We are at older sons place in northern New Mexico at 8000. The temperature dropped to 9 F with 10 of snow. We put a 60 W lamp in front bay with the LFP battery suite and it kept the space above 40 F. Son ran an extension cord to fifth wheel after I whined about needing to probably run generator in morning since I choose not to climb on top of fifth wheel to sweep off snow at age 78.
Son has 10 kW of panels with 50 kW-hrs of lead acid batteries with automatic generator turn on.
Reed and Elaine
How does his lead acid batteries go in 9*F (roughly -13*C)? The LFP and LYP cells can handle that as long as you don't try to pull big amps out or push big amps in, then again the Russian DIY electric vehicle people talk about capacity loss at -30*C if they are hard on the throttle first up rather than gentle and let the internal resistance warm the battery causing the resistance to drop.
Lead acid batteries are full of a water based electrolyte, wouldn't that have started freezing and expanding at 32*F (0*C) so wouldn't it have broken the lead plates by the time it got that cold? Or is his battery shed heated?
T1 Terry
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Terry the freezing point of the fairly strong sulphuric acid would be well below 0*c, so I think -9* would not be a problem. The freezing point of aqueous sulphuric acid varies markedly depending on its concentration. The freezing point at 31% acid is -73*c and the normal concentration in a battery is around 30%.
Thank you Jaahn, well that makes better sense now. As long as the acid is in a high concentration and not stratified as happens often in under charged AGM batteries, then the risk of electrolyte freezing is greatly reduced. So at 9*F, as long as the batteries remain above 40% SOC there is little risk of electrolyte freezing. This also answers the question why lead acid batteries in cold climates maintain a higher concentration of acid than those in hot climates. The higher concentration eats the plates away faster when the electrolyte heats up, but the off set is a lower freezing point.
You seem to think I'm anti lead acid batteries but I'm not, they have their place and under the bonnet starting batteries is their domain where they still rule as king in the flooded cell format, they don't fair well in the AGM or Gel format and I think you will agree with me there.
T1 Terry
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If you do really want to know. Looke here; https://www.trojanbattery.com/pdf/WP_DeepCycleBatteryStorage_0512.pdf
However I suspect that Terry is just using this post as his usual put down of lead acid batteries. Never gives up
Jaahn
PS there is also a recharging table there as well for people who are interested in that, instead of a tirade of BS like we usually get here lately.
Tunnel in deep enough shows this is relevant for a 105Ah flooded cell battery. An interesting thing to note is the recharge time at 20 amps to raise the SOC from 50% to 100%. 50% discharged would represent 52.5Ah depleted from the battery, yet the recharge time is 6hrs x 20amps, 120Ah to replace the 52.5Ah used out of the battery ..... Then look at the 5 amp charge rate, 26hrs, so a total of 5 x 26 = 130Ah.
I don't have to put crap on lead acid batteries Jaahn, you have given a link that does it for me
T1 Terry
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Sons batteries are in basement of his office/workshop (new workshop and office in Las Vegas, New Mexico which saves his staff half an hour of driving each way on snowy roads). The batteries are kept well above freezing there.
Son set up blower in our 19 Roadtrek so that the battery compartment volume is changed every minute with air pulled in from main body of vehicle. We have a catalytic propane heater near bed and we keep it about 50 F (10 C). The blower turns on at 40 F (5 C) in battery compartment under bed. Woke us up in confusement the first time it turned on.
Thinking about doing the same with 34 (11 m) fifth wheel. It will just be a 2 (50 mm) PVC pipe with blower from cabin.
Reed and Elaine
The PVC blower has worked well and kept forward bay in mid 30s F (4 C) when temperature was 15 F (-9 C). We also insulated the bay a bit. Have a 30 W DC (12 V) bulb that can be used as well if it gets colder. Prefer to use the DC when possible since the 4.5 kW PSWI uses about 60 W just being on (parasitic draw).
The electric vehicle DIY builders use heating mats under their cells to keep them at a temperature they are happy to deliver high current and accept high current. Fortunately we don't have serious low temperature problems in Australia, but one wonders about these extra fast DC chargers designed to rapidly top up an EV battery when it's freezing outside. Probably a heater powered by the plug in charger to get them up to temp or to cool them as required.
T1 Terry
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The heaters require a lot more energy than a blower which only runs about 10 W. We keep the cabin about 10 C at night with combination of propane catalytic heater and the forced air heater. This 10 C air is blown into battery compartment at about 0.3 cubic meter per minute. the battery compartment is about 1.5 cubic meters. The catalytic heater is an Olympian Wave 8 of 8,000 BTU or 2.3 kW. The fifth wheel is 34' long (10.4 m)
The Roadtrek is 19' (6 m) and we use an Olympian Wave 3 (3000 BTU) or 0.9 kW. We can heat it quickly if we wish to combine the catalytic heater, the forced air heater and turn on the engine and use the vehicle heater. Have only done that once at -8 C on way to Mexico. Had to de-ice the windscreen as well.
It has been overcast and snowing at 2350 m but we are still harvesting 3 kW
Hi Reed, you heat the living area to 10*C, most folks over here would have difficulty functioning at 10*C, they are heading for the heater switch when it drops below 18*C while clutching their arms and rubbing frantically to fight off frost bite :lol:
But then, I'm guess you mightn't handle the 49.9*C plus days too well though .....
T1 Terry
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Different regions in the US make fun of those in other areas. Minnesotans brag about how miserable it is in winter: shorts and T-shirts at below 0 C. Phoenix residents get used to 48 C. They have a saying that it gets so hot that "the trees are bribing the dogs."
We are New Mexicans and lived in Las Cruces for 37 years and 38 C iwas hot. Max was 47 C and I went out for a 10 K jog. Weigh before and after running and went through a liter running and 2 l when I returned. Humidity was 5%. Albuquerque is famous for folks playing tennis or golf in the morning and skiing in the afternoon in the Sandias or Sangre de Cristos. I have worked at 52 C as a scientist during tests at China Lake. I have had more enjoyable experiences.
It snowed heavily last night at our son's place and we woke up with about 15 cm of snow. Son's panels are tilted and the snow has slid off. Ours are flat on roof and will have to wait. We are 78 and I am not going up on roof to scrape off the snow. We are down 2 kW-hrs and can do such for 4 days of energy conservation before worrying about using a generator. Son's 5 kW of solar are going great and we can always tie in to his system to charge the batteries. We do have a 1 kW Honda generator and we have trialed it and charged our 9 kW-hr LFP at about 800 W.
The Roadtrek does have a built in 2.5 kW generator. It charges our 4.5 kW-hrs LFP at about 1.5 kW. We have used it once. We were in San Cristobal de las Casas, Chiapas, Mexico and were site in trees at a lovely RV park and the line power was out for a day. Our batteries were at about 3/4 capacity so we decided to see if the generator/battery charger/battery system still worked.
Snowbirding folks from Canada and northern US usually wait till end of April to head north.
Reed is spot on Terry regarding getting used to different extremes.
I have a very clear memory of high school in Canada.
The rule was we had to go outside and a distance away to have a smoke.
One day in spring we didn't bother to get our coats and just went out in shirt sleeves.
There was still several feet of snow on the ground.
It was a lovely sunny day and several commented that a coat was unnecessary and how warm it was.
Then somebody pointed out it was 33*F. Well, that explained everything didn't it? It was the first time the temp had risen above freezing that winter. No wonder we all felt so good in the sun.
Jim
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Reed personally I absolutely hate the cold cant imagime poor people haveing to shovel there way into there front door our wheather here is preety good ,I have a Canadian friend who stores his van in Australia at his sons place,he and wifey are here when its cold smart people..
I was in England on a holiday waiting for a friend. It was 7°C & I was frozen to the bone, I put on every last piece of clothing including 3 pairs of socks. A week later in Germany I was getting too warm walking around in teeshirt & shorts, it was -12°C. The air was so dry you couldn't get cold, whereas in England the air you could cut with a knife due to the humidity.
Last year in Midura it was 47°C but due to the dry air it didn't feel too bad. I've felt worse in Sydney at 25°C due to the humidity.
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:lol: We moved to Mannum SA around 3yrs ago. Before that we lived in the Wollongong NSW area. Mid of summer was a killer if it reached 32*C and winter if it dropped to single figures. Here in Mannum 32*C is a nice day, 50*C is at the stage you stay out of the sun and the air is that hot and dry you just can't keep the water up to stop getting a dry mouth and nose. Today we had our first frost for the yr and the white across lawn didn't disappear until 9:30am. There is no way I can to get conditioned to 50*C and sub zero in the same yr, the LYP batteries can handle it without any issues, I sure can't :lol:
T1 Terry
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