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Old 12-02-2021, 03:03 PM   #239
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Bylandorsea, it is starting to sound like you own stock in a SiO2 battery company.


As to the rest, if the kitchen cabinet where I have my LiFePo4 batteries installed drops below 14F (the discharge cut off temperature for my LiFePo4 batteries), or even 32F the charging cut off temperature, I am likely having bigger problems than not being able to charge / discharge my LiFePo4 batteries. This trait is the exact reason why I moved my battery bank from its exposed location under the entry step to the kitchen cabinet.



Yes heated batteries do consume some capacity to heat them up to 32F, but really not that much, in most cases a 5-10 watt heating element can raise the battery above 32F in fairly short order, at which point in time it can start charging, the better / newer BMS units that support internal heaters will even work down to below the 14F discharge point, so that if you have a charging source it will heat the battery up using the external power source.


As to SiO2, yes they may be better in the cold, but they do have other negative traits, as to the cold again this is a moot point for me as I never intend for the temperatures under my kitchen cabinet to drop below freezing, and if they do I can easily enough start my generator and blow a hair dryer on the LiFePo4 battery until it warms up to operating temperature.
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Old 12-02-2021, 03:39 PM   #240
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Originally Posted by Bylandorsea View Post
Why are the owners of LiFePo4 batteries in denial of the glaring fault with LiFePo4.
Who is in denial here? Me and every LFP owner I talk to is aware of the temperatures needed to charge them. Its not considered a glaring fault because its not normally that big of deal, you use these things normally around a heated space and they don't need venting so its not difficult to keep them above freezing and a heater that runs from charging current are not difficult to setup if necessary, for most its not needed.

I would venture most RV's try to avoid freezing temps, I know I do, but even so without any effort my open battery bay stays 10F above the outside, its not like I am trying to charge them in the dead of night when its gets the coldest.

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SiO2 charge as fast as lithium to 90% and easily top off to 100%.
If they charged as fast as lithium then you would have alternator considerations as well. They charge at .25C to just under 90% then need a lengthy multi-hour absorb to 100% similar to my old AGM's. Lithiums are rated at 1C and will accept that right up to nearly 100% charge, if you want extra long life then .5C or twice as fast as Si02 again no absorb time needed. Pretty difficult to charge at even .5C, that would be 206 amps on my SOK's I can hit about .25c with my 125 amp charger and they go right back up to 100% full blast in 4 hours from 0.
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Old 12-02-2021, 06:17 PM   #241
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Bylandorsea, it is starting to sound like you own stock in a SiO2 battery company.


As to the rest, if the kitchen cabinet where I have my LiFePo4 batteries installed drops below 14F (the discharge cut off temperature for my LiFePo4 batteries), or even 32F the charging cut off temperature, I am likely having bigger problems than not being able to charge / discharge my LiFePo4 batteries. This trait is the exact reason why I moved my battery bank from its exposed location under the entry step to the kitchen cabinet.



Yes heated batteries do consume some capacity to heat them up to 32F, but really not that much, in most cases a 5-10 watt heating element can raise the battery above 32F in fairly short order, at which point in time it can start charging, the better / newer BMS units that support internal heaters will even work down to below the 14F discharge point, so that if you have a charging source it will heat the battery up using the external power source.


As to SiO2, yes they may be better in the cold, but they do have other negative traits, as to the cold again this is a moot point for me as I never intend for the temperatures under my kitchen cabinet to drop below freezing, and if they do I can easily enough start my generator and blow a hair dryer on the LiFePo4 battery until it warms up to operating temperature.
Isaac-1 you must be one great sales man.
After reading your reply it made me think of how the conversation with my wife would go:
Me: Honey can you please take your stuff out from under the kitchen cabinets?
She would ask what for?
Me: To put in batteries that have to be kept warm.
She would ask why don’t you put then in the compartment with the big slide out battery tray that our batteries are in now.
Me: It will be too cold for the LiFePo4 batteries.
She would ask just how many RV dollars will this cost?
Me: 2 to 3 times the cost of going back with 6V deep cycle lead acid, and I almost forgot we have to purchase new battery cables so we can put the new batteries under the kitchen cabnets.
Her next question: Is that all it will cost?
Me: Oh I almost forgot we will need a DC to DC battery charger to protect our alternator from the LiFePo4 batteries.
This is when she would get that look and ask what is the cost for new cables and the DC to DC charger?
Me: About a thousand dollars or so in addition to the 2 to 3 times the cost of going back with 6V deep cycle lead acid.
This is the point where she would ask: HAVE YOU LOST YOUR MIND
Sorry to disappoint you but I don’t own a SiO2 battery and as to stock in a SiO2 battery company possibly in a mutual fund. I don’t have a single SiO2 battery!
One day soon I will replace the 14 6V deep cycle lead acid batteries on my boat and if by then LiFePo4 batteries are 40-50% less. I did factor in a DC to DC charger to protect my alternators. Because on my boat cold weather performance is not a factor (climate controlled battery compartment). By the way only if they are drop in replacements for 6V deep cycle lead acid batteries.
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Old 12-02-2021, 06:43 PM   #242
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Originally Posted by Bylandorsea View Post
Isaac-1 you must be one great sales man.
After reading your reply it made me think of how the conversation with my wife would go:
Me: Honey can you please take your stuff out from under the kitchen cabinets?
She would ask what for?
Me: To put in batteries that have to be kept warm.
She would ask why don’t you put then in the compartment with the big slide out battery tray that our batteries are in now.
Me: It will be too cold for the LiFePo4 batteries.
She would ask just how many RV dollars will this cost?
Me: 2 to 3 times the cost of going back with 6V deep cycle lead acid, and I almost forgot we have to purchase new battery cables so we can put the new batteries under the kitchen cabnets.
Her next question: Is that all it will cost?
Me: Oh I almost forgot we will need a DC to DC battery charger to protect our alternator from the LiFePo4 batteries.
This is when she would get that look and ask what is the cost for new cables and the DC to DC charger?
Me: About a thousand dollars or so in addition to the 2 to 3 times the cost of going back with 6V deep cycle lead acid.
This is the point where she would ask: HAVE YOU LOST YOUR MIND
Sorry to disappoint you but I don’t own a SiO2 battery and as to stock in a SiO2 battery company possibly in a mutual fund. I don’t have a single SiO2 battery!
One day soon I will replace the 14 6V deep cycle lead acid batteries on my boat and if by then LiFePo4 batteries are 40-50% less. I did factor in a DC to DC charger to protect my alternators. Because on my boat cold weather performance is not a factor (climate controlled battery compartment). By the way only if they are drop in replacements for 6V deep cycle lead acid batteries.
Or just put them in your heated basement. Easy peasy. Try shoving 400Ah of SiO2 in that space and stay under 100 lbs.
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Old 12-02-2021, 07:34 PM   #243
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It really was not all that involved, we have a somewhat hard to access kitchen corner cabinet space where in the past we have stuffed things that we did not often use (spare crock pot, inflatable bed, etc.), it is well located weight distribution wise as it is almost directly above the rear axle, the pair of 210AH LiFePo4 batteries just fit in the space with an inch of so to spare around the sides. I debated putting them in my electrical bay, but felt the kitchen cabinet above the electrical bay would be more climate controlled.



As to the economics of things, we have always been limited by only having room for 2 GC2 6V batteries under the entry steps without having to do extensive modification to the battery tray, which would likely cost $750 or so to have a professional welder build a larger custom battery tray. So the 420AH of LiFePo4 effectively more than doubles our battery capacity, with no need to involve a professional welder. The cost of the installation total came to to right around $2,000 once you count the nickle and dime stuff, the batteries were $1492 delivered, the 50 amp Renogy DC-DC charger with integrated MPPT solar controller was another $230 on pre-black friday sale, BT-2 blue tooth module $25, the electrical bay where the inverter, converter, etc is housed is just forward and below the cabinet where the batteries are installed, so not that much cable. 11 ft of 4/0 mil spec surplus battery cable off ebay was $48 (I cut it up and added new lugs as needed), 10 pack of 4/0 tinned marine grade lugs $19 off Amazon, A/B 350 amp Blue Sea disconnect switch off amazon $19 (open box warehouse deal, regular price $42), 6 34 inch 1 AWG mil surplus cables off ebay for various connections, bridging between pairs of batteries, $40, Class T fuse and holder $43 new (ebay), a pair of electrical distribution bars $25, 30 ft of 1/0 battery cable for $30 off ebay, needed less than half to run new cable from alternator to DC-DC charger, plus various odds and ends, ring connectors, electrical tape, wiring loom I had on hand. If you want to add it all up go ahead, but it comes out in the $2,000 ballpark.


p.s. there were some other side benefits too, like getting to upgrade to an MPPT solar controller from the old PWM controller, plus now we have detailed state of charge monitor over bluetooth which tells us charge level, discharge rate, charging rate, and on the Renogy DC-DC charger with MPPT BT-2 both amount of power coming from solar as well as the engine alternator Vs the old digital voltmeter on the SeaLevel 709 panel.
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Old 12-02-2021, 07:45 PM   #244
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Or just put them in your heated basement. Easy peasy. Try shoving 400Ah of SiO2 in that space and stay under 100 lbs.
Corn 18 if I could get Isaac-1 to do the talking and you to do the install, I bet my wife might let me put 400Ah in her jewelry box!


Corn 18 If that is all the room you have I agree LiFePo4 batteries would be a good choice
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Old 12-02-2021, 07:50 PM   #245
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Where in the —-blank—- is anyone camping in sub freezing temperatures. If I am camping and the temp outside is less than 38F (when I would charge my battery’s (10am-5pm) I am packing up and moving.

All this talk about temps is driving me nuts you can discharge lifepo4 down to -4F and that battery temp not air temp. Just pulling current from the battery’s will raise the temp.

Yes you can not charge under 32F but who would, by mid day your temps would be above that unless your camping in a blizzard and if you are you should reevaluate your living conditions.
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Old 12-02-2021, 07:57 PM   #246
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Well I did get caught in an early season arctic blast at 7,000 elevation in eastern Arizona in October of 2019, went from high in the 80's to an overnight low of 12F with the wind blowing in about 36 hours, and temperatures below freezing from 4 pm one afternoon until about 9 am the next morning. I burned a lot of propane that night.
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Old 12-02-2021, 08:07 PM   #247
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Corn 18 if I could get Isaac-1 to do the talking and you to do the install, I bet my wife might let me put 400Ah in her jewelry
You have a Dutchstar right, this guy just insulated the existing battery bay https://www.irv2.com/forums/f103/sol...ll-421015.html

I thought Newmars had great basement insulation and some heat down there to begin with but is the battery compartment open or something for venting the LA’s?
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Old 12-02-2021, 08:27 PM   #248
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In the winter, we camp in 20 degree days and the nights drop in the teens. I still work full time and cannot chase the seasons. I also camp at ski resorts for weekend trips.
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Old 12-02-2021, 08:38 PM   #249
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That still leaves the question of how often does it drop below freezing in the living space, closet, cabinets, etc where one might locate a LiFePo4 battery bank?
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Old 12-02-2021, 08:44 PM   #250
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I thought Newmars had great basement insulation and some heat down there to begin with but is the battery compartment open or something for venting the LA’s?
That is correct. By law, the battery bay has to be open to the atmosphere for venting.
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Old 12-02-2021, 10:20 PM   #251
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Bedlam

So your basement stays below freezing 24/7 how do you keep your water tanks from becoming a block of ice. I am going to guess you have some heat down in the basement where the lifepo4 could be located.

Lt Dan

having the battery compartment vented only applies to lead.

Issac

As I said your temps where over the charging cut off temps by 10am the next morning when I would start charging the battery’s

None of these show that the lifepo4 could not be used in any of these situations. That’s why I am asking for someone to tell me a time that you camped and your temps, where your battery’s would be charging was below 32F for days ……
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Old 12-02-2021, 11:13 PM   #252
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Another point that has not made it into the conversation which seems to keep focusing on cost, are the secondary expenses, like amount of fuel burned in a generator to fully recharge each type of battery. This is another place where LiFePo4 tends to win with 1C charge rate up to about the 99% charge point. No need for that slow absorption cycle for the last 20% like on lead acid, and no penalty for not fully topping off (Sulfation in lead acid)
Dang, yet another advantage! Along the vein is the much smaller solar array that solar users need if they go with LiFePO4.
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