Forum Discussion
- pianotunaNomad III
3 tons wrote:
"
“Should not charge/discharge below 32F”.
Wrong, in most cases LiFePo4’s can be discharged to about -4f, (e.g. BB, et al) and can be charged below 32f, but at a much reduced amperage. Though my LFP is interior mounted (by a repurposed battery box), in many cases one should be able to do this passively via solar due to seasonally reduced winter harvest.
3 tons
3 tons the quote from the article qualifies itself:
"Keep battery temperature above 0 C (32 f) when discharging if possible"
I agree with the -4 f (-20 c)
I don't know why the seller's site is so negative about LiFePo4. It would seem to be bad for business. I do wonder if it is a "wiggle" on warranty?? - 3_tonsExplorer III“Should not charge/discharge below 32F”.
Wrong, in most cases LiFePo4’s can be discharged to about -4f, (e.g. BB, et al) and can be charged below 32f, but at a much reduced amperage. Though my LFP is interior mounted (by a repurposed battery box), in many cases one should be able to do this passively via solar due to seasonally reduced winter harvest.
3 tons - BendExplorerThanks for the discussion! And, considering:
https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/
and the above comments, here is what I got out of it...:
Should not charge/discharge LPF's below 32Fand should not consider charge/discharge above 113F.
So now BB has self-heating LPF’s that will over-count charging AH/WH on a shunted battery monitor. Do you think BB will also add a chiller to the BMS to keep the batts less than ~110F and do the same for a shunted battery monitor? 1 or both will add another parasitic drain.
And thus, its back to using a VM to guesstimate SOC.
I’m going to start calling LPF’s the “fair weather batts” because using them during many summer and winter situations without heating and cooling will make them limited if not just useless.
This makes the all(most)-weather capability with a weight penalty and lower cycle-life of FLA, AGM & SiO2 batts most attractive.
And, you might outlive a set. YMMV. - GjacExplorer III
MEXICOWANDERER wrote:
I guess everything we buy now has a lifetime warranty.
It has gotten to the point where I think twice about buying green bananas. - MEXICOWANDERERExplorerIt has gotten to the point where I think twice about buying green bananas.
- GjacExplorer III
pianotuna wrote:
Your right. My 2 6v Sams club batteries which I paid $74 apiece 13 years ago are still going strong. I will be 74 in 1 hr so one more set would last me until at least 87. If I needed to buy another set at that age, I would consider that to be a high class problem to have.Gjac wrote:
I realize everyone on here has different electrical req's with how they camp. I don't fulltime and don't camp in the winter and have minimal electrical req's. I dry camp don't watch TV or play on the internet, so basically some lights, refer, WH, and water pump. He kept talking about real world experience and did 20 amp discharge test down running MV's to 8 amp tests and then concluded that LI was cheaper over the life cycle of battery usage. What I would have rather seen was low amp draws "real world" how I use my batteries and how long each battery would last. At $900/ battery for lithium and $90 for 6v flooded that is 10 times the cost. Will the LI's last 10 times longer to recover the initial cost?
The only advantage for you would be never ever having to buy a battery again. Like me, you may be dead before you manage 2800 cycles.
If I camped every weekend, and took the SiO2 that meet my needs to stone bone dead (claim 620 cycles), then I'd reach 80% of oem capacity in only 4340 weeks, or about 83 years.
But, the float life is about 16 to 18 years--and I'll be 89.
My needs are cold weather performance, and enough storage to run an O2 concentrator over night. - StirCrazyModerator
Gjac wrote:
I realize everyone on here has different electrical req's with how they camp. I don't fulltime and don't camp in the winter and have minimal electrical req's. I dry camp don't watch TV or play on the internet, so basically some lights, refer, WH, and water pump. He kept talking about real world experience and did 20 amp discharge test down running MV's to 8 amp tests and then concluded that LI was cheaper over the life cycle of battery usage. What I would have rather seen was low amp draws "real world" how I use my batteries and how long each battery would last. At $900/ battery for lithium and $90 for 6v flooded that is 10 times the cost. Will the LI's last 10 times longer to recover the initial cost?
900? wow, I just saw them on canadian amazone for 650.00 so probably close to 500 Us. they are droping fast over the last year as more companys come out. at 600 they are only twice the price of a realy good 6V flooded GC battery up here.
Steve - StirCrazyModerator
pianotuna wrote:
Hi,
I got that from one of the sellers pages. Heat and Li don't party well together.
Here it is with the source:
"To sum up, for long and happy LFP battery life, in order of importance, you should be mindful of the following:
Keep the battery temperature under 45 C (113 f) (under 30C if possible (86 f)) – This is by far the most important!
Keep charge and discharge currents under 0.5C (0.2C preferred)
Keep battery temperature above 0 C (32 f) when discharging if possible – This, and everything below, is nowhere near as important as the first two
Do not cycle below 10% – 15% SOC unless you really need to
Do not float the battery at 100% SOC if possible
Do not charge to 100% SOC if you do not need it"
The above are from https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/
I would find a different place to read from. to me that sounds liek either they havent got a clue wht there talking about and just going off old info from different types of LI or that there just trying to pad there side against warenty issues. every LiFepo4 cell that I have looked up in the last few days stated 60 or 65C as the max operating temp, which is pretty much the same for SiO2. the charge rate isnt reay an issue as not many people in the rv industry are ever going to hit 1C and even so the manufactures all state 5 to 7C as the max charge rate (but the ceviate is the internal temp of the battery.) if it startes getting to hot you have to slow down the charge, but when people build them they put in 1C bms limitations to be safe. they are floated all the time at 100 percent in power backup roles, but if you are worried about it the BMs sets charg and discharge cutoffs so that should be taken care of by the person who puts the battery togeather so no issues. as for the 10 to 15% thing I wont even go there as it is complete bunk, the life is an average of 4000 cycles at 100% depth of cycles. so if you stay at that 10% as a bottom floor you will probabaly extend it to 6000 cycles, but how long is 4000 cycles. my Lead acid batteries are only 800 cycles and they have lasted me 14 years now as I don't do deep cycles so I extended there life but lets say you camp 15 weekends a year (optomistic for most of canada haha) and you cycle once each weekend thats still 266 years of camping so lets say you do 52 cycles a year , thats still 76 years worth of cycles. lets say its a bad batch of batteries and you only get 2000 cycles now we are down to 38 years...
In all likly hood I would only drop down to 14% at anypoing as that is where the voltage drops below 12.5ish. but most of the built batteries are made so there i actualy more capacity than what they are selling, I believe a 100ah battle bourn is actualy an 120 AH build and the BMS is set to limit top and bottom charging and discharges so you end up with a 100% usable advertised capacity with out worring about dammage. they also have temprature compensated charging through the BMS.
I am always sceptic when I see a company that assembles batteries (and most probably dont even do that, they get get the manufacture to slap there sticker on them and resell.) put stuff like this on there website. we have a few here that do that also. they know people wont spend the money on average so they make them sound great but finiky at the same time.
Steve - pianotunaNomad III
Gjac wrote:
I realize everyone on here has different electrical req's with how they camp. I don't fulltime and don't camp in the winter and have minimal electrical req's. I dry camp don't watch TV or play on the internet, so basically some lights, refer, WH, and water pump. He kept talking about real world experience and did 20 amp discharge test down running MV's to 8 amp tests and then concluded that LI was cheaper over the life cycle of battery usage. What I would have rather seen was low amp draws "real world" how I use my batteries and how long each battery would last. At $900/ battery for lithium and $90 for 6v flooded that is 10 times the cost. Will the LI's last 10 times longer to recover the initial cost?
The only advantage for you would be never ever having to buy a battery again. Like me, you may be dead before you manage 2800 cycles.
If I camped every weekend, and took the SiO2 that meet my needs to stone bone dead (claim 620 cycles), then I'd reach 80% of oem capacity in only 4340 weeks, or about 83 years.
But, the float life is about 16 to 18 years--and I'll be 89.
My needs are cold weather performance, and enough storage to run an O2 concentrator over night. - Itinerant1ExplorerIt would be 2 6v to equal a 12v or $180, it's 5x more. For your little use of power it probably is more economical for the upfront cost to stay using lead.
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