a 40 W incandescent bulb will keep the main baggage compartment above freezing (40 F) at 10 F ambient so these bulbs are the only ones we have not replaced with LED. This keeps the pipes from freezing but probably does not heat the water tanks (fresh/grey/black) from freezing. This may be of interest to OP.
So we are going to place two 12 V bulb receptacles in front bay to make sure that we do not charge at temperatures below freezing. We can run a single 40 W bulb for 175 hours from battery bank. We have a 508 W Mean Well 48 V to 12 V converter so have plenty of 12 V power to run a number of 40 W bulbs.
We purchased an Olympic Wave 8 catalytic converter several years ago and find it will keep the main cabin comfortable (high 50s) when the outside temperature is below 20 F. We did turn the forced air heater on when it got below 20 to keep pipes from freezing; however, as noted above, we find that a single 40 W bulb keeps the main baggage compartment above freezing. We have sufficient battery storage to run the 40 W bulb for 175 hours.
All of this depends on the sun shining somewhat during the day. Nothing works well when there is snow on the panels. This means that it is time to head south.
Reed and Elaine
There are a lot of advantages to LFP and three primary disadvantages: cost, high temperature degradation and low temperature degradation. You also have to monitor the voltage of the individual cells to keep them below 3.4 W. A Battery Management System is expensive but works superbly.
The Technomadia folks have discussed their problems with high temperature degradation. Their battery bank was installed in a small compartment with the inverter which had no air circulation with the outside. The inverter would release a lot of heat when they were running the a/c and they were parked in Phoenix with extreme insolation of the vehicle sides. Temperatures probably were well above 140 in that compartment.
Our battery suite is in forward baggage compartment under the overhanging kingpin and would not expect that the temperature would get above ambient when the front panel and side doors are open. There could be a problem of heating when the inverter is running the a/c from solar/battery suite. We have emplaced an inexpensive (cheap) remote thermometer in this compartment to monitor tEmperature and will install two 12 V receptacles so that we can operate 12 V fans (12 W) for air circulation.
LFP operates well down to -20 C; however, there are problems in charging at moderate C rates below 0 C (32 F). We have found that a 40 W incandescent bulb will keep the main baggage compartment above freezing (40 F) at 10 F ambient so these bulbs are the only ones we have not replaced with LED. This keeps the pipes from freezing but probably does not heat the water tanks (fresh/grey/black) from freezing. This may be of interest to OP.
So we are going to place two 12 V bulb receptacles in front bay to make sure that we do not charge at temperatures below freezing. We can run a single 40 W bulb for 175 hours from battery bank. We have a 508 W Mean Well 48 V to 12 V converter so have plenty of 12 V power to run a number of 40 W bulbs.
We purchased an Olympic Wave 8 catalytic converter several years ago and find it will keep the main cabin comfortable (high 50s) when the outside temperature is below 20 F. We did turn the forced air heater on when it got below 20 to keep pipes from freezing; however, as noted above, we find that a single 40 W bulb keeps the main baggage compartment above freezing. We have sufficient battery storage to run the 40 W bulb for 175 hours.
All of this depends on the sun shining somewhat during the day. Nothing works well when there is snow on the panels. This means that it is time to head south.
Reed and Elaine
