Hypothetical Winter Camping Electrical Limits

Bill

Chris of Technomadia did write-up of success and failures after 3.5 years of lithium battery usage.

He expressed their failures quite nicely: primarily in the realms of not paying attention to the temperature limits of the cells and maintaining upper voltage limits of the individual cells. They used a Voltage Management System (VMS) instead of a Battery Management System (BMS). We can watch our BMS monitor as it balances all 16 cells (48 V nominal system) by the second.

Individual cells should not go above 3.4 V (long winded discussions on this on Aussie and Cruiser forums - up to 4000 responses on one thread).Chris notes "...The balance boards 3.5 years ago did not trigger a balance load until the cell voltage reached 3.7V. This is actually slightly above the over-voltage cutoff on the EMS.." 3.7 V is 0.3 V over recommended cutoff and result in quite a bit of cell degradation.

As you note, battery technology should develop over the next few years and hopefully prices will drop. The theoretical work was apparently done in the US but the Chinese are doing the engineering since their internal usage of solar and energy storage is greater than that of the rest of the world.
Reed and Elaine

It's been awhile since I watched the Technomadia folks lithium video, but wasn't that system nearly 3 years old.

I am thinking more in terms of future development of lithium, that is I expect the batteries will develop in the next couple of years.

Interesting information tho.

Thanks,
Bill

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

3 tons wrote:
A one speed furnace is a huge 10+ amp battery drainer, if possible opt for a 2speed 15/22btu furnace, on low speed (post initial warm up) saves power at only 4amps and conserves LPG.

I fully agree about the lower amperage but find hard to see where noticeable LPG usage savings come from?

It's hard to justify replacing working furnace with a 2 speed one just for lower amperage draw.

By the way, my Atwood Excalibur 8525-III with 19,000 BTU output is supposed to pull 5.5 Amps according to it's specs.
It's still quite a bit!


Has anyone heard of conversion kits?

adambeck7 wrote:
We got an Eagle Cap 960 this year and spent 5 nights out in summit county. it was getting down to around 5 degrees at night. we have a 2 year old so we had the thermostat set on a comfortable 70 all night. would lower it to 55 during the day when we were out in the snow. great insulation, heated basement, insulated windows etc. had the slide out about half the time. only went through 10lbs of propane surprisingly enough. it has room for two GC2 6v batteries. 40lbs of propane and has a generator compartment.

Currently I am thinking along an Eagle Cap or an Arctic Fox,
Thanks,
B

3 tons wrote:
A one speed furnace is a huge 10+ amp battery drainer, if possible opt for a 2speed 15/22btu furnace, on low speed (post initial warm up) saves power at only 4amps and conserves LPG.. Also from my own basement winter temperature measurements, the factory 2" corrugated basement duct proved nearly non- functional due to its high internal flow resistance...After adding a 4" duct from the furnace plenum (inside cabinetry) basement temps (with outside temp about 6d F) stayed within 10 degrees of main interior. The only problem with the slide- out was air leaks beneath the slide at wiper gasket, this I fixed by removing the loosely cut wiper gasket and inserting 3/4" foam pipe insulation.

Very handy to knowl
Thanks,
Bill

adambeck7 wrote:
We got an Eagle Cap 960 this year and spent 5 nights out in summit county. it was getting down to around 5 degrees at night. we have a 2 year old so we had the thermostat set on a comfortable 70 all night. would lower it to 55 during the day when we were out in the snow. great insulation, heated basement, insulated windows etc. had the slide out about half the time. only went through 10lbs of propane surprisingly enough. it has room for two GC2 6v batteries. 40lbs of propane and has a generator compartment.

It sounds like you were plugged in to AC outlet! If not - how did you recharge the batteries after a night or two?

A one speed furnace is a huge 10+ amp battery drainer, if possible opt for a 2speed 15/22btu furnace, on low speed (post initial warm up) saves power at only 4amps and conserves LPG.. Also from my own basement winter temperature measurements, the factory 2" corrugated basement duct proved nearly non- functional due to its high internal flow resistance...After adding a 4" duct from the furnace plenum (inside cabinetry) basement temps (with outside temp about 6d F) stayed within 10 degrees of main interior. The only problem with the slide- out was air leaks beneath the slide at wiper gasket, this I fixed by removing the loosely cut wiper gasket and inserting 3/4" foam pipe insulation.

Bill001, I've been winter camping in TCs for 12 years now. First with a 2003 AF 1150 with Solar and currently with a Lance 861 no Solar. Solar makes a big difference as does battery selection. Batteries on my AF were aweful, started with 12V Group 27 batteries and they only lasted a few years and were not good the last year I had them. Switched to Optima Yellow top AGM batteries and they only lasted a few years, big waste of $$$. Past 7 years I've had a pair of Trojan 6V batteries in my 861 and they are spectacular, especially in winter. In the White mountains in January we're typically below 0F at night and single digits during the day, furnace runs basically full time. I have wet camped but since I mostly do wknd trips found it a PIA, full timing would be different. Also hard to find places to dump tanks in the winter around here. My AF had a 100W solar panel and that saved me with my aweful batteries. Plan on putting a panel on my 861 before this coming winter.

Note, if you run more than two batteries you need to make sure you know how you're going to keep them charged. I did this for a short period with a battery switch to go between my dual 12Vs in the battery compartment and my 6Vs in the genny compartment. I also bring a portable Honda E2000i with me during the winter.

If you have a long bed truck get a TC that can handle the bigger Propane tanks. My AF 1150 had 2 big tanks and that was huge, 861 can only fit 2 small tanks like you use for your grill at home though the nice option is I can run to local supermkt and do a Blue Rhino swap where with the bigger tanks you have to find someone in winter to fill them. You are correct that there's lots of sunshine in CO but there's also lots of snow so you're going to need to be able to get up on the roof and clear those solar panels off for them to work.

Best of luck. Winter camping is awesome, no bugs and usually get my pick of sites as there's so few of us brave enough to go.

We got an Eagle Cap 960 this year and spent 5 nights out in summit county. it was getting down to around 5 degrees at night. we have a 2 year old so we had the thermostat set on a comfortable 70 all night. would lower it to 55 during the day when we were out in the snow. great insulation, heated basement, insulated windows etc. had the slide out about half the time. only went through 10lbs of propane surprisingly enough. it has room for two GC2 6v batteries. 40lbs of propane and has a generator compartment.